Sunday, January 31, 2010

Skeg and Capping Peices Fabricated

The lumber (1 1/4" thick white oak) is placed on the boat and a block and pencil is used to draw the shape of the boat onto the lumber.

The lumber is cut using a circular saw and the edge is cleaned up using a belt sander with 50 grit sand paper ... (which makes a great power planer for this task). I made sure there were no gaps underneath the skeg and that it was not leaning to one side.

The top of the skeg is perfectly horizontal ... (yay a straight line finally!) So I used a tight string (leveled with a string level) to mark the top edge. Then it's cut with a circular saw.

The front of the skeg is checked out to accept the next capping piece. This was done with a table saw set at a low blade height. This worked well, except the bottom edge got chipped a little.

Next the holes are drilled and countersunk for the through bolts. These bolts are hot dipped galvanized steel. It's normally not a good idea to mix metals like these galvanized steel bolts and bronze screws and nails. However, since this is a trailer boat, this won't cause any corrosion problems most likely. Also, bronze is higher on the galvanic series than galvanized steel, so the steel will corrode first if there is a problem. I may have to replace the bolts once every 20 years, but at least the permanent bronze screws will last forever. (For those of you still concerned, just pretend the bolts are sacrificial zincs).

The two capping pieces on either side of the centercase slot are made the same way as the skeg. (Except these pieces are going to be installed using large screws instead of through bolts).

They are also faired slightly on the sides where they meet the skeg using a belt sander. (I'm kinda embarrassed that I use the belt sander so much, but it works so well!)

Next week I'm going to make some more capping pieces for the front of the boat, then take it apart and install all of them with glue.

Fiberglass Hull

After the hull is shaped about right, the fiberglass goes on. Here's how I did it ... I hope it lasts.

I spread a coat of epoxy on the hull, so the dry spots could soak it up. I let it cure for a half a day, then while the epoxy was still slightly tacky, I stuck the fiberglass fabric onto the hull. The fabric is overlapped at the seams.

Then the epoxy is wet out. The epoxy is poured onto the hull, then squeegeed off using a reasonable amount of pressure. Just enough epoxy is used to glue the fabric to the hull, but not to fill the weave. It was pretty easy, except little wet fiberglass hairballs and frayed edges made it a tedious and messy process.

The fabric becomes transparent when wet out, but the weave is still raised and visible.

Each coat of epoxy is applied before the one before it completely cures. (If I didn't do it this way, I would have to sand between each coat to get good cohesion).

The next coat fills the weave partially. The bumps in the hull caused by the fiberglass overlaps, etc. are sanded off and some thickened epoxy is also used to fair these areas a little. Then another coat is applied to fully fill the weave.

After these coats, I noticed quite a few bumps in my once smooth hull, so I decided to completely sand the hull down again (being careful to not dig into the fiberglass cloth). I'm glad I did this extra work because now the hull is much smoother. I'll later apply another coat of epoxy before painting to make up for this extra sanding. But first I'm going to install the skeg and capping pieces.

Sunday, January 17, 2010

Bottom Planking Installed

The bottom planking was successfully installed ... with a little help from the missus. We used some screws to help bend the front part down and nails everywhere else. Valerie held the ply in position while I screwed the front few screws. Then I climbed up on top of it to bend it down and screw the rest of the screws.

We then hammered all the nails in.

And while Valerie was covering the nail heads with glue, I was crawling underneath trying to clean up and fillet the glue around the stringers and chines inside the boat.

The process wasn't too difficult and we were able to do everything before the glue set. Having a helper sure is nice ... even if it is a rare occurrence.

Here are some pictures of the boat now with both bottom plywood pieces installed and it all sanded smooth. The epoxy is really difficult to sand, but it didn't take too long. I mainly used a belt sander believe it or not. A flat spot all along the centerline was planed using a belt sander. (Capping pieces are later going to be installed there). There were some spots on the hull that weren't fair and some nail heads still uncovered, and I applied some thickened epoxy to these areas. So that's what the wet spots are in the pictures below.

After I sand again, I'll start applying fiberglass, probably next weekend.

Sunday, January 3, 2010

Bottom Planking

So far I have installed 4 planks of plywood on the sides of the boat. Next are the two large pieces on the bottom. Here are some pics of one of them being scarfed together. I have to make another one for the other side. Yeah, it'd be nice if I could teach my dog to stay off the plywood while it's being glued. I used a 4x4 post (and other heavy stuff) as a weight on this long scarf joint. The 4x4 is too rigid to give even pressure on the joint, so I put some cardboard under it to distribute the weight more evenly.

I decided to scarf the plywood pieces together instead of using butt blocks like shown in the plans. Scarfing is actually pretty easy. However, what I'm doing is more difficult, because the scarf joint has to be glued on the floor, (unlike the butt block joint that can be glued after the first section is on the boat). This means that I have to install the entire plank all at once instead of one section at a time. Nailing down this large piece of plywood before the glue sets is going to be quite a challenge. Wrapping it onto the hull requires a good twist and bend, adding to the difficulty.

I should have installed the bottom plywood first, since it's the most difficult. I don't have many spots to clamp it down, because the side planks are in the way. I think I may use a few screws toward the bow, like mini-clamps to hold it down while I bend it.

I'll let you know how it goes. Right now I'm not quite sure how its going to work, but I think I can do it.