How to Build and Arm a Scale Model Battleship From Scratch




Introduction: How to Build and Arm a Scale Model Battleship From Scratch

Welcome to the fascinating world of R/C BIG GUN Warship Combat. So what exactly is R/C Warship combat? It is a hobby where scale model warships, armed with low-pressure CO2 cannons, fire small ball bearings at an opposing ship.  When enough holes are put in the easily punctured balsa wood covered hull to overload the internal bilge pump, the ship will sink.  All ships have a float and recovery line so there is no need to go swimming unless you want too. Yes, we shoot holes in our models on purpose. How else can you simulate real sea battles. It's Allied versus Axis; Battleships, and Cruisers and Destroyers maneuver for attack, or struggle to protect the cargo ships that are valiantly trying to get supplies through.  Oh, and we cannot forget the need to defend your port city from bombardment from sea. Any questions?  Good, you can ask any Midwest Battle Group member. But, we have to warn you, you're going to get hooked on this hobby.

The Ships:
The ships are 1/144 scale (range from 3 to 6+ feet in length), WWI - WWII era (1900-1946) warships, transport ships, and occasionally submarines. The wood or fiberglass hulls are covered with balsa wood skin. They have bilge pumps to simulate damage control, are electric powered, and are armed with low-pressure CO2 cannons, that can rotate and depress. The models are equipped with a float attached to a recovery line. This allows easy recovery of the ship when it sinks. The ships are quickly recovered, repaired, and put back in the game. The only damage is to the balsa wood on the hull, since the internal components are protected by shielding, and the electronic equipment is usually waterproofed. 

This instructable walks you through the process of building a model warship from just a set of overhead and side views.


First things first – decide what ship you want to build.  This decision alone may take many months of procrastination while sorting our all the facts that seem pertinent when in reality, it doesn’t make all that much difference.  I have participated in about 50 rc combat warship battles over the past 5 years and have followed the action of other clubs closely.  One thing that I have learned is generally, there is no such thing as a bad boat.  Assuming a boat is reliable and well balanced so it is seaworthy, and put in the hands of a skipper that has learned how to use the features of the particular ship to his advantage any ship can be an effective part of a team.
Ask yourself why you want to participate in this hobby.  Presumably the reason is to occupy free time and consume some disposable cash, for this hobby will certainly do that, but more likely the real reason is to have fun.  The best way to have fun is to have a ship that is reliable and seaworthy.  It’s very frustrating to have your ship role over and sink as soon as it begins to take on water, or to spend the day sitting at the side of the pond working on your ship instead of participating in the game.
Consider a used ship as your first ship.  This will allow you to begin playing the game sooner and there is no better way to decide what ship fits your style than to participate in the game for awhile in order to learn your strengths and weaknesses.  Ideally the owner will allow you to battle the ship before you purchase it.  If you like how it responds to your style of battling and it operates reliably through the day it is a good choice to get you in the game quickly.  When you get a ship test all systems to ensure that they work, and how they work, then use this ship to gain combat experience and as a construction aid and test bed for your new ideas.  That’s right.  To test out your new ideas.  About every modeler I have ever known has his or her own ways of accomplishing tasks and you will find yourself asking, “Why did the original builder do it this way?”  Most often there was a reason, but sometimes it was just a mistake, an attempt to implement a new idea that didn’t work very well.  There is no substitute for experience in building a ship and learning combat techniques. 
Avoid small ships and complex ships for your first building experience.  There are many operational systems in our warships and every system is equally important in its own right.  Think about it, which is more important, cannon, drive motors, pump, steering, or balance?  After a little reflection you will probably decide that all systems are equally important since your ship won’t be combat effective if any of these systems don’t work well.  It’s by far and away easier to learn the basics of maintenance and installation on a ship that has fewer operational systems.  It is easier to get the hardware installed in a larger ship.  Small ships test the talents of the most skilled builder.  For your first ship you will be well advised to build a larger ship rather than a smaller one.  Larger ships are more survivable in combat as well.
Keep it simple.  Another sound tidbit of advice would be – don’t try to reinvent the wheel.  Stick to the basic and proven methods of implementing a function.  Look at the ships of the seasoned skippers and pay attention to how they implement the various functions, then follow suit.


I have often been asked what I felt was the best way to construct a hull “from scratch.”  I’ve seen several methods used with some methods working better than others, yet still I’m not sure if there is one best method.  I believe if the hull doesn’t warp, isn’t overly heavy, and floats somewhat level when empty (no major list) it’s a good hull.  I suppose I should add in one other criterion as well, it shouldn’t leak.  This article will cover: Making a Pattern Set, Selecting Construction Material, and Assembly.
The premise for developing patterns sets for a scratch built hull is that the ship will be built on a flat bottom plate with ribs, bow and stern keels being glued in vertically all topped by a caprail.  BDE offers several such pattern sets ready for cutting and assembly, but this section will cover the basics of developing your own pattern sets should they not be commercially available.  Using the baseplate method of building is recommended otherwise you will have to set the ribs on a keel, which requires jigs and fixtures to achieve good results and the keel will be in the way later anyway.  Flat bottom boats are much easier to build, but don’t confuse a flat bottom with a shoebox shaped hull.  The sides will still be rounded, as will most of the hull below the waterline.  Real warships are generally flat on the bottom as can be verified by your ship plans.
First, obtain a set of plans for your ship.  The greater the detail shown on the plans the better, but don’t be surprised if the detail is lacking.  Often a set of plans consists of a top and side view of the hull and superstructure and a drawing of the ribs at a few stations along the hull, but this will suffice.


A photo of a typical rib station drawing is shown to the right. The plans usually don’t provide enough ribs for the required spacing (1, 2, or 3 inches) so you will need to draw additional ribs.  Look at the overhead view of the provided rib locations.  Next decide the spacing you will use.  Use of ¼” wide ribs on 2” spacing is the most common selection, but for large ships 3/8” wide ribs on 3” spacing is also used.  With your spacing selected you will need to draw lines on your overhead view where you need to add ribs.  You will often need to add one and sometimes up to three ribs in between those provided by the plane set.  What I recommend is making a copy of the original ribs and hand sketching the correct number of ribs in-between the provided rib profiles.  Just eyeball even spacing for the number of ribs you are adding.  Be sure to reduce the overall rib width by the thickness of the balsa sheeting on the hull, and the overall height by the thickness of the caprail and bottom plate.  Do this by drawing a line below (3/8” for plastic ¼” for wood) the top of the rib for your new rib top and a line 1/8” above the bottom of the boat.  Also draw reference lines for  the water line and a line one inch below the water line across the ribs. Note that often only half of the ribs are drawn, so you’ll have to draw the mirror image of each rib the best you can including the added ribs.  When I do so I use a light tracing paper that you can see through easily, draw half the rib, fold the paper in half then copy the other half of the rib off the first half.  Another method is to make a copy of the ribs then trace them on the back of the paper copy, thus making a mirror image.  When you have a complete set of full width ribs COPY all of your work and save the original drawings.  Make one copy for each of the ribs.
For each rib highlight the correct exterior hull line the top and bottom (remember to follow the lines that allow for the bottom plate and the caprail).  Also on the exterior line mark an 1/8” deep notch on each side of the rib at a point starting one inch below the waterline and extending to the bottom of the rib.  Hardwood stringers will be installed here later on to help form the impenetrable area of you hull.  On some of the wider ribs you will not need a rib that goes completely across the bottom of the hull.  If the flat spot in the rib is more than 4.5” wide then you will draw a left and right piece.  You may wish to read the section on water channels at this point so you can design your rib patterns to accommodate water channeling.  The water channel will be 2.75” wide so measure 1 and 5/8” inches left and right of the center point on the flat bottom of the rib profile to allow for the water channel stringer.  Make these marks ¼” high.  At the outer edge of the flat spot measure ½” up and draw a diagonal from that point to the top of the ¼” tall line that marked the top of the innermost edge of the rib’s bottom.   Next sketch in a line about ½” in from the exterior hull line to complete the inside edge of your rib. You will want to mark the location of the prop shafts on the appropriate rib patterns, usually the rib just forward of the propeller and the two ribs forward of where the shaft enters the hull.  For the rib just forward of the prop you will need to draw in braces to support a circle big enough to drill the hole through for the prop packing tube.
The next items to make patterns for are the bow and stern keel plates, the caprail, and the baseplate.  Start with the base plate.  Take your rib patterns and measure the “flat” width at the bottom of the ribs.  For all ribs with a flat spot at least 3/8” wide and that touch the bottom plate transfer those measurements over to a sheet of paper.  Remember to also measure the distance from the bow to each rib from your overhead view and transfer these to your base plate pattern.  You should end up with a center line with rib locations marked and each rib location will have a perpendicular line centered on the center line that represents the width of the flat bottom of the rib.  To complete the base plate pattern just connect the outer edge of the rib lines.  Next to make the bow and stern keels trace the side view of the bow and stern profile.  Measure in about ½” in from the profile and make another line.  You will want to make the keels long enough to overlap the base plate at least 3 inches.  Remember to make a 1/8” allowance for the base plate.  Also note that a few of the forward and stern ribs will not attach to the base plate but to either the bow or stern keel.  These rib drawings should be modified with a notch to slide onto the keel and remember to keep the depth of the ribs all the way to the bottom of the keel, since they do not rest on the bottom plate.  Some ribs that are on the base plate may need to have a notch added to their pattern to allow for the overlapping bow and stern keels.  To make a pattern for the caprail trace the outer edge of the ships deck from the overhead view (please note that some odd ships are wider at the waterline then at the deck or caprail level).  Draw a second line a ½” in to complete the pattern.  You may also wish to design in some cross braces into the caprail pattern.  These help the ship maintain its desired width and to reinforce the hull should it ever need to be pulled from the water with 100 pounds of water in it!!!.   Make copies of all these patterns as well.


You are now ready to select the material for your scratch built hull.  Some people prefer 5-layer plywood, while the MBG now has three plastic hulled ships.  The plastic is foamed PVC and can be obtained in various thickness’ from an industrial plastics supplier.  Foamed PVC enjoys the advantage of being lightweight and strong, easily cut and glued with CA glue, is inherently waterproof and will not warp or rot.  If you do chose to use plywood the following precautions must be followed.  Cut your caprail and base plate patterns into pieces between 12 to 18 inches to prevent the wood from warping.  Cuts should be made at a rib location.
Glue the copies of the tracings to plywood using Elmer’s glue, or some other water-soluble glue, then saw them out slightly oversize.  Use material of the appropriate thickness corresponding to the rib spacing of your pattern.  For the base plate use 1/8” and for the caprail use 3/8” for plastic and ¼” for wood.  Next sand the pieces to the correct size.  Finally remove the paper from the wood or plastic with warm soapy water, then dry the parts well.  Don’t be concerned if the wood parts warp somewhat.  If the wood is going to warp, now is the time to find out.  If warping of the longest sections of the cap rail or bottom plate occurs just cut them into shorter sections, preferably at rib location.  A little warp won’t hurt anything at this stage of construction.  We’ll fix it later.
If you chose wood as your material you will need to glue sections of the caprail and base plate together, end to end on a flat surface and while laying over a tracing of the plans.  This will ensure the sections have the proper curve to match the hull.  Likewise, with the bottom sections of the hull.  Epoxy glue works well for this purpose, but CA is too brittle and will not work well.  Don’t be concerned if they look weak lying there.  We’ll strengthen them plenty later on. When the glue dries, lay these sections over the plans and mark the positions where the ribs will attach.  Now attach the ribs to the base plate with 1 or 2 drops of CA glue.  Don’t glue them too well right now since you may need to remove the later if something doesn’t line up right.  Next, look at the hull from the end and visually verify that the ribs are symmetrical on both sides of the hull.  There’s a photo of this step later in this article.  Now attach the cap rail to the top of the ribs.  Some of the ribs may not line up with the cap rail well, but don’t force the caprail down, or up to the ribs.  Trim or file the ribs as needed to line up with the level caprail.  Note the word level!  There are photos accompanying this article that will help you visualize how the hull will go together.
Once the hull is glued (tacked) together in this state it will still be very frail so handle with care, but don’t panic yet.  Next will come the strengthening.  Place the hull on a flat surface and inspect carefully to see if the hull has developed a warp.  If so just break a few glue joints to relieve the pressure, then glue them again.  You may also need to make a few cuts through the caprail or base plate to relieve pressure to eliminate the warp.  You’ll find photos of this step ate the end of this article.  Make as many cuts as needed to get the warp out.  Once again, don’t worry, you’re not weakening your hull permanently.
Now the strengthening of the hull begins.  For wood hulls install hardwood (spruce) strips the thickness of the balsa sheeting allowed (1/16 to 1/8 inch).  These stringers will be 3/8” wide.  This width will allow the strip to overlap the ribs by 1/8”, since the wood caprail is only ¼” thick.  These strips are installed around the caprail on the inside and outside of the hull.  You can cut the stringers into shorter sections, but make sure the joints are staggered and the inside stringer joint does not occur on the same rib as the outside stringer.   Again installing them on the bow and the stern is the trickiest part to accomplish.  To allow the hardwood to bend around the curved areas cut notches about 2/3 though the wood stringer about every ¼” in the inside the side that will be next to the hull, then bend the stringer until it cracks at the notches.  I use the Dremel tool and cut off wheel to make the notches. 
Next, install 1/8” by 1/8” stringers (preferably spruce) in the notched portion of the ribs that starts 1” below the waterline and extends down to the base plate.  The stringers do not need to butt up closely together, as you will cover this portion of the hull with fiberglass.  Assuming your hull is still true and not warped go back and brush epoxy glue on all wood joints that were tacked with CA glue.  For plastic joints a bead of CA glue along both sides of the joint will permanently bond the plastic parts together.  Invert the hull and brush the epoxy inside the sandwich formed by the two hardwood stringers and the caprail.  Wait for the epoxy to cure and you’ll see that this step will have strengthened your hull dramatically.
Now the hull should look nearly complete save for the side skin.  Sand all outer surfaces of the hull so that they are smooth in preparation for fiberglassing the bottom.  Next, place the hull top down on a flat surface and add spacer beneath it to allow it to lay flat and be supported.  If the hull has taken on any warp you must get the warp out at this time.  Check the hull closely for warping.  Don’t be afraid to cut the hull in two and glue it back together if needed to correct a warp.  Now is the best time to fix them.
Fiberglass resin has quite an aroma (it stinks) so find an area to work with good ventilation.  Cover the work area with a sheet of plastic.  Now make a stand to hold the hull off the work so it can lay inverted (upside down) and be stable.  The stand must hold the entire hull (for wood only) off the work area to include the bow and cap rail since we’ll be glassing them also. 
Next, cut the lightweight fiberglass cloth in to small sections about 12” square, or whatever size or shape is needed to cover the hull.  Small sections of cloth are easier to work with and to keep air pockets out of.  At this point I would recommend purchasing an ultra violet cured resin sold by SolarEZ.  This stuff is just like epoxy resin with the added bonus of only hardening when exposed to about 30 minutes of strong sunlight.  If you keep the windows covered in your shop you will be able to work at your own pace rather than at the pace of the setting time of normal resin.  Apply a thin coat of resin to the hull bottom and sides down to the penetrable area, then lay on a section of fiberglass cloth and apply another thin coat of resin over the cloth.  Repeat this procedure to apply the next section of cloth, overlapping the previous section by ¼ to ½ inch.  Continue laying cloth until all the wood stringers on the bottom of the hull are covered with fiberglass cloth and resin.  Remember a thin coat of resin is all that is desired.  Applying more resin just makes a mess and increases the amount of sanding needed.  Sanding fiberglass is no fun.  The cloth will try to “slip” across the wood as you brush resin on, so reverse directions of your brush strokes regularly and use a gloved hand to push or pull the cloth.  As you are progressing smooth out the cloth, working out all air pockets and wrinkles.  Cut the cloth with an Exacto knife to let the air escape if necessary and overlap the cloth at the cut then smooth it down.  This will be especially necessary in the bow and stern where there are a lot of curves.  Continue this effort until the hull is covered, bow to stern, to include the solid bow and stern blocks. 
Allow the fiberglass resin to partially set, then using an Exacto knife cut away any excess fiberglass cloth that has extended into the penetrable areas of the ship.  After cutting, smooth the cloth down again along the cut edge using a gloved hand.  Wetting the resin with water first to provide some lubrication helps to keep the resin smooth.  As soon as the resin on the bottom of the hull is set enough (but not fully cured) invert the hull and apply cloth and glass to the top of the bow stern and cap rail, overlapping the sides of the caprail down to the penetrable area.  When you are through the entire outside of the hull will be covered with fiberglass cloth and resin except for the penetrable areas.  Once the resin begins to set up trim away any cloth that extended into the penetrable areas and smooth down the cloth.  Remember no wrinkles or air bubbles should be allowed in the cloth.  Now invert the hull and sit it back on the wooden block upside down. 
Apply another layer of glass cloth and resin down the center of the hull bottom from bow to stern.  This sheet does not need to extend up the side of the hull to the penetrable area, but just cover the flat part of the hull bottom to provide more reinforcing in the base plate to strengthen the butt joints that were glued together. 
At this point you may want to install optional frames to butt your balsa sheeting up against.  Some people like these since they create a “window frame” that you cut the balsa to fit into.  The advantage is that all the work in tapering the balsa sheet to the hull profile is done once with the frame the disadvantage is that when you install the balsa it has to be cut to fit this frame.  If you decide to add this frame you’ll need to get some wood stringers that are 14” wide and the thickness of your balsa sheeting.  Glue these 1.25” below the waterline (this gives a ¼” of hull for you balsa to glue on to) and ¼” fore and aft of the penetrable areas.  Use automotive putty to taper the edge of the framing to the ship’s hull.  Let dry and sand.  You may need to apply a few layers to get it smooth. 
Brush another thin coat of resin over the entire hull and caprail.  As this coat of resin sets make sure the job “looks right.”  Look for thin spots in the resin.  If it looks good and you are happy with it then let the hull dry completely.  Otherwise, apply another thin coat of resin.  If there are a few “rough” areas it won’t make all that much difference and they will be corrected later.  On a warm day this could take only a few hours for the resin to cure, other times it can take several days for all “tackiness” to vanish.  Again the two part resins are tricky things to mix and the solar cured resin is preferred although use of an old mirror might be required to get the sun to all parts of the hull for complete curing.
Once the fiberglass resin has set completely sand lightly with fine grit (150) sandpaper on a sanding block or orbital sander.  Sand lightly is a key word.  You do not want to sand through the resin and into the cloth anywhere! After the sanding is complete wipe off the hull with a damp cloth then skim on a coat of automotive putty over the entire hull surface that was fiber glassed.  A plastic putty knife works well to skim on the filler, allowing the filler to fill in only low spots and to smooth out rough areas.  I recommend the automotive filler putty because it is easy to work with, is waterproof, and is easy to sand.  Once it dries sand the hull again.  You may have to repeat this procedure to get a really smooth finish, especially in the areas where the glass cloth was overlapped.


4.5 Making Prop Stuffing Tubes
The fabrication of prop shaft tubes can be a very simple task.  Just visit your local model shop and find their assortment of brass tubing.  Or purchase a stuffing tube kit from BDE.  To do most jobs you need a 12” piece of 7/32” brass tubing for each prop stuffing tube, one 12” piece of 3/16” brass tubing, one 12” piece of 5/32” brass tubing, and one 12” piece of 1/4” brass tubing.  You’ll also need some thin brass sheeting for your shaft stand-off supports, but you should have plenty left over from making your rudder.  You may also consider buying a special fitting from BDE that will slip over your 7/32” tube and allow you to use a standard grease gun fitting to fill your prop shafts.  I’ve used this on several boats and it sure  beats filling a needle with grease and squirting it into the shaft.
You’ll also need something to cut the brass tubing with, a dremel tool with a fiberglass cut-off wheel is recommended.  To solder the tubing together you’ll need a 100 Watt soldering gun or a small torch, a pair of modeler’s helping hands or a vise and some clamps, some flux, and a roll of silver solder.
Use your plan set to identify the location of your props and study your hull to determine where you will place your motors.  Measure the length necessary for each of your prop tubes and subtract ¼” transfer these measurements to the 7/32” tubing and cut them to length.  Next cut two 1” long pieces of 3/16” and 5/32” tubing and one 1” long 1/4” tube for each stuffing tube.  Remove all burrs and use light sandpaper to clean all tubing till shiny.
Next to prepare your Hull standoff support cut one ½”x1” strip from your brass sheet for each stuffing tube.  Use either your vise or helping hands to hold the ½” wide end of the brass strip against the 1” long section of 1/4” tubing.  Apply flux and solder together.  Let cool then slip over your 3/16” tubing.  Make sure you keep this away from any soldering operations so that it does not become attached in the wrong place.  You’ll be gluing it in place when you install it in the hull.
If you have the grease gun fitting from BDE slide it over your 3/16” tubing now and hold your tube over your boat and identify where would be the best place to have access to your grease gun fitting.  Mark it and apply flux to the 3/16” tube and heat the BDE fitting and apply solder.  You’ll need to take a 1/8” drill and use it to drill through your 7/32” brass tube going through the hole in the BDE fitting that the grease gun fitting screws into.
Next apply flux to your 3/16” sections and slip them into the 7/32” tubing leaving about 1/8” sticking out.  Then apply flux to your 5/32” sections and slip them into the 3/16” sections leaving about 1/8” sticking out.  You now have a the tube stepped down from 7/32 to 5/32 and ready to solder.  Heat the 7/32” tubing just behind the two inserts and apply solder to both joints.  Heating the bigger tube behind the joint helps draw solder into the joint.
Clean them up and you are ready to install them into your boat.


2.2 Installing Prop Packing Tubes
 Before you get started locate the position of your rear cannons in your hull set them inside and determine approximately where you want to locate your motors and where you want the packing tubes to end.  This will eliminate the need for modification of your prop stuffing tubes later on when you begin installing the hardware into your boat.
Installing prop shafts and packing tubes is far less difficult than most builders make it.  An important thing to remember is not to be overly critical when cutting a hole(s) in you hull for the prop shafts.  The holes will probably be in the wrong place no matter how much time you spend thinking about anyway, so just cut them.  Oversize holes are easier to fill later.
If you have a wood frame hull you can install the prop shaft packing tubes before or after the hull is sheeted and fiberglassed.  Due to the nature of the Iowa prop and skeg arrangement I chose to install them first.  Just remember that it is very important to determine how and where your cannon will mount in the hull before installing the packing tubes, otherwise you will surely install them in the wrong place.
The upper photos show how the packing tubes were aligned parallel to one another and level, glued to a wood dowel that was carefully measured and marked.  If you are using a fiberglass hull and brass stand-off supports for the ends of your packing tubes then use the dremel to cut a slot for your brass stand-off support near the end of the packing tube.  Slide the brass support into the slot as you  tilt your packing tube in place and glue to the wood dowel.  Ribs were ground away as needed to allow the tubes to lie level with one another and fit in place at a slight downward angle.  The tubes were secured in place with epoxy putty, which also reinforced the ribs that were ground down substantially.
If you are using the brass stand-off support for the end of your prop shaft and have not yet sheeted the bottom of your wood hull then glue cross support between ribs so that you have something to glue the supports to.
Wood sheeting was installed around the tubes and stand-offs (editors note: the above article on wood hull construction suggests the use of hardwood strips instead of balsa wood sheeting), but a small space was left open around the rib.  This hole was filled with epoxy putty, which is a great water seal and also gives a nice appearance to the hull and looks like the packing boxes on real ships.
The third photo shows how the over size holes cut into a fiberglass hull were filled with epoxy putty.  It also shows the extreme angle on the coupling for the motors that was required to allow the cannon to fit between the motors.  As it turns out, the center motor was still in the way of the stern cannon and had to be removed and installed “backwards” above the packing tube using an o-ring drive or gear drive.  The motors are installed by attaching small sections of brass tube to the hull with epoxy, then slipping plastic wire ties through the brass and around the motors.  This is a system that has proven to work very well.
The bottom photo shows the running gear of the Scharnhorst, which is one of the most difficult ship hulls to outfit.  Three props and two rudders fit into a very small space, but it can be done.

STEP 7 Constructing the Water Channel
Have you ever wondered why some ships settle fairly evenly in the water when they flood internally while others take on a severe list?  The reason is most likely inadequate water channeling.  Water, being a liquid will seek out the lowest point of the ship and move in that direction.  It also follows the laws of physics and reacts whenever the ship moves.  If the ship turns right the water will move to the left, and visa-versa.  Also, when the ship moves forward the water will run towards the back.  This is why nearly all ships sink by their stern, rather than bow first.  In fact, of the several dozen of ships I have seen sink I have never seen one sink bow first.  Although sinking bow first would be a good feature since this has the potential to save the rudders and props from damage when the ship hits the bottom, or is recovered.  I say “potential” damage because after 6 years of battling the MBG has yet to see any props or rudders damaged by sinking, but it could happen.
I’ve developed effective water channels with the past 9 ships I’ve constructed and the method I have come to like the best is the foam filled water channel.  I like this method since I’ve found it the easiest to accomplish.  To make the water channel I first installed two wood stringers down the center of the hull and separated by about 2.75 inches.  The stringers should be ¼” x ¼” hardwood.  These stringers also serve to add some strength since the bottom plate of this ship (wood construction) was made up of seven sections to prevent warping.  Next grind down the portion of rib that is glued to the baseplate so that it will form a sloped line going from the ½” tall height of the rib to the center ¼” tall strip (editor’s note: its easier to layout the rib patterns with this slope in mind and save the grinding).  In addition to the channel down the middle you may want to leave an open section sized for your batteries so you can keep this large piece of weight low in your hull.  Make this battery space an 1” longer than the battery you intend to use and typically centered amidships with the batteries placed out towards the side of the ship to allow for a CO2 tank between them.
If you are putting a channel in a fiberglass hull your job is a bit easier.  After attaching the sides of your channel to the bottom of the hull you will need to add a stringer that goes from the edge of the waterchannel out to the side of the hull about every 4” along the length of the hull.  You will need to cut a slope on them such that they are ¼” tall on the waterchannel edge and ½” tall on the end near the side of the hull.  I recommend you work with 3/4” by ¼” hardwood strips.  Measure off the length of stringer that will fit in the section of hull you are currently working on and measure in ¼” on opposite ends of the rectangle and draw a diagonal line between the two.  The result should be a matched pair of wedges that are the same length and ¼” tall on one end and ½” tall on the other.  Make your diagonal cut first down the center then make the cross cut.  Glue these two pieces to the hull and you’ve created your own “rib” stringers and you are ready for the next step.
I then installed a piece of balsa over the ribs between the water channel stringer and the side ribs of the ship as shown in the accompanying photos.  Since the part of the ribs that were glued to the hull keel plate were sloped towards the center this allows any water coming in through holes on the sides to run into the water cannel and towards the pump.  Then I drilled a hole in the balsa sheet between each rib and using a can of “Great Stuff” minimal expanding spray foam I filled each rib section with the foam.  My first attempt at this several years ago the foam simply forced off the balsa, cracking it to pieces.  The accompanying photo shows how even minimum expanding foam still expands greatly (there are some new very minimal expansion foams on the market get some and experiment).  The spaces between the ribs were only 2/3 filled! 
Using a small blade on my pocketknife I cut away the excess foam, which was quite easily accomplished, then sheeted over it with more 1/16” balsa sheet.  Be sure to use epoxy glue for this since CA glue will melt foam, as will fiberglass resin.  When the whole hull was sheeted on the inside so I couldn’t see foam anywhere I put a thin coat of “SolarEZ” UV cured polymer resin over the inside of the ship.  This product won’t hurt the foam and cures more predictably than conventional fiberglass.  The trick is sunlight must be able to reach it in order to cure the resin. 
Now that the water channel is installed you should have a ship that will settle level as it takes on water.

Ship Construction Sequence
A detailed description of each item will follow the list below.

STEP 8. Install cannon .  Mount all cannon first when outfitting the hull.  Cannon must be installed in their proper location and motors and other hardware must go where the cannon are not located.  About any hardware installed in the hull before the cannon are mounted will surely be in the way and have to be reworked. 
STEP 9. Install rudder and rudder shaft.
STEP 10. Install props and prop shafts. 
STEP 11. Install drive motors. 
STEP 12. Install batteries.  Install batteries lying flat usually amid ships, below the waterline.  Install them such that they can not shift, changing the balance of the ship.  Use of wood blocks glued to the hull with hooks and rubber bands to secure components is recommended.
STEP 13. Install the CO2 tank.
STEP 14. Install the pump.  Pump should be in the water channel as far aft as possible.
STEP 15. Install the electrical wiring.  Keep power switches easily accessible without having to remove the deck to get to them.
STEP 16. Install the hull skin.
STEP 17. Apply silkspan and paint.
STEP 18. If you have room for a watertight box or tube install it now.
STEP 19. Mount all radio control gear.   All electronic devices should be high in the hull and upside down if possible.  Never install servos on the bottom of the hull where they will get wet too easily.
STEP 20. Conduct initial sea trials.  This will give you a sense of accomplishment and allow you to check speed, displacement and balance.  If you are way off in any area you will want to make corrections now before proceeding to the following steps.
STEP 21. Install CO2 plumbing and test.   The safety switch should be located near the electrical switch in an easily accessible spot.  This is a must when recovering a sunken ship that may be shooting uncontrolled when pulled to the surface.
STEP 22. Build deck and superstructure.  Build them light, very light!  This is an area where most new builders fail, resulting in ships that are top-heavy and unstable.
STEP 23. Install Recovery Line.
STEP 24. Back to the pond for the final check out.  Bring lead ballast with you to adjust the trim of your ship.  It needs to float on the scale waterline according to the ship’s plans.  Keep the ballast low in the hull and secure it so it will not move.  Now practice your gunnery skills before a battle.  Have floating targets to shoot at and practice rapidly changing your aim from one side of the ship to the other about 6 feet from your floating targets.  If you can swing your guns over and drop your elevation and hit the target within the time it takes for your ship to travel 6 feet at full speed you’ll hold your own in your first combat furball.


8.1 Installing Cannon for Ease of Maintenance
Phil S. has long been a proponent of mounting your cannon on modular platforms that can be quickly installed by hooking, snapping, or bolting to the bottom of the ship.  Tim M. took the modular platform on step further by attaching posts that are cut level to the deck and secured to the deck structure.  Since Phil’s method is easily modified to Tim’s we’ll start with that one then finish with Tim’s idea.  Personally I like Tim’s method since the screws that hold the platform assembly in place are much easier to access.
First create a paper pattern for your gun base plate.  If you are mounting a pair of cannon on the same plate it works best if the baseplate is long enough so that it sticks at least ½” forward and aft of your two cannons.  If you are rotating your cannon you will need to extend the length of your base plate to accommodate your rotation device.  If you followed the instructions for the water channel you should cut a 2.5” wide piece of paper and tape it centered in the water channel.  Make it more than long enough so you have paper to work with.  Next measure the plans to determine the location of the center of the turret(s).  Transfer this measurement(s) to the piece of paper in the bottom of the water channel.  Also mark the waterchannel itself at these locations so you know where to put the platform later on.  Sit the two cannons and your rotation servo in and measure to make sure they are in the correct positions and centered.  Use a pencil to mark the forward and aft edge of your platform.  You want to make the pattern long enough so that you can see and edge on both ends.  This will give you a spot for attaching the platform to the bottom of the deck, which will be discussed later on.  Remove the cannon.  Remove the paper and draw in your for and aft ends of the plate.  Now draw a ½” wide by 1” deep rectangle centered on the fore and aft ends of your base plate pattern. Draw an X in this rectangle as it will be cut out to make a fork shape on each end that will allow you to center your base plate.   Cut the baseplate for your cannon from a ¼” thick piece of 5 layer plywood.  Use your marks to locate the center position for each turret and drill a 9/32 whole through for attaching the cannon.
Set your baseplate back into the waterchannel and line it up with the marks on the water channel and make sure it is centered.  Trace the sides of your forks on the bottom of the hull as well as the fore and aft edges of the baseplate and remove the baseplate.  Cut two ¼” slices from a ½” by ½” piece of hardwood to form two guide blocks.  Also cut four ½” long pieces of wood from ¼”x ¼” hardwood to form four stops.  Next glue the guide blocks on the marks made in the bottom of the water channel with some epoxy so that they line up the outside edges of the baseplate and sit between the marks for the sides of the “fork”.   Also glue the stops on the bottom of the hull at the end of each “tang” of the two “forks” of the baseplate.  While you are waiting for the epoxy to set apply a good coat of either paint or epoxy to your baseplate.  After the guide blocks have set mix up some more epoxy and coat the guide blocks and stop blocks completely.  Note the guide blocks will center your gun baseplate, while the stops will keep it from moving for and aft.
When everything is dry attach the cannons to the baseplate with the screw provided.  Use some silicon adhesive to ensure the cannons will not rotate.  Test fit in the hull before the silicon sets up. 
Now you need to install a platform for your rotation servo.  First measure the depth of the hull in the location where you plan to put the servo (usually directly aft of the B cannon or foreward of the C cannon).  If you have about 4” and at least one layer of superstructure above the servo position then you will be able to mount the servo upside down.  Cut four pieces of 1/4” x 1/4” hardwood 1 and 7/8” inches long these will be your legs.  Cut two pieces 3 inches long for rails and cut two pieces 2.5” long for servo supports.  Epoxy two legs to each rail at either end, resulting in a C shape 3” high and 2.125” wide.  Now epoxy the legs of each rail set to the outer edge of the cannon’s base plate so that the rails run parallel to the cannons accumulator and are close to the edge of the cannon’s magazine.  Now drill 1/8” pilot holes in your servo supports so that the servo’s mounting holes are centered on the support.  Sit the servo supports on the top side (drum side) of the servo’s mounting holes.  You’ll probably need to use a dremel tool to grind down an annoying little tab there so the support sits level.  Bolt the servo to the support with #6 x ¾” machine screws and nuts.  Turn this assembly upside down and straddle the rails.  You’ll want to string up your drive belts or wires at this point (see other article).  With your drive system in place pull the servo along the rails till the drive belt/wires are taut.  Then drill 1/8” pilot holes through the supports and into the rails.  Fix in place with #6 x ¾” wood screws. 
Now you need to decide how you wish to lock down the cannon platform.  You can either put your lock down tabs on the bottom of the hull or extend pillars up from the cannon platform so the deck can be attached to it and then used to lock the guns in place.  Like I said I prefer the deck method even though it is a little more work because as you plumb and wire your boat getting your hands down to the bottom to lock the platform in place can become tricky.
If you wish to use the simple method of the bottom lock down here is what to do.  First drill an 1/8” hole through the center of your guide block right through the bottom of your hull.  Yes through the bottom of the hull.  Use the cone shaped sanding attachment for your Dremel tool to flare the hole on the outside of the hull so that you can flush mount a screw.  Take a 1.25” long #8 flush mount machine screw and screw it from the outside in and cover over with some epoxy for a watertight seal.  Next cut two pieces of ½” by ½” hardwood 1inch long.  Drill a 9/32” hole through the center.  Paint both pieces and let dry.  Next slide these over the machine screw and secure with a nylon lock nut.  Make it tight but not two tight to turn.  Rotate this latch so it parallel with the sides of the waterchannel.  If you attached the guide blocks in the correct place and cut the “forks” deep enough your baseplate should be able to go around the latches.  Try rotating the latches if they clamp the baseplate too tightly remove the latch and install a thin washer between the guide block and the latch bar.
If you wish to attach the deck to your baseplate follow these steps.  First carefully measure the height from four exposed parts of the cannon platform (two at each end) to the bottom of the deck and cut two pieces of ½” x ½” hardwood to this length and epoxy them to the platform.  You should now have four pillars that extend from the gun platform up to the bottom of the ship’s deck.  You’ll want to cover the tops of your pillars in epoxy and some thin fiberglass to prevent splitting the wood when you screw the deck to it (remember to drill pilot holes).  Also paint all wood pieces to prevent water damage.  Depending on how sturdy your pillars are you may need to add some cross braces diagonally from the top of each pillar to the platform about half way between pillars.  Going across the cannon you’ll have to work around the cannon.  Remember, once it’s in the boat your guide blocks and stops position the cannon the pillars just keep the cannon from popping up.  Making the pillars sturdy is mostly so you can remove the cannon for maintenance.

STEP 9. Install rudder and rudder shaft.

2.5.2 Making and Installing Rudder(s) and Rudder Stuffing Tubes
Building the rudder assembly is relatively simple.  First locate where the rudder shaft should be located and transfer the measurement from your drawing to your ship’s hull.  Next cut a block of balsa about 1” square and tall enough to go from the bottom of the hull to about 1” above the water line (or as high as possible).  Take this block and sand the bottom contours so that it sits perpendicular in the hull.  Then use a vice and drill press to drill a 5/32” hole down the center of the block.  Then glue the block in the hull insuring the hole is correct location and the post is perpendicular to the hull.  Now you can use a hand drill with the 5/32 bit to completely drill through the bottom of the hull.  If the block is too deep for your bit a piece of 5/32 brass tubing with a roughened end can be chucked up in the drill and it will eventually cut its way through.  This method is suggested since it is easier than trying to sit a battleship squarely under a drill press, however if your shop will support doing that it would be a quicker and perhaps more accurate alternative.
Next cut a section of 5/32 tubing that is a little longer than your rudder post block.  Put a little CA glue on it and tap it through the wood support post.  You will want to leave about a 1/16” of an inch above the post inside the hull and below the bottom outside the hull.  Use a dremel to cut the tubing down if necessary.
Next cut an 1/8” solid brass rod the appropriate length for the rudder shaft.  The shaft should extend ½” above the rudder support block (or higher depending on where your rudder servo is located) and the entire depth of the rudder below the hull.  Test fit the shaft and check your measurements.
The next step is to cut out a rudder from thin brass sheeting.   It should be thick enough so it does not bend easily, but not so thick you can’t cut it with metal sheers.  My favorite method is to use very thin brass and layout a pattern such that you will fold mirror image rudders around the shaft.  The thin brass is easy to cut and the finished rudder has a more hydrodynamic shape.
Next file the rudder shaft flat where you will be attaching the rudder.  You will only need to flatten on one side if you are using a one sided rudder, but on both sides if you plan to use the wrap around rudder.  Put flux on the flat side(s) of the shaft and then use vise grips to clamp the rudder in place.  Use a small torch or a 100 Watt soldering gun to heat the rudder and shaft and apply silver solder.
When installing the rudder you will need some sort of bushing between the hull and the rudder.  If your ship’s rudder is flush against the hull just use a small thin washer and slip it over the shaft then slide the rudder into place.  If the rudder needs to stand off some distance then use a wheel collar to lock down the correct stand off distance.
The final step is to install the control arm.  If your arm will be above your post you will also need a wheel collar to ride against the rudder stuffing tube.  In most ships a simple lever that locks onto the shaft with a setscrew is sufficient, but for those really narrow sterns a toothed pulley and toothed belt can be used.  The toothed pulley method works very well for the twin rudders in the narrow stern of a Scharnhorst.  The belt goes around both rudder pulleys then around a matching pulley on your servo and you’ve got a quick and simple dual rudder drive.  The caution is that belt driven rudders can slip easily if the rudder is bumped during ship launch or run aground when going in reverse, so use conventional control arms and wire rods where possible.

STEP 10. Install props and prop shafts.

You’ve already built and installed your prop stuffing tubes during your hull construction so all that is left to do is to install the shaft(s) and prop(s).   First slide a piece of 1/8” brass rod into the prop stuffing tube.  You will want to have 3/8” (you may need more depending of the type of drive system hardware you are using) of an inch protruding from the stuffing tube inside the hull and ½” protruding outside of the hull.  Mark the shaft(s) and cut to length.  Next locate where the setscrew for the prop will be on the shaft and mark.  Use a file to flatten this spot.  A trick I’ve learned is to hold the file at an angle so the flat spot is deeper on the ship’s side of the shaft.  This makes it much harder for the prop to slide off the shaft since the setscrew would have to be forced up a ramp.  Attach the prop with the setscrew sitting in your angled notch and slide into the stuffing box.  Now double check the length inside the hull remember how much shaft you need will be a function of the type of drive system hardware you are using.  Adjust the length if necessary.  Mark the spot where the drive hardware’s set screw will be located on the shaft.  Remove the shaft and cut an angled flat spot this time with the deeper end towards the prop side of the shaft.  Next put the shaft back in and attach the drive hardware.  Finally fill the stuffing box with grease.  Pump the grease in till you see it squirt out both ends of the shaft.  Just a few minutes of ungreased operation will destroy a shaft (been there done that).

STEP 11. Install drive motors.
Once you’ve selected the type of drive system (see later chapter) how do you secure your motor(s) to your hull.  The most simple method is to buy a plastic motor mount from BDE or you can build your own with some thin walled PVC tubing that just fits over your selected motor(s)’ diameter.  Then cut off a length to match the motor’s length.  Then cut off about the top third of the tube and epoxy two lengths of ¼”x ¼” hardwood perpendicular to the bottom of the tube to make legs.  The legs serve two purposes first the raise the motor up a little off the bottom and second provide a space to slide two zip ties under the pull the tube tightly around your motor.  With the motor strapped in and the legs firmly attached, mix up another batch of epoxy and coat all sides of the legs and set into the desired location in the boat.  Hook up the motors to the shaft and hold in place while you test the drive.  If it runs quite and the props are turning then everything is lined up correctly and you can let the epoxy set up on the stand.  Now when you need to swap out motors just cut the zip ties put in a new one and cinch it back up.

STEP 12. Install batteries. 

You will need to select what batteries to use see the appropriate section in the Chapter on the Electrical System.  You should already have a space laid out in your water channel in which to sit your batteries.  You want to keep the weight as low in the hull as possible and to lay large lead acid batteries on their side.  The quickest and easiest method is to put some self adhesive Velcro loop strips on the bottom of the battery and the matching Velcro hook strips where you want to attach the batteries.  If you left sufficient space to move the batteries fore and aft and a little side to side the Velcro allows for quick changes in battery location and hence the trim of the ship.  If the Velcro ever starts to peel off, just use a little CA glue to tack it back onto the battery/ship.

STEP 13. Install the CO2 tank.
STEP 14. Install the pump.  Pump should be in the water channel as far aft as possible.
STEP 15. Install the electrical wiring.  Keep power switches easily accessible without having to remove the deck to get to them.
STEP 16. Install the hull skin.
STEP 17. Apply silkspan and paint.
STEP 18. If you have room for a watertight box or tube install it now.
STEP 19. Mount all radio control gear.   All electronic devices should be high in the hull and upside down if possible.  Never install servos on the bottom of the hull where they will get wet too easily.
STEP 20. Conduct initial sea trials.  This will give you a sense of accomplishment and allow you to check speed, displacement and balance.  If you are way off in any area you will want to make corrections now before proceeding to the following steps.
STEP 21. Install CO2 plumbing and test.   The safety switch should be located near the electrical switch in an easily accessible spot.  This is a must when recovering a sunken ship that may be shooting uncontrolled when pulled to the surface.
STEP 22. Build deck and superstructure.  Build them light, very light!  This is an area where most new builders fail, resulting in ships that are top-heavy and unstable.
STEP 23. Install Recovery Line.
STEP 24. Back to the pond for the final check out.  Bring lead ballast with you to adjust the trim of your ship.  It needs to float on the scale waterline according to the ship’s plans.  Keep the ballast low in the hull and secure it so it will not move.  Now practice your gunnery skills before a battle.  Have floating targets to shoot at and practice rapidly changing your aim from one side of the ship to the other about 6 feet from your floating targets.  If you can swing your guns over and drop your elevation and hit the target within the time it takes for your ship to travel 6 feet at full speed you’ll hold your own in your first combat furball.

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    7 years ago on Introduction

    if you get a chance i'd love to see some more detailed photos of construction. it looks like it could be a really fun project!