Das Boot – some of the elements

Much of it, after the actual design is done, is achieving the effect. “Effect” may seem shallow, vacuous but it’s important in some ways:

1. For a start, you have to live with her for long periods, so the overall combination of design, accommodation, colours and sailability or canalability is pretty important.

2. Ted Brewer wrote that no boat under 40′ should have portholes and he’s right – it looks silly, it’s a small craft trying to act like a big ship. The rig, the windows, the keel, should all blend into a whole which is appropriate for the size of boat.

3. This last point is exacerbated when going multihull. Even the trimaran, the most “boaty” looking of them, can’t really carry a full schooner rig and not be laughed at. It’s bad enough having four masts and three hulls but as “tri” suggests modern, though it’s actually ancient, there are ways around it.

One of those is to run lug sails rather than gaffs [they’re gaffs in the photo at the top] and to reduce to one jaunty headsail [roller furled]. All the courses [the main sails on masts] roller reef onto the booms, which use jaws [as in the photo at the top]. They also use lazyjacks from the masthead, under the booms and back up again, to keep everything ship-shape.

There’s been a quite deliberate attempt – it took ages to achieve – to reduce the mast length to 17′ maximum [15′ for the aft jigger.  This quite excessive “lowness” is not really for stability, as it is a trimaran and is stable enough anyway but to enable the carrying of more sail, coupled with distributing it over the length of the boat – as it is a shoal keel and the pontoons act as blades too, the whole rig and foil combination must be elongated.

This has the effect of making “helm” less critical, i.e. it doesn’t really matter how much of which sail is up, it will not drift downwind or swing upwind.  It’s also easily trimmed.

Even though she’s a trimaran, I still feel the side elevation is one of elegance.

This is the view from the bow:

The crossbeams or akas don’t look so elegant but they’re painted in the duller red/brown so they don’t stand out.  The walkways are on the lower side of the frames, multiplying the usable space.  There is 3′ of walkway either side of the main hull and netting from there to the pontoons [amas].  Overall beam is 21’8″.

Excuse the iPad pics which distort the scale – this is folded, as on the canal:

This might sound stupid but her excessively fast speed – this hull will do 20 knots if the lug sails don’t backwind, is a bit of a problem at sea.  You want fast but not this fast.  Note the twin rudders – idea is to mount them on the sides so they don’t fall behind a transom but behind skegs.

The major advantage of the fast hulls is that so much less sail area can be carried and the various numbers become “nice” – that’s a long, lean boat, which designers would always want but can’t afford with large crew/passenger carrying.  Mine carries three adults or two kids for any adult.

And that’s it – somwhere in the compromise you must pay and I pay in payload.

Pleased to say, on this Brexit weekend, that should she ever be launched, she’ll be flying the red ensign from the staff at the stern, with her home port stencilled onto the transom. She will never never never fly the flag of slavery of the EU.

Post navigation

2 comments for “Das Boot – some of the elements

  1. Doonhamer
    June 24, 2018 at 23:30

    Nice boat. I’m jealous.
    The pontoons (last picture) have ropes which will stop them folding forward, but surely drag will tend to make them told back. Or have I missed something. I have been following your project for a while now with great interest.

    • June 25, 2018 at 08:18

      Doonhamer, it was an issue of a diagram with no explanation.

      They are not ropes, they are 1.5 inch dowel and run from the vertical level of the aka [crossbeams], 4 feet above the water, down to the level of the cockpit sole [18 inches above the water line. They pick up a minimum of wash that way, given that they are a fair way above the waterline even at the lowest point, plus they’re leading sternwards.

      I think I’ll dispense with the forward diagonals [since drawing them in] because of this:

      What I did not draw in was the four inch by half inch planking either side of the main hull, finished timber from Wickes, Travis Perkins or the local yard. These make the walkways.

      The 2 inch fishermen’s netting [available from a place up the road here] runs from there to the pontoons [amas]. It is knotted, therefore much cheaper.

      On the canal, the storage spaces in the stbd pontoon house my long term valuables in sealable plastic boxes [from Costco], all the timber, masts, booms, yards etc. are wrapped in vizqueen and go on top of that closed pontoon [ama].

      The port pontoon is used for everyday storage, e.g. water, food, things not necessary to keep in the cabins. I’d like to keep the cabins largely free of clutter.

      All materials are readily available online and locally – this is why this project can be done by anyone with yard space.

      Once on the river/sea, half a day is spent extending the amas and screwing a length of 4×2 [until then stored under the vizqueen] each side of the main hull, 26.5 inches out from the gunwhales, screwed down to the akas at predrilled and glued points.

      Then short 26.5 inch 2x2s are screwed from gunwhales to those fore and aft planks, spaced every 2 point something feet.

      Now screwed down to the akas, plus the short planks, is the 4 x half an inch finished planking and there are the walkways. It goes like this – a length of 4 inch flush with the gunwhale, then half an inch gap, 4 inch, then half an inch gap and so on – 6 planks either side. At half an inch thick, they re quite light to lift and place.

      The beauty of straight sides and straight lines is that these planks can be screwed in parallel and perpendicularly, no curves to negotiate.

      I’m going to run the risk of not putting in the forward diagonals for now because I do think this planking will hold the amas and akas in place, plus the aft diagonals are still there to help keep the whole crossbeam and walkways structure forward.

      Those walkways are critical to living on the boat because:

      1. Structurally, up flush with the boat, they add great rigidity;

      2. They release deck space for sailing purposes, not for sunbathing, for example;

      3. They heavily reduce wash coming up the straight sides from below, with very little “slap” at four feet above the waterline.

      This is one of the beauties of going for the longer boat too, even if that does create its own issues. Longer boat means greater water plane and cubic area inside, meaning greater carrying capacity. Those planks are truly nothing in the overall weight.

      The generally accepted beam of a trimaran is just short of its length but that’s using massive sail area [900 sq ft]. I really don’t like their layout, with that tall mast waving about up there.

      I’m using 530 sq ft, spread out and low, therefore the beam can be narrower, which means less weight and more structural rigidity. But it also means that all the boat sits on the same wave, so to speak, whereas super wide boats can have one hull on a wave and others in troughs – that adds too much stress for mine.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.