Cracks in Gelcoat and Fiberglass Near Keel

[nelly]

Hi all,

So when this boat was surveyed a few sections like this were noticed. During the survey we did scrape down to below the gelcoat in a few areas and it did not seem that the cracks extended into the fiberglass. We also looked inside the bilges and scraped some of the paint down and inspected where we could and noticed no fatigue.

No signs of hard grounding that I can see: meaning the keel looks fine, no signs of damage, etc.. Keel bolts are absolutely fine and cannot be tightened (nuts aren't loose). No cracks around the keel bolts, no water through the seal, everything good.

However, when i went to remove some thru-hulls I exposed some additional cracks that could not be seen previously. Most of these were just gelcoat. However, as you can see in attached photos in a few there are what seems to be a few stress fractures that extend into the fiberglass.

The boat hull here and elsewhere is incredibly think. Over 1.25" thick as measured after a bit of grinding.

Fiberglass was also 100% dry both during the survey (boat was on the hard for a while) and after I took the boat out of the water for the winter. Tested with a moisture meter and with the nylon hammer (sound test).

As I ground out the fiberglass it was also extremely solid. I've worked on boats previously that had damage and water intrusion: the fiberglass becomes brittle and easy to sand. Not so here. Extremely hard work these down even 1/4-1/2 of an inch with the disk sander!

Also after I ground down a bit the cracks were no longer noticeable to my untrained and inexperienced eye.

I imagine everything is fine, but would like additional thoughts.

Gallery: https://imgur.com/a/iDyi53n

[Discovery 15797]

It seems very unusual to have 'stress fractures' around a thru-hull.

Given the fact there was no apparent water damage, the 'cracking' may have occurred when you removed the thru-hulls.

Since it seems superficial I would grind it out and refill with glass strand reinforced putty...it sounds like you know what you're doing there.

[nelly]

Originally Posted by Discovery 15797

It seems very unusual to have 'stress fractures' around a thru-hull.

Given the fact there was no apparent water damage, the 'cracking' may have occurred when you removed the thru-hulls.

Since it seems superficial I would grind it out and refill with glass strand reinforced putty...it sounds like you know what you're doing there.

Not actually around the thru-hull at all. Worst of them were about 8-10" away from the thru-hull.

I imagine this is just an old boat put through a lot, and the fact that the fiberglass is like grinding down stone I'm not too worried about it.

[gmakhs]

I think telling the model of the boat it will help people to give you more information.

I don't believe is a serious issue , if it was my boat I would examine and reinforce the stringers and floors from.the inside just in case .

For the external I recommend you grind it put 1 or 2 chopped mat and resin and then gelcoat . If you want a nice finish try gelcoat with funed cilica it's very easy to sand .

Even if there is an issue it can be fixed and reinforced without big expenses .