Composite Boatbuilding 3

Hull Construction - Bottom Sides

We are building the hull with two different materials and methods.

For bottom sides, we are using timber(western red cedar) and it needed to be strip-planked.

1.Calculation.

In the first, what we need to do is how many timbers(or stripped planks) we need for the bottom sides.

We checked curved width of hull and divide it with width of timber(Approximately 45 around?). Then, we got the number of stripped planks we need for the bottom sides and we got how many timbers we need for the stripping. That was 2.5 timber.(around 20 stripped planks from a timber, not sure)

- Ripping(Above right) & Sanding(Above left and center). We ripped the timber into 8.7mm thickness and processed it in speed sander(Wide Belt Sander) to 8mm.

2.Canoe Body Rest (Not official name)  

 Before we lay stripped planks on the frames, we needed to cut a sort of girder on which stripped planks will sit on at the very bow of the frames. We got measure from CAD drawing but there was a little discrepancy in its height because frame itself was lifted up to be leveled.


3.Applying stripped planks on the frames.
We started applying 2 strip plank on the middle.

Since the bottom and bottom sides are made of wood, we put one plank on CHINE line and checked where tension works and how we could bend it. 

Then, Chris started tapering the first plank and let James work on the plank on the other side - Handing.

Then, we dry fitted on the frame and adjusted its tapering shape.

When we got the right shape of taper, we started covering the frames with masking tape so that it doesn't stick to the hull.

Then, we nailed one side of the plank(Starboard) to the hull then fit another side to center line and put a nail on it not thoroughly, so that we could nail it onto the frame right away after we put glue on its butt joint face.

Then we glued its butt joint face then, nailed it to the frame aligned with center line to butt-joint.

Then, we cleaned up excess glue with putty knife and then add masking tape where much tension works to join them hard.

Next planks we did were the planks on chine line, so we could start attaching plank from there to downwards.

Before we fit the plank on the chine line, we needed to dress one face of the plank for butt joint. When we were doing strip planking, we dressed(through buzzer) only two faces of timber then stripped it. So, of those two butt joint faces of the stripped plank, one face is still coarse. So we did skim it off with buzzer.

 But it turned out to be waste of time and resources.(men power)

So we set the jig on the table and did it manually with plane and it was a lot quicker.

Richard and Chris are working on the table to plane the plank. It would be desirable that we use long plane(No.4~No.5) and do it all the way through at a time.

Then, we tried dry fit on chine line with hands holding it and found that there's much tension on it to bend it to be fair.

You could feel the tension working on the plank even with eyes through the photo above.

We also did tape on the frame where plank sit on with masking tape.

We tried dry fitting with nail with blocks and clamps but so much tension was working there when we bent it.

So we decided to to attach wood block to a frame on which much tension's working so we could screw it to the wood block to hold it fair.

For wood block attached to the frame, we get the shape of it from the frame, then, make it beveled to fit the fair line of the plank.

But soon after this, we found some problems.

Since so much tension was working on some of frames, clamping damaged the plank and wood block to hold the plank to be fair kept plank from being fair. We fixed block so that plank touch the fame to be fair but we couldn't fix the clamping problem right away. We just moved on to next thing and later we could fix the clamping things.

Then we cut the fore end of plank to touch the FP and make it beveled to fit the other side of plank.

Then we get measure of bevel depth on the plank so that top sides could sit on perfectly as below. We attach block or rule on the plank and measure A and transfer the value to A'. 

And we put a batten on the frame to make it fair.

If you see the photo on above left, it's touching the forward edge of the frame, which is station right and it means it's on right point. But above right shows that it's not touching the frame at all, which means it's not fair. So we adjusted the frame to be fair using a batten on it.

To get the shape of taper on the very forward of the plank, we used off cut.  We also needed to keep the one tapered off cut because it needed to be handed to another side of plank

And when we are doing "handing", it is desirable that we mark which is on which side to avoid confusion which will keep us slow down. Also when we get the tapered shape, it doesn't fit perfectly at first try, we always keep the plane close and adjust the taper until it fits perfectly.

When it finally fit, we glued and nailed onto the frame. It didn't have much tension on the frames but it did have a difficulty to hold onto frames firmly at the very forward end of the planks. So we used masking tape and also came up with another way to hold the planks onto the frames.

Then we thought that things were going real smoothly but Chris told us to fix the tension on the plank aligned with chine line. Much tension's there only in the forward part where fair curve change drastically. That was a problem we needed to solve.

So the idea is that we divide whole plank into multiple pieces so that it could be bent with less force. Compared to B, cutting it into 3 pieces, C is relatively gives less job.(Less nail, less glue and thus less filling)

So we took C method.

Then glued and fit.

From here we started work as a small team. 

A team work on bottom planks and B and C team worked more closely because when one side of plank is ready then, it needed to be handed to other side of plank. But after we got the shape of the planks when we glue it, we had two groups - Glue team and applying team.

So we all worked as team quite well depending on jobs.

 And here are some things to be considered applying planks on the frames.

1.After we got the planks to be tapered then, we marked its position with numbering rules to avoid confusion (Port side-A, B, C.. / Starboard: 1, 2, 3..) 

2.We marked surface of the plank which needed to be glued to avoid confusion.

3.We covered all the frames with masking tape so the planks don't stick to the frames.

4.Get the shape of the taper at the bow, then fit the shape of the stern on the plank. This is what we're told to do.

And it makes quite sense because at bow it doesn't have much space to fit the plank in.

But while we were doing it, one of team members kept insisting that we should do shape of stern on plank first then shape of the bow on the plank. We could't make ourselves understood to him so we let him do his way. So later we had a hard time to fit the bow side of the plank in including people kept asking us why we're doing wrong way.

So, fit the shape of the bow on the plank first, then, the other.

When we were done with all those bottom and bottom sides planks, it became real messy. 

Then we did sanding, filling, sanding and sealing.

First, we did sand after butt joint of the stripped planks for the hull are done. 

Then, we filled the nail hole and gap with glue. 

Finally we did sanding again and sealed the hull with resin. 

So this was hull construction for bottom and bottom sides.

And here's more.

* Hull prep for laminating.

I made a piece of foam and fitted it into the very bow of the hull and the reason why we're doing this was to make it easier when we're doing laminating the outside hull later.

As you see photos above, outside hull is quite rough and it is more rough in the bottom of the bow than top of the bow.

And even if we sand off the hull later, it will still be with sharp edge and lumps, which are enemy of glassing.

So we attach foam into the hull and fill it with glue(WEST Resin with glue powder) and we sand off outside hull. 

Then later, we cut the bottom bow under the foam and make another foam into the shape of the parts we cut off and fit it into the hull before we laminate the hull.

* Water splash(Not sure about the term,) on chine at the bow

We also added water splash(?) onto chine line at the bow.