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17 February 2014

Rethinking the Rig

Our first shot at SJR Ketch...
Looks good, but doesn't feel right

Second thoughts are ever wiser.
- Euripedes

Rethinking the Rig

In a previous post (Rig o' Morale), we introduced a variation on Slieve McGallister's SJR (Split Junk Rig), and the above ketch sailplan.

But a few points have been gnawing at me:

The mizzen (after sail) is most valuable to us as a maneuvering/weathercocking sail. Efficiency is welcome, of course, but not a prime consideration.

To leave anchor, for example, we raise mizzen, haul anchor, drift back on backed rudder and back mizzen to fall off reliably on our preferred tack, then raise main and sail off. No muss, no fuss, even with dangers close at hand. For sailing backward, again, we're backing sail and steering with rudder reversed. Occasionally, we'll leave the mizzen standing for a riding sail. We'll often drop the foresail, haul the mizzen close and drift, bow into wind of virtually any strength. This stops our headway, and eases motion for such chores as bailing the dory.

For each of these tasks, SLACKTIDE's flat-cut, low-lift, high drag mizzen has been perfect. Picturing these maneuvers with an extremely high-lift sail, with a large balance (area forward of the mast), jiblets cut full with a loose leech... well, it gives me pause. The high-lift can kick in abruptly, turning a backed sail into a driving one... a willawaw in close quarters could get tense. The large balance moves the mizzen's CE forward, reducing its positive effect aft. The jiblets are likely to flog in irons, which is hard on the sail and nerves... no problem for normal sailing, but... well... we're not normal!

If we want, therefore to go back to a good ol' unsplit, flat-cut mizzen, it reduces the balance by about 4ft, vacating considerable 'airspace' over the hull. Our sailplan is already snug, partly to avoid micro-burst surprises, and also as we don't like to handle very tall/heavy masts. So we want to fill that gap, at least to some extent.

Schooner rig (main mast at the forward end of the pilothouse) would do the trick, but the less efficient, after sail would be far bigger than it needs to be for our needs, and a relatively expensive tabernacle is required to deck-step the tall, free-standing mast. Also, the sheets sweep the cockpit (doable, but annoying), and we'd then want a driver (transom mounted sail) to improve balance, induce weather helm and take over maneuvering (more gear/handling/maintenance/expense). So we'll stick with ketch.

How to close the gap?

First way is to grow the mains'l, extending the battens from 18ft to 20ft. This is as long as one can get commercial lumber, in our parts. We generally prefer shorter battens for higher sail aspect ratio on a given height and less weather helm. But with this design's long mid-deck, we'll make the stretch.

Second, we'll reduce the mains'l balance to 25%. Slieve's first sail set in this proportion. He felt that more, up to 35% would improve performance (subsequent experiments confirmed this), and handling by reducing sheet stress. But even at 25%, the rig performed and handled well. We'll be rigging six part sheets, which will easily handle any extra sheet stress.

Another consideration is that our favored sailcloth comes in 60in width (5ft). At 25% balance, the jiblets can be made from one swathe, while the body can be made from three. Material efficiency!

 As a trade-off, this arrangement sounds reasonable to us.

The result now looks like this:

Note the mizzen slot is gone.

Since these changes, I'm breathing easier. That tight feeling I've gotten - trying to picture our first sailplan in an emergency exit, after dark in rising wind - it's gone away. Confidence is high. Without realizing it, that SJR in the aft position had been working at me.

Funny thing with design. We doesn't always know exactly what we want, or why. Things feel right, or not, and it may take a while to figure out why or why not. But it's almost always worth the effort.

And changing our minds on paper is cheap!




13 February 2014

The Dark Side of DIY

Harboring a Drudge

I gave ya one,I gave ya two
The best that rotten ol' boat would do
Ya won't be happy til I've given' ya three
But I'll be damned if you'll get me!
From The Ways of Man by Gordon Bok


The Dark Side of DIY

I once took a battery of aptitude tests for a range of 'skills'. I confident and capable with all of these (pretty rudimentary). And being good at multiple-guess, I was breezing my way through. 

But then I came up against this one section...

Oh, I was competent, but that was the problem. So I have to admit that I cheated.

Here's the deal. I had little control over where I would eventually be assigned; I would be stuck where a) I showed 'competence' and b) they needed me.  If I scored equally well across the board, it stood to reason, that I could end up in any field in which they had a short-fall.

Here's what the aptitude test looked like:

OOCOOCOOOCOOOOOCOOOCOOOOCOCOOOOOOOCOOOCOOOOOCOCOOOOCOOOOCOO

A whole page of this! In each line, they wanted to know how many C's - a) 12, b)13, c)14 or d)15? Please mark clearly with a number 2 pencil.

My sight purpled with a vision of spending years of my life in a windowless cubicle, doing whatever task for which that aptitude would recommend me. 

The thing is, I'm good at this sort of masochistic detail, but I loathe it!

So I fudged every third-ish answer by one, one way or the other, praying that I was being random enough to evade detection. The final scores showed a satisfying dip at that aptitude... clearly, detail was by far my worst feature.

Now what, you might ask, has this got to do with boat-building?

Well... we're going to be building remote. We'll have a shot at one - maybe two - deliveries in the course of the project. Every sheet, piece of wood, stick, foamboard, nail, glop of glue, smear of paint - not to mention tools, gloves, brushes, trowels, spreaders - not to mention shed materials, generator, fuel - not to mention our daily bread (by which we do not live alone) - all this and more, more, more needs to be counted, recounted, shopped for (on-line), ordered and transportation arranged.

Design is fun. Building is fun. Sailing is outrageously fun.

But did I mention that I loathe counting it all up???

About Me

My photo
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.