The big question here is do you know what the paint is? Is it Awlgrip, Imron, some kind of 1 part urethane porch paint from the hardware stores?
I've done lots and lots of both gelcoat and paint work over the years, and can tell you just about anything you need to know. But in the long run, once you go to paint (over gel) your better off staying with paint. It is way to much work (money) to go back.
Is the paint peeling, chipping, bubbling right now?
Out of curiosity, if you don't know what type of paint is on it, and he(this someone) does not know what type of paint is on it. Then how do you know which compound to use on it?
Also, you wrote "has a compound to use to remove the paint and bring the gel"
Compound is not used to remove an entire paint job. Compound is a fine cutting buffing material, just used to knock a few thousandths of an inch out of a paint job to knock off oxidized paint, but not so much that you burn through the paint into the primer or basecoat.
If your looking to strip the paint completely off, then your looking at a commercial paint stripper. Which is typically Xylene in a jelly base so it does not evaporate as quickly as it normally would. But what you have to be carefull on with strippers on painted boats is the stripper will also strip the gelcoat if you don't catch it in time.
Now on top of all that, you are not going to know what the gelcoat looks like until you get the paint off. For example, is the gelcoat loaded with spider cracks? Which you would have to grind and fill, or really just re-gel the whole boat? (which is way more expensive than painting it) That you won't know until the paint is off.
I've got family in Marblehead, but I made the move from Mass to FL a few years ago. I'm 1500 miles away, on the gulf of SW Florida.
Your making the right decision, stripping paint down off to gel is extremely hard to do. So much that your better off sanding the paint off until you hit gell, which takes way to much time. The materials for a high quality paint is much more expensive than gel. But the labor and prep is so much easier. When I do boats, if a customer is looking for a re-finish job, I do paint. Most of the higher end boat builders do paint nowadays as well. Your 2 major paints are Awlgrip and Imron, they are both as excellent as it gets, but a little different to work with. I personally do Awlgrip paints. Hatteras yachts does as well.
For example, with Awlgrip. if you have a bit of a beat up hull, regardless of if it is gel or paint. All you do is sand it rough, 80 grit. Fill in deep digs with a decent quality fiberglass filler. (I use US Chemical fillers, but there are many high quality fillers out there). Fair out your filler work, and re-fill if necessary. Roll or spray the primer coat. Knock it down with 120, 180, and then just 220. Then roll or spray the 2 part Awlgrip. A few coats, about 45 minutes apart. Let it dry a week before touching it. And thats it, your done. No finish sanding, no buffing, no polishing, no waxing, no buffing (no buffing/waing ever, you never have to buff or wax Awlgrip) The prep with paint is easier than gel. There is no finnish work to do once the paint is applied. And the paint is as hard as nails when it is cured. You end up saving so much money because of time. For example, if you re-gel a boat. Using a dump gun and laying on the gel is only the first step. After that you have to knock it down with sandpaper before you even get into buffing, polishing, and waxing. Gel coat does not flow all that well when your not using it in a mold. It is very thin, and does not cover well/opaque. It is much harder to work with than paint when your applying it over an external surface, like you normally would with paint. But a high quality paint is the way to go. A good Awlgrip job will look as good as the day it's 10 after 10 years in saltwater. Without compounding, buffing, waxing once or twice a year. All of what you would do with get.
That should wrap it up here. But I do work for tips so I want to make sure you are happy with me before you rate me. If you have another question on this feel free to fire away.
Thanks in advance,