Thanks for the replies Richard and Pikey Dave
I'll try and work out how far into the wood the problem has gone - I estimated 2cm yesterday and if it's dry at that point I guess the resin filling will be OK. Wood seems to be soft at the outside edge but hardens up pretty quickly (I tried to gouge some out but it wasn't that easy)
I did have a tarp which I was going to tie over the bow yesterday to allow the wood to dry out but then discovered it had some holes in it
Ended up just putting the hatch back in so it doesn't get any worse.
For the sealent I always like to see the stuff squishing out all edges so there is no ambiguity! I have found that baby wipes make an excellent cleaner for removing excess SikaFlex but yes, stibbling it into the deck is a good idea. Had intended to wire brush it, clean with solvent then apply sealant.
I suspect that most of the water will be fresh. Given that the boat gets well washed down after use and lives outside, the amount of salt water is proabbly pretty small. I don't stuff the bow into waves that often
In terms of Ribcraft replying - I have left at least 3 emails and 2 voicemail messages this year about various things and haven't heard a peep out of them but will email tomorrow anyway.... Boat is under 5 years old so is still under warranty but it would cost a huge amount (time and fuel) to tow the boat from Glasgow to them for repair. I would like to think that they could authorise a local repair shop to fix it or come up with another solution.