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Picture of Build a Greenland Kayak Part 3
Now that the gunwales are done, the next step is to build the deck.
To build the deck we join the ends of the gunwales and spread them apart in the middle to establish the shape. Then we put deckbeams in between the gunwales so they hold the shape that we created. What we end up with will look sort of like a ladder that comes to a point at each end.
 
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Step 1: Determine the beam of your kayak

Picture of Determine the beam of your kayak
Beam is boat builder speak for the width of the boat.

Standard Greenland procedure was to make a kayak 6 inches wider than your hips. My hips are 15 inches wide so my kayak would be 21 inches wide. 21 inches is a good width.

If your hips are narrower, your kayak could be narrower, but unless you are an experienced kayaker, I would not recommend a kayak narrower than 21 inches. Even a 21 inch kayak may feel very unstable to an inexperienced kayaker. If you have never kayaked before, make your kayak 23 inches wide and you will feel a lot more stable.

Of course if your hips are wider than 15 inches make your kayak 6 inches wider than your hips. If you make your boat too narrow, your butt will get pinched. Keep in mind that the sides of the kayak taper in toward the bottom, so that the floor of the boat is narrower than the beam.

Step 2: Materials

In addition to the gunwales which you already have, you will be adding 9 straight deck beams and 2 curved deck beams.
Deck beam material for the straight deck beams is clear (knot free) wood 3/4 x 1-1/2 inches in cross section. You will need a total length of about 16 feet. The boards that you cut the deck beams out of don't have to be knot free as long as the boards have enough distance between knots for you to cut the relatively short deck beams out of.
Deck beam material for the curved deck beams is clear wood 1-1/2 x 3-1/2 inches in cross section. 4 feet of total length should suffice.
You will need about 60 four-penny finishing nails for temporary nailing of the deck.
You will need about 100 inches total length of quarter inch dowel rod for pegging the deck beams to the gunwales.
You will need about 48 inches total of 5/16 inch dowel rod for doweling the gunwale ends together.
You will need a roll of nylon mason's twine for lashing the deck beams to the gunwales.
You will need 40 feet of 1/4 inch rope to make windlasses out of and to temporarily hold the ends of the deck together.

Step 3: Tools

You need your drill, for drilling doweling holes
Hammer for pounding nails and dowels and pulling nails
Hand saw for cutting deck beams
Jig saw for cutting the curved deck beams
A knife or rat tail file for making kerfs in the gunwales to recess lashing twine into
A short piece of wire for threading lashing twine through lashing holes

Step 4: Cut the center spreader

Spreaders are temporary pieces of wood 1-1/2 inches wide and 3/4 inches thick. You will need three of them, a center spreader, a bow spreader and a stern spreader.

The center spreader will be the maximum width of your kayak minus 1-1/2 inches.

The other two spreaders will be half that length. Don't cut the end spreaders until you have installed the center spreader because you won't know what the angle of the gunwales will be until you have put in the center spreader.

The ends of the center spreader should be square when viewed from above and cut at a 25 degree angle when viewed from the side. This angle will match the angle at which the gunwales will be inclined with respect to the vertical.

Step 5: Spread the gunwales to establish the shape of the deck

Picture of Spread the gunwales to establish the shape of the deck
Do a wrap of rope in the front and one in the back of the gunwales. The rope should be about 36 inches long and tied into a loop. Turn the loop into 3 coils and slide it over the gunwale ends.

Step 6: Spread the gunwales with the center spreader

Picture of Spread the gunwales with the center spreader
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Push the center spreader between the gunwales at the longitudinal center point of the gunwales. You won't have to measure since you already marked the center on the gunwales in a previous step. The top of the spreader should sit about half an inch under to top edge of the gunwales. Use two 4 penny nails at each end to nail the spreader into place. Leave 1/4 inch of nail sticking out since you will be pulling them later.

Put a windlass around the gunwales just to one side of the center spreader. This will help hold the spreader in place.

Step 7: Set up your saw horses

Picture of Set up your saw horses
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Set up your saw horses about 8 to 10 feet apart so the tops of both are in the same plane. You will be building your deck on top of the saw horses. If they are out of plane, your deck might end up warped.

This should really be step 2 but right now the reorder steps feature doesn't work.

Step 8: Cut the two end spreaders

End spreaders will be one half the length of the center spreader. The angle of their sides as viewed from above should match the angle that the gunwales make 5 feet ahead of the center. Their sides as viewed from the side should slope in at a 25 degree angle.

Step 9: Install the bow and stern spreaders

Picture of Install the bow and stern spreaders
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Jam the bow spreader between the gunwales about 60 inches forward of center. Sart closer to the center and then push the spreader forward. 60 inches is an approximate number. The wider your boat is in the middle, the closer to center this spreader will end up.

You might have to adjust the position of the ropes at the bow and stern as well as their length to make the spreader fit.

Jam the stern spreader between the gunwales about 65 inches back of center. Start closer to the center and then push the spreader backward.

65 inches is an approximate number for the back spreader. Whatever the exact distance is, the back spreader should be about 5 inches farther back than the bow spreader. The idea is to make the back deck taper down more gradually than the front deck. The back deck should be fuller than the front deck.

Move the rope wraps at the ends in or out so the ends mate up more or less flush. You might have to adjust the size of the loop to get this to happen.

WARNING!

If the gunwale boards are of differernt stiffness, the stiffer board will want to stay straighter and its tip will want to slide forward of the other board's tip. Keep them lined up. Do not under any circumstances trim one of the boards to make the ends match up or you will end up with an asymmetrical deck.

Step 10: Run a saw between the gunwale ends

Picture of Run a saw between the gunwale ends
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At this point, you want to make sure that the ends of both gunwales line up at the bow and the stern and that both gunwales have the same amount of flare (incline inward from the vertical.)
When you have gotten the inside faces of the gunwales at the bow and stern as close to mating up as possible, run a saw between them two or three times. This will remove any high spots and improve seating. For very narrow or very wide boats, the ends may not mate up as well as for the median 21 inch wide boat. But don't worry, we will next dowel the ends together and that will hold them in place.

Step 11: Dowel the bow and stern

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You are now almost ready to dowel the bow and stern together. But before you do, check the deck one more time. Make sure that the gunwale ends line up both at bow and stern so you don't end up locking them into an asymmetrical shape.

Peg the gunwale ends together using 5/16 inch dowels driven into 19/64 inch holes. Use 6 dowels for the bow and 5 for the stern. Do not put any dowels through the risers. As before, when you dowel, drill and drive one dowel at a time. Resist the temptation to drill all the holes at once.

Drill the first hole closest to the end straight through and make sure you don't get the ends out of alignment when you are drilling.

Drill all other doweling holes through the gunwales at an angle from the horizontal as shown in the photo below.

Step 12: Trim dowels

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Trim off any protruding parts of the dowels.

Step 13: Deck beam layout

Picture of Deck beam layout
There are 11 deck beams, six deck beams forward of the cockpit and 5 aft. Deck beam 1 is closest to the bow.

Deck beams 5 and 6 are curved. All others are straight.

You have already marked all the deck beam locations on the tops of the gunwales. All that remains is to cut the deck beams and install them at their proper locations.

Step 14: Prepare Deck Beam Stock

Picture of Prepare Deck Beam Stock
For the straight deck beams, that is, all but deck beams 5 and 6, you will be using stock that is 3/4 inches thick and 1-1/2 inches wide.

Deck beams are important structural elements and should not have any knots in them.

Step 15: Install the straight deck beams

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Install straight deck beams in the following order: 7, 8, 4, 9, 3, 10, 2, 11, 1.

Mark deck beams by laying them across the gunwales at the locations you have marked on the tops of the gunwales earlier and running a pencil along the top of the gunwale.

Trim the ends of the deck beams at a compound angle. The angle in the horizontal plane will be the angle the gunwales make with the longitudinal center line. The other angle will be 25 degrees to match later gunwale flare.

Step 16: Nail deck beams in place

Picture of Nail deck beams in place
After you cut a deck beam, nail it in place with two 4-penny nails at each end. Keep 1/4 inch of nail sticking out because you will be pulling the nails later and replacing them with dowels.

Keep in mind that the top of the deck beam should sit about 3/4 inches below the top edge o the gunwales. You can move the deck beam slightly forward or backward if it sits too high or too low. The only exception are deckbeams 4 and 7, the foot brace and back brace which must be located exactly where you marked them.

At this point you will see a gap between the bottom edge of the deck beam and the side of the gunwale. Later we will close up the gap before driving dowels.

Step 17: Carve the masik-knee brace

Picture of Carve the masik-knee brace
The arched deck beam just forward of the cockpit is called the masik. It supports the front of the cockpit coaming and it also functions as your knee brace. If you like to have good control of your kayak, you want the masik arch as low as possible while still allowing you to get into your kayak. A low masik keeps your thighs tightly clamped in place. However, if you're a more casual paddler and like more wiggle room, a taller masik might be for you.

Whatever your preference, distance from the floor of your kayak to the tops of the gunwales will be about 5-1/2 inches. To figure out how much more clearance you need, sit on the floor again with your legs outstretched and put a board across your thighs just behind your kneecaps. This is where the masik is going to be. Measure the distance between the floor and the bottom of the board. This is the elevation of your thighs. For me, this measurement is 7 inches. I would like another inch of clearance for my thighs, possibly a little more. So I need the masik elevation to be 8 to 8-1/2 inches above the floor or 2-1/2 to 3 inches above the tops of the gunwales.

So I need to carve a curved deck beam which is 2-1/2 inches elevated in the middle.

After carving it, I need to cut the ends to the proper angle and nail it into place.

Step 18: Cut deck beam 5

Picture of Cut deck beam 5
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Deck beam 5 is our other curved deck beam. To figure out how much elevation it needs, we lay a short piece of straight wood across deck beams 4 and 6 and measure how high the stick is above the tops of the gunwales at deck beam position 5.

If you have big feet and want extra toe room, lay the stick across deck beams 3 and 6. This will give you even more elevation. You will later add deck stringers to stretch from deck beams 4 to 6 or from 3 to 6 and this is what this stick simulates.

Step 19: Windlass the gunwales

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Once you have nailed all the deck beams in place, you are ready to give the gunwales their final shape. You will do this by applying windlasses and tightening each one in turn to increase the angle of the gunwales to match up with the ends of the deck beams.

Install the windlasses as shown using ¼ inch rope and a short stick. Take turns tightening each windlass a little bit to bring the bottom edges of the gunwales in.

Step 20: Dowel the deck beams to the gunwales

Picture of Dowel the deck beams to the gunwales
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Now that the gunwales and deck beams are mating up flush, you are ready to dowel them firmly in place.
Each deck beam is currently held in place by 4 nails. Remove one nail, drill a 15/64 inch hole through the gunwale into the deck beam 2-1/4 inches deep and drive a quarter inch dowel into the hole until it bottoms out. Drill the holes so they come in at a slight angle in the horizontal plane. Then remove the next nail, drill and dowel and so on until you have replaced all 4 nails with dowels.

Step 21: Plane the tops of the gunwales

Picture of Plane the tops of the gunwales
Plane the top edges of the gunwales from deck beam number 5 forward and from deck beam 7 backward. Plane them so they slope toward the inside of the boat at about a 5 degree angle. This way the skin of the boat will contact only the outside edge of the gunwales and not trap water between the skin and the wood to encourage rot.

Step 22: Lash the deck beams to the gunwales

Picture of Lash the deck beams to the gunwales
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The picture below shows one of the traditional Greenland lashing patterns.

Deck beams 2, 4, 6, 7, 9 and 11 are lashed to the gunwales. Opposite ends of each deck beam are lashed on opposite sides. Direction of lashing alternates from deck beam to deck beam.

To do a lashing, drill a 3/16 inch hole in the deck beam and the gunwale. Picture where the lashing will cross the deck beam and carve a little notch there for the lashings to lie in. Likewise carve a notch from the lashing hole in the gunwale to the bottom edge of the gunwale. The notch in the gunwale prevents the lashings from making a lump under the skin.

To do the lashing, take about 3 feet of string and tie a loop in one end. Using a wire bent double as a needle slip the unlooped end of the string into the wire needle and thread the string through the bottom of the deck beam, around the top, around the outside of the gunwale, through the hole in the gunwale and then through the loop in the other end of your string. Tighten up the string and position the loop halfway between the deck beam and the gunwale.

Now do a few more loops, approximately 4 or so. Then tie a series of half hitches around both sides of the loop to tighten the whole assembly up. Melt off the end of the string.

Step 23: Gunwale to Gunwale Lashings

Picture of Gunwale to Gunwale Lashings
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In this step you will add gunwale to gunwale lashings near the bow and the stern. These lashings will re-enforce the dowling work in the bow and the stern and keep the gunwales from pulling apart.

Turn the deck upside down. At both ends where the gunwales are separated by about 4 inches at the bottom, drill a 3/16 inch hole about 3/4inches up from the bottom edge of both of the gunwales. Notch the outside of the gunwales so the lashings will not show.
Run about half a dozen turns of lashing around the gunwales. Tie off in the middle with a series of half hitches.

Step 24: Your deck is done

Picture of Your deck is done
Your deck is now done.

This is a good time to give the deck a coat of varnish. You coud wait until the whole frame is done, but then it will be harder to get at the undersides of the deck.

Next instructable, Greenland kayak building part 4, we'll be adding the stem and stern boards and the keelson

Do I use Glue at this time for the deck beams and dowels?

nativewater (author)  douglas.francis.1610 months ago
No glue needed. The joints are backed up by lashings. The boat is less likely to break if it is allowed some movement.