Epoxy

[fastcat435]

We employ over 100 people working in and with epoxy , as should be the case they do not touch the resin since all wear protective clothes and gloves , in 5 years time only 1 person got a epoxy rash. the nice thing is that the epoxy allergy stops again.
Many more people are not aware of the dangers of working with polyestrer and vinylester and even living in a boat build of these materials.
the solvent in these resins make man impotent after working in a styrene environment and this is one of the reasons for us not to work with resins that contain styrene
We do not think is is fair to employees that they even have a chance of becoming impotent. And the smell in a polyester boat after it is finished , even sometimes years down the line on a warm day can be very uncomfortable. I know it is cheaper to build but who wants to live in a bad smelling boat. In the kyoto protocol the use of Styrene is slowly outbanned just as happenedd with ddt years ago that is not for no reason.

[fastcat435]

here is a link to research done on styrene dangers and impotence

Temporal association between serum prolactin concentration and exposure to styrene -- Luderer et al. 61 (4): 325 -- Occupational and Environmental Medicine

[cat man do]

I'm fine with epoxy, no rash no probs.

I also find that when using polyester that I use more of it than I would doing the same job in epoxy, not sure why.

Dave

[delmarrey]

Originally Posted by cat man do

I'm fine with epoxy, no rash no probs.

I also find that when using polyester that I use more of it than I would doing the same job in epoxy, not sure why.

Dave

I would chance to say that poly saturates and swells the cloth much more then epoxy due to its viscosity.

[OldYachtie]

Hi, CruisingCat44 I call it Quadraxial uni that because I'm an old-timer, and I finished out a 34' boat designed by Ed Monk Sr. back when fiberglass meant woven roving and mat, or in some boats, just mat. You can see that boat, Batwing, in Hasler & McLeod's book, "Practical Junk Rig." I cruised it from Seattle to Hong Kong in the 70s, via the scenic route. Actually, the boat I am building is my design. It is a radius chine design. I got my inspiration from Kelsall, and will make the panels on a laminating table the way he does, with resin infusion. I designed my hulls as developed hard chine with a program called Prochine3, and used an old CAD program I have to add radii to the chines. One hull half topsides will be one panel, and the hull bottom will be another. I am giving the chines a 2' radius, which I will make by laying strips of Masonite or similar above and below the outside of the chine on a simple female cradle-type mould at each section, filling the "v" with resin and filler, and scraping out the excess with a 2' semi-circle cut in plywood. This will give me a "mold" for the radiused portion of the hull which I will overlap onto the top and bottom infused panels. I got the idea after taking a close look at Kelsall's 38 foot design being built by "Tacoma Cats", and realizing that it was either a radius chine design or very similar to one. See: NWMA - Builders Gallery - Tacoma Catamaran - K-38 Those not familiar with radius chine design should check out, "http://dixdesign.com/radmetal.htm" and other pages on the dixdesign.com website. He has plywood and steel designs in radius chine. Also see: Radius Chine Hulls -Re toxicity, I met a boat builder who became deathly allergic to red cedar. So did my brother-in-law, a wood craftsman who builds instruments, cabinets, boats, etc. Diesel can become a potent allergen, too. I have heard stories about diesel mechanics who had to give it up due to developing allergies to diesel. Tim Dunn, near Seattle

[Agility]

Given the sensitivity to heat, how do you decide on the color for the Alwgrip. Gunboats tend to have fairly bold colors but are all pastel or light. Some seem to be metallic. The Chris White boats that I've seen are often white. White would dissipate heat the best but it's kind of bland. How would you do the math on certain colors to determine an acceptable compromise of color and heat absorption.

Would a black or similar dark strip cause softening of the epoxy?

[44'cruisingcat]

Originally Posted by BlueRhapCity

Given the sensitivity to heat, how do you decide on the color for the Alwgrip. Gunboats tend to have fairly bold colors but are all pastel or light. Some seem to be metallic. The Chris White boats that I've seen are often white. White would dissipate heat the best but it's kind of bland. How would you do the math on certain colors to determine an acceptable compromise of color and heat absorption.

Would a black or similar dark strip cause softening of the epoxy?

No. Not unless temperatures get to over 200'c ...

[44'cruisingcat]

Originally Posted by OldYachtie

Hi, CruisingCat44 I call it Quadraxial uni that because I'm an old-timer, and I finished out a 34' boat designed by Ed Monk Sr. back when fiberglass meant woven roving and mat, or in some boats, just mat. You can see that boat, Batwing, in Hasler & McLeod's book, "Practical Junk Rig." I cruised it from Seattle to Hong Kong in the 70s, via the scenic route. Actually, the boat I am building is my design. It is a radius chine design. I got my inspiration from Kelsall, and will make the panels on a laminating table the way he does, with resin infusion. I designed my hulls as developed hard chine with a program called Prochine3, and used an old CAD program I have to add radii to the chines. One hull half topsides will be one panel, and the hull bottom will be another. I am giving the chines a 2' radius, which I will make by laying strips of Masonite or similar above and below the outside of the chine on a simple female cradle-type mould at each section, filling the "v" with resin and filler, and scraping out the excess with a 2' semi-circle cut in plywood. This will give me a "mold" for the radiused portion of the hull which I will overlap onto the top and bottom infused panels. I got the idea after taking a close look at Kelsall's 38 foot design being built by "Tacoma Cats", and realizing that it was either a radius chine design or very similar to one. See: NWMA - Builders Gallery - Tacoma Catamaran - K-38 Those not familiar with radius chine design should check out, "http://dixdesign.com/radmetal.htm" and other pages on the dixdesign.com website. He has plywood and steel designs in radius chine. Also see: Radius Chine Hulls -Re toxicity, I met a boat builder who became deathly allergic to red cedar. So did my brother-in-law, a wood craftsman who builds instruments, cabinets, boats, etc. Diesel can become a potent allergen, too. I have heard stories about diesel mechanics who had to give it up due to developing allergies to diesel. Tim Dunn, near Seattle

G'day Tim, it's good to see there are some home multihull builders over there. West coast too!!

People can be allergic to just about anything, it seems to be a matter of luck as much as anything, but certainly mimimising your exposure right from the start is the best way to go.

Derek Kelsall has held some workshops over here recently, and the word is, his system works well. It looks like it might be a real handful to try doing without any assistance though. I have done my whole boat so far by myself. (Apart from turning the hulls, which was only a 1/2 hour job anyway) I got the wife to sand for about 10 minutes before she quit.

Do you have any photo's of the build you can post in the gallery here?

Good luck with the project, Alan.

[OldYachtie]

Hi, Alan I am just starting. I've got my shed up, a quonset-hut type tarp building 70' long. I'll do some posting when I have something to show. I am making this boat USCG certified to carry passengers, so I have to wait for the USCG to approve my plans. What a job that is. I must have a thousand hours in study and paperwork on that alone. Kelsall's method looks really good to me, but in a boat as large as mine, his method requires more than two panels per hull, so my method probably isn't any more work than it would be with his patented cut dart system. Doing a 44' boat from scratch by yourself is quite a project. I wouldn't dare ask my wife to do any sanding. I'm old and decrepit, so I'll hire a helper-maybe a high school student part-time. As to allergies, you can definitely be allergic to anything. The soap aisle in the grocery store gives me a splitting headache. -Tim

Originally Posted by 44'cruisingcat

G'day Tim, it's good to see there are some home multihull builders over there. West coast too!!

People can be allergic to just about anything, it seems to be a matter of luck as much as anything, but certainly mimimising your exposure right from the start is the best way to go.

Derek Kelsall has held some workshops over here recently, and the word is, his system works well. It looks like it might be a real handful to try doing without any assistance though. I have done my whole boat so far by myself. (Apart from turning the hulls, which was only a 1/2 hour job anyway) I got the wife to sand for about 10 minutes before she quit.

Do you have any photo's of the build you can post in the gallery here?

Good luck with the project, Alan.

[fastcat435]

Epoxy can actually turn soft give a high enough temperature , over 120 C for that reason our decks are always sprayed off white to not get the glare that we get from paper white but to keep the deck as cool as possible. the hull can be painted in any color the customers like Also Foam has a temerature where it might collapse , around 130 C.so it is a good idea not to use dark colors on top of a boat it also keep the interior cooler.

[OldYachtie]

I have seen a number of boats where the specification is for foam in the hulls but balsa in the deck. I would suppose balsa in the decks to prevent softening of the foam in the deck from solar heating, or it may just be to economize where the builders/designers are not concerned with shock loading causing cracks. Still, Kelsall has been using foam in decks since the 60s, and is still happy with it. My old boat Batwing was built with balsa in the deck in 1973, and is still going strong after many voyages. Also Foam has a temerature where it might collapse , around 130 C.so it is a good idea not to use dark colors on top of a boat it also keep the interior cooler.[/quote]

[Alan Wheeler]

Sorry if this has already been said. But usually the main difference between Epoxy and Poly resins is in the construction differences. The way a hull is built in Poly is usually a chopped strand method, in which Poly is the easiest and supperior method in this technique. Epoxies are usually used in more eacting type layups. While yes Epoxy is more expensive, because they application is more controled, the quantities used are often significantly less. So all in all, the price of the resin is mostly balanced out. However, the applications are often far more complex as are the materials used. So Epoxy type designs are often expensive because of the materials used. For example, it would be silly to use Poly's to layup Carbon fibre.
It is also important to understand that the strength of a layup does not totaly come from the resin. It is the material that gives you 90% of the strength.
And finally, if you have decks approaching 130deg, it won't matter if the resin is Poly or Epoxy. Both will have similar reductions in strength. However, epoxy will actually cure more, where as Poly just gets hot.

[fastcat435]

The real smart thing to do after building a hull and deck after it has been put together is post curing it no matter if it is Polyester , vinylester or epoxy it always makes the boat stronger unfortunately very few boat byuilders bother to do so although in mosst technical specs of both Vinylester and polyester it is advised to come to maximum strenght, and yes all resins can soften if the temperature is high enough. An added advantage of post curing polyester and vinylester is that you get rid of the smell of the solvent faster: styrene

[Sparohok]

Tensile strength isn't everything though. My experience with sailboards, where very thin & light composite structures tend to suffer a lot of impact loads, is that epoxy is far tougher & less brittle than poly, far less likely to crack on impact. I'm not a materials engineer, I can't quantify the difference, I don't even know how you would measure & compare something like this, but it has certainly seemed to me like a night & day difference.

Hopefully impact loads that threaten the integrity of the composite are a lot less common on cruising boats than sailboards. Still I'd feel safer on an epoxy boat. I'd certainly be more comfortable beaching an epoxy boat. I think it would be more likely to survive impact with debris, logs, containers, etc while sailing as well.

Martin

[fastcat435]

The fact that epoxy is stronger than polyester or vinylester is one of many reasons for us to use it , besides using epoxy we also use the Twaron Impact protection system , this is a layer of aramide on the inner hull up to 400 mm above the waterline , this is 9 times stronger than glass for the same weight and on the outside of the hull we use basalt fiber against abrasion or cutting of the hull
On the bottom of both the keels and the rudders we have laminated Twaron because it is very resistant against rubbing on the sand
(Excuse my english it is not my native language.)
and it is possible to set our cats on the dry without a problem