Car Bog on Epoxy

[SimonV]

Polyester over epoxy has always been a no go, but sometimes things just stick. I would contact the manufacturer and get thier opinion, they will know. Verbily they may say it should be okay but you can bet it won't be in writing.

[Kestrahl]

I've had some experience with car bog, its actually pretty good, I think the main disadvantage is its heavy. I've seen professional boatbuilders using it as final small fairing, as it goes off fast and they don't have to wait around. As long as its covered in epoxy undercoat etc it should be fine.

We used it once on a epoxy carbon rudder that had a big hollow, on a 23ft race yacht, never cracked, and it was being flexed constantly. It was supposed to be a temporary thing till we built another rudder, but never got around to doing that.

[surfynic]

Originally Posted by Kestrahl

I've had some experience with car bog, its actually pretty good, I think the main disadvantage is its heavy. I've seen kprofessional boatbuilders using it as final small fairing, as it goes off fast and they don't have to wait around. As long as its covered in epoxy undercoat etc it should be fine.

We used it once on a epoxy carbon rudder that had a big hollow, on a 23ft race yacht, never cracked, and it was being flexed constantly. It was supposed to be a temporary thing till we built another rudder, but never got around to doing that.

Hmm thanks kestrahl, I was hoping to hear from someone that has actually done it. As I know I did the wrong thing and am kicking myself now, but just I'm not sure how wrong. Like I might be making a mountain from a molehill.. In any case I'm going to try get a Shipwright down in the next few days to get his opinion. I still think even if I do leave it I will put the layer of surface tissue on top to try seal it in

[Kestrahl]

I don't think you would need to bother putting any glass over the top of it. Its probably fine but talk to a good boatbuilder who has experience actually using it. I'll email a friend (ex cookson boatbuilders) who would know and will let you know if I get a reply (holiday season).

[HappyMdRSailor]

Originally Posted by surfynic

Hmm thanks kestrahl, I was hoping to hear from someone that has actually done it. As I know I did the wrong thing and am kicking myself now, but just I'm not sure how wrong. Like I might be making a mountain from a molehill.. In any case I'm going to try get a Shipwright down in the next few days to get his opinion. I still think even if I do leave it I will put the layer of surface tissue on top to try seal it in

Just some more "gut feeling" for adding to one side of the scale or the other...

I don't think you're making a mountain out of a molehill as doubt and worry piled on said rodent hill quickly add up... I personally would not put polyester anywhere under the waterline, but this is the hand we have, so let's make the best of it, and try and beat the house....

If you do take your "core samples" and find some thicker areas... You will always wonder if you got them all, and probably restart from scratch...

The best I see it is make that barrier with epoxy... your choice if you're going to add another layer or not...

Honestly... With careful prudent direction from here, I think it;s going to work out....

Contact minaret our resident "resin head".... His advise would likely be the best course, and the one I personally would take...

PS! Don't leave us hanging on the progress or final results!

[surfynic]

Thanks mate that would be awesome to hear what he has to say. It's so perfect and fair now, I'd hate to have to take it all off!

[surfynic]

Originally Posted by HappyMdRSailor

Just some more "gut feeling" for adding to one side of the scale or the other...

I don't think you're making a mountain out of a molehill as doubt and worry piled on said rodent hill quickly add up... I personally would not put polyester anywhere under the waterline, but this is the hand we have, so let's make the best of it, and try and beat the house....

If you do take your "core samples" and find some thicker areas... You will always wonder if you got them all, and probably restart from scratch...

The best I see it is make that barrier with epoxy... your choice if you're going to add another layer or not...

Honestly... With careful prudent direction from here, I think it;s going to work out....

Contact minaret our resident "resin head".... His advise would likely be the best course, and the one I personally would take...

PS! Don't leave us hanging on the progress or final results!

Thanks mate, I might even post some pics of how it is now, and I'll let you know how I go.

How do I get in touch with someone (miranet) on here to ask advice?

[HappyMdRSailor]

That's what we're here for.... Should I need help in your neck of the woods... I would call on you!

Pics would be a fantastic route !

To send a PM, here is his profile page... Cruisers & Sailing Forums - View Profile: minaret

Under the scary picture there is a drop down menu to send a private message....

FYI.... any time you see a CF member in a thread... you can just (left=regular) click on their name and the menu appears...

[minaret]

Definitely try to post some pics. Do you know what resin system the boat was built with? How old is it?


Much solid info already posted here. The issue is that poly resin based products will not fully cure in the presence of amines. Epoxy is a polyamide, the hardener is made with straight amines. But there are of course many different flavors. All epoxies blush amine, but some more than others. In many cases, very thorough prep will remove all amine blush and allow a perfectly acceptable bond, at least initially. WEST will in fact tell you it is OK to do this with their resin. My experience has been that it is not. Most resin systems will continue to leach amines long after a full cure has been reached. This can cause what appeared to be a good bond to fail after a year or two. There are many factors involved in whether or not this will occur, including resin system used, how old the laminate in question is (is it "done" leaching?), temperature and particularly humidity when originally applied, resin ratio, etc. etc.


Personally I would not rest easy in this scenario, but if it really represents a years fairing I wouldn't remove it either. It's a gamble, but chances are if it's already been on for a year with no failure it may work out. Do some adhesion testing. If everything is still well bonded, paint away and hope its all still there in ten years.

[Cotemar]

Originally Posted by surfynic

Hi all!
We have been doing a MAJOR re fit on our Simpson 40 catamaran and have just spent the last year fairing the decks, at the start we had a painter slash supposed boat builder working with us and he was showing us how to fair the boat. To do this he was using car bog (goldrush) as it went off fast and was good to sand. Now thou we are pretty well finished and had someone come and say that the car bog will crack so as you can imagine we are a bit panicky...

Does anyone have experience with a situation like this? The boat is a ply with epoxy glass over the top construction. We are considering laying a surface tissue with epoxy over the whole lot and faring that back with q cells to enclose the bog... We are open to suggestions!!!

Thanks
Nic

At this point after a years worth of work and it looks great.
What are you thinking man, put the sails up and go sailing. In ten years you will say "What Was I thinking" its all good.

[surfynic]

Originally Posted by Cotemar

At this point after a years worth of work and it looks great.
What are you thinking man, put the sails up and go sailing. In ten years you will say "What Was I thinking" its all good.

Haha yeah well I'll tell you we are so keen to get back in the water it's not funny!

[Kestrahl]

He said:

"I guess it depends on how thick the bog is and how flexy the boat will be, it won't be the only boat around with car bog on it. It's probably ok if the epoxy is scuffed up well to start with"

I guess as minaret said its a risk, as there are different epoxys and different car bogs...

Attached a photo of my old rudder, had a hollow in both sides about 3mm deep and 75mm wide and 3/4 of the length that was filled with car bog and painted over. used it for a good year if not longer and its still being used 2 years later(don't tell the new owner).

It got the hollow as we vacuumed the gudgeons on in a heat box and there was a leak in the blade.

[HappyMdRSailor]

minaret makes your head spin with knowledge huh???

The "put the sails up" route sure sounds attractive....

[fkittson]

I've been working with fiberglass for years poly/epoxy. As long as your base has a good key (meaning sanded addiquitly) the shouldn't be a problem. I have had cases where the boat was epoxy faird with poly bondo 20 years earlyer and painted with single PAC paint. There was never any sign of cracking or debonding. Like others have said as long as it's not to thick. Les then 3-4 mm. The key is proper prep with any good fiberglass job.

[surfynic]

Just thought I'd update this old thread. All the big is now gone and replaced with the correct micro balloons in epoxy. She's now painted and looks great. Almost water time!! But yeah that ended up been a one year set back

Thanks everyone for your help!


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