05H36 Keel Stub

[Al - s/v Persephone]

Glenn -

When ordering Persephone, the salesman was unable to tell me the sinkage rate and AVS.

You were kind enough to provide both the sinkage number and a PDF of the entire stability curve. While I was a little concerned to find the AVS was only 114 degrees, seeing the ratio of positive area to negative area swung the deal for me as adequate for my intended uses.

Thank you. Otherwise, I might have missed out on owning a boat that has given me more than 6,000 nm of sailing between Nantucket Sound and Penobscott Bay, easily (though not always comfortably <g>) handling conditions from Force-1 to Force-7 with ladylike aplomb.

(Her dry cockpit when pinned over by a thunderstorm with port sidedeck awash showed me that the very substantial form stability of your high freeboard design made my earlier theoretical concerns about a single ultimate stability number out of context rather naive.)

Since no good deed goes unpunished, I'd like to ask you another question about your excellent H36/356 design.

Noting the recent post about the keel peeling off a J-boat (and that it may not be an isolated case),
http://forums.hunter.sailboatowners.com/showthread.php?p=614169#post614169 ,
I'd like to know the thickness (or other relevant parameters) of the stub through which the keel bolts pass, and its potential for avoiding such a problem of a supposedly "better" (at least more expensive) boat.

I measured the hull thickness at the only point I could - the through-hull for the depth sounder - at just under 5/8". While that's not exactly like a Caliber, the hull reinforcement provided by your grid seems to have made it quite adequate in avoiding hull flex.

As was the case with my naive AVS question, I guess the thickness of the keel attachment surface may have to be taken in the broader context of whatever other considerations you took into account in that part of your design, so please describe them as well.

Thanks for your patience in answering such questions, and thank you for a great boat design.

Fair winds,
Al
s/v Persephone

 

[ghen]

Al,

To make you feel even better about your AVS question, that number was calculated in Mmpoc ISO configuration. That means the headsail and mainsail were bent on ,raising the center of gravity. The anchor was in the bow roller. In short, there are many configurations to set up a boat for stability calculation. Your was in sailing trim with two crew at sheer height. If you were measured in Americap configuration, the AVS would be somewhat higher. Also, the CG was calculated by actual physical righting moment test. Not theoretical weight study calculations. 114 degrees is real. How the boat is configured to obtain VCG is something than needs standaridzed in the industry. I have a magazine article I hope to get published on that subject.

Regarding the keel, all my laminates conform to ISO and ABS standards. Both standards are very conservative and produce an extremely strong boat. The keel sump where the keel bolts attach is way over spec. I can't remeber exactly but I think the 356/36 is about 1.5" thick. I spent a good part of my youth cruising and delivering boats, many of the junkers. I appreciate what it is like when the "red lights go on" and you are all alone. I will not design anything I would not take my own family out in and I love my family. If I had more time I would tell you about a crack-up I did with a Hunter 41. It shouldn't have survived but she did. It was one of those South West Airline commercials, "Wanta get away?".

 

[Al - s/v Persephone]

AVS follow-up

Thanks, Glenn.

Just looking down into my bilge, I can easily believe the 1.5" but just had no way to tell.

I was interested in your comment on different configurations for determining AVS.

A mere 5% increase in the number would meet the 120 degree minimum for some ocean races in which, some day, I might be interested (Boston-to-Halifax, and possibly Newport-to-Bermuda).

Is it possible that some of the boats meeting or exceeding that number are doing so with methods that might make the H36/356 equivalent number compute out at or over 120?

Thanks again, and
Fair winds,
Al
s/v Persephone

 

[ghen]

Al,

Most regattas use the ols IMS or Americap system that has the sails off the boat, and other VCG raising measures. It is possible depending on how you have your boat set up. If you have radar arch on the mast and life raft on cabintop, maybe not. Those regattas require you to be measured by a certified measurer.

 

[Al - s/v Persephone]

Oh, well.

There's no way I'd ever give up my RADAR.

I'm pretty confident in Persephone in sub-storm conditions, based on actual (not always by choice) experience (but I do sail with all drop boards in, having been pooped in a previous boat).

I've fitted her out with custom 8.8oz Doyle sails (all-full-batten main w/3 reef points) and all lines led back to the cockpit (including vang) w/extra Spinlocks and oversized winches, permanent SS jacklines, extra cabintop grab rails, bottom hold-downs for companionway steps, etc.

The triple-reefed photo in my icon was only Force 6 in pretty flat seas, but shes's easily handled higher winds and much heavier seas. I think she can handle a lot more than I can.

But, to "meet the numbers," I guess I'll just have to trade up to a 41AC <g>

Thanks again.

Fair winds,
Al
s/v Persephone

 

[Maine Sail]

Al your boat looks good..

I was visiting a client in Newburyport the other day and swung though the yard (don't we all do this when we see a boat yard). Persephone looked good with the cover off. You've actually had it off now for a few weeks!! I always look for you but have yet to catch you...

 

[Al - s/v Persephone]

Thanks for the kind words, Maine Sail.

Persephone will be pleased, and I like to have her in a good mood before launch time <g>.

I haven't, however, "removed the cover," as she has never been covered since I took delivery in late Dec. '04.

My last boat was always covered, and having to remove the scour line around her topsides from fine yard dust blowing under the edge of the blowing/moving shrink-wrap really annoyed me. So did removing the deck crud when one Winter I tried a tarp.

When I ordered Persephone, I noticed that the dealer, whom I respected, had a lot of expensive inventory which sat uncovered throughout the winter.

When I asked him about it, he said "these boats are built to withstand a salt water environment. Snow is nothing."

With a cockpit that's open to draining at the stern (a feature I greatly appreciate on Hunters, from the time I got a cockpit full of an out-of-sync 8-10 ft breaker when crossing the Merrimac River bar) I figured (and have found) that FRP crazing/cracking from ice expansion against the cockpit walls wouldn't be a problem.

So I tried it that first winter, and have been happy with the results. She's just cleaned off by the Spring rains, washed and then gets one coat of Collinite 870 before launch.

So far, so good. I assume someday the sun effects will make me have to put more effort into it, at which time I'll certainly try to take lessons from your polishing/waxing postings that display far more knowledge on the subject than I have.

Fair winds,
Al
s/v Persephone