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petrified · 08-02-2018, 07:09

Getting things ready to build a small proa.

Im looking for the simplest type of epoxy. Im assuming i will go with west systems. What type??

Will be glassing with 4 or 6 oz cloth also.

Privilege · 08-02-2018, 08:15

Why are you making it with epoxy? None of the production boats use epoxy for their hulls. I'd build it with polyester resin which is a 1/4 of the price of epoxy. Epoxy is second-to-none if you need it for an adhesive but is not necessary when making a hull.

petrified · 08-02-2018, 08:39

Yes sorry. New to building. That is what i meant

Privilege · 08-02-2018, 09:09

In my opinion using epoxy for the basic construction of a hull is not necessary. Epoxy is stronger and is a much better adhesive but polyester sticks to itself quite happily and is a good choice for building layers. You will need to Google the difference between the two in order to properly decide which is best suited for your purposes.

See http://www.boatus.com/boattech/casey/polyster-epoxy.asp

Terra Nova · 08-02-2018, 09:13

Avoid polyester. WEST system is excellent epoxy, 105 resin and 205 hardener.

catsketcher · 08-02-2018, 09:39

Gday Petrified

If the boat you are building has a timber core - you have to use epoxy. Polyester is fine if you are building over foam or a solid glass layup.

I like using the WEST 105 resin with 206 hardener. I now buy a similar version produced here in NSW Australia. I pay about $300 AUD for a 24 litre pack. You will also need some silica powder (to make a glue) and microballoons (to make filler). I buy big 80 litre bags of each and these large bags are much more affordable than getting small lots.

https://trojanfibreglass.com.au/stor.../fumed-silica/

https://trojanfibreglass.com.au/stor...-microspheres/

You should not use polyester over any wood. Epoxy is the only thing to use unless the boat is a cheap prototype or test bed.

What type of proa are you building?

cheers

Phil

chris95040 · 08-02-2018, 10:02

So your options are basically epoxy or polyester (or vinylester but I don't know anything about that.)

Polyester is a lot cheaper but holy cow does it stink. At least the various brands I've used are always loaded with styrene or something and it's god awful. I think epoxy is worth it just to get away from that.

With epoxies, an important and annoying consideration is "blush". Many epoxies, including West, will "blush" when there is any humidity in the air, at least I think that's the cause. That blush is a waxy film that forms on the surface, so if you are doing your layup in batches and allowing it to cure in between, you need to clean that waxy film off with soap and water before scuffing for the next batch.

So thats why I'd recommend Progressive Epoxy Polymer's basic no-blush. Don't know how epoxy works, but the formulation he sells is a non-blushing variety.

Marine Epoxy Resin NON BLUSHING w BUBBLE BREAKERS / 603.435.7199

I've used it a bunch of times. I think for big jobs the pumps / etc with west are just a pain in the ass, too, Progressive's 1 gallon plastic jugs are easier to pour from.

Holy cow is that guy's website dizzying, though.

petrified · 08-02-2018, 11:09

Thanks for all the responses

Plywood boat
Gary dierkings tamanu

Tacking outrigger

I will look at all the recommendations.

I think the plans called for 2 gallons of the epoxy/resin

44'cruisingcat · 08-02-2018, 12:13

Use epoxy. The difference in cost will be a small fraction of the overall cost. Polylester isn't water proof. Epoxy has far superior secondary bond strength.

If you spend a little while reading here: https://diy-yachts.com/forum/index.php , you can learn a lot. Also worth joining and asking questions there.

PS, look into peel ply. It can save you hours of sanding, virtually eliminates blush issues.

Good luck!

Randy · 08-02-2018, 12:37

Polyester has no place with this application. It doesn't hold up with 4-6 oz glass and like others say - it's not waterproof. My experience says West is great if the environment is managed during application. System Three is more forgiving in uncontrolled environments.

frozenhawaiian · 08-02-2018, 17:45

Quote:

Originally Posted by Privilege

Why are you making it with epoxy? None of the production boats use epoxy for their hulls. I'd build it with polyester resin which is a 1/4 of the price of epoxy. Epoxy is second-to-none if you need it for an adhesive but is not necessary when making a hull.

this, epoxy is light and strong but stupid expensive, only high end racing sailboats use it as a building resin.

smj · 08-02-2018, 17:57

Plywood boat, only epoxy. Polyester doesn’t even enter the equation.

HopCar · 08-02-2018, 18:19

I have built several small plywood boats. You need to use epoxy to adhere the glass to the wood. If you use polyester it will eventually peal off in big sheets. Don’t want to say how I know this.

I use West 105 resin and 207 Special Clear Hardener. The 207 Hardener avoids the blushing problem and it gives me enough working time in high 70’s temperature. I use the plastic pumps to dispense the resin and Hardener.

US1Fountain · 08-02-2018, 18:33

I'll use vinylester over polyester any day, every day. Vinylester is so much better than poly at very little more. Have done alot of work with West System epoxy and love it. Doesnt get any easier than epoxy. Instead of using WS epoxy, use the epoxy from US Composites. Its less the cost and easier to work with. WS epoxy is great, but is overpriced.

True most boats are made from poly, but using poly to repair vs build are 2 different conditions. Repair relies on a secondary bond.