DIY Gelcoat Crazing Repair on Bottom of Hull

Hey All,

 

Doing a bit of maintenence on the boat at the moment to spruce her up a bit.

She's an old Chivers Thunderbird and the next part of doing her up is addressing the spider crazing on the gelcoat on the bottom of the hull

I could just leave it but i'm looking at possibly selling it in the coming year or so, so i'd like to have it tidier

 

I've researched it nearly to death and it seems the best way is to expand the cracks, clean and then fill with Gelcoat putty filler and sand back

Some say use the cone shape burr from a dremel, some say use a church key to open it up (Don't know how to get my hands on one of these)

I'm hesitant to use the dremel as i'd be upside down and wouldn't have proper control and those tools can rip through fibreglass like butter

 

Anyone had experience in doing similar and want to weigh in on their experience?


chris raff's picture

Posts: 3257

Date Joined: 09/02/10

How bad is it ?I had spider

Mon, 2015-08-24 10:34

How bad is it ?

I had spider cracks all over the shop on the upper not the hull .. no chance of individually opening them all up .. so just rubbed them back as much as possible and used a 2 part marine bog , then 2 pack paint . Held up for 3 years but starting to come through again now ..  
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z00m's picture

Posts: 1086

Date Joined: 10/05/14

 How bad is it? Maybe a

Mon, 2015-08-24 10:46

 How bad is it? Maybe a picture would help.

There are other products out now which can be used to fill spider cracks if it is just some flexing. www.magicezy.com

I'd be a little concerned at the integrity of the hull with cracking below the rub rail. If it is not from a defined impact it could indicate softness in the internal structure.

Posts: 286

Date Joined: 21/07/14

some say use a church key to open it up

Mon, 2015-08-24 12:55

 A Church Key is what us oldies used to open bottles and cans years ago.

 

Have a look at https://en.wikipedia.org/wiki/Churchkey

nico's picture

Posts: 226

Date Joined: 17/08/10

 If these are indeed

Mon, 2015-08-24 20:41

 If these are indeed structural you may as well use a 4 inch grinder and get right in to the glass as the area affected wil just be a haze of white due to a impact.

If they a just spider cracks this is caused by impact  though they are not structural, what happens is that the fibreglass has flex and has movement and gelcoat has no give so it is common to see crazes in older boats especially on chines or on tight radiuses you will only have to sand off the gelcoat in most cases but have seen repairs where the crazing has gone in to the glass which means glass work which requires a layer of split strand mat 225 chop strand in other words .

I would be inclined to leave them, if your going to do the job I would use a good filler like micro beads and a vinylester  resin that way you can re gelcoat, otherwise you can use epoxy resin then high build prime and 2 pac  could turn in to a big job and trying to colour match can be tricky. Concentrate on the fairing to keep it nice and straight nothing worse than a boat forsale with bad repair jobs and looking patchy. I would make sure the tape lines finish out of sight from the naked eye and wet rub any hard lines out for a seem less finish.

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