I need to get some spare fin bolts and I'd like to order through Bolts, Nuts Screws Online (as per ad on this site) but I'm not sure what the standard thread is - metric or imperial? Is it 6mm? I'm assuming I should order 316 grade? I know what length to order. Most of my fins are Select or Choco tuttle box. Thanks.

I had pretty much the same question last year (I am no bolt expert either). As directed, I took my fin to the nearest Chandlery (I place that sells marine supplies), and they matched up bolts for my fin.

The only thing you need to do then is hacksaw them down to size.

Ja

Hi, All,

If you have to cut the bolt, also buy a nut that suits the bolt. Thread the nut onto the bolt 'way above where you will cut the bolt, cut the bolt then grind or file the cut so that there is a slight taper leading into the thread. Hold the nut head, then wind the nut off the thread.

When you cut a thread, the manufactured thread "lead in" has gone, making it difficult to start the bolt or making it easy to cross-thread the stainless steel bolt in the brass thread of the nut. By filing the thread and unscrewing the nut, you create a lead-in, which should allow an easy engagement of both threads.

Hope this helps

Just drop into board crazy, I think simons got all the bolts you would need in stock, save you from messing around cutting, filing and guessing sizes.