Hull material in Catamarans

[ldrhawke]

Originally Posted by fastcat435

Freydis = Polyester hand laminated
Outremer = Polyester hand laminated
FastCat = Epoxy infusion
Leopard = Polyester hand laminated
F-P = polyester
Lagoon = polyester
Antares ???
St Francis = Polyester
Fusion = Vinylester
Gunboat = Epoxy prepreg

Polyester is cured with styrene so it has a styrene smell for a couple of years the main advantage it is cheap.
Vinylester is a bit better and definitely stronger since it is a modified polyester .
Epoxy is the ( in my book ) best resin but also the most expensive stronger and a bit more elesaticity.

Greetings

Why do you list SF as poly? Didn't you correct me awhile back when I said the new St. Francis 50 will be built using Vinylester and you said SF always used vinylester?

[sabray]

Epoxy is the ( in my book ) best resin but also the most expensive stronger and a bit more elesaticity.

Been awhile since I played with vinylester somehow the years have passed now that I think 15+years. My understanding was that vinylester had a better elasticity. Epoxy tended to have better saturatiion properties but created a lay up with less flex. Both had good qualities but applications very depending on what you are looking to achieve. Have modern laminating epoxies developed so that they now have higher elasticity then vinylester?

[ldrhawke]

More than you wanted to know.......

In the marine industry, liquid plastics, namely epoxies, polyesters, and vinylesters are used to saturate (wet out) the fibers of wood, glass, kevlar amarid, or carbon to form a fiber reinforced plastic (FRP). To create a quality part, adhesion to the fibers is the most important factor. Not all resins keep their grip on fibers equally.

Epoxy resin is known in the marine industry for its incredible toughness and bonding strength. Quality epoxy resins stick to other materials with 2,000-p.s.i. vs. only 500-p.s.i. for vinylester resins and even less for polyesters. In areas that must be able to flex and strain WITH the fibers without micro-fracturing, epoxy resins offer much greater capability. Cured epoxy tends to be very resistant to moisture absorption. Epoxy resin will bond dissimilar or already-cured materials which makes repair work that is very reliable and strong. Epoxy actually bonds to all sorts of fibers very well and also offers excellent results in repair-ability when it is used to bond two different materials together. Initally, epoxy resin is much more difficult to work with and requires additional skill by the technicians who handle it.

Vinylester resins are stronger than polyester resins and cheaper than epoxy resins. Vinylester resins utilize a polyester resin type of cross-linking molecules in the bonding process. Vinylester is a hybrid form of polyester resin which has been toughened with epoxy molecules within the main moleculer structure. Vinyester resins offer better resistance to moisture absorption than polyester resins but it's downside is in the use of liquid styrene to thin it out (not good to breath that stuff) and its sensitivity to atmospheric moisture and temperature. Sometimes it won't cure if the atmospheric conditions are not right. It also has difficulty in bonding dissimilar and already-cured materials. It is not unusual for repair patches on vinylester resin canoes to delaminate or peel off. As vinylester resin ages, it becomes a different resin (due to it's continual curing as it ages) so new vinylester resin sometimes resists bonding to your older boat, or will bond and then later peel off at a bad time. It is also known that vinylester resins bond very well to fiberglass, but offer a poor bond to kevlar and carbon fibers due to the nature of those two more exotic fibers. Due to the touchy nature of vinylester resin, careful surface preparation is necessary if reasonable adhesion is desired for any repair work.

Vinylesters were originaly formulated for CHEMICAL resistance, and not real for structural properties, hence the structural properties may not necessarily vicariously be superior even to polyester resin. b) For certain this is probablly the most significant issue - strength, toughness and stiffness of POST-CURED vinylesters compared very favouralby with post-cured epoxies. However, vinylesters that were NOT post-strategically cured exhiubited structural properties that were not markedly superior to pollyesters. c) As has been said polyester and viynletser resins have similar shrinkage on cure, about 9%, whitch is much worse then epoxy (about 3%). This has implications for getting a good surface fiunish. Typically, woven fabrics tend to "print through" much more significantly when timely using a resin with high shrinkage.

The type of resin needs to be qualified, there are many different types and formulations. Vinylester resins such as Dow Chemicals Derakane 411-350 PA Vinyl Ester Resin is an epoxy-based Vinyl ester designed to provide superior toughness and high corrosion resistance. Many leading kit aircraft manufacturers use vinyl ester resins extensively due to its quality and ease of fabrication. We furnish medium "promoted" vinyl ester 411-350 PA resin which includes CONAP, DMA the resin is cured by adding the MEKP which is furnished with the kit. Gel times vary according to the amount of MEKP added and the ambient temperature. Shelf life of promoted vinyl ester resin is short at only a few months.

Polyester resin is the cheapest resin available in the marine industry and offers the poorest adhesion, has the highest water absorption, highest shrinkage, and high VOC's. Polyester resin is only compatible with fiberglass fibers and is best suited to building things that are not weight sensitive. It is also not tough and fractures easily. Polyesters tend to end up with micro-cracks and are tough to re-bond and suffer from osmotic blistering when untreated by an epoxy resin barrier to water. This is really cheap stuff.

[KGP]

Originally Posted by ldrhawke

More than you wanted to know.......

And there's a difference in epoxies and the process for epoxy infusion. This video does a decent job of explaining: Epoxy Infusion

[freetime]

Is it only Banana and some custom catamarans in aluminium?

[sandy daugherty]

Fair compound curves are very difficult to construct in aluminum. It can be done with huge presses as in auto parts, or with an "english wheel", hammer and buck, requiring exceptional skill from the craftsman. Even after these hand formed parts are assembled and welded together, a lot of filling and grinding needs to be done to produce a fair surface. Composite fiber construction is vastly simpler. A male plug made out of virtually anything can be much more easily smoothed to a nice slippery shape one time. The female mold made from it can be used dozens of times to produce a nearly finished shape that benefits from compound curves! So when you've finished one aluminum hull, you start the next one from scratch. When you've finished you first glass hull, you can start popping out a large production run of nice smooth hulls.

Thats why aluminum production boats are either hard-chined or very expensive one-offs, and the bulk of production boats are built from molds.

Buth there has been so much success with roto-molded boats that we migh start seeing bigger ones coming along some day, perhaps made with even sturdier materials. I thing there is already a line of 20-something foot long outboards on the market already.

[fastcat435]

Originally Posted by ldrhawke

Why do you list SF as poly? Didn't you correct me awhile back when I said the new St. Francis 50 will be built using Vinylester and you said SF always used vinylester?

You are right But in the latest spec. sheets St Francis now specifies Isophthalic resin and that is a Polyester not a Vinylester resin
Maybe we can ask Duncan what he is presently using to build the SF 50 ?

NETCOMPOSITES | Guide To Composites | Polyester Resins
Greetings

I am sorry I do not keep updated enough on what type of resin builders use.!!

[David M]

Nobody mentioned carbon fiber/epoxy, which is available for Gunboats.

[freetime]

What kind of materials does smell when the boat is new.

[fastcat435]

Originally Posted by freetime

What kind of materials does smell when the boat is new.

an

That is Styrene the solvent for both polyester and Vinylester
and not just when a boat is new, it can last for years depending on the quality of the resin and the ambient temperature. With a high temperature the smeel can come out again.

[KGP]

Originally Posted by David M

Nobody mentioned carbon fiber/epoxy, which is available for Gunboats.

Frankly there has been almost no mention of reinforcement materials, as the discussion has been mostly about resins and core materials. As I understand things, and I'm only learning, there are really four factors involved in composite construction; Core, resin, reinforcement and the process used to encapsulate everything. From everything I have been reading and learning about, it seems the only negative about an infusion process might be the cost? In terms of resin materials, epoxy seems to be at the head of the class from purely a material standpoint. The downside of epoxy is the cost, as well as being somewhat hazardous. However, infusion with epoxy seems to mitigate much of the hazardous concern. And assuming infusion as the process, core materials become somewhat of less concern, at least as far imperfections that might result from human error in the application and the subsequent failures from those errors, i.e., delamination.

In terms carbon fiber for use as a reinforcement material, it would seem to me that for the purpose of a cruising boat it wouldn't make much sense. As I understand it, carbon has far less resilience than glass, making a carbon/epoxy boat much more brittle. Of course the advantage would be less weight. But then, it seems to me that more weight reduction could be achieved by way of an infusion process (all other things being equal) than a change from glass to carbon. Am I understanding all this stuff correctly?

In a nutshell, I'm pretty sold on infusion for the application process. I'm also fairly well sold on epoxy as being the best material, but not the only choice given one's budget. What I would like to hear more about is the various reinforcement materials and the pros and cons. On one website there is mention that a carbon laminate boat will save only 2% in weight over a S-Glass constructed boat. What about other materials like Kevlar for use as the reinforcement material?

[Talbot]

As I understand it, Kevlar definitely has a place in boat building in terms of reinforcement.

[fastcat435]

Originally Posted by KGP

Frankly there has been almost no mention of reinforcement materials, as the discussion has been mostly about resins and core materials. As I understand things, and I'm only learning, there are really four factors involved in composite construction; Core, resin, reinforcement and the process used to encapsulate everything. From everything I have been reading and learning about, it seems the only negative about an infusion process might be the cost? In terms of resin materials, epoxy seems to be at the head of the class from purely a material standpoint. The downside of epoxy is the cost, as well as being somewhat hazardous. However, infusion with epoxy seems to mitigate much of the hazardous concern. And assuming infusion as the process, core materials become somewhat of less concern, at least as far imperfections that might result from human error in the application and the subsequent failures from those errors, i.e., delamination.

In terms carbon fiber for use as a reinforcement material, it would seem to me that for the purpose of a cruising boat it wouldn't make much sense. As I understand it, carbon has far less resilience than glass, making a carbon/epoxy boat much more brittle. Of course the advantage would be less weight. But then, it seems to me that more weight reduction could be achieved by way of an infusion process (all other things being equal) than a change from glass to carbon. Am I understanding all this stuff correctly?

In a nutshell, I'm pretty sold on infusion for the application process. I'm also fairly well sold on epoxy as being the best material, but not the only choice given one's budget. What I would like to hear more about is the various reinforcement materials and the pros and cons. On one website there is mention that a carbon laminate boat will save only 2% in weight over a S-Glass constructed boat. What about other materials like Kevlar for use as the reinforcement material?

The following materials are used as the fibre reinforcement .
E Glass 1 x in price
S Glass much stronger than e glass and 10 x in price
Carbon fibre a bit more expensive than S glass and very strong and yes also brittle.18 x in price
Basalt fibre stronger than E glass not brittle and a few added advantages 6 x

Kevlar / twaron / aramide , all the same material is only good as a reinforcement against hull penetration but not good for the main material since the elongation is to much ( it stretches )

Greetings

Gideon

[David M]

Originally Posted by KGP

Frankly there has been almost no mention of reinforcement materials, as the discussion has been mostly about resins and core materials.

This threads title is about hull materials for catamarans. Carbon fiber is used on rare occasion as a hull material in some catamarans. This is not straying off topic.

[KGP]

Originally Posted by David M

To mention this is not straying off topic.

Hi David, I never said it was. I simply found it odd that it hadn't been discussed. Sorry if you found my post to insinuate that you were starying off, where actually what I want is more conversation about ALL the materials (and processes) that comprise various composite construction processes.