Bolt on boat windows - advice?

[mabbs]

Replacing four cabin windows in an old Shetland which are currently held in by rubber, I was wondering if anybody has replaced something similar with bolt on and ny advice. Advantages are with 4mm polycarbonate it is far stronger with any rogue waves, but less attractive. Initial thoughts were to have a 20mm overlap, using black scapa (isobutyl) tape with s/s 6mm pan head bolts through the grp with domed buts every 15cm = any thoughts?

 

[PCUK]

I'd go thicker, but that's up to you. Fit flat washers onto the bolts between the poly and the GRP as this prevents the tape being squeezed out when tightening. (Standard professional practice).

 

[Plum]

Replacing four cabin windows in an old Shetland which are currently held in by rubber, I was wondering if anybody has replaced something similar with bolt on and ny advice. Advantages are with 4mm polycarbonate it is far stronger with any rogue waves, but less attractive. Initial thoughts were to have a 20mm overlap, using black scapa (isobutyl) tape with s/s 6mm pan head bolts through the grp with domed buts every 15cm = any thoughts?

Recommend you buy from a supplier that can guarantee their grade of polycarbonate has a high UV resistance.

Also, 15cm spacing for 4mm polycarbonate will result in a wavy edge.

 

[Freebee]

15 cm ptch of the bolts is too far apart they will just squish locally and the gap in the middle with 4mm thick will bow out leaving not much clamping force.. I wonder if this is going to be such a work up, that replacing the windows in some new rubber will work no problem....... after all it must have been a fit for purpose method once...