.
.
You're right.. There is some play in the box.. and I wil pack it next time to try and less'n the slop.. and that bit of flex might even be doing some good.. and it didn't feel any slower.
I think tapeing the fin box will do more good than shaping those threads.. maybe i'll do both.
DJ
What about putting in a FCS insert and use a smaller forward / mid board fixed fin like a small dagger board.
Another option would be a few FCS inserts on the rails near the tail at a 45 degree angle to the fin?
Your fin is by lengthening it is just giving a greater fulcrum effect, but the drag from the bolts must be more than just making a new longer wider fin from a cast or cut down from an old windsurferer dagger board.
Here's a post on making a fin I liked:http://www.grainsurf.com/forum/viewtopic.php?f=11&t=570
Thanks for your ideas and the link.. Your idea might work better if it was tracking that I'm after but I'm only after 'stability' to help with board tippyness.
IMO two, three or four shorter fins with a total fin area of let's say.. 40 sq inches.. would have no where near the same effect on stability as one fin that's 10" long and 4" wide even tough they have exactly the same total fin area.. The fin that gets down past that 4-6" of surface water will have much better stability because it's reaching the denser water.
DJ
.
Thanks.. So it's pressure and not density.. I remember reading about it once.. There is a depth that is close to the surface where the pressure sudddenly changes and it's not just a gradual change from the surface of the water to the deepest depth in the water.. There's a word for that point where the 'pressure' changes.. Any idea what that is.. or what depth that is?
DJ
dj, you need to set up some mini hydraulics. drop the fin down deeper and then pull it up in the shallows
Every 10m of water is approx 1 ATM in pressure. That is why divers regard the first ten meters as the most dangerous, biggest change in pressure. Ie it doubles from surface
..
. I have paddled an old D2 wind surfer a fair bit on flat water ( super round long skinny thing) Its about 24 inches wide and very unstable at rest but fine when moving. if I am turning around or boat wake is comming I just give it a bit of centre board (its fully retractable) and its more stable then a 30 inch flat bottom.
That would be interesting to try.
Maybe the foil on that thing is close to what our fins should be even tough you would think that being thick would mean lots of drag and slow.
DJ
I'd imagine sticking the fin all the way forward in the box - or even adding a box further forward would reduce the roll as well....but then you'd lose some of the straight tracking.
Your new modification looks a lot like a rudder that I used to have in my DC14, pictured below.
I really liked the feel of this rudder and it made a significant difference to the stability. I ended up swapping it for a shorter wider one as it was too long - it always used to hit the bottom. As a rudder only has a single rod this made to concept too weak. Something was bound to break. You may find you will end up with the same problem with your modified fin
My fin is pretty solid now and should be fine.. A can imagine a fin like that being used as a rudder might be a bit risky.
I tested my fin out today.. and also plucked out a few of those nasty bad starfish.
The new fin worked great.. It made a big difference.. It was 11 1/2" long.. Now it's 14 1/2" long..
DJ
Nice DJ was just waiting for the 1.15 am sea breeze report up date and jumped in at end of all that fin stuff man got to get rid of those star fish there bad news nice steady vid shots good stuff .
