TTEC4724

Small Craft build Portfolio. TTEC 4724

Our small craft build started off with half of our class carrying on with an existing project that another class had started, They had made all the framing and the transom. Our aim was to complete the 2 boats starting from planking through to the finishing touches.

We first had to work out the area of the boats to determine how much planking we would need to cover them, we did this with a rough estimate plus a little extra and a few of us thought we would run short of planking but later found out we had enough. Another more accurate way we could have done this is by using the Simpson’s Formula

A problem we encountered is that our lengths of cedar were not long enough to span the length of the boat so we had to scarf the joints, we used a 1:7 ratio on our scarfings which is the minimum ratio to safely use. We set up a jig to help us accurately cut our scarfings with a hand plane which took a very long time.

This is a picture of our jig set up to hand plane the bevel off the planks

Our planks were 24mmx12mm so our scarf ended up being 168mm long (7:1)

Before joining our scarf’s together we painted the end grain of each piece with resin and hardener and let it set, this ensured that the timber soaked in as mush resin as possible ensuring that we had a strong bond. We had to cover the jig in parcel tape to stop our planks sticking to our jig or even together. After doing so we could join them together and let them set over night. The next day we came to use them and a few of them had not had enough length added on to them so we assigned a team of 4 people to carry out the task of adding about 500mm more onto each piece that needed it.

While the other group fixed the muck up, the others set out to start dry fitting the planks that were the right size, The sheer line had already been marked along the frames which helped us along a bit so we could attach out first plank and work our way up from there,

After fitting that plank we ran a level plank just above it to create an easier way to plank with less shaping, As you can see in the bottom of this picture. We then filled in the gap by bandsawing and then hand planing planks to make a nice and clean fit .

After that gap had been filled we the marked up 10 planks from our level line and pinned a plank there, then started to work up from that, also shown in the above picture.

We then placed another plank parallel to the keelson 10 plank widths out which gave us:

Then just below that plank we ran another from station 1 back around the boat to the centre of station 4 and 5 this gave us a gradual change in shape which wouldn’t add to much stress to the planking when bent around the shape.

After the marker planks had been placed we could then continue to dry fit the rest of the boat, We ran into a problem with one side of the frames 6 and 7 they had not been made correctly and we had to add timber and reshape the frames so we could achieve a fair boat.

We did this by running a lofting baten through the frames and measuring how far off the frame is from fair then adding a piece of timber and planing it so when the baten runs through it touches all frames and looks fair.

Once we were happy with how the planks fit, we divided into 2 groups and began mixing our resin with a 3:1 ratio of filler powder and glue powder, so that further along the build we could easily sand the excess resin…

We had to work as a team to apply the resin to each plank and then fit the plank, I felt that the easiest way to do this was to apply the resin to the plank on the boat then place the next plank ontop of it.

Trying to achieve a consistant resin line along the plank is difficult, we had a lot of spills and made a mess on the inside of the boat which came back to bite us later on in the build.

This is how we were supposed to spread the resin but in most cases it wasn’t even close to looking like this.

After all the planking had been completed we had to wipe the inside and outside of the boat clear of excess resin, we did not do this properly and when we came to sanding it was a long procedure.

We then had to fair our boats so we could glass them, we used our hand planes to get the worst of it off then we used long boards to further fair the boat. The fairing of the boat took a long time to get right because of our lack of expertise in the fairing department but eventually we got it to a point that we could seal with resin and hardener then place the boat cloth over top and compression roll resin into it. But before we sealed it we had to clean the kelson up by skil sawing a trench along the centre of the boat and taking a chunk out to place a piece in that will tidy up the join where our planking hadnt lined up correctly. Once the Glass was dry we then put some filler on the outside of the boat so we could further fair it without taking anymore out of the timber.

When we released our boats from the frames it was as simple as removing a few screws and it popped off. We turned the boats over and inspected how they had turned out some of the planks had gaps and they weren’t flush , we moved the boats one at a time into the grinding bay to be sanded, we used pneumatic random sanders and a rotary disc sander to sand away the excess resin and to flush up the timber, we used quite a coarse grit on the rotary sander and some people got a bit carried away with it and sanded some patches more that others creating hollows in the hull. Which means that there is now weaker spots.

After we had been in the grinding bay sanding, me move the boats out into the better light to give it a final check over before glassing. We found that there was still a few gaps that we filled with resin and filler powder with a tiny bit of cedar stain, this made the fill not so noticeable. When we were happy that it was relatively fair we sealed the inside with resin and hardener.

After sanding and cleaning up the keelson from pencil marks we started to discuss and prepare how we would seal and glass the inside.

So we first draped the boat cloth over one half of the boat and positioned it so it would fit snuggly against the kelson and the stem when wet and put into place. We used compression rollers to make sure that the cloth was in place and no air bubbles were appearing between the cloth and timber.

We then began fitting the gunwhale, inwhale and ribs. they had all been made for us by the previous class so all we had to do was cut them to size and fit them, we started by fitting the gunwhale on the outside edge of the boat using resin and glue powder to glue it and clamps to keep the pressure, then placing the ribs in the right way around and on the right station, we marked the height from the deckedge down the thickness of the inwhale. and bandsawing it to the right angle we then cut a scarf on to our inwhale at each end about 200mm from the front and back of the boat so that the breast hook and quarter knees could fit in neatly and be strong. we then pinned one of our inwhales in place with glue powder and resin and then painted resin on the underside of the rib and placed it in the under the the inwhale and worked our way along the boat doing each rib then coming back around put the opposite inwhale in place to hold the ribs down. We also placed a pin through the centre of the rib into the keelson to help hold it in place. then clamped along the inwhale to hold that tightly in place.

Then we started to cove the edges around the ribs and keelson we did this using a small flat spreading knife with a 10mm radius ground on the end of it so we could get our required cove.

Once this was all dry we began to clean up the edges of the coving and keelson with sand paper so it looked tidy, we made a bit of a mess with our coving so there was alot of sanding to be done.

We then set out to put the thawt and bulk heads in, these were also pre made so we just needed to scribe them slightly to make a nice clean fit, we then glue them in with resin and run another cove around the edge of the bulk heads and thawt.