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| T32x8 with 5ft sides, 8in crown |
Keep a clean mind. Change it often.
Cap'n Billy's Whiz Bag
Honey, I Shrunk the Boat!
Well, there have been a few changes at the ol' drawing board. And I'm only being funny with the title... WE shrunk the boat (y'all don't mind if I call you 'Honey', do you?).
As we started to work out the details, it became clear that the T36 gives up a lot of the synergies that make the T32 such an easy boat.
Another change is a waffle back to 5ft sides (up from 4-9-0), and now with an 8in crown (5ft8in headroom down the centerline). This allows bigger windows (though takes an extra pair of acrylic sheets). It also raises the height of the 'duck-through' the bulkhead between the raised galley sole and the lower salon, and increases the cut-out height between the galley counter and salon (lets the cook be more a part of the party).
It also gives Anke full standing headroom throughout the boat! She's 5ft6in. A 6in crown would be at a bad height, for her... she could stand, barely, but would be encouraged to slouch... resulting in 'that hang-dog' feel. At 6ft even, I'm not tempted to stand, but rather scoot into seats with ample seated headroom.
What we give up is Anke's clear view forward. At mid-deck, standing on an 8in raised sole, the bottom of the forward pilot house (galley) window is at 5-3-6... exactly her eye height. She has to crane a bit to see over. But it falls away, outboard, as the deck curves downward, and she feels as though it's a good trade for the headroom.
Consequences:
Material-wise, the T36 represents an extra half-panel of side (ply, foam, ply) port and s'brd, with an extra butt each side; an extra sheet (ply, foam, ply) of deck, spread over the boat; an extra panel of copper, an extra piece of bronze angle. The 10ft cockpit, 9ft pilot house deck and sides, and 22ft mid-deck exceed an 8ft sheet of ply, so require piecing; that 22ft deck exceeds generally available 20ft dimensional lumber lengths, so requires piecing stringers, edging timbers and worse, hand-rails.
Displacement-wise, we lose about a ton, at any given draft, which is about the equivalent of 2in of extra immersion. And the T36 loses about 500lbs advantage to the weight of that extra 4ft of hull (not all payload, that is).
T32 allows us to be lighter - about 11Klbs at 12in draft) if we can manage - and can go as high as about 15Klbs at 16in draft, which I can't see needing to pack aboard.
In otherwords, there's about 2 tons of overlap, the upper end of which is likely moot.
Speed-wise, we lose some hull-speed, and two feet off our aft curve (increased drag). The mizzen is cropped, so we lose some sail-area, and reduce our SA/D ratio. The consequence is that we drop from potential of a 7.8kt to 7.3kt vessel (half a knot), and it will take a little more to reach hull speed. Tolerable, especially considering we spend so much time puttering along at far less, due to conditions.
Harbor-wise, or any time we have to pay length-wise rent, the T32 will be 11% cheaper.
On-the-hard-wise, I expect that extra 4ft makes a fair difference, when push comes to shove. Aground, the smaller and lighter the better! Even a kayaker can tell ya that.
Interior-wise, we lose a foot in the galley, aka 9ft3 of stowage. This is perhaps the most grievous loss of that one thing that really drove the desire for more. Yet we're gaining a foot on LUNA, whose galley was already ample. Crazily so when compared to other yachts our size. Really, we were just getting plumb greedy.
We lose 6in each in the bunk and salon. I doubt the bunk area will even notice it. The salon, neither, with the exception of guest storage.
Regarding Anke's brother, Peter (our extra-tall guest), we had a brainstorm. He sleeps on the made up dinette, which is slightly longer than he is... problem comes when he extends his feet, running up against the bulkheads. Not a big problem, but it annoys. We'll cut a removable plate in the galley bulkhead, allowing that extra few inches of clearance that should make all the difference! Problem solved.
Cockpit-wise, the two extra feet would surely have been nice for processing foods aboard on deck. But at 8ft x 8ft, The T32 gains a foot (of width) on SLACKTIDE's cockpit, which already handles everything we need. Ample for projects, and has enough room to set up a cooker in one corner, opposite the bench seat. Really, it would just have been a longer walk.
*****
And so, we give up the... ahem... sleek lines, extra space and displacement of the T36, and return to LUNA's comfortably adequate dimensions, as extended by conversion to box barge.
After all, when it comes to stuff, more-than-enough is too much.
This may not be directly apropos to the present blog entry, but I'm curious. Why do you choose to remain with the off-center boards, rather than sacrificing a little shoal draft with long skegs/bildgekeels? Is it your experience, making managing off-center boards little in the way of challenge, or are you reluctant even to sacrifice 9-12" of shoal draft? In any case, I would be very interested to read your thoughts.
ReplyDeleteHi Peter,
DeleteMostly, it's that extra range into skinny water that keeps us with OCBs... for now. The boards are a bit faster (less drag) and let the boat turn quicker. We decided that, for the decade or three of active sailing we hope to enjoy, yet, OCBs had the edge.
We might, down the road, convert to skegs if the extra work of the boards gets to be too much. Once mechanical advantage is in place, most of that extra work is in maintenance. Skegs would be a great foundation if we hauled ashore, permanently.
What pulls us toward skegs is cheaper copper (don't have to armor the whole bottom for grounding, only the lower face of the skegs).
The last part is something hard to put my finger on... the T LUNAs seem to call for OCBs, while the T STANDARDS seem to call for skegs (OCBs are actually hard to fit). But not really sure why... the hulls are identical.
So we waffle between them, split pretty evenly, depending on how we envision using the boat.
Dave Z
Is the standing head room compensated for floor insulation? As in Anke is 5'6", + 1.5" floor insulation, giving her 1/2" clearance before bumping her head? I ask as I am 5'7".
ReplyDeleteHi Dennis,
DeleteIn our case, the answer is a little complicated...
We won't have any bilge, nor insulation other than the ply, some thin foam and carpet.
The bottom is 2 x 3/4ply, built outboard of (downwards from) the lower edge of the sides. Thus our draft is actually 1 1/2in deeper than nominal. But over the deadflat, we're going to add a third layer of 3/4ply upwards, and therefore into the interior.
Headroom before that extra layer is a true 5-8-0 over the inside face of the bottom, and 5-7-2 afterwards. Any foam/carpet further takes away from that.
At your height, I'd either add an inch or so of crown (checking for your eye height in the galley vs the lower edge of the fwd window cut-out) or lower back down till it's positively uncomfortable to try to stand (encouraging sitting down, instead).
LUNA was designed around sitting headroom... that the materials, Anke's eye height and basic geometries all lined up to give her full standing headroom was an unlooked for bonus. Each builder/crew will likely want to play around with possibilities until a workable match is achieved.
Trade-offs are that fwd view (lower deck or higher galley sole) vs through-blkhd considerations (higher deck and/or lower sole) vs salon headroom (higher deck) vs materials (side height extensions and dimensional lumber/ply combinations) vs hull geometries (lower decks and sheer for reduced windage and easy boarding). Mock-ups help with the decision process.
In my book, materials are the least important... my policy is to build it the way we want it, as we'll forget the chump change as time goes by.
Good luck! I hope we're presenting a sense of how difficult, yet how rewarding the decision process is!
Dave Z
Oops...
DeleteI should further point out that the mid-deck (over interior spaces) is ply/foam/ply totaling 0-2-2, built upwards from the sides, and the window lower lip is 0-1-4, for a total of 0-3-6 over the top of the bulkhead (5-8-0).
A 0-3-0 beam runs along the top of the bulkhead, which reduces the duck-through between galley and salon.
It's a numeric jungle out there!
Dave Z