Stan,
If it were me, ( Well that was me last year). I would scrape back until you have removed all loose paint, feather out the rough edge's then fill and smooth. If you just fill the cracks they will keep spidering out on you and your new paint job will be for not.

I have every kind of paint problem on my project 32'. It is like a paint problem laboratory. It had the original finish. It had pinholes, feathery cracks, and chipping filler. I concluded that they rushed the topcoat before the primer was dry causing the pinholes. In spots the paint was too thick and cracking occurred. Most of the filler was OK but in spots it was soft and lifting out. Some forum members have the tools and skill set needed to blast and sand down to bare aluminum and start over. Not me.

GENERAL APPROACH: I decided to aggressively sand (80-120-150) but only just past the loose paint and leaving the sound brown undercoat. When I broke the paint surface to bare aluminum I hit it with a compressed spray bottle filled with the etching primer which was the first part of my paint system. The top coat was a one part enamel.

DEEP HOLES: I used Interlux Watertite Epoxy Filler to fill in some big holes in the filler where water tended to accumulate. First I dug out all the soft stuff and sanded any bare aluminum. So the epoxy had to adhere to fresh sanded aluminum and old but sound filler and maybe a little etching primer. It did but with other problems. It kept shrinking back. When I humped it up it was to hard to sand level with the surrounding area. It also rejected my top coat even after I thought I had sanded all the Aniline Blush off. Epoxy is still the way to go for deep holes. Next time I will take some forum advice and mix up my own filler with micro-balloons. I just found a web site featuring aniline free epoxy. Maybe I will try that. Another forum tip was to apply a first layer of epoxy directly by rubbing it in with sandpaper. That makes a lot of sense.

CRACKS AND PINHOLES: After sanding, many areas still had hard topcoat but with many shallow pinholes and cracks down to the original primer. An auto shop recommended Evercoat 100421 polyester finishing and blending putty. It has a strong enchant so you put it right on fresh sanded aluminum or old finish. New finish must be fully cured. It is ready to sand in 20 minutes. Mix a little at a time on one of those paper sheet palettes or you will be throwing most of it away. It works very well, sanding easily and level.

PAINT: Use a system which can be tinted, sprayed, brushed, rolled or rolled and tipped.. A large part of the paint job is deck. To spray a deck you have to tape and mask all of the stuff on it or else remove it. Then you get to cover the rest of the boat. You can’t do any of this at the dock and after all that work you are going to walk on it anyway. Later you are going to have to patch and blend the paint until the next full paint job. Pick a flexible paint system. The best part of my paint job was the fly bridge and side cowls. I sent them off to a body shop to be painted and the trim stripes applied by professionals.

Your boat sounds rough with the multiple layers. My 32' has original paint so an electric orbital sander works. I have a 28' that needs paint before I sell it. It has those multiple layers hiding who knows what. I can step up to an electric 4 1/2" grinder or a 6" circular sander. There are also air tools. Now that both my boats are on trailers I can move them near a big compressor and maybe use my UNIRAM sand blaster. I sucks the sand back into a collector so you don't need a moonsuit to run it. You just need a big expensive compressor. I keep scouting the auctions for a portable gasoline model. As my Dad used to say "Use the biggest tool that fits".

75 Express,

Welcome to the site. This is how we did it....

http://marinetteboat.com...oamings-and-gunnels.aspx

Thanks DiverDennis, I thought I saw that post a couple of weeks ago, but could not find it again. This will help a lot.
Dougrose thanks for explaining the WEST product. I am looking forward to using it.