---

Left exposed, any cracks in the gelcoat can and will allow water to reach the fiberglass and eventually lead to delaminated and compromised fiberglass. Wax will help, but because the cracks can move the wax barrier will also fail over time and is only a bandaid.

There are a couple of reasons gelcoat gets cracks.

1. The original gelcoat was put on too thick , a common problem with some boston whalers I have refinished (I have seen 1/8" or 125 mils +). Thick gelcoat cracks under minor flex where thinner will not. Also, gelcoat shrinks over time and exposure to the sun makes the effects worse.

2. The fiberglass under the gelcoat has been compromised, too much flex will cause the gelcoat to crack, these will typically be spider cracks.

In my opinion, the correct repair would be to re-gelcoat anywhere that has cracks.

First, You need to identify which problem caused the cracks.

If the underlying fiberglass has been structurally compromised and flex is causing the cracks, the area needs to be repaired and made structurally sound.

If the cracks were cause by shrinkage only and the underlying fiberglass is still sound.

First, sand any areas with cracks down to the glass, being careful to not to go into the glass at all. Its ok if you leave a mil or 2 of gelcoat unless there is any delamination or loose gelcoat. at this thickness the cracks in the gelcoat will not be a problem for the new gelcoat sticking.

Clean with acetone or laquer thinner.

You have two optons here.

You can gelcoat to 35 - 40 mils thick, sand out orange peel which will leave you at ~ 20-30 mils, then top coat with a paint of your choice.

Or,

Gelcoat to 35 - 40 mils thick, sand out orange peel working your way up to 1000 grit, followed up with compound, which will leave you at ~ 20-30 mils

It is very important that the final gelcoat thickness after sanding / polishing should be 20 - 30 mils, any thicker and you risk cracking over time. The thicker it is, the sooner it will crack.