I have a sweepback b3 freeride powerbox fin. I have recently sandback the top part of the wooden box to allow better fit into the board. Today i have noticed the fin the losing grip, it tend to skid and slide 30 degrees from from i am driving the board. The fin is too loose, and behaves like a wave fin on choppy and flat water.

nanja

starboarder said...

I I have recently sandback the top part of the wooden box to allow better fit into the board.

are you saying you sanded the box

starboarder said...

hi hoop & keef

I should clarify this problem is very recently and i didnt have this problem when i used the fin in Tarifa, spain.

sanding the fin box was my last resort as the box is sticking too far out and were creating too much drag to the board, it still fits good and does not fall out. What can i say brought it cheap second hand...

any sugestions?

You mean you've sanded part of the fin head? The part that fits inside the fin 'hole' in the board? (I'm yet to see a wooden one though!)

My suggestion is to move your harness lines back a bit.

Any fin will "work", but they all have different amounts of sideways force which you can apply at a given speed before they will spinout. Moving your harness lines back a bit will take some of the sideways load off your back foot (and body), and load the fin up less. It may also be that you need to go faster before really pushing against the fin.

Maybe the water in Tarifa is just more grippy?

You may be on to something there oldie.
I thought that if the screw didn't seal to the top of the board properly it would always suck air.
But nebian informs me, he has a small jet of water coming out of the screw hole.

So starboarder, check the rubber washer on the fin screw head, if it's worn, try replacing it.

There are many things that affect fin performance, are there any other differences between your Tarifa sail and the last one?

Even sail set up, downhaul/outhaul, mast track position