Thin water tidal changes and wing keels? - SailNet Community
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Thin water tidal changes and wing keels?

Looking for advice about wing keels and other wider, flat(ter) bottom keels at very low tides, particularly in thin waters with mud/sand bottoms. Each boat and keel will be different, but in general, are there bigger potential problems for smaller cruising boats with a wing keel (or say a beavertail bulb keel) when sitting on the bottom during an occasional very low tide, vs. those for a more conventional shoal fin keel, keel/cb, or full/long keel?

Two potential issues occur to me, being: (1) possible structural damage to the keel itself, or more likely to the hull or bolts above the keel, from the boat resting on the bottom for several hours at a time; and (2) the possibility of the keel becoming stuck in a mud bottom even after the tide starts rising (with little/no room to kedge from abeam).

The depth in my Florida slip at low tide varies from about 3 feet to 5 feet, depending on the season, winds, etc. A neighbor has a Flicka (3'3" draft, long keel) that rests on the bottom of his slip during especially low tides, maybe 6-8x year, particularly in winter. (The Flicka is a tough little boat and seems to have suffered no damage as a result.) This doesn't happen often enough to warrant the disadvantages of twin/bilge keels, but it does happen often enough to prompt this question.

Yes, there are differing opinions about the merits of various keel structures in a grounding while underway, but today my question is mainly about any adverse effects of too-low water due to tidal changes at the dock (or at anchor) for wing-keeled boats.

Recently a couple of wing keel boats with drafts in the 3' to 4' range have caught my attention, in particular the Pearson 27 (3'4" wing) and Catalina 30 (3'10" wing). Any thoughts on the keel structures of these boats resting on the bottom in particular?

Advice based on first-hand experience is preferred, but I'll be grateful for other reasoned opinions too. Thanks in advance.

Joe in SPB
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Re: Thin water tidal changes and wing keels?

The only first hand experience I have with a winged keel boat was on an O'day 272. We were sailing on Long Island Sound where the tidal range is about 8' when we ran aground on a falling tide. Could not kedge or motor off so we waited and waited until...
all the water left with the tide and the boat was left standing, upright, on the winged keel on a sandy bottom. We could get off the boat and walk around it.
It was a bit precarious, walking around on a boat that was perched in this manner but it stayed upright until the tide came back in again. Eventually we floated off with seemingly no ill effects.

This keel type seems to be a bit more tender under sail than a long keel (like my boat) and certainly makes a bit more leeway than a fin keel would.

Every shoal draft boat will have it's compromises.

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Re: Thin water tidal changes and wing keels?

Certainly there are compromises with very shallow draft. Have you considered one of the English bilge keelers? They are designed to rest on their keels with every low tide. You would have to look around to find one, but there are a few on this side of the pond. We have a Moody in our club for example.

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Re: Thin water tidal changes and wing keels?

I had a Cal-39 with a huge wing and went aground the first time I took it out. The tide was going out and there was no way I was getting off and the boat ended up with the hull completely out of the water sitting on the keel/wing. My experience is the that most force during this is when the hull is just in the water enough to allow it to float a little and bounce. During that period you call watch the bottom of the hull whre the keel is bolted flex like a bitch.

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Re: Thin water tidal changes and wing keels?

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I had a Cal-39 with a huge wing and went aground the first time I took it out. The tide was going out and there was no way I was getting off and the boat ended up with the hull completely out of the water sitting on the keel/wing. My experience is the that most force during this is when the hull is just in the water enough to allow it to float a little and bounce. During that period you call watch the bottom of the hull whre the keel is bolted flex like a bitch.
Don -

Other than the (bitchy) visual, was there any damage to the boat? Did you have the keel bolts examined or replaced afterwards?
How long did you have to wait until the tide came in enough to get underway again (or until you were towed off)? Thx.
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Re: Thin water tidal changes and wing keels?

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The only first hand experience I have with a winged keel boat was on an O'day 272. We were sailing on Long Island Sound where the tidal range is about 8' when we ran aground on a falling tide. Could not kedge or motor off so we waited and waited until...
all the water left with the tide and the boat was left standing, upright, on the winged keel on a sandy bottom. We could get off the boat and walk around it.
It was a bit precarious, walking around on a boat that was perched in this manner but it stayed upright until the tide came back in again. Eventually we floated off with seemingly no ill effects.

This keel type seems to be a bit more tender under sail than a long keel (like my boat) and certainly makes a bit more leeway than a fin keel would.

Every shoal draft boat will have it's compromises.
Caleb -

Was there any damage to the boat? Were the keel bolts examined or replaced afterwards?
How long was the boat resting on its keel before the tide came in enough to get underway again? Thx.

Joe in SPB
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Re: Thin water tidal changes and wing keels?

Joe,
The boat continues to sail to this day (it was not my boat). As far as I know there was no apparent damage.
The amount of time the boat stood on it's winged keel was only several hours; long enough for the tidal cycle to ebb and flood again - so no longer than about 6 hours total until we floated off again.
Probably the biggest damage was to the owner's ego as he has sailed this boat in this locale for years and prided himself on local knowledge.

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Re: Thin water tidal changes and wing keels?

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Don -

Other than the (bitchy) visual, was there any damage to the boat? Did you have the keel bolts examined or replaced afterwards?
How long did you have to wait until the tide came in enough to get underway again (or until you were towed off)? Thx.
The only damage was one edge of fiberglass mat in the bilge sump area cracked loose . It wasn't structural and I expoyed it back down later (like 2 years later). Bolts didn't come loose and I didn't replace them (they were massive) and the keel didn't even break the caulking where it was mated to the hull stub.

Tow boat finally pulled my over on the boats side at about 45 degree angle as hull was completely, I think this cause as much stress on the boat as it prevented.

I think it was about 5-6 hours before I could get off.

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Re: Thin water tidal changes and wing keels?

Boats with fixed keels are built to sit on the keel.

Every boat I see sitting on the hard, sits on its keel whether wing, fin or otherwise. Jackstands are used to keep the boat from falling over, not to support the weight of the boat. Most of the weight of the boat is on the keel, not jackstands.
I would guess with my 14000 lbs. boat, less than 1000 lb are sitting on my jackstands.

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Re: Thin water tidal changes and wing keels?

If you are open to other designs, you might consider a retractable keel. Some of these boats are pricey, however.

There is the English-built Southerly series and the US-built Hakes (albeit daggerboards in this case.) No longer in production are boats like the Sequin 40 and the Clearwater 35. My Clearwater 35, shown here, has a weighted swing keel and has more lead in the very slack bilge. With the rudder retracted (like a centerboard) and the keel completely retracted, she draws less than 2 ft and can sit on a reasonable soft bottom of mud/sand without any problem. I keep her at a shallow water dock and she does indeed sit on the muddy bottom on some of the really low moon tides. The weighted keel does not stick like a centerboard after sitting in the mud.

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