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Built your own boat from scratch

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Yes, again an other instructable on how to built your own boat. I will not give any detailed plans etc. (because I did not made them). But i think that you all are capable enough to design it your self so I will concentrate on the mistakes I have made so you do not have to make them twice.

First decide which kind of boat you want to built, I wanted a light boat (less than 50kg) but it needs to be still large ENOUGH  the one I have made is 4 metres long and 1,50 mtres wide and weighs araound 40kg. while building a boat dimensions and shapes are very important. First take a good look at existing boats to get a "feel" of the dimensions used. A good guideline is the next one:

The widest point is at the middle of the lenght.
The bottom has an V-shaped form (stability)
The backside has an wide of approx. 2/3 of the width
the sides will need to have an angle (this has no function at all but it makes your boat look more naturally.

Building an boat is all about curves.

When you have an basic design in mind you can start building.
To choose the matirials you do not need to buy special boat building wood (for which an rain forest is cut down) any cheap plywood and some square wood will do. Take care in your design that plywood will only be bent in one direction. I have used an square 40x40mm 2,70mtrs long for the main strut and 15x15mm for the sides. The diagonal struts were made of 12mm plywood and the side is made from 4,5mm plywood while the bottom is made from 5,5mm plywood.

Make sure you use waterproof glue.
Use screws and NO nails (nails will come out)


How to make it:
1:) make cuttings in the central strut for the diagonal (plywood) struts
2:) fit the central strut on an workbench
3:) Make the bow no fine-tuning or cutting is necessairy yet
4:) Saw the diagonal struts and fix them
5:) Attach the side struts.
5a) Oops the 15x15mm square can not be forced to follow the curves of your design.
5b) laminate some 4,5mm plywood to solve this
6:) now the base structure is ready and you can start finishing it up. I hae used an shaving tool for the central strut and the bow to make sure it makes an perfect fit with the diagonal struts.
7:) now you can start to make your boat waterproof by applying plywood to the bottom and sides.
8:) First start with the bottom make sure the sheet is too large.
8a) &@!*^% The sheet is too small for the lenght and the final curve at the bow is too big for the 5,5mm plywood.
8b) Use some thinner plywood to make the curve and cheat with some polyester
9:) when the glue is dried you can saw off the exes sheet use an belt-grinder or so to make an perfect finish
10:) now you can attach the plywood sides make sure you have enough "cut-off"on the sides
11:) finish the sides again by sawing and sanding
12:) finish your boat by putting sidewalks / flooring / benches etc to it.

What went not completely according to plan.
An floor of 4,5mm was applied directly to the diagonal struts, it was too weak I broke it several times. 5,5mm is fine.
While cruising at full speed (5hp enginge) it goes really fast around 30km/u and when encountering a wave I got a little skared while I have more weight than the complete boat with motor etc. so I finally applied polyester to the bottom side to improve strenght and make sure the plywood will not get wet.
I applied normal outdoor housing paint to the underwater part, DO NOT DO THIS it will come off whitin two days.
While bending the 15x15 square it was not achievable to get the desired curves whitout breaking them, this was solved by laminating plywood to the correct shape an afterwards finishing it up with the belt-sander.

Before you start make sure you have a proper plan and an clear idea of what you want to make
Sander-grinder (author) 7 months ago
I could not upload an extra photo to the comment so I have put it into the instructable
igoff997 months ago
And how long the boat is
Sander-grinder (author)  igoff997 months ago
The total length is 3,8 mtr and max width is 1,40 mtr.
I have first made a frame and than roughly cut the plywood to the final size. I have first attached one en to the frame with screws / glue and than pulled the plywood to the frame with an rope and fixed it with screws and glue to the frame. Afterwards the oversize of the plywood I cut off and finished it with an belt sander.

The reason why I have done it this way is that it is almost impossible to measure and cut the plywood this accurate to fit the curved frame.

The length of the boat is longer than the standard size of plywood (1,22 / 2,44 mtr) so the sides of the boat are made of two pieces. At the bottum side I did exactly thesame way.

I hope this answers your question
igoff997 months ago
Can you email me or please write more about the boat. I would like to know more about how you assumed the plywood to the frame. It just looks like from the pictures it wouldn't work. Thanks
Hi thanks for sharing your boat building tips, I also like the shape of this boat and would love the site that you got your plans from. cheers gus
Sander-grinder (author)  gussy_sydney1 year ago
Sorry for the late reaction,

I did not used any excisting plans. But I took a good look to excisting little boat designs. And then I made a rough design.

During construction I have made the final plan by doing it. I understand that this is not any useful plan. Unfortunatelly I threw away my rough sketches.

If you are interested I can make some new. If you have some 3d imagination it is quite easy to make a little boat.

Regards Sander
mommyhen421 year ago
I have been looking for a similar boat design, but I like the hull design on this one, can you tell me the name of the design and where you got the plans?
Sander-grinder (author) 1 year ago
Thanks, I have made this instructable a little in a hurry, when some more people are interrested also in designing and building I will make a proper instructable out of it.
During build I encountered a lot of simple things that went wrong so I tought of writing them down so someone else will not make the same mistakes twice.
This looks great! Thanks for the great photos and advice- always useful to know what not to do.
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