sealing a GRRP hull

[newby boat owner]

I have just bought my first boat, so I'm new to everything boaty, my boat has quite a bit of osmosis my plan is to strip back the hull and dry it out after grinding back any osmosis damage.

My question to you is can I use this (or similar product) Everbuild - Aquaseal Wet Room System Tanking Kit

to the hull before gel coating and anti foul?

 

[Tranona]

Welcome.

Simple answer NO

If you have small blisters then grind them out back to the laminate. If there is no liquid in the blister then fill with epoxy filler. If liquid is present then you will have to wash out with fresh water regularly and allow to dry before filling again with epoxy filler. There is no need to gel coat, just fair , prime with underwater primer and antifoul. This is a useful guide
wessexresins.co.uk/wp-content/uploads/sites/13/2018/08/Gelcoat_blisters_-_diagnosis_repair__prevention-1.pdf

 

[PCUK]

Quite agree. Equally if you need to remove the entire gel coat, you should apply epoxy primer, then fair with epoxy filler and finish with further coats of epoxy primer followed by antifouling. Don't scrimp by trying to do it on the cheap with the wrong materials.

 

[newby boat owner]

Thanks for the advice. I will probably remove all the gel coat and epoxy the hull then apply new gel coat.

I was just wondering if using a tanking product would prevent any water ingress to the hull in future if osmosis reoccurs

 

[Tranona]

Thanks for the advice. I will probably remove all the gel coat and epoxy the hull then apply new gel coat.

I was just wondering if using a tanking product would prevent any water ingress to the hull in future if osmosis reoccurs

Why do you think you want to that? not a simple job and certainly if you do not understand the process. What sort of boat is it?

Osmosis is not just caused by water ingress but primarily by fluid already in the lamination and blisters are signs of the fluid pushing the gel coat. The normal repair is to deal with the blisters. stripping gel coat, drying the laminate, filling, fairing and coating with epoxy is a skilled and expensive job and only really justified if the blistering is extensive and the boat has a high value.

 

[kashurst]

Osmosis gets over hyped. It is not the end of the world - unless the boat is covered in blisters as big as your palm, bursting over the entire underwater surface.
As other have posted just grind out and wash out any blisters you have, let it dry out for a month or so if time/space allows and fill with epoxy filler. Thereafter store the boat out of the water in the winter months and any moisture content will slowly reduce over the years.
Removing all the gel coat is a seriously big job, hard work, very noisy, expensive with all the materials. For what? You also run the risk of doing more harm than good if you go too deep.

If you can post a few pics.