Full Keel vs shoal Keel reduction

DianaOfBurlington · Aug 23, 2012

The answer you probably don't want.

Cutting depth off the keel will result in a much tippier, less stable boat. There is no way to avoid this without adding the same amount of lead to the bottom of the keel, perhaps in a different shape to faciliate a shallower draft.

But, a caveat-- all shallower-depth fin-keeled boats are, to some degree, tippier and less stable than their deeper-finned counterparts. They also do not point as well to windward. It's a matter of leverage, not merely arm-and-moment. You rarely see tall-rigged boats with shoal keels; and this is why.

You might consult some designer(s) or yards who have done this sort of project to see how they refastened the cut-off lead back onto the fin and what shape they used. I have seen boats on which this has been done, however, and few of them were to my own standards. But then, that's me; and I chose a deeper-finned boat on purpose.

I would not, under any circumstances, merely cut off the keel and leave it that way. I know of a guy who did this but the boat was so tipsy he then cut down the mast to regain some stability and ended up with a bodged-together shadow of his former boat. The truth may be that you might just have too big of a boat for where you mean to sail it; and that's happened many times to many people. Do consider this. If the boat were 60 ft long and 9 ft deep, would you still intend to make the same sort of modification to sail it in 4-1/2 ft of water?

Jim Legere · Aug 24, 2012

Although I have never seen shoal and deep draft Hunter 37Cs "side-by-side" there are significant differences. The shoal draft has a much shallower bilge (although deep enough compared to many modern production boats!) so it carries the lead higher up. This also means the mast step is higher and the mast butt shorter. The shoal draft also carries a bit more lead, since the weight of the keel is 7150 lbs versus 6650 lbs. I think cutting a foot of your keel, even if you used that lead to make some 'winglets' on the sides of the keel, would seriously hurt the performance of the boat. And a foot less draft might make a difference in some anchorages, but I would not want count on a mere 12 inches to keep me safe under sail - just my opinion.

coleman · Aug 24, 2012

brooklyn3 said:
The first solution that I am looking at is to cut 1 foot of the lead off the bottom of the keel, however, I am not sure what effect this will have on the boat.

Ask a professional keel fitter that can make a properly engineered bulb keel:
http://www.marskeel.com/repairs-modifications/draft-reductions

From MarsKeel:

Hull profile sketch shows some detail but doesn't appear to be totally accurate under the waterline:

H33CRich · Aug 24, 2012

Like Coleman says, consult Mars Keels. I have seen a mod they did for an H33C (went to 4.5 from the deep draft version). This is not cheap. 15k-20k if memory serves. It might be cheaper to sell the H337C deep draft and buy a shoal draft version or different boat like a older Morgan 38, Tartan 37, or the like. On the H33, the shoal version is a modified sheel keel. It is not only shallower, but it is much thicker at the tip than the deep draft. The aft edge of the deep keep is vertical vs. swept back for the for the shoal. I do not see this in the two H37C versions. So it may be easier to adjust the depth with the necessary experts doing the work.

There is a nice H37C shoal draft version located in Babylon, NY: http://www.sailboatlistings.com/view/27510

SamLust · Aug 29, 2012

Sail Magazine did an article on this years ago. Couple moved a boat they liked and was paid for to a shallower area. They were able to consult designer who advised and condoned mod as shown in the Mars wire frame drawing. chainsawed off keel, bolted on bulb halves, faired, and sailed happily into thinner water. Weight to a great extent can be compensated, but loss of surface area of keel allows more side slip and reduces pointing. If you want the boat on Great South Bay and are willing to front the money it might be worth while.

H33CRich · Aug 30, 2012

SamLust said:
Sail Magazine did an article on this years ago. Couple moved a boat they liked and was paid for to a shallower area. They were able to consult designer who advised and condoned mod as shown in the Mars wire frame drawing. chainsawed off keel, bolted on bulb halves, faired, and sailed happily into thinner water. Weight to a great extent can be compensated, but loss of surface area of keel allows more side slip and reduces pointing. If you want the boat on Great South Bay and are willing to front the money it might be worth while.

I think you may be referring to the CS30 keel mod/refit: http://closereach.com/csoa/cs30refit.html

The H37c deep draft does not have the CS30 profile and may suffer more in the performance area with an equivalent chop. However, do the necessary home work, consult a keel engineer, and have fun with.

David in Sandusky · Aug 30, 2012

Trade for the right boat

I'm in the school that says find a shoal draft 37c (or another you like, then sell your boat, and buy the one that was designed for your waters.

Doing the job right will cost serious money, and there are lots of boats available at a good price now. (Of course the value of your boat has probably also declined accordingly.)

It's also worth close study of your sailing area, and thinking about tidal opportunities. We bought a shoal (3 1/4 foot) draft h27 instead of a deep draft (5 1/2 foot) Catalina 30 12 years ago because our marina was worried about getting a 5 1/2 foot draft into our berth. In fact, there has never been a time when we couldn't have motored to our berth with 5 1/2 feet of draft. Sailors talk about Erie being a lake for shallow draft. But despite our gunk-holing adventures in the Islands and bays of the lake, our four touches on the bottom are all related to chart reading or piloting errors, and I can only think of one anchorage we have found where 5 1/2 feet would be a problem.

Good luck, whatever you do!

MLampner · Aug 30, 2012

Won't enter into the debate on if this makes sense or not but as someone who grew up on the south shore of Long Island there is another issue even with a shoal draft. If you don't plan to go out beyond the barrier islands, Long Beach, Jones etc, there is only limited room to tack even with a shoal draft.

As a kid growing up in Oceanside we rarely saw anything but the smallest of sailboats not because of the depth shallow as it can be but because room to tack was to constricted in most of the bays.

H33CRich · Aug 31, 2012

Here is a high level view of the depths in the Great South Bay. NOAA charts would be better. http://www.gsbclams.org/uploads/MAP_2_GREAT_SOUTH_BAY_DEPTHS.pdf
I had a Joel White Row/Sailing boat in LI. The GSB was perfect for it, but I still sailed it off the north shore because it was within walking distance from my house. The LI sound (albeit wind challenged much of the time), Hudson River or the Raritan Bay might be better options. I have friends who travel 2.5 hours to get to our marina each weekend; the winds of Barnegat Bay being the key draw.

anchorclanker · Aug 31, 2012

Regardless of the boats current value, it will be significantly more economical to trade boats. If you proceed, you'll be out whatever the cost of the modification ($20K?), plus whatever reduction to the boats value afterwards, which could be very substantial. Even if the work was done well, it could make it virtually unsaleable at any price beyond salvage value.

Blaise · Aug 31, 2012

One thing that no one has mentioned is lateral resistance. Contrary to the line drawing, the two hulls are different. Hunter had a seperate mold for the shoal draft 37. The keel was not only a foot shorter, about a thousand pounds heavier (to compensate for the reduced lever arm of the shorter keel) it was also approximately 2 feet longer to compensate for the reduced lateral resistance of the deeper keel. Then there is the issue you will have of running aground with your rudder first. Never good.

If you need a shoal draft boat go get one. I am sure that there is a SD owner out there that would love to have the deep draft boat. The sailing differences are dramatic.

DianaOfBurlington · Sep 2, 2012

David and Anchorclanker and others raise important points about the value of the boat both before and after this modification. Allow me to add that I think it a shame that any deep-draft Hunter boats of this vintage should disappear; there are already so few of them (left). The scrap value of the larger keel makes them targets for scrappers trolling boatyards for derelict boats. And there weren't many of them made, in some cases. Take the H27, for example-- the deep version is a joy to sail compared to the shallow one, and yet the shallow one outnumbered the deep one in production by about 4 to 1. You just don't find many deep H27s any more-- and the same for the H25. A deep-draft Hunter in pristine sailing condition is a valuable thing-- in part because it's kind of rare.

So it really comes down to what your priorities are; and I'll reiterate by original point, that maybe you have just got too much boat for your intended sailing area. I mean-- I would like a deep-draft H54 too; but I won't expect to do much sailing with it in Barnegat Bay.

gray_penguin · Sep 28, 2012

I have a shoal draft h33 that I would love to trade for a deep draft 37

I bought mine without having it hauled out, my surveyor did a diving survey. I trusted him and the seller and the Coast guard docs that said it was a deep keel. When I hauled out a year later I measured it and found out it was actually a shoal draft :-(