Shoal draft keel versus regular fin keel - Page 2 - SailNet Community
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post #11 of 22 Old 08-14-2007
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Basic physics - a little weight further out has leverage to equal substantially more weight closer to the fulcrum point.
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post #12 of 22 Old 08-14-2007
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Given that many boats offer shoal and deep draft versions, would it be possible to change the shoal version to a deep draft version? Would that prohibitively expensive? I understand the rudder may need to be changed out too.

This is assuming it's not poured in place, and is rather attached with keel bolts, and that the ballast is the same type of material between fin and shoal draft. (in order to stay within the original manufacturers design parameters).

It seems totally nuts, but this is sailnet, so maybe someone has tried it?
It has been done. Mars Metal is a good company to contact to explore the option. The keel itself may not be as expensive as having it shipped to you, lifting the boat, getting rid of the old one and refinishing the area...

http://www.marsmetal.com/newpages/keelhome17.html
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post #13 of 22 Old 08-14-2007
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I am sure that people have changed out keels....but why?

On my boat, which is a 34' shoal draft, the keel weighs 5,200 pounds. Anyone price 5,200 pounds of lead formed into a keel with bolts lately? There are way to many boats out there for sail to get into this kind of a refit.

With new rudder, probably in the neighborhood of $20,000. Buy one with the keel you want!
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post #14 of 22 Old 08-14-2007
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I'd have to agree with tommyT... doesn't make sense to swap out a keel, unless there is something wrong with it or the boat is extremely large and expensive.

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post #15 of 22 Old 08-15-2007
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SOme of the newer 4 digit Tartans are designed such that one can change out the keel in a simple fashion. So if one were to buy a deep draft as is typically speced here in the puget sound region, and you sail to a shallower draft region, or move it too, you can get the shallower draft keel installed easy enough. Personally, I can not think of ANY advantages to a shoal draft. But that is from some one that is typically reading "---" on the depth guage! ie too deep to read! Then again, maybe if I was on the east coast, I might thing differently. I personally will take the deepest lightest keep I can get! Makes you faster to some degree, may not be a lot, but it is faster none the less!

Marty
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post #16 of 22 Old 08-15-2007
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You would definitely miss out on much of the really good sailing on the Chesapeake Bay with a 6 ft. keel!
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post #17 of 22 Old 08-15-2007
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Quote:
Originally Posted by paul77 View Post
......would it be possible to change the shoal version to a deep draft version?
There was a guy in our yacht club who changed his fin keel to a wing keel. He would have consulted with the designer or a naval architect before he started. He did the work himself with friends helping. He cut a 2 or 3 feet off the keel, made a mold for the wing and casted it with the lead he removed, plus some more. He drilled and lagged several bolts into the fin and bolted the wing on. Major job, but do-able.
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post #18 of 22 Old 08-15-2007
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I think it really depends on your needs. I f you don't need shoal draft I would advise not to get it.

Our club is located inside a channel that at moon low is only two feet. Shoal draft is very desirable because it means waiting less time to go in and out of channel. Typical low tide is almost 4 feet so many shallower draft boats are not very affected at all.

The next point is that it all depends on the boat and the design. Research the performance of each before deciding. Even die hard cruisers who repeatedly state that "speed is not important" like to have a boat that performs well if possible. As has oft been stated here an extra bit of pointing or speed means you reach your next destination sooner ...

Several examples I have seen at our club. C&C30 mark 1. We have had two with shoal draft version and 4 with the standard fin. The "shoal" version is actually a fin but is a bit longer and about 1 foot shallower. It does not give up a lot on performance to the other C&Cs. In my mind this shoal version is a winner. Other examples are a 1990 MacGregor 26 - not shoal but a swing keel or centerboard or something. The rest of the boats had all finished our end of season fun race and that boat had not yet made the windward mark. Yet another is an ODay 27 with a stubby wing keel. Again the performance to weather is lacking.

I agree with above posters. There are enough used boats out there that it is probably cheaper to sell your boat and buy the same baot with a shoal keel than it is to change your own keel. Then there is the fact that the designers of the boats with shoal keels probably attempted to get maximum performance from that shoal keel as well as stability. A DIY keel mod would always make me nervous. The boat is designed with the keel on it. Unless you area very knowledgable naval architect I can't see chopping off 3 feet to be a good idea in any circumstance.

Buy the right boat for the area. Do the research. Then post your question here about how such and such a boat you have found and how well it is built, performs, etc ...

Good Luck!

Looking is the best part!

Mike
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post #19 of 22 Old 08-17-2007
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Unless you are planning on racing a fair bit, the performance issue is not a big one. The difference between a specific boat with a shoal keel and the same boat with a fin keel is usually measured in the single digits (per mile). You need to be a very good sailor to take advantage of this.

If you like the boat - buy it and don't worry much about the keel. If it was designed to sail with a shoal keel then chances are it will work well. BTW - a properly designed wing keel will provide slightly better off-wind performance than a fin...

Last edited by Sailormann; 08-17-2007 at 01:02 AM.
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post #20 of 22 Old 08-17-2007
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I keep hearing what I consider the somewhat the misleading information that one misses out on great Chesapeake sailing with more than 6' of draft but having cruised the Chesapeake with 6'4 - 6'6 draft current boat for the past five years I see almost no difference in where I can go between my current boat and the 5' draft boat that I had before her. For many years I cruised with a boat that drew over 7 feet and they seemed to go wherever I went with my 5 feet, just more carefully. I would think that you needed to get down to less than 4 feet to see much of a difference in cruising grounds.

The thing about deeper draft fins vs shoal draft or wing keels is that the shallower boats have a lot more drag. The difference in speed doesn't show up much in higher breezes, and so the relatively small rating difference, but in the Chesapeake with our predominantly light winds, it makes a huge difference in the number of sailing days per year that you will actually get to sail vs motor.

Jeff
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