Thursday, 30 October 2014

Finishing the birdsmouth mast prototype

Continuing the exercise, I opened the slot up with a 6mm router bit, cut a couple of V cuts into the back of the sailtrack section to lighten it, and bevelled the sides of the sailtrack section with a plane. Then I glued the rest of the staves together, forming a rough birdsmouth section.

Once this had set up I planed off the sharp edges, then planed it into a sixteen sided figure.

Then finally I planed it further to a 32 sided figure, and sanded it reasonably smooth. I think the results speak for themselves. If nothing else, it's rather pretty.

And now for the moment of truth. 489g for 30cm. That's 1.6kg per metre, or right on 10kg for a 6.1m length. I reckon that's reasonably light.

Wednesday, 29 October 2014

Prototyping a modified birdsmouth mast with an integrated sail track

Out here in the boondocks in Western Australia we don't have terribly much access to traditional boatbuilding timber. Douglas Fir? Not a chance. Spruce? You've gotta be joking.

What we do have in very plentiful supply are Jarrah and Tasmanian Oak. Jarrah is an incredibly dense, strong, durable timber. Great for railway sleepers (all the railway sleepers in the London underground were made from Western Australian Jarrah), but challenging to build a boat with. Tasmanian Oak is slightly less dense than Jarrah, but still isn't exactly a lightweight timber. So I'm wanting to build a wooden mast. You can see my dilemma. There's no way I'm going to build it out of Pine or Western Red Cedar, because both are much too soft. I'm interested in the birdsmouth construction, but I want a sailtrack, and I can't think of a straightforward way to do that with normal birdsmouth.

Well if a simple method won't suffice, surely a complicated method will. If I build a sailtrack piece out of Jarrah, then use that to replace the back three birdsmouth staves in an eight sided spar, then mirror everything so the left and right sides are the same, I end up with something that will do what I want.

So I designed my mast in sketchup. The birdsmouth bits are 30mm x 12mm Tassie oak. The sailtrack bit is made from two pieces of 30mm x 12mm Jarrah, cunningly joined after cutting the track with biscuits. Then a pair of 18mm x 30mm tassie oak bits get laminated on, and more cutting happens to make the back of the mast. After assembly the whole lot is planed to an oval shape 63mm wide x 76mm long.

Sounds easy! I wasn't so sure, so thought I'd prototype something. Importantly I want to use only methods of construction that will work with 6.1m long bits of timber. I'm thinking that means doing everything with my trim router.

I started by cutting the birdsmouths into my 30mm x 12mm tassie oak. I used a 12mm dia 90 degree V bit in my trim router, with some guides screwed into the base.

I repeated the exercise with a 12mm round bit in the side of some 30mm x 12mm Jarrah to make half the sailtrack.

Then I laminated two pieces of the sailtrack Jarrah, plus two lengths of 30mm x 18mm tassie oak. This is going to be the hardest part with the full length mast. Keeping squeezage out of the sail track is going to be hard. For the prototype I forced some wadding down the track once it was assembled to clear the squeezage. Doing that over 6.1m is going to be challenging. It might be easier to cut the slot part before gluing so that I can get access to the inside of the track.

Once my lamination had set up I cut rebates into the tassie oak part to locate the front five staves.

This is what my prototype looks like now. I still need to bevel the back sides and cut open the sailtrack slot, glue the whole shebang together, then plane it to an oval. I weighed this 300mm section this morning at 649g. That's with a fair bit of material still to be removed. That means a 6.1m mast built like this should weigh around 13kg, and hopefully be as strong as they come...

Saturday, 25 October 2014

Inner deck supports, two goes at a mast tabernacle, and battery tray

I haven't been able to spend terribly much time on the boat of late, on account of being away for work rather more than usual. Much of the time I have spent was wasted, building a tabernacle that I ended up chucking out. Here's the first go. I had it in mind that I'd run it down either side of the spine through the bridge between the centerboard case and front thwart.

The result looked really awful. The tabernacle looked very heavy and the spine rather light. It looked kinda perched there.

After spending some time in the moaning chair, I decided to beef up the spine, and mount a smaller tabernacle to the top of a wider, thicker bridge piece rather than the sides of the spine. So I got the saw and chisel out and removed the reinforcing either side of the spine, then replaced it with a larger piece. I also put a second reinforcing piece under a wider bridge, horizontally. This makes the bridge about 25mm thick rather than 6mm, and mostly solid Tassie oak, sitting on a thick reinforced spine.

The tabernacle is made from Jarrah, with 16mm thick side plates and a solid wedge shaped piece between them. I bored an 18mm dia hole for the mast pivot bushings. I'll turn up some bushings to go in there and use a 12mm bronze shaft for the mast pivot. I'm waiting on some 12ga bronze screws to screw the base of the tabernacle down to the bridge piece. I'll attach the centerboard lifting block to the back of the tabernacle once it's installed.

I'm done with steaming for now, having steamed the inner deck supports. I also steamed a thinner piece of Tassie oak with which to form the back of the fo'c's'le. Nice gradual curves. When you sit on the forward thwart facing aft, the curved piece should make a nice comfy back rest.

To further procrastinate before starting planking, I knocked together a battery tray, which goes in the front thwart. This accepts a 20AH 12V sealed lead acid battery, which should be plenty to power a fixed VHF radio plus AIS transponder. I've put a slot in the tray for a tie-down strap, which will affix to the bulkhead above the battery. That way the battery will stay put even if the boat is capsized.

Tuesday, 30 September 2014

Inner gunwales, seat tops, and fillets

Before trying again on the inner gunwales, I spent a little time fitting the cockpit seat tops nicely, and cut out a seat top for the forward thwart. Here's both my men enjoying coffee (frothy milk in the case of our cat) aboard the boat:

Rather than have small round hatches in the bulkhead to access the space under the forward thwart, I elected to put larger rectangular hatches in the top, ala pathfinder. This will make this space a lot more useable for stowing gear that I want to stay dry. I'm already making a battery mount for this place, and will be putting all the electronics (radio, ais transponder etc) in here. The coaming will need to be trimmed a little to ensure the hatches can open, I think.

I also enlarged the centerboard pivot hole and did a test fitting of the pivot and bushes. It all fits nicely, and the centerboard turns easily on its pivot. I'll add some caps to either end of the pivot to locate it, and some o-rings to keep water out of the boat.

Much work is still needed to clean up the centerboard slot and glass it. This can wait until I've done planking and decks, and even painted the inside of the boat.

After the initial failure, putting the inner gunwale in turned out to be quite easy. I just steamed them in two halves, leaving a clamp on the scarf. One other tip I learned was to ensure none of the Tassie oak tea that collects in the tubing runs back into the kettle, as it causes the kettle to boil over. This is easily accomplished by ensuring the kettle is at the top, so the water runs down away from it into a handily placed bucket. Also there's no need to wait while steaming. I had my best success when I just started pulling the gunwale in to the frames as soon as the steam was running. I'd pull each tie in a little, then work back along the gunwale and give each tie another pull, until after ten minutes or so it was held in its notches. Then I just kept the steam up until the kettle boiled dry. Much less exciting than trying to guess when the kettle was about to run dry and rushing to get it tied in place.

After running the plane and spokeshave down the gunwales, and a little time finessing the fillets and coating much of the boat in epoxy, it's really starting to look the part. I really love the curve the deck will take, swooping down around the cockpit, coming up for the foredeck, and mostly levelling off by the time it gets to the bow.

Wednesday, 10 September 2014

Finished stringers, steaming and inner gunwale scarf failure

We finished the stringers today. It's really starting to come together. Here's a side view, taken from the vantage point of my bench:

It was actually pretty easy - we used 12mm x 20mm Tasmanian oak for the stringers, and there was no need for steam - they just went straight in. The bow is really rigid now.

There were a few difficult bits. A couple of the frames were not quite spot on for fair stringers. I found the lowest stringer had to come up about 3mm from plan on bulkhead 3, and the top stringer had to come down about 6mm on bulkhead 6. I'm vacillating about dropping the middle stringer on bulkhead 6 a couple of mm too. Here's the detail for the stringer join on bulkhead 6. Note the spacer that I've made that sits above the stringer.

Once the notches are adjusted, the line of the stringer is really lovely.

We experimented with steaming on a deck reinforcing piece - I added some 18mm square Tasmanian oak half way between the inner gunwale and coaming, from bulkhead 1 back to bulkhead 4. The plan has a fair bit of unsupported deck - I thought it would be useful to add something. Anyway, we used a technique I've seen on youtube for steaming the timber, where you stick it in some tubular bag material and pump steam through. After twenty minutes we just stuck it in its slots while it was still in the bag - easy peasy.

We tried to repeat the exercise with 20mm x 30mm Tasmanian oak for the inner gunwale, but had rather less success. The process was a bit of a comedy routine - the bag came off the steamer just as we were ready to put the gunwale on the boat, then George's mobile rang causing much juggling. I tried to bung it on the boat but found I couldn't tie knots with oven mitts on. Then finally the scarf join half way along the gunwale came apart, and that was the end of that. Here's the scarf join before we started. I'd have said it was a real good one.

And here's the sorry mess afterwards. It was definitely a failure of the epoxy. Both sides look much the same. I'm thinking epoxy and steaming are fundamentally incompatible. I'll either have to scarf after steaming, use timber the full length without scarf joins (not available locally) or else build the gunwale up from multiple thinner pieces that don't need steaming.

Sunday, 7 September 2014

Stringers!

With the transom on, there's nothing for it but to get stuck in to installing the stringers. I'm trying hard to catch up to John Florance's Navigator build. It's hard work, as he's already up to the second course of planking. To give myself a bit of an unfair advantage I've enlisted the help of my mate George, who I used to go sailing with on his Tasman 26, and who's flown all the way across the country to help out.

Here he is scarfing stringers while I supervise. Using him as slave labour like this is only reasonable. I mean he's the one who gave me the whole sailing bug anyway. I suggested today that he should sail his boat around next time so we could duck out to the Abrolhos islands. I think that's only fair.

Indeed George was doing such a fine job, I figured I might as well spread my sleeping bag out on the cockpit floor and have a nap. It's very comfortable there, and my boat doesn't snore at all!

We started by roughing out cockpit seat tops from 6mm ply, which hold the rear four bulkheads nice and securely. Then we started at bulkhead 8 and cut a notch in each bulkhead for the lower stringer. We did this using the tenon saw, and then knocking out the ply from the middle using a 19mm chisel, with the bulkhead supported by a length of pine clamped to it to prevent splitting.

By doing one bulkhead at a time and test fitting with a piece of timber, we were able to ensure the angle of each notch is right for the path of the stringer, with no huge gaps.

Once we were happy with the notches in the rear four on both sides, we glued the stringer in and clamped it overnight, before finessing the notches in the bow. This was mainly because we don't have enough clamps to do two stringers full length. Here's the aft port side all glued up and clamped.

Then we worked the notches in the bow to get nice fair curves in both stringers, and finally notched them into the stem. The goal for each notch is to bury the stringer deep enough that a couple of wipes with the plane on both the stringer and bulkhead will five us a decent gluing surface for the planks.

The view from forward shows things are nicely symmetrical. There's quite a bit of bracing to ensure the stringers don't pull the bulkheads out of true, especially towards the bow where the bends are more interesting.

From aft, you can see the rather interesting collection of clamps to pull the stringers in while holding everything true. I'm thinking fewer clamps will be needed as we move up, because the prior lot of stringers will hold the boat true for us.

Wednesday, 3 September 2014

Putting an arse end on the boat

Never one to do things the easy way, I wanted to put some nice timber on the arse end transom of my boat. I'm really liking Jarrah, for its warmth, durability, and absolute pigheadedness. Unfortunately I couldn't find Jarrah in thin planks to use as a veneer locally, so had to make do with 20mm thick stuff. Here's the first couple of planks, having been planed accurately flat on edge and glued together.

Now that I was working on the transom, Mogget lost interest in the rowing thwart, so I had an opportunity to take a photo. Cool, huh? I rounded the edges over with a 6mm round over bit, making them easy to work with and comfy to sit on.

Once the four planks for the transom veneer were joined edgewise, I planed the back flat, and mixed up an enormous batch of epoxy, which I slathered on both the Jarrah planking and some 6mm ply. While it was setting up, I put as much weight on it as I could conveniently do.

Barrett Faneuf was all fancy with her transom, and used a saw to cut the planks edgewise into thin slices. I have no saw. What I do have (thanks Dai!) is a thumping big router with a 25mm bit, a huge hand plane, and a whole lot of stupidity enthusiasm.

After a couple of days of going at it with the router, I had a really rough surface approximately 6mm thick, which I could then plane smooth. This I did with my awesome English Stanley no. 7, the smootherator.

So then I cut my veneered ply out into a transom shape, and sanded out some minor diggage from the plane. One of the things that makes Jarrah so strong is that the grain goes all over the place. So the plane tends to dig in a little, even when it's set for a really fine cut and extra sharp.

To celebrate, I applied a quick coat of epoxy. It's protective, honest. Doesn't that look nice. Actually seriously the epoxy is a barrier to ensure no grey silica gets into the grain, hopefully meaning there's less sanding needed on the transom once the planking is done.

Building the doubler out of Tasmanian Oak took longer than building the transom itself. Much work with the tenon saw and chisels. One advantage to having really sharp chisels is that when you cut yourself, they make a lovely clean cut, with no bruising or jagged edges. Said cut heals much quicker and neater than a cut from a blunt chisel.

Putting the doubler on the transom gave me another opportunity to use all my clamps at once.

Here's a test fit of the transom on the arse end of the boat. Look ma, no clamps!

And finally here's a view from the rowing thwart, all glued up. I used some rope to pull it forward towards bulkhead 8, seating it positively against the back of the cockpit seats. A couple of clamps pull it downward into the floor, and a final spreader clamp ensures the cockpit seat fronts are properly seated.

The astute will note there's nothing between the two sides of bulkhead 8. It's a deliberate deviation from plan, along with ditching most of the bits between the two sides of bulkheads 5 and 6. I worked out that if I ditch the back of the cockpit seats, there's enough space on the floor for me to lay out my sleeping bag and sleep. Not dreadfully comfortably, mind, as there's not a huge amount of space down the side of the centerboard case, but certainly doable. Here's a test fit of my sleeping bag on the floor of the boat, complete with cat (and you thought you were going to read a whole blog post without a picture of my cat). Here's a pro tip. If the cat goes deep into the sleeping bag and his eyes turn completely black, it means he's about to kill you.

Monday, 25 August 2014

Playing with paint, finishing the rowing thwart, sharpening my spokeshave, and centerboard pivot

A bit of a laundry list this week. I'm saving some money to buy Jarrah for laminating on my transom, so have been doing other bits and pieces in the meantime. Firstly I thought I'd have a thorough play with my new aquacote paint, and use it to paint my centerboard.

I've used epoxy paints before, I've used water based paints, and I've used polyurethanes. This stuff is a bit of a mix of all of the above. The undercoat is a two part waterbased epoxy. No isocyanates as far as I can tell (yay!), and simplified clean up because you can flush most of the mess out with water. There's a brush-clogging residue left though that has to be removed with epoxy thinners.

This stuff is extremely thick. It builds quicker than any paint I've used before, and refuses to level. I used a 5mm nap roller to put the first layer on, then tried a brush for the second coat. I think I'll try thinning it out rather more than the recommended 10% next time, to save myself quite a bit of sanding.

Based on my experience with the undercoat, I tried spraying the top coats, a polyurethane with a cross-linker that you bung in just before going to work. Again, 10% thinning as recommended is nowhere near enough. It sets up in mere minutes. I can see a path to gloss without buffing, but I've got a ways to go before I reach that. Anyway, here's the centerboard. From two feet it looks fantastic. Just don't look too closely!

I finished the rowing thwart and Mogget immediately decided it was the perfect perch. He's been sitting there all day, and I haven't the heart to move him to take a photo.

I also installed inspection hatches in the cockpit seat fronts, plus lots of bits of Tassie Oak reinforcing for the cockpit seats, and lots of epoxy fillets. I'm hoping that if I'm really methodical in filleting everything that's supposed to be watertight, then they will be. Watertight, that is.

All this work left my new spokeshave rather blunt. The blade is very short and won't fit in my honing guide. I fashioned a little adapter from some scrap aluminium so I can fit it in, with an indexing thingy to ensure it's held at the right angle:

With it securely held in the guide, my new Japanese waterstones do a sterling job of honing the blade. This Veritas spokeshave is just such an amazing jewel of a tool. I can see myself buying more in the future.

Last but not least, I turned up a pivot pin and bushings for my centerboard out of phosphor bronze. The pivot is 19mm diameter, and the OD of the bushings is 25mm. Should be plenty strong. Alas nobody I know has a 5/8" UNC die I can blag to make the threads, so I'm going to have to buy one. This is a much closer view of the centerboard, and you can see the imperfections in the paint. To be honest I'm not sure how perfect a boat has to be. I'm used to painting really over the top stuff (bicycles and motorbikes, which get people looking from a few inches). The boats I've sailed have been rather rough and ready, and worked fine. This centerboard is going to be under the boat, and is likely going to be smacked against rocks and sand. I think I'm just going to have to shove my OCD in a box and get on with it. I can let my OCD back out for stuff that's really visible.