hey, first question, what fin are you using...in what wind, what sail...your weight.
That can give you a first aproach to the problem. If you are using an incorrect fin then you can feel some spin outs when sailing. Also, some rigging and incorrect setup can add a lot to the spin outs as people mention here.
But try to find one sailor that can gives you the original fin to try it and check the differences. Or look for other fins out there, try them. Dont be afraid to try lots of fins and check which one works better for your board. Also, check always your setup is the correct one because sometimes you have lots of spin out because the center of gravity of your equipment is too high (very high boom, or mast foot too far back)...so, check all this and have fun.