My original pair of Turbo fins have seen a lot of use and have suffered damage resulting in the mast end tearing through the fin:
I would use Gaffer tape to temporarily repair the fin but it would lift after a couple of trips and the edges would catch seaweed. The tear lengthened over time. This repair has stopped the tear and allows the fins to flex. The PVC cement has low viscosity and can be applied in very thin coats that remain strong but flexible.
The materials needed are all easily available from a good hardware supplier:
-bicycle tube repair kit
-plumbers PVC pipe primer and cement
-self adhesive fibreglass easytape (used in gyprocking)
1-Clean the fin and roughen the leading edge on both sides using the tool in the tyre tube kit. It is important to thoroughly roughen the fin so the cement adheres properly.
2-Prime the area and apply the tube patch (as you would on an inner tube) over the fin where the mast ends. This adds strength to this critical area.
3- Cut the easytape to length and wrap it around the leading edge of the fin on both sides.
4-Apply the cement in thin coats ensuring coverage over the entire roughened area only. Allow each coat to dry.
Do not allow the cement to extend outside the roughened area or it will lift.
It’s not pretty but after 3 months of use is showing no signs of lifting.
Roadrunner has reported that the newer fins are made of a tougher material. This repair applies to the original Turbo fin material.
It beats Gaffer tape!