8. The base of the fin

Fin boxes like US-Box, Power-Box, Tuttle-Box and Deep Tuttle have to provide an absolutely stable fit for the base of the fin. If the fit is not perfect there might arise vibrations which will reduce the performance of the fin and, spin-out will occur more often.

The US-Box is the only system that allows to shift the fin forwards and backwards but, it is not very robust. Therefore, it is only good for small fins.

The Power-Box is a simple and stable system for fins of medium length. They should not be longer than 50 cm.

If the fin is longer than 40 cm or if you want to have a real stable and robust box, the Tuttle-Box would be the best choice. As both sides of the base are parallel to each other, it is quite often necessary to adjust the base to the box either by grinding or with the help of adhesive tape.

For Formula fins, the Deep Tuttle Box system is being used. It is the only system that is able to cope with the strong sideways forces affecting such a long fin. Like the Tuttle base it mostly has to be adjusted to the box.