I'm pretty new to windsurfing and gradually putting together a kit to get me out in most conditions (second hand mostly). I'm 70kg and have a 78l Goya waveboard for when there's some good wind. My thoughtful wife bought me a 25cm MFC freewave fin for it for my birthday. It already came with a 21.5cm MFC wave fin. I've only ever had the one fin and changed sails to handle the conditions so was just wondering how much of a difference the bigger fin will make. Is the 25cm too larger jump from the 21.5cm for that board (for sailing in the bay mostly). Any advice would be great.

I weigh the same as you and use a 23cm fin on a 78litre JP fsw board. Works well and is a bit longer than yours. I have a lot to learn about fins though so I would bolt it on and see how she goes.

Sorry. I forgot Waggles56 no longer exists. He is me

It all depends on sail sizes.

25cm would be the biggest I would go on 78l board. The jump in sizes is a little big, but if the two shapes are different then that also comes in to play.

Best to try it out and its always good to have a number of fins.

If u are new to windsurfing u might want to get a board with a bit more floatation.Maybe 100 litre or so.

I would look at using a bigger board, if not look at the Black Project website and get in touch with Chris or Tom and ask their advice, there fins are really good and with the exchange rate at the moment are cheap. They are probably the best fins around at the moment too.

They will also post direct to your home, ask them for regular postage.

Also fin size depends on sail size, one on underside should match the top side.

That board will probably only take a 5.7m sail at the most.