"Triple epoxy" building method and rox

wklein

wklein

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"Triple epoxy" building method and roc 129

I was looking at yachts for a friend who is looking for liveaboard and possible long distance cruiser and found this boat:

http://viajante.webs.com/


Its a 1974 Roc 129 french boat pretty attractive quite well set up, in serious need of a pot of white paint down below. excellent value. Looked on the owners association (which was annoyingly only available in french) and there was a review in french which was translated as this by google:


"Launched in late 1970, the Rock is a 129 offshore cruiser or sloop-rigged ketch. If the first method for building (near the ferro-cement), suffers from a bad reputation, he must flee the units in "triple-epoxy", whose material has proved very fragile."


I have never heard of this triple epoxy construction and would be interested if anyone had any knowledge of it.
 
Last edited:
Lancé à la fin de l'année 1970, le Roc 129 est un croiseur hauturier gréé en sloop ou en ketch. Si le premier procédé de construction (proche du ferro-ciment), souffre d'une mauvaise réputation, il faut fuir les unités en "triple-époxy", dont le matériau s'est révélé trés fragile. Dès 1975, Roc Marine International revient au polyester. On se dirigera bien sûr vers ces unités, appelées 43C, plus récentes et plus sûres.
C'est le chantier Matonnat qui commercialisera les dernières unités.

Sounds pretty ominous non?
 
The current owner also sent me this describing construction which is equally bizarre:


ROCs are generally described as GRP, which is true to an extent, there
is a fibreglass layer but it's also bonded to a unique composite epoxy material. I believe that the hull is one of her best attributes as it's immensely strong and not susceptible to osmosis.
 
wklein said:
The current owner also sent me this describing construction which is equally bizarre:


ROCs are generally described as GRP, which is true to an extent, there
is a fibreglass layer but it's also bonded to a unique composite epoxy material. I believe that the hull is one of her best attributes as it's immensely strong and not susceptible to osmosis.
Click to expand...

Another site: http://www.raiatea-yacht.com/index.php?page=roc1&lang=en

said this: "Hull and deck in epoxy resin: low maintenance, no osmosis." (OK, it said it in French) and "Materials: silica-filled epoxy"

The boat is quite attractive but I imagine that she'll need a few quid spending on her.
 
doctorfresh said:
Another site: http://www.raiatea-yacht.com/index.php?page=roc1&lang=en

said this: "Hull and deck in epoxy resin: low maintenance, no osmosis." (OK, it said it in French) and "Materials: silica-filled epoxy"

The boat is quite attractive but I imagine that she'll need a few quid spending on her.
Click to expand...

"Materials: silica-filled epoxy" so silica could describe sand, so it may be a fero but not with cement and sand but epoxy and sand.

Good luck and fair winds. :)
 
oldsaltoz said:
"Materials: silica-filled epoxy" so silica could describe sand, so it may be a fero but not with cement and sand but epoxy and sand.

Good luck and fair winds. :)
Click to expand...

More likely to be fumed silica, which is a common thickening additive for epoxy resin. I have heard of a method of construction that uses a steel armature like ferrocement, plastered with thickened polyester resin (back in the 70s, so a common thickener was asbestos fibres). It's called Fer-A-Lyte, and no I wouldn't recommend it to anybody as a method of building a boat. This could be something similar (especially as some of this design were built in ferrrocement according to what I've found on Google and my schoolboy French), or it could be a very different method.

Whatever it is, given that nobody seems to know and the only references I can find suggest it has problems, I'd be very wary (certainly if I were surveying it I'd want to see a core sample or two to work out exactly how it had been put together).

Whilst I do feel a bit for the sellers, who obviously had plans that didn't come to fruition, I think they may be stuck with her for quite a while. She's reasonably well equipped, so although it pains me to say it, she might be a good donor boat for a more conventional hull (either a sister boat in ferro or GRP (which they moved to in 1975), or something of a similar size and purpose).
 
Nothing is perfect. Steel is a never ending battle against rust, GRP you have lurking osmosis, wood you need to be an enthusiast and quite insane, ferro could have constructed in someone's back garden, Viajante is none of the above.

The hull is an epoxy composite partly of silica about one inch thick and does not have a steel armature to rust. She was professionally built and is hull number 19 so earlier snags have been ironed out. Hull and rig are immensely strong and absolutely no cause for concern.
 
jings said:
Nothing is perfect. Steel is a never ending battle against rust, GRP you have lurking osmosis, wood you need to be an enthusiast and quite insane, ferro could have constructed in someone's back garden, Viajante is none of the above.

The hull is an epoxy composite partly of silica about one inch thick and does not have a steel armature to rust. She was professionally built and is hull number 19 so earlier snags have been ironed out. Hull and rig are immensely strong and absolutely no cause for concern.
Click to expand...

What is the silica for? It is a thickening agent, so surely it would be madness to add to epoxy before laminating as it would be even more difficult to wet out. all i can think is that they are using something other than glass in construction.
 
jings said:
Nothing is perfect. Steel is a never ending battle against rust, GRP you have lurking osmosis, wood you need to be an enthusiast and quite insane, ferro could have constructed in someone's back garden, Viajante is none of the above.

The hull is an epoxy composite partly of silica about one inch thick and does not have a steel armature to rust. She was professionally built and is hull number 19 so earlier snags have been ironed out. Hull and rig are immensely strong and absolutely no cause for concern.
Click to expand...

Might I take an educated guess that you're the owner of the boat in question?

If so, I'd be very interested to know any detailed information you have about the method of constructing the hull, as it's not one I'm familiar with. So far we seem to have ascertained that's it's epoxy-based, with some glass fibre and silica. Exactly how is all of this put together? Have you ever taken a core sample (put in a though-hull fitting or suchlike)? Was she built inside a female mould, or over a male mould? Are there layers of glass on the inside and outside with epoxy/silica in the middle? (If I had to take a guess this would seem to be the most logical arrangement of such materials, but that's a relative term, as I can't see an engineering reason to build a hull like that as opposed to any of the other, more widely used techniques.)

You assert that the hull is 'immensely strong', on what data do you base this assertion?

Unfortunately, 'professionally built' does not have any bearing on quality or suitability for purpose - plenty of professionals have built bad boats (and plenty of amateurs have built good ones). I'd also suggest that whilst hull #19 would probably have fewer faults than hull #1, it's still not a great many in the grand scheme of things, and absolutely no indication that any faults in the construction method would have been found and fixed. (You don't give any indication as to how much time has passed between building the first hull and number 19, it may not have been long enough for any faults to manifest themselves.) The fact that the builders moved to conventional GRP construction two years after this boat was built would suggest that they didn't find the method of construction entirely suitable. (Which doesn't not necessarily mean that it's bad, just that it may not have been cost-effective, or that buyers may have been put off by it's novelty and preferred to go with a more widely-used technique.)
 
In the early '70s when ferro yachts were popular there was a company in Victoria Australia building a 24/25 foot yacht. It was unusually small for a ferro yacht but it was built in a female mold with no reinforcing with a hull thickness of about 6 mm up the sides. One was on eBay for sale a few weeks ago, I regret not saving the details now.
 
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