hairline cracks in hull gell coat need advice

[wesleysherman]

I have a 1982 hunter 27 new purchase last year. I have done a lot of work to "Abandon Land" Over the summer. Repair rudder, repair hull to keel joint, I stripped the hull water line down to bare glass and put 5 coats of interlux 2000e. Currently I am about to remove the rigging u-bolts to replace alone with some standing rigging.

After cleaning the hull very well last week above the water line I noticed three areas of very fine cracks in the gel coat. if you dont look carefully you have a difficult time seeing them.

This one is on the Starboard side just in line with the cockpit and cabin wall.. its only located in the center between the boot strip and hull deck joint. None of the spider cracks go very far.. (what you are seeing line wise is the result of me drawing lines along the cracks to that they can be seen.. other wise the 5 mega pixel camera does not show them)
The second photo is on the opposite side from the first pictures...
They are both behind any of the rigging ubolts by about 3 feet to the stern of the rigging lines.. There is no impact sight or evidence of anything hitting it that I can see.

I am wondering if anyone else has run into this and what you may have done to repair this.. I am suspecting its gel-coat and not thru the fiberglass.
If I need to grind this down to be safe to the fiberglass then Id like to get on it before it gets to cold this year...

If it indeed is gel coat cracks can one grind then down to fiberglass then prime and fair to lvl again. Asking this as I am going to paint the above waterline ....I am hopping that this would stop the cracking through the new paint... I am sure it would crack through the new paint.

My concern is two fold.. water getting in through the cracks in gel coat and the appearance after painting.

 

[braol]

It almost looks to me like an area perhaps rubbed by a fender as the boat moved in an up-and-down fashion pierside. Usually gel-coat cracks are kind of "spider-webby" (usual) or star-shaped (from impact). Regardless, repairing them is not too difficult...it's all in the surface prep. And no need to go all the way to the fiberglass either, just dewaxing and 320-grit paper if I remember correctly. Color-matching the gelcoat can be hard, but chances are that at some point you will be painting the hull anyways so you only need to get close (plain white will do).
Jamestown Distributers has a good write-up on this topic: http://www.jamestowndistributors.com/userportal/document.do?docId=257

Also, the West brand epoxy guides are good. I also recommend the Bill Casey book "Complete Illustrated Boat Maintenance" and the pbase web site (search pbase and boat to get to the site).

I'd like to know more about your rudder repair and your keel/hull joint issue. I'm always looking for tips and tricks. (Us H27 owners need to stick together!)

 

[wesleysherman]

Hello Braol,

Thank you for some insight into the hairline cracks.. I am thinking you are right because that is exactly where I have my fenders on the starboard side (where they hang and on the port there is also one small area right under were the fender hangs.. I am not worried about matching the white gelcoat at this time anyway.. as I will be painting the above water side soon.....
I posted most of the repair process to my rudder while on the boat...
here is the link http://forums.hunter.sailboatowners.com/showthread.php?p=1120285&highlight=wesleysherman

What I did to the keel to hull joint was because I had a small smile at forward keel join and a slight one at the aft part of the keel.. I ground it out with a grinder (very carefully) I ground out about 1/4 being very carefull not to hit the fiberglass portion of the hull.. I found that the cracks (smile) was rather superficial for the most part.. so I brushed in 2 part west system epoxy to seal it up...liberally.. then 2000e and then I took a rubber bondo spreader and cut it so that it was flush to the hull and flush to the keel with a small flat part in the middle to smoothly fair in 5200. I know allot of people dont like 5200 but it was I believe the original method used. So with the spreader cut I filled the valley in all the way along one side... I diped my spreader in denatured alcohol to wet it and then spread the 5200 slowly in one long draw from one end to the other.. it came out perfect caulk line bead. I then scraped off any extra that remained from the spread off the hull and keel.. after a week on there I sanded it with 120 grit paper rolled on paint roller to smooth out any ridged left from the dried 5200. So now its smooth and perfect seal...I did this spreader design after talking to a older friend of mine that has been repairing fiber boats for better part of 55 years.. He used to work for Hunter over 20 years and also for sailboat company in Europe before that , I foget now who it was... So anyway wasn't to much work .. but I would suggest before you do such a seal up if you have similar problem that you get all the wrenches and torque bars needed to snug up your keel bolts if you haven't done so lately.

Ive done worse repairs on rudders and keel lines if you have any questions I would love to help out if I can... we all need help in areas we know little about and help others with what we know more about.

 

[braol]

Glad I could help. The repair of your gelcoat would, of course, be the same whether it was crazing or rub marks. The best longterm solution is to sew together some canvas fender skirts. Simply putting canvas covers on your fenders is a bad idea because fenders roll, and when they roll they pick up dirt and debris that can ruin a nice hull. The skirts can be made with a felt or fleece backing to provide even MORE protection. In fact, my friend has felt backing and the area where his fenders rub is actually MORE shiny than the rest of the hull!