We started hull construction with Stem and Transom.
1.Transom
We made transom and bottom out of one piece of plywood and it gave us some trouble.
James's group made two pieces of bottom parts and one whole transom in one piece. But we couldn't do the same because the size of plywood was smaller than James's group.
So we spent quite a time figuring out the cutting plan and we decided to scarf joint on transom.
So we cut two pieces of transom parts. Scarfing is one way of joint. It has scarfing ratio and the bigger the ratio, the harder the joint goes. But it doesn't need to be jointed way harder so proper scarf joint ratio is needed.
I think we used ratio of 1:6,7,9 ration with our own discretion on some parts under Chris's direction.
For scarfing, we set up scarfing jig then used hand plane. Scarfing was kind of "handing" job and was quite interesting job to me.
As we keep planing plywood for hand plane we could see its inner grain or layer and width of grain on both plywood must be the same. And that's one fun of scarfing to me.
And in scarfing, one of the most important thing is this handing. Before we start planing and gluing we need to make sure that which surface need to be sanded and how it need to be folded for gluing. Because of this, we almost screwed up with one of side panel.
We knew how it's important and how to do it, but no one was cautious on this while we were doing it. But due to Chris's direction, "Always make it bigger and longer", somehow we could have a chance not to screw things up.
Once it's properly sanded, then it needs to be glued and jointed with resin(1:4, hardner:resin) and glue powder mixture. With proper protection from glue contamination with plastic film, we also need to figure out how to give some pressure downward so it could joined firmly. We used long strip of stick and place it between scarfed face of plywood and steel beam on the roof. So with leverage pressure of this stick make the joint hard.
When it's firmly done, we planed the excess glue and later sanded for smoother surface.
2.Stem.
With stem making, we learned variety of technique and prep things.
To make a stem we used strip planked timber. Before we cut it out from whole timber, Chris stopped us and talk about cutting plan again. Since we still have parts to make and some of those are quite long including 2 gunwales and 3 skegs. So we need to make sure that we still have long enough piece for those parts.
With strip planked timber, we laminated those pieces into one piece so that we could have proper shape and strength for the stem. Out of whole piece of timber, it is hard to get proper shape and strength, so we needed to make a stem with laminating.
For this, we set up laminating jig on particle board with real scale for stem. Proper laminating holders were placed and clamp were ready.
Even though it's thin enough, dry panel was not soft enough for the shape of stem, so we steamed those stripped planks in steamer and dry fitted onto the laminating jig.
While we were steaming, we stacked the plank to get it steamed properly and efficiently.
We dry fitted the stem a few hours so that it could remember the shape then make all things ready, plastic film protection, clamp, glue, protection block and jig.
We did the same for mid ship frames. So all the laminated pars were almost done together.(One stem and two mid ship frames)
When it's done, we undo the all clamps and it seemed fine but when we checked it with real scale plan, the shape was slightly different. While it's going hard, it's shape also has changed and depending on position of clamp and its pressure, laminating was not in uniform, some has gap and twisted.
Now we got transom and stem and fixed it onto the jig.
Next thing is bottom. We did bottom planking and scarf joint while we were cutting the transom and its ready.
First thing we need to do for bottom is to place batten on bottom of the boat(top edge of the frames) and check whether is fair and bevel angle on each station and get it beveled so planked bottom could sit on the frames properly.
Then, we place some weights on top of the bottom, so it could bend properly bend to the shape of the bottom hull.
Once it's done(for more than 12 hours, so that it could remember the shape), we fixed it onto stem and transom
3.Bottom Sides(Garboard) & Top Sides(Strakes)
To get the shape of side panels, we learned technique called spliling.
For this, we brought spiling board which is flexible enough to fit the fair curve of the boat and fixed it to the hull. Then, We mark distance between certain point of spiling board and bottom and frame at each station. Then we transfer the value and did lofting on plywood.
Plywood wasn't big enough so we did scarf joint for the top and bottom sides panels.
When glue's gone hard and before we attach it to the frames, we needed to bevel the side edge of bottom plywood to fit the panel to the bottom smoothly. Also for strakes, we needed to bevel the bottom edge of the bottom sides too.
When we attached the strakes to garboards, we did rebate planing on each board for box landing.
4.Gunwale.
Gunwale was quite hard in a sense. It needs lots of fixing device and men power too.
We cut two long strips of wood stick and then we process it through thicknesser with gunwale jig inside the machine.
Then we dry fitted it to the hull with clamp and it looks okay, So we glued and try to fix it but, not to lose its fairness and for firm bonding, we also used screw to hold it. These screw needs to be pulled out and filled unless it's stainless.
For the other side of gunwale, it was hard even to bend to fit the curve of the hull. I think we should steam it once but we did it right away again with more men and more screw.
For the last, before we flip the boat over, we get the patter of bottom then transfer it to skeg and made it onto bottom.
So that's all for hull construction.
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