Gelcoat discoloration and strange cracking shapes

[Extorn]

I'm looking for advice on how to solve this gel coat fault. It's an 8ft Ian proctor Blue Peter sailing dinghy.

The discoloration is on the inside of the cockpit. It seems to be inside the gel. No amount of Y10 or hull cleaner or cif seems to affect it at all.

The inside of the Hull is wet due to cracks where water has got in I wondered if this has been the cause.

Any ideas how to remove the staining?

The second image shows a series of semi circular cracks coming through the transom, though lots of other places too less badly. Maybe glass bubbles under the surface?

Any suggestions for a fix beyond heavy sanding and re-gel coating the whole boat.

Many thanks

 

[johnlilley]

Possibly due to lack of pigment in the original gel coat mix making the gel coat a bit transparent allowing the laminating resin colour to show through which has probably been affected by uv and darkened over time. Almost certainly irrecoverable with regard to colour. Probably not structural though.The semicircular cracks look as if they are fully circular but only cracked on part of the circle. Possibly swelling in the gel coat that have expanded, cracked the gel coat and collapsed once the pressure has been released. Possibly pockets of air or fluid trapped in the gel coat at original build eventually escaping and leaving the crater.

 

[Extorn]

Thanks. Really interesting.

 

[Keith 66]

I have seen similar many times, blue gelcoats are prone to such discolouration & my son had a boat that was like this. As for the semicircular cracks, it can be caused by osmosis on boat hulls but equally can appear on decks & cabins too. Its just old age & probably UV light, basically the gelcoat is breaking down, nowt you can do except sand it off & paint it with a 2 pack epoxy & polyurethane paint on top.
Lot of work for a little boat.

 

[Extorn]

Thanks for your explanation and suggestion as to the fix.
Am I to understand that I cannot remove the 3mm gelcoat and replace it where it is failing? Does that not solve the issue because the damage originates in impurities within the fibreglass component (hence adding an epoxy seal) ?
This is true - a lot of work for a little boat - one can only presume a lot less than on a large one.

 

[Extorn]

To be clear, what I was considering was to strip the affected areas back to fibreglass and re gel-coat it. The areas to patch would be somewhere in the region of 30cm * 15cm at the outside, albeit around an inside curve as seen on the photos. The other area that is failing is the anti-slip areas where the gelcoat has flaked leaving little pits all over. I was thinking I could just paint thin gelcoat straight over the top of this to refinish it. They all stand proud of the rest by maybe 2mm anyway so after sanding back 0.5mm, I could re-coat and then fair the edges into the shiny gelcoat around.
I started wondering if it would be better to take it back to fibreglass all over and re gel-coat the entire boat, but I wonder if getting an even thickness all over might be tricky. The exterior of the hull isn't too bad, so could likely just redo the transom area, but the entire cockpit would ideally want freshening.

If anyone is interested in more detail of the damage, its on my website Blue Peter Sailing Dinghy (available 7am till 10pm BST most days)

I totally understand that the cost is more than that of the boat, I just don't like throwing things away, and having made a steel trolley and cover for the boat, it feels sad that it is in such a state.

 

[Stemar]

If it bothers you enough, rub it down and paint it. Then be ready to do it again when you drop something.

It's very unlikely to have affected the strength of the layup, so personally, I'd just go sailing.

 

[Extorn]

For those interested in historic change only:
This is what the inside of the boat looked like in 2016 (apologies for the human distraction - I wasn't evidencing the damage back then!).
Clearly the staining has worsened over the past 4 years, but the osmosis (little circles) are much worse now.
It's kept with a cover on at all times and it hasn't been sailed at all the last year or two really, so UV shouldn't be the issue. The club does flood, so presumably water has saturated the fibreglass and then not dried out again quickly enough.

 

[johnalison]

I am impressed with an 8’ boat that has a cockpit. Does it also sport a saloon and heads?

 

[Scotsailor]

It’s an old boat. It won’t affect its use in any way. Just think of it as part of its character.

 

[Extorn]

I am impressed with an 8’ boat that has a cockpit. Does it also sport a saloon and heads?

Hmm. I appreciate your response is in just, but as a non boating person I'm afraid I wasn't sure what else to call the hole you sit in as compared to the fore deck area etc.

 

[Extorn]

Jest not just. Blasted autocorrect.