Building a small trolling boat.

[Lurvio]

ancient kayaker
A great idea and I might have even better material for it than plumbing pipe. Roll hearts from silage balewrap. The pipe is about 3 '' dia but is three times as thick walled as the plumbing pipe. I have to test how it works. The wood clamps I had in mind would be just two 4'' long blocks (30mm*30mm) with screws in both ends.

[hoytedow]

To use polyester you would have to paint the styrofoam with at least 2 coats of latex paint, and you had better not miss any spot or it will dissolve the styrofoam.

[ancient kayaker]

Originally Posted by Lurvio

ancient kayaker
A great idea and I might have even better material for it than plumbing pipe. Roll hearts from silage balewrap. The pipe is about 3 '' dia but is three times as thick walled as the plumbing pipe. I have to test how it works. The wood clamps I had in mind would be just two 4'' long blocks (30mm*30mm) with screws in both ends.

Some materials creep under stress. To test it, clip it over a block of wood of the thickness you plan to use and see how much force it still has the next day.

[Lurvio]

Hello

Got some small things done on the boat again today. I solved the lack of clamps by making my own. I already had all the parts needed so I just needed to cut the wood blocks and assemble the clamps. I took some poor quality (knots and twists) 32x32 mm (1 1/4'') timber and cut it in 100 mm pieces (got rid of the knots ), all 40 of them. Then I bored 10 mm holes through and 22 mm holes about 5 mm deep for the nut and bolt heads. I pressed M8 punch nuts in half of the blocks and assembled the clamps with M8x70 half thread bolts. I think they cost me under 10 euros for the 20 clamps.

Of course they had to be tested so I glued the second layer on the chine on one side. The cordless drill is a perfect tool for tightening the clamps, I only used 5/16 torque setting in my Makita. Temperatures are again on the low side, so I'm not sure if one day is enough for the glue to dry, we'll see.

Making the clamps


All 20 clamps done


And the second layer of chine


I am also finalizing the plan for the prop, so I'll also start making that in the near future. I originally thought of using 6061 aluminium for the blades but I'm not so sure anymore. I don't have tools or experience for welding alu so if I end up making a solid prop instead of a folding one, I probably have to change the material.

Lurvio

[TeddyDiver]

Originally Posted by Lurvio

The glassing is only for abrasion resistance, so it doesn't matter very much, what kind of rowing it is.

Wasn't meaning for strength either. It just happens be that 45/45 biax is very easy to set on concave and convex forms..

[hoytedow]

Smart clamps.

[Lurvio]

TeddyDiver
The bottom doesn't have convex/concave shapes so it is the easy part. The tunnel part does need a fabric that forms easily as it has pretty much all the troublesome shapes possible.

hoytedow
Thanks, they work well after I realised I only had to open one of the bolts to get it over the chine.

[Lurvio]

Hello

I've got a bunch of work done since last update. The sheers and chines are glued and the bottom faired. Also made the first major mistake.

This is the 'dayjob', glueing styrofoam pieces around plastic waterpipes. That's the heating pipe that'll connect the boiler house to my workshop. Big pipes (black) are for heating water and the smaller ones (orange) for the hot water (left dry at this point).


Gluing the sheer, layer #2. All 20 clamps in use.






And layer #3, I started the last layer from the frame #1 forward because the stern end already had the shape needed. I clamped the last layer a bit more loosely (clamps further apart), so I could do both sides at once and save a day of waiting. Turned out okay.


Starting the fairing, the angle grinder with 40-grit sanding disc made short work of the plywood. I had to take about 15 mm off the sides and one 3mm ply off the center.


Looking good so far


And then the mistake. When I originally attached the bottom battens, I had to make notches to frame #3, turns out I made them a bit too deep. So when I used the chine and the batten as a guide in fairing the stem, I planed out too much and made a flat spot. The battens weren't glued yet so I added 2 mm shims under the problem spots and glued the battens in place. I glued a leftover piece of chine veneer to the stem, waited over night and tried again. Turned out good enough.

Patch glued on...


...and re-faired. The piece of tape has the word 'Muista' on it, and 'ruuvit' on the other side of the stem. Remember the screws.




Fairing the other side, the grid is pencil lines to keep track where I had planed.


The sanding disk I used in the angle grinder, 40-grit. And the hand plane of course.


I have been thinking about the prop tunnel and finally reached a conclusion, I am going to drop the prop a bit lower in the water, 2 cm should be enough. I made a piece to modify the tunnel shape in the transom and glued it on.


Also the stem between sheer and chine needed some extra wood so I faired a spot and glued a block to it.


Next time fairing the sides and then I have to start making the cardboard patterns for plywood panels. I found a supplier for the fiberglass and resins nearer than I thought, I have actually bought something from them some years ago. The guy suggested I´d use 450 g fiber mat and on top of that fiber cloth on the boat bottom. Seems overkill to me, what do you guys think?

And then a question I've been pondering, what panel comes first? I think transom first, then the sides and last the bottom, is that right?.

I think I had yet another question, but I forgot it.

Lurvio

[Lurvio]

Oh, I remembered the question I meant to ask. I have been thinking about the plywood, it has the surface veneer the wrong way. Structurally shouldn't be a problem, but visually and probably in the transom curve. If I made the panels the 'right way', I'd have to make a joint in front of frame #2. That method would probably save some material also. But how do I make the joint invisible in the finished boat?

[hoytedow]

Apply some decorative paint such as the U.S.C.G. uses to hide theirs.

[Lurvio]

hoytedow
Haha, that's a good one.

Don't know how the stripe would look, if its the only paint on the boat. I think I have to make some test pieces.

L

[hoytedow]

Here's another view. See how well it hides the seam.

[Lurvio]

Hello

Got a couple of hours on the boat today and faired the sides. Turned out to be a bit easier than I had thought. Then I removed the screws that held the frame to the building form and pried the frame off the form. It was well stuck in a couple of places due to glue running to wrong places. I took the frame off the form for two reasons, I wanted to see the fairing of the sides from a better angle and I also wanted to weight the frame alone.

I should have good chances to keep the boat well under 50 kg, the frame weights exactly 10 kg. Deck framing will probably add 1 kg when done.

And some pics.






Lurvio

[Lurvio]

Hello

Been a bit busy lately with other work but I got the transom skin glued yesterday, I used 6 mm birch ply for that. The 4 mm ply probably would have been sufficient but I had a nice piece of the thicker ply so I used it.

I also got the resin ready, first 4 kg. It is polyester, mainly because of the price, epoxy is 4x more expensive around here.

Then I made a test rig to find a good position for the pedals and back rest. Looks like I have to shorten the stern deck about 10 cm from the original drawings.

I'll post more pics in the near future.

Lurvio

[ancient kayaker]

I get great birch ply here in Canada and you probably get even better. It is very strong. Birch is said to have poor resistance to rot so seal it well. I haven't used polyester resin but I have read that it requires good temperature control.