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Go Back   SailNet Community > Skills and Seamanship > Seamanship & Navigation
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Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


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Old 08-30-2007
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Shallows in a swing keel

I am curious about general techniques used by experienced swing keel boater in shallow water. Do you raise it part or all the way up and keep sailing with a lot of slipping? The PO of my boat told me he had sailed in shallow water in light air with the keel up, rudder pulled to the surface and it did fine. I would expect it to blow all over the place (well, blow down wind anyway). I am thinking about going under my boat with a diving mask and a yard stick to figure out how many cranks back up give me different depths.
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Old 08-30-2007
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If you have a swing keel—which is just a weighted centerboard in reality—then you will blow about a bit, but depending on the draft of your boat and the hull design, it may or may not be a big problem.

I find on my boat, which is a centerboard design, that if I don't have the board at least a third of the way down, the bow tends to blow off pretty easily. This is probably due to the fact that the boat's hulls have a very shallow draft—only 14" or so, and that the boat is rather light for its size—3800 lbs and 28'... and that it has a bit more windage than some boats its size, since it is a trimaran.
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Old 08-30-2007
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Sailing shallow

Andy, are you really going to be spending that much time in water less than three or four feet deep?

If you're talking about only those occasions when you're running up to a beach to picnic, or leaving from or returning to a shallow ramp, You'll probably still be able to have the keel dropped a foot or two, and in a boat that size, that will give you some amount of steering predictability and help minimize leeway.

Much as I like the image of you with a yardstick and diving mask, how about this ...

First time you launch in water deep enough to accomodate the keel all the way down, count the number of turns on the crank it took you to get it down. Then you can probably safely assume that half that many turns brings the keel about half-way up, etc.

You gonna splash her this weekend?

Kurt
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Old 08-30-2007
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I found that when beating back to the dock I also need the keel at least 1/3 down to maintain headiing. Otherwise I end up doing circles out there just short of the ramp/dock.
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I sailed my boat for two years with the centerboard up. Did it make a lot of leeway? Sure, but she still pointed fine and I never had much trouble going to windward. When I finally got it working this year, it was a pleasant performance improvement - but because of my experience without it, I don't regard using the CB as a requirement. So, it's down when pointing, up the rest of the time, and when in doubt (i.e. in shallow water) the board stays up.
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Old 08-30-2007
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Kurt,

Barring unforeseen complications, the hull will be wet on Sunday.

The specs say 4'9", so to be on the safe side I want 5+. Time wise, the closest "coastal" sailing to me is the upper reaches of the Pamlico at Washington, NC. Drafting 2.5' instead of twice that would make it a decent sailing ground. EDIT - This trend continues for quite a ways further down.



There are other places in nearby fresh water that are iffy for a real keel also.

Last edited by arbarnhart; 08-30-2007 at 10:26 AM.
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Old 08-30-2007
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Whoa!

I see what you mean, Andy. After Gaston, I had more water than that in my back yard.

Well, like others have said, you'll make leeway with the keel all the way up, but since you're not racing or trying to hit Bermuda on the nose, that shouldn't matter a great deal.

Have a great sail, sir.

Kurt
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Old 08-30-2007
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A question I've been meaning to ask. I'll probably move up to a SJ21 in a year or two -- my first ballasted (swing) keel boat. The owner's manual says you should pin the keel in the half-up or full-up positions, don't just let it hang from the winch cable.

Granted, I can see that shortening cable life, but.... There may be intermediate settings that are useful, and grounding on a cable-hung keel sounds better than having it bolted to the CB box. Yesno? Two other questions in this vein:

1) The SJ21 has a wee reputation as a boat that needs to be steered -- short waterline/OAL, narrow keel, flat bottom, etc. Also initially tender. Will moving the chief foil's center of mass & resistance up and back cause wicked lee helm or rolling? And if this boat requires so much tiller work, how does a singlehander leave the helm, duck into the cabin, and play with the keel?

2) I'm a windsurfer and dinghy sailor by training; we tweak the centerboard every time we maneuver or change headings. Guess that's not so practical with a 400lb lead swing keel. So on small lakes, what to do? Set it to half depth and accept crabbing and tippiness; or to full depth, stay away from shore, and pray you don't trip over it when jibing hard?

Sorry if these are idiotic questions -- it's the one issue that kinda scares me about keelboats. (Love those sailboards -- you can curl your bare toes around the CB knob, raise it, jibe, and lower it all in one fluid move. With a rooster tail. )

ETA: Gosh, Andy -- all that's missing from that chart is the minefields, giant whirlpool, and a kraken or two. Should keep you on your toes!

Last edited by bobmcgov; 08-30-2007 at 11:18 AM.
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Old 08-30-2007
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Kurt,

To be honest, it isn't all that much more of a drive to Goose Creek, where it starts having larger open areas of decent depths, but you still have to stay pretty far from shore except in specific locations if you are drafting moer than 2 or 3 feet.

There are a couple of freshwater lakes that I am thinking about that are mostly thought of as fishing lakes, which will be one of my reasons for being there, but if I go for the weekend, getting in some sailing as well would be fun.

Last edited by arbarnhart; 08-30-2007 at 11:27 AM.
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Bob,

I did see a note on one of my charts, out further off the coast, where there is an unexploded depth charge. ;-> Seriously, I am sure a few old salts from that area are rolling their eyes and saying nobody sails there; they just motor down the channel out to good water. A more legitimate spot is between Harkers Island and Shackleford Banks if going the back way from Beaufort to Lookout. It's a motor boat ride in a crowded corridor, but if you draft only a couple of feet you would have a few options (some potential sailing lanes open to you).

My keel wench is in the cockpit, so it is feasible to mess with it while sailing. The instructions actually recommend pulling it part way up when reaching or almost all the way when running:

http://web.utk.edu/~pdf/newport/newp.../N17_MAN_2.gif

It is not specified as a "drop it and forget it" operation and they don't have a warning about cable stress except when trailering.
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