Being the person who put the Kim keels on his Eco 6 let me contribute some thoughts. When I ordered the plans for the Eco 6 and began building I accepted that the design called for the daggerboard in one hull, and I also knew this would provide the best windward performance. But while I was building the hulls and joining them together I didn’t think too much about the daggerboard, but I did think a little about keel options. At the same time I was building my boat an Eco 6 was being built in Australia which had drop down keels,(centerboards?) on the inside of the hulls, but as I looked at photos of that build I thought that it seemed a complex structure and would add a lot of weight. I did think about the option of low aspect keels under the hulls, such as on the Wharram Tiki catamarans.

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As I began assembling the hulls to the bridgedeck and forming the cabin structure I realised more and more that the daggerboard case as designed was going to really impact on the interior and make access to the port hull difficult, and I was starting to feel a bit lazy about building the daggerboard and case. About this time Rien in Australia decided that his exterior drop down keels were not working, more because of the weight issue combined with what was already a heavy build, and he needed another option, and that is when Bernd came up with the kim keel design as a solution for Rien and also gave me the drawings. I decided to at least give the kim keels a try and see how they worked because they would be a lot more simple to construct than any of the other options. If they did not work out then I could always retrofit a daggerboard.

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Construction and fitting of the kim keels was very quick and simple and used up about $20 worth of timber which I purchased specifically for that job, and of course a little bit of epoxy product and glass cloth which I already had in abundance. ??

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So as to the sailing performance. As already stated in other posts I am very happy with the way my little catamaran goes to windward. We have a long narrow harbour with up to a one knot tidal flow, and sometimes more at the entrance. I have now many times tacked my way either up or down the harbour against the tidal flow and to me in that situation the boat seems to go to windward just fine. Keeping in mind that it is a cruising yacht, but for cruising needs there is nothing wrong with the windward performance of the kim keels. I do also have good sails and pay attention to sail trim so this will also contribute to the windward performance of the boat. In truth I think there are three factors which contribute to the boats leeway resistance; firstly the deep almost vertical forefoot which extends aft from the bow for quite a distance, the kim keels, and lastly the deep high aspect rudder foils.

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So in summary, the kim keels were quick and easy to construct and fit to the hulls, they add almost no weight to the structure, they do not intrude into the vessels interior, they do not protrude below the hull so hull draft is only 200mm. For a coastal cruising catamaran which needs to be able to sail to windward at times the windward performance of my Eco 6 is perfectly acceptable and certainly equals the windward performance of other cruising yachts I have owned, so happily I see no need to retrofit a daggerboard.

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Cheers,

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David

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That is the hard question isn’t it, is it worth all the trouble for what might be a very small gain. Without a doubt Bernd’s design for my ‘Kim Keel’ is brilliant. I don’t know how Kim Keel translates back to English, but I don’t think it means anti-vortex panel. But for me it means that I have leeway preventers which work, the hull draft is still only 200mm, and there is no daggerboard case cluttering up the interior. I am always asked – ‘how close does she point?’ But I have never measured pointing angle, what is more important is being able to effectively make way upwind towards my destination, and goodness knows I seem to have done a lot of upwind sailing since launching the boat!

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Keep in mind that hull shape and keel profile is only one factor in a boats upwind capability. Equally important is sail shape and sail trim. So having a fairly taught forestay is important, even for a cruising yacht. And having sails sheeted correctly is also very important. So even if your were to add anti-vortex panels, it probably won’t do much good if your sails are not setting properly, or are so old that they have lost all their shape. I have a self-tacking headsail on my little boat. Until recently I was just allowing the traveler to go across to the outer end of the track each time I went about, not controlling the position of the traveler, even though I knew I should do something about it. Eventually a couple of months ago I fitted a simple control line so I can control the position of the traveler on the track. Now the jib is setting a lot better going to windward, and both the lower and upper tell tails are flowing the way they should be. And I am sure I am going better to windward.

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The other big factor in windward ability is helming. Once again, no matter how good your hull shape, how good the sails, you still will not go to windward well if the helming is poor. Sometimes in certain sea conditions VMG can be improved by not pointing so high, ease the boat off the wind a bit for better speed and power to punch through the waves. Being able to make that last little bit of VMG may be important for racers, but not so important for cruisers, especially in offshore sailing conditions.

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Probably for you the important thing is to get the boat sailing. Pay attention to your sails and sail trim, see how the boat performs for the type of sailing you want to do, and then assess whether you want to get that last bit of windward performance. If you do and think it is worth the trouble, then I am sure that Bernd can come up with something for you. Of course the other thing to think about is the cost of any improvements. If you can do the work yourself and the material cost is not too high, and the extra yard time is not too expensive, then it may be a worthwhile experiment.

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Anyway get out there sailing and start enjoying the boat. Good luck with it.

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David

Bernd may reply, but with all due respect why would you even think about fitting anti vortex panels to a Tiki 38? You already have the V shaped hulls and the low aspect ratio keel. A friend of mine built a Tiki 38 on which I have sailed a few times. I have always been impressed with the way that boat pulled up to windward. Admittedly he had very good sails with full length battens and also a little camber built into the sails, so better than the average Tiki sails. But for cruising yachts the Tiki designs go to windward very well.

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If you wanted to add more leeway resistance you could fit something like the Kim Keels I have on my little catamaran, pic attached. They would be more suited to the hull shape. But save yourself the trouble and look to whatever other improvements you can make which would include sail shape and trim.

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David