I wonder if someone can help. I have a 92L AHD with a 6m wave sail and have a handling problem. This is in an average wind. If you are overpowered no problem. What normally gives this away is that you hear it start to gurgle from around the fin and you loose drive. If you go downwind, sometimes the problem clears and sometimes not. Also with this set-up it seems that you don't accelerate well. The wind will pick up but the board still seems to be labouring. I moved the back strap to the middle position and forward one space and it rode better but still not perfect. I am guessing the fin is too small, it is a 32cm, but when I use a smaller fin with my 4.5m sail the problem does not exist.

Don't think the fin is too small for a 92L board, but sounds like it might be a bit rough around the edges. Like my head this morning

Maybe your sail is a bit too big for a 92lt board. I used to struggle with a 5.8 on a 92lt wave board. But try moving your front harness line back a couple of cms. Worked for me.

Iceman, its a bit hard to tell from your description, but it sounds like the fin is partially cavitating, that would explain the symptoms. I'd try another fin, make sure its a good quality one. As to if the sail's too big, it depends on the model and type of board and width etc. I've used a 7 metre sail on an 82 litre super-x board with a 36 cm fin and it went upwind like a train, but on other bigger boards it was a struggle. Best of luck.

get a weedy while your at it ,got the new board dialed in yesterday , done a pb on it before wind died 33.2 knots how mutch fun can a koala bear

a thought try the buy and sell section or put an add in the wanted section

Every time I've heard gurgling from my fin it's because there's a ribbon of weed attached to it... I reckon monster's on the money

I've never heard gurgling from a fin, whistles and hums yes, but gurgles sounds very weird.

Is it in a bolt thru the deck type box??? If so it may be sucking air down thru the box, that may cause a gurgle. If so make sure you have a good seal under the bolt heads with rubber washers.

How flexi/twisty is it. I've heard about fins with the wrong sort of twist, bending so that they stall, then straighten up, then bend again etc. That may also cause a gurgle I guess.
If that's the case throw it out or try an extra layer of carbon, but that's a lot of work to get it right.

i run a 23cm wave fin on my 95L, it spun out for the first time the other day but i was pushing extremely hard on it trying to get up wind underpowered, spin out from the fins point of view these days is a rare thing, well decent fins anyway, (i only use MFC fins now) it's very important to have your fins in perfect condition, i.e no chips or deap scratches, especially on the leading edge, they can look rough as guts but they reall should be silky smooth to touch, any chips out of your fin will cause air bubbles to for on the fin which will cause spin out.

Decrepit, It is a bolt through fin (power box) but I do have a rubber seal under the metal washer. From all the comments the fin is the correct size so I'll forget about getting a larger one. One thing monster noticed was that when the fin is fitted to the board, a small nib of the mounting plate is still proud from the under surface of the board. I am going to file this off and see if it makes a difference, possibly it is cavitating around this point and sucking air from the back of the board.

Monster, looks like I'll be taking lessons from you in the future.

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Iceman said...

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One thing monster noticed was that when the fin is fitted to the board, a small nib of the mounting plate is still proud from the under surface of the board. I am going to file this off and see if it makes a difference, possibly it is cavitating around this point and sucking air from the back of the board.
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Yes that's possible, but better than filling the top surface, (it's very hard to keep it flat and square without also cutting into the fin face at the base). Attack whatever is stopping the fin from seating properly.
From my little experience with tuttles it's usually the rear edge of the fin base, but it could also be the bottom of the base.