Gelcoat can be successfully applied over Epoxy repairs

[donradcliffe]

Originally Posted by minaret

As I said, haven't seen one yet. And I often do poly on poly repairs in major structural work. As in, the boat went on the rocks and is missing large portions of the hull type work. Don't know a single pro who would approach such a major structural repair in epoxy. Not one. And I went to school for this, have a degree in it, and know just about everybody worth anything in the business in my area. Every failed secondary bond I've ever seen was due to a total lack of prep work, because they were actually trying to get a primary bond and missed the window. Never seen a single failed secondary bond with grinder marks under it. Ever. This means that wasn't a secondary bond at all.

I've seen a lot of tabbing popped loose which is poly on poly. Of course on Bene's its poly on gelcoat....

[minaret]

Originally Posted by donradcliffe

I've seen a lot of tabbing popped loose which is poly on poly. Of course on Bene's its poly on gelcoat....

Which, as I said, is a case of poor or non existent prep work.

[smj]

Originally Posted by Exile

I'm curious what you then used as a topcoat for your extensions. Gel? Paint?



In general, if you use epoxy for minor repairs on a gel deck, can you bypass using 545 if you then use an epoxy based paint to try & match the gel? For minor stuff, I've used epoxy, but also gel with some Cabosil mixed in as a filler/thickener. So long as I got the color matching right (terrible at first but improving . . . maybe), then using gel alone seemed to eliminate a lot of the work & uncertainty of getting gel applied over epoxy.

We used paint. It matched up well with the gelcoat and in my opinion the epoxy gave us a far superior structural job.


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[smj]

Originally Posted by donradcliffe

I've seen a lot of tabbing popped loose which is poly on poly. Of course on Bene's its poly on gelcoat....

I've also seen a lot of tabbing broken loose, poly on poly. A pretty well known problem when you use poly as a secondary bond.


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[Reefmagnet]

I think poly on poly has a lot to do with prep. If the wax isn't removed then the strength of the bond will be seriously reduced. I just went through an exercise mechanically removing both old polyester and old epoxy from my boat basically with a hammer and chisel and I actually found the epoxy to be both more brittle and easier to chip away. The polyester was tenacious and there was no separation of tabbing, even against some area of dry-rotted plywood. Admittedly, the epoxy looked more like araldite and is probably over 30 years old (as was the polyester).

[Exile]

Originally Posted by smj

We used paint. It matched up well with the gelcoat and in my opinion the epoxy gave us a far superior structural job.

This seems to be one of those perennial debates where sometimes even the experts disagree. Heck, there's even a section of the West Epoxy Systems manual devoted to it. Countless forum threads I'm sure.

In my case, I've addressed mostly cosmetic deck repairs both ways at this point, so time will tell. For non-structural issues, it seems that epoxy requires an extra finishing step which is always nice to avoid when practicable. A couple of years ago, and after enduring countless issues with my centerboard apparatus & below waterline sheave boxes, I decided to secure the board up into the keel and glass over the slot. A vulnerable area, obviously, and after a lot of research I ultimately went with the recommendation of the yard techs to use poly resin vs. epoxy. The finishing in this case wouldn't have mattered, of course, since it amounted to 3 coats of epoxy barrier and 2-3 coats of bottom paint.

The rationale of the techs who did the job was the same as Neil & Minaret, namely better to use the same materials the boat was constructed with originally. This amounted to using poly resin with 2 layers of 1408 mat/biax heavy glass, then 2 layers of satin weave cloth, and then a 3rd layer of 1408 applied to the middle section. I witnessed a LOT of grinding & prep work (laying on their backs & grinding uphill -- didn't look fun). No leaks or weeps in 2 years, but I'll see how she looks this spring after haul-out. Doesn't mean epoxy wouldn't have worked just as well, of course. Just hoping I made the right choice.

[clockwork orange]

Originally Posted by smj

I've also seen a lot of tabbing broken loose, poly on poly. A pretty well known problem when you use poly as a secondary bond.


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Must be a lot of crappy repair guys down your way. Ive seen my share of failed poly tabbing myself but I have the experience to recognize poor prep and don't blame the materials. I cant remember seeing a properly done repair fail with poly or epoxy. To many amateurs read the West system publications and don't have the experience to recognize that every method they propose is aimed at consuming mass quantities of their product. The same kind of lack of knowledge leads people to blame the balsa when they see a rotted balsa core when it is always the fault of human negligence.

[smj]

Originally Posted by clockwork orange

Must be a lot of crappy repair guys down your way. Ive seen my share of failed poly tabbing myself but I have the experience to recognize poor prep and don't blame the materials. I cant remember seeing a properly done repair fail with poly or epoxy. To many amateurs read the West system publications and don't have the experience to recognize that every method they propose is aimed at consuming mass quantities of their product. The same kind of lack of knowledge leads people to blame the balsa when they see a rotted balsa core when it is always the fault of human negligence.

No lack of knowledge, epoxy is well known to have better adhesion qualities than polyester, especially when trying to adhere to cured polyester. Do as you wish, I will stick to the product that has been continuously tested and come out on top. I would say there are to many old school glass men that don't know the superior qualities of epoxy, and may be to old to learn. Please bring on the publications that state polyester has superior secondary bonds as compared to epoxy.


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[Exile]

Originally Posted by clockwork orange

Must be a lot of crappy repair guys down your way. Ive seen my share of failed poly tabbing myself but I have the experience to recognize poor prep and don't blame the materials. I cant remember seeing a properly done repair fail with poly or epoxy. To many amateurs read the West system publications and don't have the experience to recognize that every method they propose is aimed at consuming mass quantities of their product. The same kind of lack of knowledge leads people to blame the balsa when they see a rotted balsa core when it is always the fault of human negligence.

True enough. The West Systems manuals & videos certainly try and minimize the problem with anime blush & adherence of gelcoat, for example. A lot of conflicting info out there. Can't even begin to tell ya how much contradictory advice I've gotten on the best way to maintain my Awlgrip topsides.

[smj]

http://www.amtcomposites.co.za/sites...0Polyester.pdf
http://www.boatus.com/boattech/casey/polyster-epoxy.asp
http://www.compresdev.co.uk/CRD%20Th...0Polyester.pdf
http://www.azom.com/article.aspx?ArticleID=997
I could go on but it's obvious. if you have to have a gelcoat finish over superior structural strength then use polyester.


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[neilpride]

Originally Posted by smj

No lack of knowledge, epoxy is well known to have better adhesion qualities than polyester, especially when trying to adhere to cured polyester. Do as you wish, I will stick to the product that has been continuously tested and come out on top. I would say there are to many old school glass men that don't know the superior qualities of epoxy, and may be to old to learn. Please bring on the publications that state polyester has superior secondary bonds as compared to epoxy.


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Insurance companys most of the time ask for OEM materials in the repairs, i see lots of holed boats , broken, from the last canes passing the islands , all this boats repaired using Poly and gel and not a single failure, to bad to paint a stern extension when the boat have gel on topsides , if you can match a gel extension with the surrounding gel this is the best aproach in my opinion,, tabbing is another history and i see lots of broken joints but honestly Ply and poly ,and the prep is not always good.

No one is saying epoxy is weaker , but if you can make a repair or upgrade using the same material much better.

[minaret]

Originally Posted by neilpride

Insurance companys most of the time ask for OEM materials in the repairs, i see lots of holed boats , broken, from the last canes passing the islands , all this boats repaired using Poly and gel and not a single failure, to bad to paint a stern extension when the boat have gel on topsides , if you can match a gel extension with the surrounding gel this is the best aproach in my opinion,, tabbing is another history and i see lots of broken joints but honestly Ply and poly ,and the prep is not always good.

No one is saying epoxy is weaker , but if you can make a repair or upgrade using the same material much better.

And faster, and cheaper. And paint matching gel!? That's ridiculous. Even if the color matches, the gloss and depth of image will be totally different, and will quickly age completely differently.

I too have always had insurance co.'s ask for OEM repairs. They are well aware of the issues with dissimilar materials.

[minaret]

Originally Posted by smj

No lack of knowledge, epoxy is well known to have better adhesion qualities than polyester, especially when trying to adhere to cured polyester. Do as you wish, I will stick to the product that has been continuously tested and come out on top. I would say there are to many old school glass men that don't know the superior qualities of epoxy, and may be to old to learn. Please bring on the publications that state polyester has superior secondary bonds as compared to epoxy.


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Come on. The last custom epoxy boat I built cost 12.8 million dollars to complete, all vacuum bagged carbon fiber and epoxy. I'd guess I've used at least 10,000 gallons of epoxy in my career, of all brands, including many specialty laminating resins which were not released to the general public at the time. Your accusation is ridiculous.

[HappyMdRSailor]

Originally Posted by StuM

That extra space made me look twice! I first read that as an enquiry about his dress sense

Originally Posted by Jim Cate

OOOpsss! Bloody keyboard...

Good catch, Stu!

Jim

HAHA! That was funny you two !

Originally Posted by minaret

545.

Not really a normal hat, tie and coat guy. Unless you count fullface respirator for hat, forced air line for tie, and a Tyvek for coat!

Bahdumpdump

Originally Posted by neilpride

Same here, I love work with Epoxy, but we work mainly with Poly, to match OEM materials and to avoid dismilar materials in tricky spots, hard spots... Last large job, a 5 ft stern extensions in a multi, made in poly and gelcoat, secondary bond obviously .. no problems at all.....

Just adding another vote after minaret's 1st, and Neil's 2nd above... I ALSO like working with epoxy more than poly... but don't eat soup with a fork... So I... like the other guys use the right tool for the job....

(ps... I;m barely worthy of cleaning up after prep grinding for the aforementioned rock stars...)

[HappyMdRSailor]

Originally Posted by minaret

And faster, and cheaper. And paint matching gel!? That's ridiculous. Even if the color matches, the gloss and depth of image will be totally different, and will quickly age completely differently.

I too have always had insurance co.'s ask for OEM repairs. They are well aware of the issues with dissimilar materials.

Hmm... paint matching gel you say...

Originally Posted by minaret

Come on. The last custom epoxy boat I built cost 12.8 million dollars to complete, all vacuum bagged carbon fiber and epoxy. I'd guess I've used at least 10,000 gallons of epoxy in my career, of all brands, including many specialty laminating resins which were not released to the general public at the time. Your accusation is ridiculous.

Let's see... $12.8M-materials/$13.73hr (happy's lam labor rate)...
****licks thumb****
**pulls life expectancy actuarial tables**
"oh dear"
Uhm...


I'd probably trust the guy who's used over 1 MILLION dollars of just resin...

Some people can't be convinced...

Speaking of which... Wonder what's going on in the bene rudder thread...