Attaching a skeg/sword/tracking fin on a surfski?

1 year 3 weeks ago - 1 year 3 weeks ago#27441by Uffilation
Thankyou so much for that link, saw the title in the DIY section when searching this Site, but did not read it ... would not have expected such a fin ... Shows together with Mr. Lippstreu's article, that obviously additional fins have been tried.
Note that my intended use of 1-2 small fins is more for taking away the wobble on tippy skis in conditions that inland racers mostly find and for the reason given in the 1rst post, 3rd paragraph.

Ps: yep, as posted above, I felt the need to lean a bit more when turning sharp.
Thanks again.

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1 year 3 weeks ago#27443by Uffilation
Fin under cockpit from spacehopper's link here in surfski.info
... now that is huge, sizes I try are 3,7, 10 and 12cm. Will add 20cm.
Currently still favour two smaller parallel twin fins behind the seat ... again all just for the fun of testing stuff...

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1 year 3 weeks ago#27445by Spacehopper
Trouble with doing multiple small fins is that you end up with more 'tip loss' drag for the same wetted and frontal area drag

First you have two (or more) tips and second a high aspect fin produces more lift relative to the amount of tip loss drag it produces.

Also, keeping the foils as far away from the surface is best as there are all sorts of weird interactions with the surface going on otherwise.

Of course if you really wanted to make the boat stable then a horizontal foil might be better - like this: www.dynamicstabilitysystems.com/faq/
but on both sides...

:)

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1 year 3 weeks ago#27450by Uffilation
Spacehopper,
"but on both sides...", actually the innovation w.b. single-sided for an automated round course trim.

Idea is to test if one could make a tippy ski a bit more stable by small fins (thus reducing the wobble factor, increase resistance against rolling). One would then shorten the fin as one improves in paddling that model until one would remove the fin(s) completly. FIns should be "detachable" without damaging the hull.
´
As posted in #1, the idea is to find out if one could make shortcuts in the "model upgrade journey" by skipping a model and coming from the other side.
E.g. as Kwolfes jump from V8 to V14, but knowing that one could use small stabiliziers, just in case that decision was too ambitious. I am not talking stabilizers for Molokai here ...

Alternative positions for testing small fins (depths up to 12 cm, see photo of so far largest fin I got):
red = under the bailer (easiest place to fix one); green = under the seat, orange = twin fins behind the seat; blue = myt small (weedless, marathon) rudder
Note: I'll also test longer dagger type fins as known from SUP/surfboards ... for the fun of it

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3 months 6 days ago - 3 months 6 days ago#29564by Uffilation
posts of dicko and mario, robin and kestrel in ... finsnplaning

www.surfski.info/forum/35-surfski-innova...destroyer.html#13210

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