Please visit our home site at www.TRILOBOATS.com.

Anke and I are building our next boat, and writing about it at ABargeInTheMaking.blogspot.com. Access to the net comes and goes, so I'll be writing in fits and spurts.

Please feel free to browse the archives, leave comments where you will and write, and I'll respond as I can.

Fair winds!

Dave and Anke
triloboats swirl gmail daughter com

Saturday, March 28, 2015

Glass House of Waffles: Looking Along a Path Not Taken

T32x8 FANCY STANDARD

This is a modified repost from abargeinthemaking.blogspot.com, where I chronicle our building of a T32x8 LUNA variant. This post goes over why we chose that type over the FANCY STANDARD version. By a whisker. Here's a look into some of our decision process.


Glass House of Waffles: Looking Along a Path Not Taken

When the tarps came up from Andy Stoner's MARY ELISABETH (T32x12), Anke and I nearly swooned from the view!


360deg View
ME is what I call a STANDARD TriloBoat design, meaning half her length being standing head-room cabin, with end curves limited to the end quarters of hull length. One long sheet wide. Sides a cross sheet and a half tall plus crown (6ft at the sheer, up to about 7ft down the centerline).

Very efficient of time and materials. Good living space to length ratio. Sedan-like aesthetics. And the windows... did I mention the windows? 


 

That upper, half sheet can be plexiglass. In a 32ft hull, the cabin is 16ft. Windows along each side are 2ft x 16ft huge! That doesn't count the smaller, end and bunk windows!

270deg View
Inspired, we designed SLACKTIDE around (almost) 2ft x 8ft windows with a 'kayak' view... sitting on the floor with generous headroom. 

And it has been wonderful!






  *****


So we were sorely tempted by a variant of T32x8 STANDARD.

The huge windows and 360deg view are attractive, as is full, standing headroom throughout the cabin. The galley and sitting room are luxuriously large (in our layout), with enough to carve out a bit - if we so desired, for other purposes. 

Quick and inexpensive construction get us going quicker, with more left in the kitty, compared to virtually any other design.

Problem to address: 


Standard 4ft side height is very efficient in terms of materials. A sheet of ply topped by a half sheet of plexiglass.

Bit it means the lower edges of windows are above eye level when seated in furnishings built on the inside of the hull (no bilge) to normal dimensions. Without some juggling, one can't enjoy most of the view from a seated position.

Andy chose to raise his dinette 10in, gaining a great, all-round view while seated at the table. 

His settee, opposite, stayed low in the hole. This worked as Andy was looking to sleep eight people on-board. The back of the low settee folded up and locked to make an upper bunk over the one at seat height.

Being greedy, Anke and I want a view from all seats.


We could raise the whole sole 10in, but that would sacrifice full standing headroom in the sitting room, and force a step up/down from the galley and to the forepeak bunk. 

But we like the bunk area to be part of the sitting room social space. Being under the foredeck, it's low already, and a 10in drop increases the isolation.

Raise dinette and settee? That leaves a full-headroom gangway between settee and dinette, with views from both. Hmm. Feet are left to dangle from the settee. A fold-up footrest could work, but on 8ft, would cramp the gangway. Boo.

Well... if we lower the bottom edge of the windows 6in it solves the eye-level problem. And it grows the windows (now 2ft6in)! 


Only draw-back (a considerable one) is that we can no longer use efficient half sheets of plexiglass. Some of the 1ft6in offcuts are usable, but it's gonna cost us. But hey, it's only money.

But OH! To sit at the table with the mornin' cup o' mud, looking round with 360deg view through those giant windows!! I'll call this variant (with lowered windows) a FANCY STANDARD.

Another consequence; the leeboardy, off-center-boards we favor are already squeezed by a standard standard (assuming blocking the view is not an option). Lowering them reduces leverage above their fulcrum, requiring tricky engineering, both of board and hull. And, when stowed, low boards can't clear the water, so clunk in any slop. 


In SLACKTIDE, we addressed the problem with traveling boards, which roll all the way aft for stowage, clear of water and windows. But they have to pull clear of the slot and they're heavy suckers! I haven't figured out a way to get sufficient but simple, traveling mechanical advantage to help (a boom works but is only so-so simple). 


As is, they're beyond Anke's strength to lift clear and stow, and it won't be long before they're beyond mine. The only options are accept boom hassle, build them lighter, and put up with blocked windows or noise at anchor.

Skegs would be our choice, but they double our draft. Only to two feet, but that's the difference between boots and hip-waders. And that extra foot would exclude us from many's the skinny and interesting perch along the high tide marks. Every now and then, it would mean the difference between skinning into shelter and not. Boo.

On the other hand, we don't have to handle them, 'specially as we age. They raise the bottom, when grounding, a foot proud of nasty rocks. Copper bottom plating can be much lighter, saving thousands of dollars. 


Hmm... there's a coupla yays to balance that boo.

One perk of the design is that, since it has flush sides (and a wet-locker arrangement that can act as a mud-room... see Getting aHead), we could build a watertight door into it. Handy for loading, and it may come to pass, as we get older, that we might want to haul ashore. Diminished agility to climb in and out of the boat would likely be a big part of that decision... a sole-level entry would come in handy.

Hmm. Hmm. Nice foredeck... 8ft square!

But the bunk has to go under it and headroom is low. There's plenty for sleeping, and enough to sit and read. But kneeling would be bad for the back (you 'vigorous couples' - as Wharram would say - will know what I mean). Could always limit the repetoire or take it elsewhere, but it breaks up the moment. Boo.


We prefer to sleep longitudinally, rocking side-to-side on (rare) rolly nights. Oriented so, the bottom curve competes with the foot of a full-length bunk. To get more length, the bunk has to stay high (can't lower it for more headroom).

We could live with a shorter bunk (but, alas! I'm 6ft). Or we could make the bow curve slightly more abrupt to clear the foot. Or lower (bigger bow transom), meaning more plunging and introducing pounding. Or we can add structure for more bunk head-room, such as a pop-up hatch, but that's kludgey, blocks the view and imposes on the foredeck.
And no storage (aside from the anchor well) forward of the bunk. Boo.

On the plus side, the big foredeck compliments the split junk ketch rig we're favoring (not shown). It's high balance (sail area forward of the mast) makes the most of that big, open space.


Turns out, after months of fiddling, we could address each of these problems to the point that they were no longer boos. But not quite yays, either.

We could sleep thwartships (easy bow curve, forepeak storage vs narrower bunk, reduced bunk lockers and book-space, and some discomfort in rolly conditions). We could extend the cabin 4ft forward (excellent bunk headroom and improved mast position vs fugly appearance and increased windows (already ample, now just expensive). The skegs... erm... not first choice but call it even.

But those windows... what would we sacrifice for those??? The windows held us in dithering limbo.


*****

What we finally decided, after months of waffling back and forth, is that - for the way we live - the fancy standard would be great in harbor vs good-but-not-great underway (draft, mostly). Great for old age vs good-but-not-great while still up-and-at-'em. Great windows vs a handful of compromises.

So, reluctantly, we decided to abandon those wonderful windows.

Boo hoo.




I could'a been a Contendah!

8 comments:

  1. interesting.. our cruising area would not be a bad idea for the skegs.. would you anticipate making them part of the original sides (4' high, then a 3' add on instead of 4 + 2) or would you add them afterwards? I would think you would want them to be extremely stout.. probably more than the 3/4 sidewalls.

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    Replies
    1. Hi TMM,

      Here's a conversation between a friend asking about the skegs and myself:

      Q: Did you work out a full length skeg for the center 1/2 that is a straight run?


      A: For that model, yes. Easy to mount along the deadflat. Not too hard, beyond, but have to build the 'deadwood' up to follow the curves.


      Q: I am curious how you envisioned them: entry, exit, angled out or just straight down for max strength, how far in from the sides, a different rib structure due to point loading, doubled up 2X stock in thickness or even bigger, armored with u-channel??????????????????????


      A: Hadn't worked out all the deets, but we were going to mount 12in x 8in-ish beams flush with the sides and vertical. If no bilge, this keeps lag screw heads/washers out of traffic, and simplifies copper plating.

      The angle can be dropped from the chine, and side plate simply butted or lapped against the hull side armor.

      If plating, we'd favor simpler shapes... probably carve the ends to curve up and outboard in planes. Carry heavy plate up the bottom plane and overhang in T flanges either side of the skeg for extra LR. Wouldn't need angle along the skeg, but might use it anyway, the L leg facing away from the skeg. This would make a very secure attachment for the T plate.

      Or, could braze one up. Or simply use U channel with no flanges.

      A problem for bilgeless Tboats would be no ordinary structure to tie into. Probably increase the chine logs substantially and use heavy side fasteners to lock it in well. With that much beef, bolts would be okay.

      If just going through the bottom, I'm thinking lags driven down into the skegs with big washers. If the skegs got stripped on a hard chance (hopefully) the lags would strip rather than pull their heads through the bottom.

      All that depends on the ply quality, I'd say. Really good hardwood marine could stand up to a lot more than the cheap AC we use.


      Q: Do you see any huge differences in sailing ability between centerboarded and skegged versions? Even tougher to tack?


      A: My guess is that skegs would make them less nimble. But, ST has been fine on tacking since we learned not to pinch going into it, so there's room to increase tracking, I'd think.

      I've heard that both long, shallow keels and bilge keels have more drag than single, high aspect ratio means, so that's two strikes on speed. Also, you can't lift them when off the wind, so will be slowed for no return unless sailing on the wind.


      Q: I'd say 2' draft is more than worth it for the security of not having all that mass hanging on the side of the boat for mother ocean to swell against. And not worrying so much about bigger stones on the bottom, etc..


      A: Weeeeelll... one is tempted to go to 18" skegs, if any, so can crawl under if need be. We haven't had any OCB/swell problems, so feel pretty confident, there.

      Avoiding stones while drying out is a big plus, but if we hit one, it can go right between the skegs. Assuming we've gone lighter copper for having them, we might ironically be in worse shape!

      I think the real decisive factor will be how we do in old age. The LUNA style allows us to lift the boards mechanically (clearing the water but not the slot) without blocking the view. So that lets us go with boards longer.

      But that was the nip and tuck of it all.

      We LOVE that ultra shoal draft, and it's saved our butts many's the time (not really, but we've skinnied into hurricane puddles ahead of storms that another couple of inches would denied us... would've had to sail further for other options).

      Hard to give it up!

      *******

      One possibility would be to drop the doubler plates (if you're using them down along the skegs. This would provide a very strong, outbrd attachment as a start towards affixing them.

      Sorry that got windy!

      Dave Z

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    2. Our doubling plates extend all the way down to cover the outboard sides of the skegs.

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  2. Dave,
    Inspiring stuff.
    Have you considered a mono-proa?
    Your hull designs are almost fore-aft symmetrical anyway.
    With two rudder / centreboards to leeward, you can still have an uninterrupted view to windward for big windoows

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    Replies
    1. Hi Mark,

      We have thought about proa and multihull options, but I doubt they'd be much good.

      In any kind of chop, a good heel really helps a box barge/scow, by putting a chine down to form a V, which also presents to oncoming waves.

      Akas, amas, outriggers and the like work to keep us on our feet. Fine for off wind, but seems like it would be clunky to windward.

      Still, there's been some experimentation - especially by Johannes posting at proafile.com - though I haven't followed up on this. You can image search "triloboat proa" for pic and video results.

      Last I heard, Johannes was playing with my suggestion to rotate the square hull by 45deg, making an easy build V hull with 90deg between bottom planes. Sections would be diamond like, similar to Superman's chest emblem.

      Thanks for reminding me... I'll try to follow that up!

      Dave Z

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  3. Was just re-reading this and realized you said 12 inch deep .. by 8 inches thick! I guess that is due to the weight of the vessel setting down on them... for some reason I was thinking 4 inches... but wonder if it could have side sheer while settling if a wave pushed you sideways. too thin would be unstable...

    I guess there is a balance between strength and usability.

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    Replies
    1. Hi TMM,

      The reason for that hefty width isn't so much for strength, but to provide a wide contact surface with the bottom. They could be tapered down, in my opinion, so long as the upper face is adequate.

      The way I picture it, the most dangerous moments will occur on lift off from a beach when a windshift has made ours a lee shore with fetch (or can happen on an emergency beaching).

      In these cases, we're up and down and SIDE TO SIDE in the surf, making intermittant contact with the bottom. A strong side-swipe with contact, especially against a rock, could really stress the short lever arm of the upper skeg. Worst case would be pulling bolt heads through the bottom or separating the chine.

      By widening it out, the stress is spread out and leverage much reduced.

      But again, I'm no engineer... if really going for skegs, I'd likely get a second, educated opinion from someone with experience (professional or otherwise).

      Dave Z

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  4. Our Skegs are seven inches wide by 9 inches deep. We will see.

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