Having established what work needed doing, it was time to get the old paint off.
Stripping paint is not one of my favourite jobs at the best of times, and my garage not big enough! The advice from one of the maritime museums was to strip paint back to bare wood using a chemical stripper. In fact I haven't altogether followed this advice. Its obviously the right thing to do for a fastened boat, but a glued boat like this has some complications. On the other hand the paint specialists tell you firstly never to let the paint get into the state where it no longer stays on the wood - good advice for boats that aren't already in that state, and secondly never to remove well attached paint, especially undercoats and primer, but just to sand into the topcoat.
With this boat the main issue is that there are areas of glass reinforcement. This has been added to the boat at various times using different technologies. The topsides seem to be made of narrow (3 ft) vertical strips of ply joined with glass tape. This tape has been glued on with polyester resins I think, and standard paint stripper attacks it fiercely. There are also areas of epoxy based glass and carbon layup with filler where the boat had been repaired after the Wave at Weston.
If reverting to bare wood is a given - and in fact, as it turns out, for at least some of this boat it wasn't - then I think chemical stripping would be the best, if it were not for the glass and filler. The epoxy filler is mildly resistant to paint stripper, but softens drastically if left on for any time. It mustn't of course be allowed to get below the filler into the laminate - but how do you tell? Leave it on for seconds only. Fortunately you can sand paint of the filler readily without losing wood -provided you know where it is. Difficult to tell until you get the paint off. The professionals tell you not to let heat or stripper anywhere near the layup, so that has got to be the prime aim. When in doubt sand. I've used a mix of chemical strippers and a heat gun, and tried to avoid too much sanding. None of these methods is ideal.
The Heat gun seems great for stripping off large areas of top coat. There are caveats though. The polyester tape on the topsides seems to be thermoplastic, and mustn't get hot, otherwise it will come straight off. The epoxy filled areas also mustn't get too hot. Post curing 5 years on with excess heat does nothing but harm!
. It seems to me that a lot of the effect of the heat gun is from evaporating moisture in the skin and blasting the paint off with steam, and this is exactly what you don't want happening under laminate you wish to keep! What I attempted to do was to warm the paint gently, and if it bubbled readily then there was wood underneath, and I could use the heat gun to strip it. If it didn't then there was probably laminate under there, and it was time to be very careful!
One interesting observation was that the level of adhesion of the paint varied considerably, even across the same piece of wood. This can be guessed from the above photograph, where a large blue area shows where only the top layer could readily be removed. In particular, while stripping the topsides, I noted that wherever there was a hard spot - bulkhead or even reinforcement, the paint adhered well and was difficult to remove, but in the softest areas is would peel away with the slightest warmth or scraping. I rather suspect that this is because a consistent level of sanding would actually have resulted in much less actual abrasion of the surface in the soft areas than the hard points. Perhaps one too easily underestimates the amount of preparation necessary. Certainly in future I shall bear this in mind when working on wood boats, and pay more attention to the "soft bits". One of the many advantages of foam sandwich construction is that one has much less reason to have flimsy areas of topside or deck. I suppose I should note that I love the look of wood boats, I like working with wood, but modern hi-tech is just so much more practical for lightweight racing dinghies.
There's room for a lot of error when scraping off the old paint. The main problem is digging into the ply or filler with the scraper. It needs to be reasonably sharp to get through layers of soft and harder paint, but not so sharp that you chop straight into wood or filler without noticing it. I'm undecided on how rigid or flexible it should be - we are talking about a curved surface, but I think bendy ones may be more prone to digging in. It will help lots if the edge and sharpness are even right along the blade, so possibly not that old scraper with all the notches on you've been using on windows and plasterwork round the house... [Bit do as I say, not do as I did here!]
The problems of the glass tape and polyester resin on the topsides makes me think that doing this sort of work on glass taped dinghies would be exceedingly troublesome. Perhaps one should just pull the whole lot off and replace, but it certainly adds a whole lot of extra work to the job. You need to consider, too, that if you do that the glass tape on the inside will be all that is holding the boat together, and should that be dubious - suddenly you could have a kit of parts instead of a boat. Be careful with old Fireballs and Forman 4's folks!
Anyway, having got the old paint off the next stage was to put on a protective layer of epoxy and see what problems had been found.