On Saturday I was on my iSonic 94, with a 6.8 cammed sail. The board felt a bit stuck to the water, so I moved the mast foot back, which helped a bit. The setup felt stable and balanced, I went upwind better than most that day, no worries.

Then once the wind picked up I rigged a 5.6. For some reason, every time a gust hit me I would get turned downwind. I think this is called "Lee helm" in sailing speak. I would have to really fight the rig to get back upwind.

I've never had this happen before, never really had that 5.6 out in nice wind before either so haven't tuned everything properly.

Does anyone know what usually causes this? Harness lines too far back? Mast foot too far back? Boom too high/low?

I think by then it was windy enough that the fin was too big, causing railing up ... which usually translates into a bearing away also.

Mark _australia said...

I think by then it was windy enough that the fin was too big, causing railing up ... which usually translates into a bearing away also.

I think you will find when you are over finned and "railng up" you will round up into the wind.

Nebs try dropping your boom a little bit.

how far back did you have your mast base nebbs? i would be tempted to put it all the way back with a weedy.i run my mast all the way back on my 105 as far as it will go with a weedy(and it could go further if the track was longer).
if your not railing or overpowering the fin then this would help.
if you are bearing off then the "lee helm" may suggest the centre of effort is forward of the centre of lateral resistance.
is the 5.6 cammed?

On a sailboat you can alter the weather/lee helm by moving the mast base and or headsail sheet blocks position. Moving the rig aft will increase weather helm (turn you into the wind), moving it forward gives you lee helm.(bad) A few degrees of weather helm is desirable. How this translates to windsurfing I dont know ?