A Shipwright in Training

Last week I signed up at the local Y because they have really good rates for full time students. So, every day for the past week or so I’ve been doing something over there… yoga, aerobics, step, spinning. I try to mix it up with yoga every other day and something that feels more like actual exercise on the other days. It’s been wonderful, even though I have to get up at stupid o’clock in the morning most days. and I keep running into these guys. They really should get a life.

But, I know, you really want to hear about the boat.

Dark night of the soul is over. No worries, folks.

The Beetle Cat has 8 planks / side. Numbering from the keel out, you’ve got: Garboard, 1st Broad, 2nd Broad, Planks 3-7 and the Sheer. Yesterday plank 7 went on like a glove. Here’s the initial fit:

And a little close up:

The stuff that looks like paint in the seam is paint in the seam. We back prime the planks with red oxide primer before installing them on the boat.

Now, the astute reader will pipe up with some smart ass comment like, “Hey boat guy, sure that’s a wicked tight seam, but where’s your caulking bevel??” Look, I haven’t put it on yet in this photo yet. And yes, I did eventually put it on, and it was wonderful in every way. Geez, don’t you have a hobby or something?

Looking at the boat here, you can see I’ve got planks 1-3 and 7-8 installed.

Plank 4. Ah, plank 4. Before going into that, let’s look at some of the wood it takes to plank 7 beetle cats. We get these Huge loads of amazing cedar.

It may not be obvious in this photo, but those planks are up to 20+ feet long, and many are 18″ wide at the base. For plank 4 I took the first board off the stack, and it was perfect in every way.

Here’s my spiling batten (and spiling block) laid out on this beauty. Note how the curve of the grain perfectly matches the curve I’ll need in the plank. Not only that, but the hood end (i.e., the front of the plank where it meets the keel) will come from the wood at the base of the tree (nearest to us in the photo) where the wood is strongest. This is particularly good since the hood end get torqued pretty hard when installing the plank.

Here’s the board with the plank line ready to be traced after I’ve de-spiled the points onto it from the batten:

The top edge of the plank’s already drawn, and the batten is there for drawing in the bottom edge of the plank. This board is big enough to get another entire plank out of it. So, I cut it out, faired the edges nicely and backed out the plank.

In case you forgot, backing out is the process of scooping wood out of the inside face of the plank so that it rests snugly on the frames. After backing out, you flip the plank over and curve the outside face of the plank to match the backed out face.

Problem was, I backed out the outside face of my plank, rendering it entirely useless to me. Dammit dammit dammit dammit dammit dammit dammit dammit dammit dammit dammit dammit dammit. Dammit.

The good news is, Kevin hadn’t cut his #4 yet, and with a little tweaking, my plank fit his side of the boat like a dream. Naturally, it was a hell of a good plank if I do say so myself.

So, I found Another board, traced my nice plank onto it, cut it out, and faired it up.

Hey, let’s talk about knots. Some boards have lots of little tiny knots called pin knots. They’re no trouble at all for planks as far as letting in water or weakening the board. And they look kind of cool. Here’s my 2nd shot at plank 4, a board filled with pin knots.

What you’re looking at here is the mating edge of the plank along the top and the inside face of the plank at the bottom. There are 4 pin knots on the inside face, and you can see how the edge of the plank cuts across a knot along the top. Essentially that’s a cross-section of a pin knot.

The tricky thing about any kind of knot is that they distort the grain around the knot. You can sort of see it in this photo when you look at the inside face. See the topmost knot? See how the grain lines from the left rise up and go over the knot, and then fall down to the right? This makes for a tricky planing problem. we like to plane with the grain, meaning that we plane in a way that tends to not tear out chunks of wood. In the above photo, to plane with the grain, you would plane from left to right until you get to the knot, and then plane from right to left, again until you get to the knot. That way you’d always be planing with the grain. With a board like this, however, with hundreds of tiny knots throughout, there’s no way to do this. You can see in the above photo that there’s a little tear out just to the right of the knot on the mating edge. That’s because there was a little grain reversal near that knot.

You can see it really well in a shaving:

On one side of the knot the shaving is cleanly cut where I’m planing with the grain, on the other side of the knot where the grain reverses, the shaving looks torn and crappy.

Tear out on a mating edge is a bad thing. You want that edge glass smooth if possible. That’s where you’re going to have a water tight seal you know.
Here’s the tricks for planing unruly grain:

1. Keep your blade razor sharp
2. Take small cuts (thin shavings)
3. Close down the mouth of your plane to the smallest gap that will still let a shaving pass through
4. Skew your plane as you take a cut.

Here’s a plane taking a skew cut, all by itself, as if by magic. Jeez, look at all those knots!

And here’s how tight the mouth is set:

You can barely see light through it.
One of the cool things about taking skew cuts is that you get really neat shavings. They curl into long dreadlocks all over the floor.

So, when you do all these things properly, you can pretty much get rid of tear out. Here’s that section of plank again after a few passes of a well-tuned plane:

You can see just the tiniest roughness now to the right of the edge knot. That’s about as good as it’ll get.

So, before backing this plank 4 out, I tested it for initial fit against plank 3. It wasn’t even close. Somehow, in the process of tracing the 1st plank 4, I made a copying error (don’t ask, I don’t know) and produced Another plank that was totally useless.

Happy place, happy place, go to the happy place. Dammit dammit. Walk around the shop. Eat a Snickers bar.

So, I found another board that worked well, de-spiled from the original spiling batten, drew it out, cut it, faired the edges, checked it for fit, and THEN backed out the proper side. I have a feeling that this one will actually end up on the boat after prepping the outside face tomorrow.

Completely changing the subject.

Here’s a cool little thing that Joel made last year. When you screw in a plank, you dip the screws in red oxide paint. That way, if any water leaks into the boat along the screws, it meets a barrier of paint, even inside the screw holes. Joel made a little dipping box. Essentially it’s a hollow box, filled with paint. You put your screws into the holes where they get exactly the right amount of paint on them. Pull out your screw, and it’s perfectly dipped. Sweet!

Lastly, here’s a photo of bedding compound. This is that stuff that stays flexible and is used to seal where planks meet solid boat parts like the stem and transom. Here it is at the transom. The string is an added barrier. If water hits it, the string swells up and acts as a gasket.

Good night, and may you only have to make your #4 once.

This entry was posted on Wednesday, January 31st, 2007 at 10:04 pm and is filed under Classes. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.