What they found after sanding off bottom paint; gelcoat cracks & delamination !

[hockeyfool]

Took my boat to a boat yard service shop for a bottom job and they showed me a bit of a bad dream;
  when the sanding off of all the layers of ablative ( 3-4 ) they uncovered deep cracks beyond the gelcoat forward of the keel ,
  and several spots around the bottom, one as big as a fat 3 foot oval - apparently soft enough to lift from the hull when air-filing.
    So they told me what the bottom really needs to be sanded to fiberglass and have the repairs with layers of polyester resin
      and then reapply gelcoat.
          More pics as they call me for next steps of process.  

[cfelle2]

I would get a second opinion.  I am suspicious of anyone recommending polyester resin for a repair instead of epoxy.  Epoxy will bond far better than polyester resin.  The previous owner of my CP 23 repaired the mast step with polyester resin a couple of years ago and it is already starting to come apart.  I have built a number of boats using wood and epoxy and I have never had an epoxy bond fail.

Chris

[brackish]

agree with chris on the epoxy for repair.  also, no need to put new gelcoat below the waterline.  epoxy repair, fair it out, then barrier coat and ablative.

On a previously owned boat, I did major core rot repairs using epoxy to reglass, worked great still intact 17 years later

[shamblin]

i wonder what hutchins/compac would advise?

[millsy]

Unfortunately someone will need to chase down the cracks, particularly forward of the keel.  I am curious, what is the orientation of the forward cracks? And how do they line up in relation to the concrete ballast, which extends into the v-section below the cabin sole? 

Where is the location of the 3' oval-shaped area of lifted gelcoat?  Is the gelcoat gatored in appearance?  Evidence of earlier repair? 

How are the other gelcoat cracks oriented, straight or curvilinear?  So many questions...

Regards,
Chris
Dolce C-23

[hockeyfool]

After doing extensive reading I see that a process of removing the gelcoat off to the fiberglass  begins the
  repair by then drying out or exposing all blisters or damaged /cracked laminates ; and several sources indicated that
epoxies don't adhere  well or will blister off eventially from the factory polyester resin-laminate . As the person working on my boat
  stated the gelcoat will adhere to the factory laminate, fill the voids ( after the cracks have been relaminated ) and make a good
surface for the barriercoats .

[MacGyver]

Being a repair guy myself and specializing in bottom repair work I will tell you in all my years of work, I have never used polyester resin to make a repair. I always use West System brand Epoxy for every repair.
The boat makers (all of them probably) use polyester resin because it is cheaper and makes the boat cost less. If the damages were all below the water line, What I would end up doing is use a grinder bit and chase out the cracks to make sure that there is no glass issues.
After that I would sand out/off the GelKote and get it down to glass and make my repairs.
Those repairs are all done with it in mind that I NEVER want to see the boat having issues there ever again.

After I smooth it back out to the hull shape previously there, Or If I have added Glass I will fair it back out so when It is painted you wont see it or notice it as a issue again. It will "blend back into the boat.

Then I coat with Interlux 2000, minumum 5 to 7 coats, and paint with whatever bottom paint.

I have done numerous repairs and am referred to as the top dog repair man in this area. People come from Indiana, Oklahoma, Wisconsin, just to name a few to have the work done by me. I am not saying that I am the one to listen too here, just saying that doing the work properly will help get you work in the long run.
Most times we meet or exceed the manufacturers recommendations on prep, and go the extra mile to solve the original issue, not just repair the problem.

A word of caution, there is a lot of stuff on the internet, dont believe it all. I recommend you call the guys at West System, or go to their site and read the technical stuff they have, etc.
If you have some more pictures of the actual issues, etc, I can tell you how many hours it would take to fix, and etc. definetly get a bid before having the repair work done.

Hope this helps, and If it sounds like bragging, it is not meant too, I just hate to see bad repair work, and usually the guys doing that work arent any good, and have little if any training in the actual subject. I have redone a lot of work, from customer repairs, to other marina technicians work.

Good luck, and I will keep a eye on here if you post more pictures.

Mac

[cfelle2]

I have to agree with Mac.  I really think you should get a second opinion. 

I am curious could you post links to the articles which talk about epoxy not adhering well to polyester resin?  I have never heard of that before and am interested in finding out under what situations that may be true.

Thanks Chris

[millsy]

I work with laminate repair specifications all the time.  Epoxy works, but I prefer vinylester resin for repair.  It is very tough, bonds well, has similar properties to poly and is generally easier to work with (similar to working with iso or ortho polyester).  Ideally you should replicate the original schedule so the material properties and laminate thickness remain the same.  Using a good barrier coat is much more practical, below the waterline, than trying to apply gelcoat.

Iso is also generally suitable- ortho not so much;)  Scarf/taper ratios are important as are proper overlapping of the laminates.  Using Attprime is also a good idea if the bonding surfaces are suspect.

It is important to determine why the cracking occurred in the first place.  Sometimes that will determine how repairs are eventually completed.

Regards,
Chris

[MacGyver]

http://www.westsystem.com/ss/polyester-over-epoxy/
I swear by West System, And the tech guys you can call anytime and ask them anything, they all sail, and not only that but the owners are still building boats with this stuff, it is amazing, read this article.

[MacGyver]

Sometimes I click faster than I think, And actually right now I am excessively sick. I meant to put this link in here.
http://www.westsystem.com/ss/west-system-epoxy-for-fiberglass-repair/

Im sorry, this link above is a good explanation why Epoxies are better suited for repair nowadays over polyester resins.

Mac