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Anyone have any experience with keel stubs or other foils? I spotted some under Cooking Fat in a photo, but don't know anything about them, or if others have tried.

Any experiences to share? Shape, size, change in upwind performance? 

Getting ready to take our Tiki on a 750-mile race from Washington to Alaska, much of which is upwind!

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Wow that's super helpful, thanks Roger. One question: I'm seeing a very long bubble trail behind each hull when going to weather. It looks as though there are lines dragging in the water behind each hull. The bubble trails don't originate on the keel or skeg, it's somewhere further forward on the hull. I'm going to image it with an underwater camera soon to find out. 

I'm not sure if this is normal or not? We have fitted some plastic lumber as protective keel strips given our rocky shores & the frequency with which we beach her - but I wonder if they are too big or if the rectangular shape of them is hurting the foil or causing some kind of unwanted ventilation.

Do you see bubble trails behind LittleCat when going to weather?

And Roger: agree about the mast being big for a Tiki. Currently it's 33' long, but I don't need all that height, I should be able to cut it to more like 28-29 feet. Definitely very different sailing around here than in the bay - I think the conditions that you find normal are what counts for a small craft advisory up here!

Hi Michael, No, I don't get bubbles. I suspect that it is very important to have the hull of a Tiki very clean and fair, given that it is the "foil".

I have been looking at the hull and rudders alot and reading about foil and rudder design etc. I suspect that there is a lot of drag in the standard rudder arrangement. If I had endless time to mess around (and didn't mind ruining a perfectly good Tiki), I would try cutting off the entire rudder skeg and using kick-up rudders from a big beach cat. The drag of the skeg would be gone, and you would have a proper foil sticking down into clean water flow (it would shift the center of resistance aft and not sure what effect that would have). Just random tangential thoughts, not an actual plan.

Thanks for sharing. Sounds like I need to fair the keel strips.

Interesting idea on the rudders. I'm still thinking about some form of keel, maybe something like you see on the Mana 24 design: http://wharram.com/site/news/2014/mana24. I may consult Wharram or another multihull designer about this - if so I'll share whatever I find/do. 

Thanks, all your input has been invaluable!

Hi Michael,

I would suggest trying the boatdesign.net "multihulls" or "foils" forums - you will definitely get some informed feedback.

I have also toyed with the idea of a center-mounted (single) long piercing dagger board. Apparently it has been tried before with mixed results. Of course, the way to do it properly would be to make dagger board boxes in each hull. I am constantly battling with these urges to fiddle and experiment, but am usually restrained by (my wife and) the notion that its best to enjoy the tiki for its strengths and beauty as it is. Different situation for you with the big race though.

BTW my multihull sailing bible is "Catamaran Racing for the 90s" by Rick White and Mary Wells. The title is hilarious and may initially sound off-putting, but this book is the bomb for sail trim technique. It is about beach cat racing, but the theory applies to any sized cat. Includes sections on techniques for boats without boards.

Cool, great tip. Richard Woods has a lengthy, awesome post on this topic here: http://www.sailingcatamarans.com/index.php/articles/12-to-be-publis....

I also like the center-mounted idea, but this paragraph from his post put me off it:

"Don't use central boards though the bridgedeck. They simply don't work well. The Prout brothers discovered that in 1953 when they fitted a central board on the prototype Shearwater. By 1954 they had fitted boards in the hulls. The Stiletto catamaran started with a central daggerboard but owners quickly found that converting to ones in the hulls improved performance significantly."

Generally agree w/you on enjoying the Tiki's strengths as is. Seattle's tricky however, as winds & waterways are all aligned N/S, and we have strong currents & often light winds. So we are often sailing directly upwind, often into a current, meaning decent upwind ability is a must. It somehow crushes my soul to use the engine to get somewhere when I feel the boat should be sailing there!

Excellent - thanks!

Roger said:

BTW my multihull sailing bible is "Catamaran Racing for the 90s" by Rick White and Mary Wells. The title is hilarious and may initially sound off-putting, but this book is the bomb for sail trim technique. It is about beach cat racing, but the theory applies to any sized cat. Includes sections on techniques for boats without boards.

I saw that by Richard Woods, and no doubt good advice. On the other hand I think that he is saying that a piercing daggerboard is not good compared to boards in the hulls. Its a relative thing - I'm guessing that a piercing dagger board is not great compared to dagger boards in the hulls, but could still be (way?) better than no board at all.

Michael Dougherty said:

Cool, great tip. Richard Woods has a lengthy, awesome post on this topic here: http://www.sailingcatamarans.com/index.php/articles/12-to-be-publis....

I also like the center-mounted idea, but this paragraph from his post put me off it:

"Don't use central boards though the bridgedeck. They simply don't work well. The Prout brothers discovered that in 1953 when they fitted a central board on the prototype Shearwater. By 1954 they had fitted boards in the hulls. The Stiletto catamaran started with a central daggerboard but owners quickly found that converting to ones in the hulls improved performance significantly."

Generally agree w/you on enjoying the Tiki's strengths as is. Seattle's tricky however, as winds & waterways are all aligned N/S, and we have strong currents & often light winds. So we are often sailing directly upwind, often into a current, meaning decent upwind ability is a must. It somehow crushes my soul to use the engine to get somewhere when I feel the boat should be sailing there!

PS if you are not proud there is always the lee board option - some people swear by them. Also, Kohler's promotion of keel winglets - though I can never see how they can work that well compared to a deep NACA foil http://www.ikarus342000.com/Antivortexp.pdf

Good point. He's been pretty active in the Race to Alaska stuff, I'll try & contact him and put this question to him. Sounds like he's  thought a lot about all these options. 

If I add anything, I'm leaning towards the simplest LAR keel option like on Mana 24. As you pointed out, the "foil" such that there is one now is the V-shape, so something that takes that & makes it work better feels intuitively nice. Plus it's the least invasive, fastest to build, easiest to change, and most consistent with the overall design aesthetic. But of course I really have no idea what I'm talking about, so I'll try & consult some experts first!


Roger said:

I saw that by Richard Woods, and no doubt good advice. On the other hand I think that he is saying that a piercing daggerboard is not good compared to boards in the hulls. Its a relative thing - I'm guessing that a piercing dagger board is not great compared to dagger boards in the hulls, but could still be (way?) better than no board at all.

Michael Dougherty said:

Cool, great tip. Richard Woods has a lengthy, awesome post on this topic here: http://www.sailingcatamarans.com/index.php/articles/12-to-be-publis....

I also like the center-mounted idea, but this paragraph from his post put me off it:

"Don't use central boards though the bridgedeck. They simply don't work well. The Prout brothers discovered that in 1953 when they fitted a central board on the prototype Shearwater. By 1954 they had fitted boards in the hulls. The Stiletto catamaran started with a central daggerboard but owners quickly found that converting to ones in the hulls improved performance significantly."

Generally agree w/you on enjoying the Tiki's strengths as is. Seattle's tricky however, as winds & waterways are all aligned N/S, and we have strong currents & often light winds. So we are often sailing directly upwind, often into a current, meaning decent upwind ability is a must. It somehow crushes my soul to use the engine to get somewhere when I feel the boat should be sailing there!

Good luck - looking forward to following the race

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