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22 December 2013

Small is Beautiful vs Bigger is Better

Small is Beautiful vs Bigger is Better

So we're looking at our T32x8 LUNA. Small(ish). Beautiful.

In Inner Space: Some Thoughts on Interior Design, I wrote about this interior layout we favor for a furnished cruiser:

Our favorite layout on 8ft beam

This diagram shows no linear dimensions. From forward, the linear allotments run:

4ft Foredeck / 6.5ft Bunk / 6.5ft Salon / 7ft Galley / 8ft Cockpit = 32ft Total

This was the layout from LUNA (AS31x8), with a bonus foot thrown into the galley. Its 20ft interior was snug and comfortable for the two of us.

But our wishlist makes it feel a little cramped...

Anke's brother (who comes sailing with us every few years, for a month or two at a time) is just a little to long to fit comfortably on the made-up dinette (6.5ft). So he likes to sleep diagonally. Which means squeezing past him on our way fore or aft. An extra 6in in the salon would straighten him out.

 The galley would benefit from yet another foot. It would allow...
  • Anke's garden on the workbench (1ft x 3ft).
  • Extended wood storage under the workbench.
  • Extended galley storage and counter space. 
None of these are critical... but an extra, extra foot would relieve the squeeze of ambition. Especially, our goal of doing more foraging / hunting / processing is more easily met with the extra counter space and elbow room. The wood storage lets us be less miserly with heat, a factor as we age. The garden will be there in any case, but it squeezes the workbench without that extra foot.

Outside, we've been happy with a (nominal) 8ft cockpit for years. But. If the yuloh is going, the other person has to squeeze around its forward end. An eight foot project (such as an oar) won't quite lie flat, so we have to fudge around. Can't carry plywood, either.

The end curves of a 32ft TriloBoat are also 8ft, which scrunches just a bit abrupt. Nothing serious, but an easier curve makes an easier driven hull.

Meanwhile, LUNA maxed out our sail plan for junk rig on masts of a comfortable height. Yet we're upping displacement over 20%. If we want to keep our SA/D ratio high, we have to go with taller masts and higher aspect ratio sails (problems with that we'll discuss later), or we have to increase boom, battens and yard. Since we don't like to overhang the hull, for handling reasons, that means we're inclined to lengthen the hull under the sail.

The T32x8 LUNA displaces about 10.5Klbs @ 1ft to 14.25Klbs @ 1.3ft. That's plenty of room to grow, but at a cost of about 1in / 1Klbs.

Soooo... lets add it up:

4ft Foredeck + 7ft Bunk + 7ft Salon + 8ft Galley = 36ft


That's a 22ft interior, slightly eased in each of its sections.

The T36x8 LUNA displaces about 12Klbs @ 1ft, with 15% ballast. This is as much as we ever hope to use, without giving up an inch of draft. And it's still a light boat, for length. If we ever need to, we could sink her down to about 16Klbs @ 1.3ft.

Just to compare, a Benford 36ft Dory displaces about 13.5Klbs @ 3.5ft (shoal option), 40% ballast. A Hess 28ft Bristol Channel Cutter displaces 14Klbs @ 5.5ft with 33% ballast.

Mmm. Waffle, waffle, waffle.

In the end, the pluses won out. The minuses don't add up to that much on such a shoal boat, and some are one-time costs. Handling is very close to comparable, and pays its way with added performance. Maintenance will be the equivalent of an extra, 4ftx8ft space. Not a happy thing, but doable. It's possible the extra elbow room will make it easier across a wider area (don't have to crawl into such tight spaces to clean or paint).

So, a T36x8 LUNA it is... we have a winner!

T36x8... We have a Winner!






6 comments:

  1. The exact size you mentioned you wanted to build back when you sold Luna, Capt. Dave!!! Ya'll must have intuitively known what you needed coming right off of (sharpie) Luna. A giant "Zeiger circle". But, a well proven design now after thinking it over for 6 years. Indeed..... 36X8 sounds perfect. Even beats the 4:1 beam-length ratio and should sail wonderfully. I'd be reluctant to give up on the increased glass of a standard trilo though. But, you thought that one through too, aye? It's going to be fun watching this come together from afar. Feliz navidad, noble mon Dave and noble womon Anke!!!

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    1. Hi Gomez,

      Thanks for reminding us! That helps counter that queasy feeling I get every time we consider a larger boat... having started small (our first DIY boat was ZOON at 20ft x 6.5ft), that's a lot of hemming and hawing over the years.

      The window decision was the toughest. We've flip-flopped on that one the whole project. But the decision is sitting well for a couple of months, now. Our mockups look good, too.

      As you know (but others might not), LUNA had wedge-shaped windows (narrower at the fwd ends), starting at a 10.5in opening and down from there. They were interrupted by big stretches of solid hull, and the biggest one (aft port) was covered by the stowed off-centerboard. We skipped the aft starboard window in favor of bookshelves. Even so, LUNA has way more light, below-decks than is usual on a sailboat, something noted by our every (sailing) visitor (yours too?).

      So the new boat will increase and connect those windows into a taller, (pretty much) contiguous, wide angle view. Definitely less than the STANDARDs, but ample.

      I tend to think this approach (biggish windows in the hull proper) is widely applicable to other hulls, so long as they're light, and aren't highly stressed by their rig.

      A light hull lifts ahead of and dodges big wave impacts, while polycarbonate can be sized stronger than the hull itself. Rig induced hull stresses in free standing rigs stay well clear of the hull... big cutouts don't compromise chain-plate transfers of A-frame crane stresses inherent in stayed rigs. Even then, bonded bulkheads create 'safe zones', isolated from that kind of trouble.

      You'd think, it being easy, we'd all be doing it!

      Dave

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  2. It's great fun following your cogitations about your new boat Dave. This is a lot more scientific than the way I went about mine: found a plan I (and my wife) sort of liked, looked at what we didn't like, made some "back of the envelope drawings". When it looked "right" (Whatever that is) we settled on it. I Haven't done any number crunching, well not much anyway. I figured that flat bottomed boats have floated for centuries...so this one will float too. After all, the sides are high so will stop the water coming in!! Mine is pretty much the same size 36' x 10' and quite similar to Triloboat hulls. Difference is there are no sails and it won't go on the sea. Strictly a river boat, made for living on.

    Happy Xmas, belatedly and a happy new years to you and Anke.

    Joel

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    1. Hi Joel,

      Well, the 'science' part is on the pseudo side! 8)

      I think what makes our process so niggly is the combination of ergonomics, shoestringiness (shoeString Theory?) and the rough nature of where and how we cruise.

      On the ergonomic front, our mortal coils compete with even fractions of plywood. On the shoestringy side, long and short term economies battle over each detail. On the rough side, displacement dukes it out with manageability on an ultra-shoal, armored bottom. Rig vs decks vs cabins. Narrow vs wide (which widens options). And so on!

      So the whole thing turns into a Goldilocks Equation... what configuration constitutes Juuuuuuust Right for us?

      But aah... livin' on the River! Sounds wonderful, too. Let the world come drifting past, rather than chasing after it! Easy does it.

      Aye, 'tis a consummation devoutly to be wished!

      Dave Z

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  3. the new design looks great......can't wait to see photos of it dried out on those beautiful Alaskan tidal flats like your other vessels have been. What are the foils and rig going to look like?

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  4. Hi Robin and Karen,

    Thanks... you and we both!

    Still thinking about foils (spoiler alert: travelling off-centerboards) and junk rig. Still working through options, which will be covered in upcoming posts.

    Very much influenced by your (KILDA's) double-sheeted junk rig, which puts fanned sails in the running. We're very attracted to their beauty and twist/camber control.

    Dave Z

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About Me

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Anke and I live aboard SLACKTIDE, our T26x7 ketch. We sail by wind, tide and muscle in the waters of mid- to northern Southeast Alaska. We try to maximize the joys of life, and minimize the chores. ........ We live between the communities of SE Alaska, but drop in to visit with friends. Lately, we've worked, every other winter, care-taking Baranof Wilderness Lodge in Warmsprings Bay. This has given us a window on Web. ........ We're working toward a subsistence lifestyle, somewhat impeded by addictions to coffee, chocolate and cheese. ........ We think TEOTWAWKI is looming, and while we won't be ready, we'd at least like comfortable seats.