Fin keel v bilge keel impression from experience

MoodySabre

MoodySabre

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For the past two successive weekends I have sailed for the East Coast to Ostend. Firstly on my Moody 31 fin keeler and last weekend on a Moody 31 bilge keeler. These were my impressions - nothing scientific.

Obviously conditions were not identical but the following impression was gained:

The fin obviously points up a bit easier and holds a high course better.

In a moderate cross sea whilst sailing fast the bilge keeler was so much noisier - air getting caught under the windward keel really makes a racket as it is forced out.

An old Autohelm 1000 on the bilge keeler seemed to cope better in lively conditions than the Raymarine St2000+ did on my fin. Admittedly the conditions and sailing angle were not the same. Perhaps the difference was the extra lift from the fin keel exerting more force.

Other than that the same sun and blue sky and both did an average of 5.5knots under sail.
 
I would agree with the comment about noise under the keel. Was sailing my Sadler 26 on Saturday in a moderate swell and all I could hear was the regular thump thump between the keels! I wonder if this is a common bilge keel problem?
 
Re: Fin keel v bilge keel differences

The first twin keelers had vertical plates so they lifted easily out of the mold; later designs had improved profiles (and therefore better performance).
My years sailing both fin and bilge Westerly Fulmars endorses your account of that thumping in any sort of a chop (tho the twin was stiffer so carried her canvas better.)

In contrast my time on a Seawolf 30 resulted in winning many races - more 'cos of a generous handicap than personal skillt! But if you ever met designer David Feltham you would know he was obsessed with windward performance, and she sailed like a shallow-draft fin rather than a twin, tho slower downwind with the greater wetted area.

There are other bilge keel designs whose performance isn't a disgrace but few who can compete with that frustrating amount of leeway. To leave Cherbourg on course for the Nab but ending up downwind and downtide of Selsey is a salutary experience, so you'll know where my vote is cast!
 
Re: Fin keel v bilge keel differences

I'm surprised that, given the same hull, a bilge keeler wouldn't sail pretty much like a fin keeler. Of course the additional wetted surface of the second keel will slow her down, but, if anything, the twin keeler probably has a more vertical keel than the fin keeler when heeled over. I haven't sailed my Pageant enough to know her, but I'm coming to her from a modified full keel so I do feel like I'm sailing sideways. I've been underwhelmed with the twin keeler's windward performance, but I've never been impressed with the fin keelers I've sailed either.
 
I purchased my M27 bilge after sailing as crew on a pals M27 fin. I find both are very sturdy stiff boats. I agree with the keel slap but have come to not notice it (except for the first couple that make me start!). At first I found the Bilge performed disapointingly against the fin in bigger seas and winds but after a visit to get a sail repaired the sail maker listened to my problems and took my sail and amended the shrunken luff rope. This season she performs like a tiger in comparison! I have beaten the fin twice now in private races (he still wins the majority mind) but its a start!
 
All the sailing mags have done more scientific back to back comparisons of bilge against fin with the same hull. They dont find much difference but then they are comparing shallow fin with bilge on a fat cruising hull. I dont know if anyone has put bilge keels on a fast hull and compared them with a deep fin.

The only real way to compare is on the race course but you rarely get 2 boats of the same sort racing the same course at the same time. Nearest I can get is to compare my old Moody 336 with a Dehler 36 deep fin. Now the Moody was a fast boat of its type and did well on handicap. Its also 34 ft so only 2 ft shorter that the Dehler. But depending on tides and wind, the Dehler was 25% faster on average round a triangular course. The difference in waterline would in theory only account for 5 %

So it seems to be the case that if you are happy with a slower family cruiser, you might as well have the bilge keeled version of it. If you want speed go for a fast boat which will have a deep fin. Or a multi of course.
 
I have had both fin and bilge keel boats like many others. Unfortunately, I don't have direct comparisons so your experiences are very interesting.

Bilge keels do seem to be fairly unique to UK waters and have not caught on in other parts of the world where shallow water areas seem to be populated by cats or lifting keels. I wonder why this is so.
 
Re: Fin keel v bilge keel differences

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if anything, the twin keeler probably has a more vertical keel than the fin keeler when heeled over.

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I've had both and felt that was a distinct plus point.

Although I prefered the fin keeler, but it was a much different boat.

See this article which makes some very interesting points http://www.brayyachtdesign.bc.ca/article_twinkeels.html
 
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I wonder why this is so.

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Tidal range. All areas have shallow water by definition but often the area that dries is small because tidal ranges are small.
 
The Portsmouth Yardstick figures for the Moody 31 [fixed 2 blade props. in both cases] are: fin keel 1043, twin keel 1075 i.e. 3% difference. Not a big difference.
 
Re: Fin keel v bilge keel differences

I have to agree with that - my first experience of bilge keels was on Hunters so I didn't realise they were supposed to be slower than than fin keelers! I'm not convinced there's any huge inherent disadvantage - certainly less weight, a decent helmsman or bit of sail trimming would make more difference with a truly fast twin versus single keel I reckon (that's based on a lot of racing round the buoys in the 70's but I don't think that much has changed).

We seem to going full circle with the canting keel and dagger-boards thing on Open 70's. I know you end up with a much bigger righting moment with the keel canted but you've still got two "keels" in the water. I suspect the next step is to bring the weighted keel right out of the water and swing it horizontally across the deck when you tack. You'd gain righting moment because you've no longer got the buoyancy of the water acting on the keel and you'd only have the drag from one wetted surface acting to prevent leeway.

Be much easier just to buy a multi-hull though...
 
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I wonder why this is so.

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I think economics and mooring space have a part in this, i.e due to overcrowded and expensive marinas in the more popular cruising areas of the UK, people can save a bit of money by using a drying mooring, which means a bilge keeler or lift keel.

I think in France, for example, traditionally the local council / authority have tended to run marinas, largely with public access in mind (i.e charging enough to cover running costs, etc) rather than the straightforward commercial investment, profit- targeted set ups we have here. In short, its cheaper and easier (and therefore more accessible for more people) to own a fin rather than a bilge.
 
I have the same fin boat as MoodySabre & I previously had two British Hunter twin keelers.I also used to race around the cans mostly skippering boats from 38 to 45 feet.I used to think that the twin keelers sailed OK.It was when I went out for a sail in the boat that I bought that I realised that a fin keeler was for me.It was just a different feel to the twin keelers, & just felt better somehow.It does point higher than most twin keelers as a friend testified in his W Storn twin.We were beating up the Blackwater & he was having to sail a few degrees freer than me & stayed behind me all the way..He said on arival he thought maybe 5degrees but I thought less.The comment that a good helsman & sails etc will make up the difference assumes that the fin keeler does not have a good helmsman & sails & therefore is not comparing like with like.The differences between fin & twin for the same boats on www.byronsoftware.org.uk/bycn/byboat.htm make interesting reading.I am not saying a fin is better than a twin as they both have attributes & drawbacks which are fairly obvious.I just like to get the best out of my boat which is why I have new sails & a feathering prop.Many people say their 15 year old sails are fine,but that is another discussion(run for cover)
 
Hi John

The bilgekeeler has much better sails than my fin. He has a fully battened main and an assymetric genoa (yes I'm jealous) and I have 10 year rags. I don't think there is anything in it with speed but the feel of a fin is different (and nicer IMO) and the noise issue was definitely a decider. SWMBO has other ideas when skipping over sandbanks!
Roger
 
I have had the same experience as ditchcrawler having had bilge and fin keelers. I remember sailing my Sonata against a twin keel Duette and there was a considerable difference upwind. Not just in pointing but in the leeway made by the twin keeler.

There are many advantages to a bilge keeler but they just don't sail as well as the equivalent fin keeler. It shouldn't even be up for debate - the fact that they aren't raced at any sort of serious level is the response to those who say they are nearly as good. Even in the 'gentlemans' class at Burnham week the bilge keelers soon fall to the back of the fleet along with the Jeanneau lifting keelers.

I am reading a jolly good book by Nicholls at the moment about the first non-stop round the World race. The one Knox-Johnson won and Crowhurst broke down on.

He talks a lot about Chay Blyth and Ridgeway who took part in Bilge keelers (a westerley and something else) and quickly concluded that the bilge keelers were completely unsuitable for the open water. He may be talking tosh but they make some interesting points.

Don't get me wrong, I like bilge keelers for lots of reasons - and might get one again, but they have limitations regarding sailing performance.
 
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