Multi's resin question

[Redbull addict]

Hi,

I'm looking through the construction specs between FP's, Lagoons and Leapords. FP doesn't seem to mention what type of resin they use. Lagoon states that it's polyester and vinylester and Leapords are GRP, which I believe is polyester.

Couple of questions...

Are there any manufacturers that do not use any polyester resin?

I'm still trying to fully understand the full implications of boats built with polyester but in one thread I read a suggestion that polyester based boats should be stored out of the water 3 months out of the year. Now I know that's not happening so how critical is this resin for cats?

thanks!

[44'cruisingcat]

I know HR refer to GRP as "Glass Reinforced Polyester", but I think it's more commonly thought of as "Glass Reinforced Plastic" - which could include epoxy construction.

[muskoka]

Redbull,

The FP's are polyester. As are the others you'd mentioned.

Polyester is cheapest (and thus the most common) but will develop some osmotic blistering given time. The next step up in quality is vinylester which isn't osmosis-prone but costs more. The top material is epoxy - no osmosis problems and very stiff - but it is quite expensive.

All are to some degree permeable to moisture but with epoxy this is nearly negligeable.

Polyester develops osmosis because many hulls contain a small amount of uncured resin, which chemically reacts with water to produce a mild acid and osmotic blistering. There's been a lot of debate & research on osmosis and the only thing I've been advised is that the best 'cure' is to post-cure the hull at very high temperature (boiling point basically) to chemically neutralize the uncured resins in the hull.

One method is the HotVac system which applies heat pads under vacuum to cure and dry the hull. One note of interest, the heat cured hulls are a LOT stronger than the basic polyester prior to curing. Manufacturers don't heat cure for the same reason they don't use vinylester - cost! Truth be told, it isn't the manufacturers, but we the purchasers who'd rather throw the extra money at length & volume rather than production quality.

The final step is to coat the bottom with an epoxy barrier coat. You can do this whether the hulls have been heat cured or not.

Hope that helps!

Cheers, Muskoka

PS - GRP = glass reinforced plastic, which I believe Herreshoff refered to as 'frozen snot'.

[cat man do]

I disagree that epoxy is expensive.

Having worked on boat's using Poly, Vinyl and epoxy resin's I can honestly say that I alway's use much less epoxy resin.

As Poly and Vinyl are'nt as tough/stiff/good as epoxy usually more glass is used to make up for the lack of strength, therefore more resin , therefore heavier boat, therefore lack of performance.

Dave

[schoonerdog]

The very top makers of catamarans who don't sell any charter boats and are obsessed with top quality materials use epoxy. Africancats uses eglass or carbon fiber (optional) with kevlar for their hulls reducing the weight an estimated 30 percent and increasing it's strength over polyester resin. Gunboat does the exact same thing with even more of an obsession to carbon fiber everything. They don't have a charter market because frankly they are too expensive and don't aim at maximizing accomodations, they aim at performance. A larger, heavier charter boat will also be more conservatively rigged, with smaller sails which will make them much more difficult to tip over by a inexperienced crew who doesn't know how or when to reef.

[cat man do]

so that must make us so called "Amateur Builder's" the very top maker's of catamarans as well.

Having seen how the so called professional's build in production facilities, i'd let them do fiberglass swimming pool's and spa's, but that's about it.

Dave

[JusDreaming]

This an exerpt from the lagoon 37/TPI write up

Construction and Execution

TPI's reputation as one of the great innovators in modern FRP technology is not lost on the 37. Hulls and deck feature Baltek end-grain balsa core throughout, sandwiched between triaxial glass fiber hand laid in vinylester resin

[44'cruisingcat]

Originally Posted by cat man do

so that must make us so called "Amateur Builder's" the very top maker's of catamarans as well.

Having seen how the so called professional's build in production facilities, i'd let them do fiberglass swimming pool's and spa's, but that's about it.

Dave

That's my experience too Dave. In most areas "amateur" builders do a much better job. It's because it's their own boat they are working on, not just a job.

[44'cruisingcat]

Originally Posted by schoonerdog

The very top makers of catamarans who don't sell any charter boats and are obsessed with top quality materials use epoxy. Africancats uses eglass or carbon fiber (optional) with kevlar for their hulls reducing the weight an estimated 30 percent and increasing it's strength over polyester resin. Gunboat does the exact same thing with even more of an obsession to carbon fiber everything..

Actually if you were being obsessive about materials you wouldn't use E-glass. If you used glass at all it would be S-glass.

[learningcurve]

Originally Posted by schoonerdog

The very top makers of catamarans who don't sell any charter boats and are obsessed with top quality materials use epoxy.

Something to consider when you read builder's specs...

Most production builders are moving to VIP (vacuum infusion process). If you are a production builder and are still using hand-layups, you are considered "behind the times". Now, my understanding, is that VIP with epoxy can be tricky compared to the other resins. It is not as easily "thinned" as polyester or vynilester for flow purposes without compromising the strength. This was told to me by an acquaintance who has done VIP on everything from megayachts to kayaks. I have experience with VIP on using esters but not epoxy.

YMMV.

[cat man do]

I would have thought thinning resin would actually effect it's performance and would not recomend this.

Better to use a proper laminating resin in the first place instead of the cheap crap that a lot of production builders would use.

I know that the epoxy laminating resin I use is much runnier than say the "west 105" for example.

Dave

[learningcurve]

Originally Posted by cat man do

I would have thought thinning resin would actually effect it's performance and would not recomend this.

Better to use a proper laminating resin in the first place instead of the cheap crap that a lot of production builders would use.

I know that the epoxy laminating resin I use is much runnier than say the "west 105" for example.

Dave

That's my point.

Resin makers have made successful formulations with P/E and V/E suitable for easy-flow VIP without compromising strength. Seems that is not yet the case with epoxy. Thinning epoxy for VIP gets you no better than using V/E, so it is not worth the cost. Of course VIP resins are non-laminating resins by definition.


Of course the whole point of VIP over hand layups is to maximize strength, minimize material (thus weight), minimize labor (maybe, with a good crew), and improve consistency. It is practically a win/win for a production builder.

I suppose they are working on VIP formulations of epoxy if they are not there already (its been a year since I researched this stuff).

Again, some of this info I have heard second hand... YMMV

[cat man do]

While I hate giving ATL a plug for anything.............

ATL Composites - engineering resin foam waterproofing carbon fibreglass adhesive fairing boat repairs structural fibreglass#

Some more info here

epoxy resin for vacuum infusion - Google Search



Dave

[knottybuoyz]

Originally Posted by learningcurve

I suppose they are working on VIP formulations of epoxy if they are not there already (its been a year since I researched this stuff).

I've got a gallon and a half in the basement. Just waiting to assemble a few more supplies (after holidays) before I do my first infusion test with epoxy and biaxial fabrics. The intent is to build up some experience with a few tests before I begin making a few of the smaller parts and components for our trawler.

The ULV (Ultra Low Viscosity) epoxy I have comes from Polymer Products in Ca. I found them on e-Bay and the price was reasonable.

Shop eBay Canada Store - Epoxy Resin Adhesive Coating Laminating UV Curing:: Glue, Coating

I'll let ya know how it goes and post some pics of my first few trials.

[SurfNRG]

Curious to hear some opinions on Quadriaxial fiberglass, balsacore & orthopthalic polyester resin with isophthalic resin below water line for osmosis protection. Vacuum bagged. How's that construction compared to the other methods mentioned?