Glynn
Having removed all the deck paint on my Fulmar, I should be able to help.
It looks as if your deck has been painted multiple times and is flaking in areas of either flexing or poor original bonding. I would not recommend using the method I used of chipping the paint off with a chisel - it took 10 days! Whichever method you use will be brutal. You could use a tungsten scrapper on all the areas of damaged paint. Equally you could use a disc sander, not an orbital. You need to get those areas back to clean gel coat. Whether you remove all the paint should be your decision, but if it seems well bonded I would leave it. Then fill the areas of removed paint with a waterproof filler like International Watertite, and fill level to the remaining paint. Sand all of the deck paint to clean the surface. My choice of deck paint is International Interdeck. Before applying deck paint, mask using 3M blue masking tape all the edges and to protect any fittings.
The best way to remove excess varnish from gel coat is easy. Sharpen a chisel (
http://www.stewmac.com/How-To/Trade_Sec ... azors.html) and then use it as a scrapper by holding it at right angle to the gel coat surface, then gently remove the varnish. If you mark the gel coat, this can be compounded out to a high shine.
To access the back of deck fittings, you will have to pull the head lining back. All deck fittings with have a layer of fiberglass over every nut as this was Westerly's method of stopping deck leaks. You will need to cut this fiberglass away using a Dremel, but be aware if the new fitting does not exactly fit the holes, then you will also need to remove the penny washer which is also glassed in.
My teak toe rails and rubbing strake had been varnished, but the varnish had broken down and water had penetrated and discoloured the wood. All the varnish was removed and the wood was sanded and left to weather to a grey finish. The hand rails and tiller were tackled later, but I decided to revarnish them using a traditional oil based varnish. Modern varnished has a very hard surface, but poor adhesion makes it easy for water penetration. With oil based varnish, the initial coats will soak into the wood and seal it against moisture and is easier to treat minor knocks. I used Le Tonkinois (
https://www.letonkinoisvarnish.co.uk/varmain.html) and am very pleased with its performance after a year. However I am now planning to sand the weathered toe rails and rubbing strake so they can be varnished.
