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post #1 of 51 Old 04-24-2012 Thread Starter
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shoal draft keel vs regular keel

Some boat builders, hunter for example, offered models that are identical except one has a shoal draft (non centerboard) fin keel and the other has a regular fin keel. My own hunter 25for has a shoal draft keel, with about a 50%page ballast to displacement ratio. Draft is actually less than 2.5' to waterline. I feel like the boat could point better, but I don't have the experience on other boats to really compare.

I am now looking at two 1981 hunter 33's. They are in similar shape, similar asking prices. One has a 4'shoal draft, the other 5.5.

Are there any other considerations to be had about this choice besides pointing ability? Just how much worse will a shoal draft boat go to windward? Is a 5.5' draft pushing it for cruising li sound? How about the keys and tortugas?
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post #2 of 51 Old 04-24-2012
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Re: shoal draft keel vs regular keel

Peter:
There is no substitute for draft in terms of performance. Of course I sail on Puget Sound where the water is deep so draft is not an issue here. I'm lucky. I tell clents that draft is a "personal problem". If you can't sail in your chosen cruising ground due to draft then that is not "good performance". Personally I would not want a shoal draft boat.

You might also find that in addition to poor performance on the wind the shoal draft boat will give up some stability.

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post #3 of 51 Old 04-24-2012
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Re: shoal draft keel vs regular keel

BobPerry is correct. Shoal draft is a "requirement" of water, not an option of preference, well, it IS an option if you are a trailer sailor (like me).

Honestly if you sail mostly shallow water, you can snicker at the deep fins, who can't get where you go! However, they'll be snickering at you when it comes to open water, and you need to sail close to the wind!

Like I said there is a special exception to this rule, and that's trailering, where it's dictated not by how deep the water, but how steep the ramp for launching (yourself)... a shoal draft keel is way easier to trailer launch than a deep fin! Some ramps don't even go deep enough for a trailer to get a deep fin launched! hell some aren't even deep enough for the shoal draft keel (stink pot ramps).

There have been many attempts at "fixing" the sailing performance of a shoal draft keel, like the scheel keel (see Compac-Yachts), and shoal/centerboard (oday's and tons others), and like mine, wing/shoal (modern hunter/catalinas) with various degrees of plusses and minuses. Generally speaking though, they all have varying problems with sailing close to the wind.
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post #4 of 51 Old 04-24-2012
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Re: shoal draft keel vs regular keel

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Originally Posted by peterchech View Post
...snip...
Is a 5.5' draft pushing it for cruising li sound? How about the keys and tortugas?
You don't need a shoal draft boat for sailing on the LI Sound as most of it has plenty of depth. Having a shorter draft might only help with anchoring in shallower spots. The big concern on the Sound is the 8' tidal range which can be managed with common sense.

Shoal draft boats are common on the Chesapeake where the water is really shallow quite far from shore. Same with the FL Keys. I've never been to the Tortugas but would assume it is similar to the Keys.

That said, boats with 6' draft sail in these places just fine. They may just have to wait for high tide to get in and out of some anchorages.

I too would avoid a winged keel design.

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Re: shoal draft keel vs regular keel

Nothing wrong with any of the keel designs, again, it's a matter of "what is best for your waters." Lots of people get away with wing keel designs all the way up to 60 footers, again for shallow water haunts (Chessie, and Keys a good example).

One keel design not mentioned, is FULL keel. I'd argue there is nothing more seaworthy than a FULL keel (and the draft is usually acceptable), however you're still not likely to point as well as a fin with one.
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post #6 of 51 Old 04-25-2012
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Re: shoal draft keel vs regular keel

As you're deciding this, also keep in mind that there can be a difference between what the manufacture says the draft is and what it actually is when in use with stores, water, fuel, etc.. On my boat, the manufacture claims 4'10", in actual use it's 5'6".
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post #7 of 51 Old 04-25-2012
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Re: shoal draft keel vs regular keel

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Originally Posted by bobperry View Post
Peter:
There is no substitute for draft in terms of performance. Of course I sail on Puget Sound where the water is deep so draft is not an issue here. I'm lucky. I tell clents that draft is a "personal problem". If you can't sail in your chosen cruising ground due to draft then that is not "good performance". Personally I would not want a shoal draft boat.

You might also find that in addition to poor performance on the wind the shoal draft boat will give up some stability.


I am curious if you would be able to give your opinion of the many Charlie Morgan's shoal-drafters...perhaps even especially the Morgan Columbia 40. Morgan seems to have designed more than his share of shoal-draught vessels over the years...though I have never sailed one..or even on one. Seafarer and McCurdy Rhodes seemed to have built alot of 'em too.My old Seafarer 24 was a good boat but I sold her before really trying to sail her upwind very much unfortunately.(or fortunately).

If I am correct then shoal-draft c/b boats evolved from sharpie-style workboats originally and so may have never been meant for much other than coastal work but I hope to do alot more than that with the old Morgan Columbia-40 I just acquired...
It has a 4'6"draft and 9-foot w/centerboard which the hydraulic-system is probably shot to hell with rust but I hope to re-engineer...or fix the existing one...I appreciate any of your thoughts you might have on that model...there wasn't many made...(54 or 55) I am wondering if I should try to re-hab of the hydraulic c/b if it's not too far gone.. Or go in a different direction such as convert to a swing keel of some sort,etc.?

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Re: shoal draft keel vs regular keel

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As you're deciding this, also keep in mind that there can be a difference between what the manufacture says the draft is and what it actually is when in use with stores, water, fuel, etc.. On my boat, the manufacture claims 4'10", in actual use it's 5'6".
Granted I don't load up my current boat, but it has a listed draft of 2'11" but when I hauled it out of the water it only had a draft of about 2'4" to the waterline, so I guess this works both ways lol

I think it is pretty apparent that upwind performance is hurt by a shallow keel, but my question is HOW MUCH. Is it a little bit of pointing and VMG lost, like 10%, or is it much more?

Most of these shoal draft keels lack a NACA profile (haha I think even the standard fin keels generally lack this but less so) and are pretty thick, so I wouldn't be surprised if the difference in VMG is pretty high. But nautical engineering seems to be an art as much as a science sometimes...

The other question is, is there any advantage to having weight down low in the keel? Assuming that the righting moment is identical, because the shoal drafter has either more lead or a bulbous bottom (my Hunter 25 has both), is there some advantage to having that lower keel? I know that when a boat is dismasted, its motion changes drastically, is there some kind of similar underwater effect to having a longer or shorter keel?
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post #9 of 51 Old 04-25-2012
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Re: shoal draft keel vs regular keel

I have a fin keel that draws 4'11". The shoal draft version of the same boat draws 3'7".

I can't get out of my marina from December - March.

It's a tradeoff.
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Re: shoal draft keel vs regular keel

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Originally Posted by peterchech View Post
Some boat builders, hunter for example, offered models that are identical except one has a shoal draft (non centerboard) fin keel and the other has a regular fin keel. My own hunter 25for has a shoal draft keel, with about a 50%page ballast to displacement ratio. Draft is actually less than 2.5' to waterline. I feel like the boat could point better, but I don't have the experience on other boats to really compare.

I am now looking at two 1981 hunter 33's. They are in similar shape, similar asking prices. One has a 4'shoal draft, the other 5.5.

Are there any other considerations to be had about this choice besides pointing ability? Just how much worse will a shoal draft boat go to windward? Is a 5.5' draft pushing it for cruising li sound? How about the keys and tortugas?
I have the Macwester 26 they all have shoal draught keels.
again problems Sailed ok but prone to weather helm and poor windward performance largely as a result of

shallow keels and wide beam preventing close sheeting of the jib

So I extended the bilge keels

Click page one for details Page 1

A long and boring job as there was not a lot of area that one could use to hold the vessel up due to the rounded shape of the hull.

But now done..
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