Scenes from a boat-building, 12/13/2011
Condon Lumber delivers the goods.
Contrary to what my most recent posts here at the League might seem to indicate, it has not been all death and taxes this last week. Amidst the burials and the bloviating there has also been some boat building!
As mentioned previously, we are building a 38′ polynesian-inspired catamaran, which we will be putting into service as a charter sailing boat in Montauk NY.
We are building this boat to US Coast Guard Inspected Passenger Vessel specs, and that meant we had to beef up the scantlings, mostly by increasing the per-side stringer count (strakes that run fore and aft on the inside of the hull) from 5 per side to 7 per side, and increase the demension of each stringer from 3/4″ x 1 1/2″ to 1 1/2″ x 2″, or about five times as much lumber as called for in the stringers in the original design.
On Friday we took delivery on over 400 board feet of vertical grain douglas fir, in the form of 2200 running feet of 3/4″ x 2″ staves. Vertical grain doug fir isn’t cheap either; it’s about 10 times what you’d pay for doug fir sticks at Home Depot. But vertical grain means it’s free from knots and other defects, and it has to be: our engineering calculations are based on defect-free lumber.
The lumber came in random lengths from about 8′ to 16′; the stringers are the length of the boat. A not unreasonable question is “How do you make short sticks into long sticks?” The answer is a scarf joint. There are a lot of different sort of scarf joints, but we’re using a simply 10:1 scarf.
Building a scarfing jig
We build a jig, and then every one of the 200 or so sticks got cut in preparation for being scarfed.
Then we stacked them all on pipe-racks on the side of the shop.
Stacked and ready
When the time comes, these sticks will be glued cut to cut, and the resulting joint will be as strong as the adjoining wood.
1800 lbs of glass and epoxy
On Monday our fiberglass, epoxy, and related ingredients arrived. That’s the resin in the black steel 55 gallon barrels. There’s another ~25 gallons of hardener in plastic jugs, about a mile of 6 oz. volan glass, and several different fillers that we’ll mix into the resin to achieve different properties in different uses.
We also started lofting the boat on Monday. Lofting is the process by which the plans are drawn out a life-size so that various part of the boat can be cut to shape.
Blue tape marks where our wire baseline is stretched tight
We stretched a wire tight enough that it sang to use as our baseline, and then started marking of points on the X and Y axis.
Lines on pattern material (1/8th" luan plywood)
For straight lines it’s as simple as drawing a line between each point. Curves are formed nailing brads into a series of points, bending a batten around the brads, and then scribing the line.
Lucky for me, Joe is a stickler for detail
Today we were able to draw and cut out the full-size patterns for the keel members and several of the lower bulkheads.
Patterns for the keel/backbone of the hulls
Tomorrow we’ll loft and cut more patterns. On Thursday the BS 1088 meranti plywood arrives and we’ll start scribing the patterns onto the wood that actually becomes the boat.
One note about Intellectual Property.
Between my wife and I we own one license for the Apple’s Final Cut Studio and one license for the Adobe Creative Suit. It’s a rare day when both of us need to use either of these programs at the same time, so we’ve elected not to pay the ~$3,000 to have two licenses.
But tonight is one of those rare days. Photos of all of the above shortly! now up!
about five times as much lumber as called for in the original design
[low whistle]
Is that the original design upon which you based your design, or the original design prepared for you that you had planned to work off of?
Do you have an estimated materials cost, and if so are you willing to share it? I’m just plain curious.
(For what it’s worth, I can’t seriously call myself a boat guy, not having grown up around them, not messing with them a whole lot, other than our canoe and kayak, but I seriously love boats. I can stand in a boat museum for a long time studying the hulls, and I can get as excited as a kid in a candyshop over a chance to drive a beat-up old pontoon. If it floats, I love it. So I’m fascinated by your project.)Report
I was unclear and have corrected in the post: The material for the stringers have been increased by about 5 times, which is an increased in materials cost for those members of several thousand dollars (like I said, vertical grain douglas fir ain’t cheap!)
What the USCG requires is that the hulls be able to withstand full submersion to a depth of 22′, as John Marples, our project engineer puts it, “We basically have to build a pair of submarines.”
Fortunately, the stringers do most of the heavy lifting, elsewhere there was little or no modification required, and overall, our weight increase is only about 6%.Report
Ah, that makes sense. I really should have got that from the original wording, since stringers was clearly the antecedent of “5x lumber.”
Keep giving us pics–enquiring minds want to know!Report
I’d be interested to hear how you fare with the Meranti. I’ve heard a few horror stories over pints and on the interwebs about falling standards in ply the last decade or so. Delam, voids, uneven veneer thicknesses, etc. I often wonder if it’s a supplier quality problem or a distributor problem (upgrading or re-marking ply or sliding in rejects or mishandled wood into orders) or just a “back in my day/get off my lawn” problem.
I usually mentally file them in the “you should know and trust your suppliers” or “I thought I got a bitchen’ deal” categories but I do wonder if there’s a long term trend out there due to the general environmental and supply issues and the metric driven corporate culture we live in now.Report
Lumber has gone down in quality. The exposed 2x4s in my attic (house built in 1964) have tighter grain than the Super Special VGDF that we paid top dollar for. Same with plywood. North American softwood plywood is not suitable for a USCG Inspected vessels; even in “marine grade” the quality control isn’t good enough.
For all of the above reasons, opted for Hydrotek, a brand-name BS 1088 ply, and purchased from a well established vendor.Report
The ceiling joists in my house (built in 1916) are honest-to-goodness 2″x4″ boards and they’re as hard as freakin’ iron bars.
There’s a reason lumber companies cut down old-growth trees wherever they could/can find them.Report
Submersion to 22′, static pressure, is a whole lot less stress than storm breakers at sea. After the many stories from teenaged girls getting shipwrecked in their cabin cruisers, it doesn’t seem an unreasonable requirement.
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In fact, the boat is being built to the no longer used ABS offshore racing boat standard, which is one of a number of standards (lloyds, et al) recogniazed by the CFRs that cover T-boats.
Operating a day sailing charter in the sorts of conditions the ABS offshore racing boat covers would be illegal and dumb, and plank on frame monohulls don’t have to be built to anywhere near this standard.
Why catamarans have to be build this way is an interesting and convoluted tale of government and self-regulation and entrepreneurial ingenuity. Post forthcoming.
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