Fin Keel v Bilge Keel

[cooper1991]

Is there a dramatic difference in safety and speed between a fin keel and a bilge keel on a 28ft boat for coastal sailing?

[boatman61]

Not as much as makes a difference.. speed maybe 1/4 knot depending on the make/models, safety depends on if your embayed with an onshore wind as a bilge keeler will not point as high as a fin.. though once again depends on the make. I have sailed fin keelers where the pointing ability was crap because of excessive freeboard.
Coastal cruising in either is fine if you don't do silly things like setting out when a F8 is imminent.. have taken several bilge keeler 70nm across the Channel to Cherbourg and the Channel Islands and a few Westerly Centaurs (bilge keels) have sailed from the UK to the Caribe and bilge keelers have also competed in the Jesters Challenge over the years.
Advantages of bilge keelers, if caught out by the tide you can dry out and wait for the flood, dry out for below waterline maintenance /antifouling saving on lift outs.

[Grippy]

I vote Bilge Keel!

Here is a photo of Vida Deriva:
An aluminum ketch, designed by Ted Brewer, and built by Walt Forsythe.
The keels are air-foil in profile.
The "lift forces" that they produce result in net force that pulls the hull deeper into the water, the faster it goes....

The result, is a very stable ride.

Any thoughts?
Cheers

[Jim Cate]

The "lift forces" that they produce result in net force that pulls the hull deeper into the water, the faster it goes....

If true, this substantially increases drag and reduces ultimate speed, so not a benefit at all.

Speed under sail is not one of the benefits of bilge keels, while the ability to conveniently dry out is a huge one in some venues.

Jim

[TrentePieds]

Cooper:

Why worry about it?

Safety at sea is certainly a function of a vessel's seaworthiness, though far more a function of the skipper's competence, particularly when you are talking about diminutive things such as 28 footers! And seaworthiness is only to a very minimal extent a function of keel configuration.

Speed through the water is certainly affected by a vessel's keel configuration. I shouldn't doubt that when VTW is measured accurately, which few 28 footers would be equipped to do, you might be able to observe that the bilge-keeler will have to give as much as a quarter of a knot to the single-keeler.

In an eight-hour day of cruising that equates to the bilge keeler doing 2 miles less through the water. What it means in terms of distance over the ground will depend on the conditions obtaining at the time and on the skipper's competence.

If in practice, particularly if your it lies to weather, you fall a mile or two short of your day's objective, you crank up the "iron wind". All boats have it these days and there is no shame in using it. In fact, in marinas, using the iron wind is really obligatory.

Bilge keels were "invented" (better said: they were adapted to modern yachts) because in many parts of the Sceptered Isle, not least the Solent, lotsa yotties, when yotting became everyman's amusement after WWII, could own boats with no worries about finding a place to put them. You just let 'em settle in the mud and wade ashore! Cheap too!

An exception to those circumstances was Bluebird of Thorne, the yacht of a man who didn't have to worry about the odd quid for moorage fees :-) Look 'er up.

Something you might like to do, as preparation for going "off-shore" in a 28-footer, is go and chat with the people at the Midland Sailing Club. Bashing a GP14 around the Edgbaston Reservoir is WONDERFUL training for handling a cruising boat. And the GP 14 goes a lot faster than any 28-foot cruising boat ever will. Regardless of keel configuration :-)!

All the best

TrentePieds

[wyb2]

Originally Posted by Jim Cate

If true, this substantially increases drag and reduces ultimate speed, so not a benefit at all.

Speed under sail is not one of the benefits of bilge keels, while the ability to conveniently dry out is a huge one in some venues.

Jim

Also skeptical of this downforce explanation. But does it seem plausible that asymmetric foils would reduce leeway, as when heeled one foil is oriented more vertical than the other? As stated, it would add drag and reduce speed, but I could see the trade off possibly being worth it. Worth it in this case would be the same bilge keels without the asymmetric foils, not trying to compare to a deep, high aspect fin.

I’m always surprised that bilge keels are basically nonexistent on the American east coast, with most of the northeastern US and Canadian coast having 6+ ft tides.

[anchorbend]

Several years ago an English magazine ,Sailing Today, ran a comparison between 2 Hunters , if I remember correctly they were called Legends (English name for Hunters. They compared Legend 290s, one had a fin keel and the other was a bilge keeler. The end result was the speed difference was negligible. Could have been a difference of the "nut" on the tiller. If your sailing grounds have big tidal changes I would opt for a bilge keeler.

[boatman61]

Yup.. caught out by the tide.??? brew up and make a picnic lunch then sit in the cockpit sipping tea and nibbling sandwiches like you meant it while your mate in the fin keeler laying on its side is stressing about getting flooded as the tide comes in..

[RaymondR]

Originally Posted by Jim Cate

If true, this substantially increases drag and reduces ultimate speed, so not a benefit at all.

Speed under sail is not one of the benefits of bilge keels, while the ability to conveniently dry out is a huge one in some venues.

Jim

I noticed quiet a few of them passing through the boat yard I was doing a hull refit in at Darwin in the Northern Territory. I suspected it was due to the lack of havens in a long stretch of coast without marinas or harbors, with large tidal ranges and rivers and creeks with bars all being prone tropical cyclones (hurricanes)

[Jim Cate]

^^^^
Well Ray, I would for sure rather be upright on my bilge keels than laying on my side... anywhere, but especially in croc territory!

Jim

[TrentePieds]

Ah, but it's luvverly to be able to have six hunnert feet of water under you when you are three boat lengths off the shore :-)!

TP

[Grippy]

Just to add a little clarity...
The Vida Deriva, is 54 foot water line, and 42,000 LB.
The offset reduction in speed by the extra drag would seem small.
Cheers

[Fore and Aft]

Cooper1991 I wouldn't stress about it too much. Shane Acton sailed an 18-foot bilge keeler around the world!
Boatman61 has some good advice. He is the right vintage to remember fleets of Maurice Grifiths butter box bilge keelers being sailed around the UK.
Cheers
https://www.cambridge-news.co.uk/new...-boat-12030337

[Pete7]

Originally Posted by cooper1991

Is there a dramatic difference in safety and speed between a fin keel and a bilge keel on a 28ft boat for coastal sailing?

We have bilge keels and draw 1.2m (4ft). This is a 1989 boat by which time the UKs boat builders had worked out a series of improvements over the earlier designs of vertical GRP lead or iron filled keels of the 1960-1970s. Ours are aero foil in shape slope outward and toed in slightly to give lift going to windward.

We did charter an identical yacht with a fin drawing 1.6m (5.5ft). There was little noticeable difference coastal sailing, both pointed equally well. However, by far the biggest difference was the Autoprop folding propeller on the fin keeled yacht. This made a huge difference and caught us out coming alongside a pontoon the first time as the charter yacht just kept gliding along when I was used to a fixed prop slowing us down.

Is the fin better at sailing? In a race around the cans there will be a small advantage for the fin. Back in the real world of ma and pa coastal sailing with dinghy and outboard, okay but not new sails, full tanks and stores on board, oh and lets not forget the solar panels on an arch, nah we don't worry about it. Good sails well set and a folding prop have a greater effect.

Do we sail to windward? Yes and quite well. When the yacht Leans over the leeward keel becomes almost vertical and the weight in the windward keel is now exerting maximum righting effort.

What it does mean is we can visit places fin keels can't and don't need expensive marinas. Instead we prefer the more traditional harbours and boatyards of which there are hundreds around the UK an French coasts which often dry out.

Pete

[Spokey Doke]

context does seem to matter...and along those lines, wonder about design/execution of the latest breed of twin keelers like the Django: