Sunday 22 June 2014

Cutting pieces of wood and gluing them to other pieces of wood.

This weekend has been pretty busy. Basically I joined bits together with epoxy, so now I can barely lift the boat.

I started by using a scarf joint to join a couple of bits of 90x19 Tasmanian oak, that'll be my keel plank. Scarf joints have been used since their first appearance at the Melbourne Cricket Ground in the eighteen eighties... Anyway this is a 6:1 scarf, and makes my two 2.4m planks one 4.8m one.

I was careful not to clamp too hard, to get optimal squeezage. That's a technical term. A quick bit of planing, and it looks quite nice.

While waiting for epoxy to go off, I joined all the bulkheads I've made to the spine, and attached the centerboard case as well with screws. I also added bits of 19x19 Tasmanian oak as bracing.

Then I cut a huge slot in the keel plank for the centerboard to poke out of, and screwed that to the spine/centerboard case combo. Mogget is impressed.

It looks kinda cool now, with the centerboard poking out.

Friday 20 June 2014

It floats! Is that a good thing?

So today I took my centerboard down to the boatramp and launched it :P Alas I totally forgot the champagne!

Bad news is it floats. Good news it it really wants to be the right way up, with the tip pointing down. It's only the bit above the pivot that sticks out of the water.

What to do? I presume it'll be okay, and the buoyancy at the top of the board won't be a problem, as that bit will be out of the water normally anyway, right...

It's incredibly easy to pull through the water, for what it's worth. Leaves barely a ripple on the surface.

Monday 16 June 2014

More centerboard work, plus centerboard case

So here's the centerboard all nicely shaped. I added an uphaul pivot, made with two pieces of jarrah that sandwich the centerboard. It's held together with epoxy plus four 38mm 8G silicon bronze screws, so it should be nice and strong. I routed a nice big 20mm wide slot to accept either a sheave and metalwork for a becket for a 3:1 uphaul, or if it's still hard to haul up, a pair of sheaves for a 4:1 uphaul.

Next I made it look ugly by laying lots of 200 gsm unidirectional carbon fibre on either side. This stuff provides the strength. Not shown here (I forgot to take a photo) is a strip of 400 gsm fibreglass tape down the leading edge and across the tip, with a second piece at the tip of the leading edge.

Then I faired it. I used much the same epoxy mix that I make for gluing, with enough glue powder to make a peanut-butter consistency. I slathered this on with a spatula that I stole from my kitchen, and then after curing I removed most of it with some 60 grit emery in a sander. Then I repeated the exercise, with slightly runnier goop.

Once I was reasonably happy with the shape and surface, I bunged a coat of undercoat on. Once this is dry I'll remove most of it before doing a couple more coats and a couple of top coats. Also shown here is the case, which is framed with 19x42mm Tasmanian oak, and held together with no less than 48 8g silicon bronze woodscrews.

The pivot is only temporary. I've been testing how it works with an M10 bolt. I've got some more bronze on order to make a proper pivot, using a 12mm bolt to clamp a 19mm tube, with some 25mm OD flange pieces epoxied into the centerboard. I'll show details of that once the materials arrive.

Monday 2 June 2014

Shaping the centerboard

I know I only glued the laminations together yesterday, but today has been a pretty big one, so I thought another post was the go. That and Perry told me that I really should stop working before I fall over :)

What a great cardio workout! I've found the perfect antidote to tuck-shop lady arms, in the form of my nice Stanley no. 4 plane. I tried my new no. 5, but found the extra weight harder to work with, so went back to my no. 4. It all started innocently enough. I cut out the profile of the board, and planed the board nice and smooth, then ruled some center lines down the board and started removing material from the leading edge:

After about eight hours of planing, my workshop started to look like a bomb had gone off:
The secret to successful planing is to remember to sharpen the plane iron often. Every time I started to get tired, I'd run the iron over the whetstone while I had a break, then when I went back to it it was easy again. I think I sharpened my iron about five times today. In terms of effort, I feel like I've just ridden about 80km. I'll sleep really well tonight.

So I reckon it's about 80% there. I went at it with some 80 grit emery to smooth things out, and it's looking pretty good. I think on payday I'll go buy myself a power sander. Note the extra little bit of Jarrah at the bottom of the leading edge. This is the area where I think the board will cop the most knocks, so I wanted it extra strong:

Check out the shavings. Planing with a proper hand plane like this is a lot like sculpting. The wood knows it wants to be a foil. You and the plane are there to help it achieve it's goal. It's pretty obvious where the non-foil bits are, so you work the plane over them, and it gets gradually closer to shape. Very rewarding.

After a day's work the profile is looking reasonably foil shaped. I have lots of motivation to remove all the unnecessary material. Otherwise I'll have to add more lead to get it to sink, and I really don't want to resort to that:

Once the shaping is done I'll add some of this stuff. It's unidirectional carbon fibre tape, and should make it reasonably hard to break:

Then do the pivot hole and the lifting bit, and this part's knocked over :)

Sunday 1 June 2014

Fun with epoxy

My epoxy arrived through the week, so I'm making the most of the long weekend, and getting it everywhere.

Here's how I'm doing my centerboard - the lead hides in a routed out pocket, so it'll be surrounded by cedar. I'm hoping this will make the board easier to shape into a foil, rather than shaping, then cutting a big hole, adding lead, and fairing:

I did the laminating in three steps: The front section with the lead brick, then the back section, then I joined the two and added the leading edge jarrah piece. This allowed me to make better use of shorter clamps for the springier small pieces of timber. Here's the start, taking a deep breath before mixing epoxy:

And after gooping everything together:

Then finally the whole centerboard, after repeating the exercise for the rear bit and adding the leading edge:

While I was waiting for epoxy to go off, I joined doublers to bulkheads. At one point every one of my 27 clamps was being used. I think my building speed is limited by number of clamps and available horizontal surfaces. How many clamps do I need to build a boat anyway?

I quite like the bote cote epoxy. It's easy to mix and doesn't stink the house out. It's certainly refreshing doing woodwork after that awful lead interlude.