Fitting a new fin yourself? Do it wrong and you can crack it or void the warranty. Here's how to seat it perfectly, choose the right screw, and tune the rake.
Upgrading to a third-party fin like an NP7 means fitting it into the box yourself — and if you damage the fin with the wrong screw length or by forcing it into place, the warranty is void. Here's how to do it right.
Step by step
- 1
Test the fit
It's completely normal for a new fin not to fit perfectly out of the box — they're semi-custom. It's actually better if it's slightly too large, because you can remove material but never add it. Slide it in by hand to see where it's tight.
- 2
Sand the tight spots
Insert the fin, find the scratched contact points, then use 120–180 grit sandpaper on a sanding block to gently remove material from those spots. Repeat until it sits flush.
- 3
Choose the right screw length
This is the critical one. A screw that's too long forces into the solid fin head — or even the blade — and that can crack it and void the warranty. Measure the box depth with a screwdriver, then choose a screw a few millimetres shorter than the measured depth.
- 4
Beach emergency fix
Stuck at the beach without the right screw length? Adding extra washers is a temporary fix — not ideal, but it'll get you on the water.
- 5
Tune the rake
To raise the nose, sand the back of the fin a little more; to lower it, screw the front in more. Slight gaps are okay — just don't let the fin stick out of the box.
Common mistakes
- Using a screw that's too long — it can crack the fin head and void the warranty.
- Forcing a tight fin into the box instead of sanding it down first.
- Letting the fin stick out of the box.
Better slightly too big than too small — you can always sand material off, but you can't add it back.
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