I started with the stern and used an orbital sander then cleaned it off. I then rolled on the primer and tipped it off with a Jenny brush. This worked well and I filled a few small scratches and imperfections before giving it a second coat.
I decided to carry on with this method for the rest of the hull, starting on the starboard quarter and then moving to the port side forward. I was by then finding the hull to be in worse condition with lots of loose paint. I was starting to think I needed to remove all the paint, but how? I looked at paint stripping machines which the professionals use but they are just too expensive to buy and you cannot rent them, as far as I know. I read lots about using a chemical paint stripper and that is still a possibility but in the end I decided I really wanted to get the boat in the water and sail. The boat cost me £200 so it is silly to spend too much on her right now and it is something I can do later.
Picture below shows the state of the paint, layers of it and very rough.
Below is where I have sanded the port bow and primed.
Despite lots of sanding and cleaning off the primer still did not adhere very well in all places. There are still loose patches where I sanded and primed and bubbles. There are also some areas where the primer simply has not adhered to the old gelcoat despite sanding to key it in. I am beginning to think there is moisture in the hull even though the boat sat in a garden for many years. The bubbles appearing do not have moisture in them though. It could well have had condensation inside which may have had an effect. I think I need to get a moisture meter to test the hull.
Strangely the below waterline hull condition looks good and no sign of loose paint, thank goodness!
Any words of wisdom welcome or ideas of how to remove all the paint down to gelcoat. I may then have to epoxy the hull.
More later when I find the solution...