Comparing twin keel types

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BobPrell

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I am always interested in the threads on the forum about twin-keeled yachts. They are not well accepted in Australia even though there are cruising areas which they should suit. The Sandy Strait and Moreton Bay in Queensland are two examples.

I have seen a couple of pictures on the yachtsnet archive which make me curious.

http://www.yachtsnet.co.uk/archives/atlanta-25/atlanta-25.htm shows the atlanta 25 has twin keels, but the draught is the same as the fin-keel version.

So does that help windward performance compared to more shallow-draft twin keelers?

Have a look at http://www.yachtsnet.co.uk/archives/macwester-26/macwester-26.htm

When I compare the shadows on the keels I can see the atlanta has a flat outer surface, and the Macwester has a convex curve.

Does this help performance either way? I have even seen a yacht with concave outer surfaces on its keels.

Some keels have "toe-in" I am told.
 
jontifosi said:
Best option is to ignore both and go for a westerly:)
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I have a Macwester Wight sloop, great boat, goes everywhere as it draws only 3 ft, takes the weather very well, masses of room inside, dries out anywhere, cheaper moorings because it is bilge keel, excellent on the reach, slow to windward; however, I overtake faster boats that do not have their sails balanced and trimmed and if I want to go faster I even put the engine on::) So, what's the problem?

If i wanted to race i would have bought a racer. The Westerly Fulmar with bilge keels, is another excellent yacht which i have sailed a lot; also the early Westerly bilge keel yachts are very good too and still are many around.

Its all down to personal preference and fit for purpose.
 
I am with you Captain Fantastic! I did have a Macwester 30 sloop for 7 years and I am now intending to buy another Macwester but with a dog house to keep the elements off me, and an aft cabin. They are ideal for the Suffolk/Essex rivers with their shallow waters and I have no intention of trying to race at all.
 
MrCramp said:
I am with you Captain Fantastic! I did have a Macwester 30 sloop for 7 years and I am now intending to buy another Macwester but with a dog house to keep the elements off me, and an aft cabin. They are ideal for the Suffolk/Essex rivers with their shallow waters and I have no intention of trying to race at all.
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I'm thinking my next boat might be a Macwester Wight 30, or a Snapdragon 890, or a Westerly 33. All classic twin keelers!!

They may not be racers but with cheaper moorings, shallow draft and the ability to dry out anywhere, what's not to like if you're not in a hurry?!
 
James W said:
I'm thinking my next boat might be a Macwester Wight 30, or a Snapdragon 890, or a Westerly 33. All classic twin keelers!!

They may not be racers but with cheaper moorings, shallow draft and the ability to dry out anywhere, what's not to like if you're not in a hurry?!
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It is definately worth looking for one that has been re-engined as the original engines will be from the late 60's and the 70's. I had a Yanmar 2GM20 in mine that was 100% reliable but it was rated at 16hp continuos and 18hp at full throttle, max 1 hour such use. I reckon they need 25hp at least.
 
NigelBirch said:
This might be worth a look:

http://www.brayyachtdesign.bc.ca/article_twinkeels.html
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This article is undated , I don't think I have ever come across anything so twin-keel keen!
I am surprised that single keel yachts have not been driven out of existence.
Why do I not see heaps of them incorporated into sea-walls, breakwaters and artificial reefs?

http://andycunninghammarine.co.uk/documents/ObservationsandthoughtsonTwinKeels.pdf
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Thanks I have only had time for a skim so far, it looks like a useful source.

What I am asking for, is people's own impressions.
 
BobPrell said:
What I am asking for, is people's own impressions.
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I have a Centaur, I don't pretend it's a racer, I'm not, but it does sail OK. I think it's a step up from the verticle keels of the earlier bilge keelers but it's not a fin keeler.
For a 26' boat with standing headroom, a good bit of room, and 5 or 6 berths the compromise is going to be towards comfort rather than performance to windward, it does that quite well. On top of that the bigish engine means that you don't have to beat to windward anyway, so if you are sensible and use the wind and tide you can have a good cruise.

The trouble comes when work, the curse of the sailing classes, makes you do things a cruiser would rather not do.
 
twin keel personal impressions/ Aust

BobPrell said:
They are not well accepted in Australia

So does that help windward performance compared to more shallow-draft twin keelers?

Does this help performance either way? I have even seen a yacht with concave outer surfaces on its keels..
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G'day Bob.
I have a 26-foot twin keeler designed by an ex-pat Pom, John Pugh. It was built in North Haven, south oz, but in my possession these past 10 years. I've sailed it from Eden to Westernport and the top of Flinders Island, Tassy.

In my inlet there are about 5 twin keelers, about 2 trailer/sailer/shallow draft yachts, and about 30 keel boats in the channel. Westernport is very tidal. Up to 3metres, with large areas drying out. When antifouling last October, there were 2 or so twin keelers; one in particular had straight steel plates with feet on the bottoms.
My yacht is called a Slipper26. It has a skeg also. The keels are curved on both sides, concave?, and 8cm thick in the middle, 80cm draft. The skeg is a flat plate, maybe 15mm steel. The yacht's hull is all steel, and at about 4500kg for 26 feet with a yanmar 8 hp, it averages about 3.5 to 4 kts on the coastal passages. up to 6 with the tide and clean bottom and devoid of full tanks, etc etc. The speed disappoints me, but that is mostly the steel rather than the size or keel arrangements. I have an untested temporary bowsprit to help in future.

I like the mooring because it's cheap; it's disadvantages are a half-tide access (1.35m above CD), and I think the tides stirs up the mud with some grit to scour off the antifoul quicker than has been the case in a berth and negligible tide situation.

I see quite a proportion of twin keel boats for sale in NZ: http://www.trademe.co.nz/browse/cat...s/boats-marine/yachts-sail-boats/moored-boats

My antifoul diagram (to get the guys to have it raised to a comfy height) shows the width of the front of the keels to be 145cm and the rear to be 146cm.

There are about 5 articles on the web to do with twin keels that I'm aware of. I think the curves help performance like with keel boats - as the sideways force applies to the boat, the curve helps making one side speed up compared to the other. (like above and below an aircraft wing).
The other main thing with them is stability. Mine stands up straighter in a 15kt breeze better than an normal boat, on account that one keel is vertical while the other is a counter-weight in the best position for a counterweight.

PM for details or photos. You could take it for a sail if you're down here.
 
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