Vinyl Ester resin ok?

[captseasick]

So I am ready to glass in the hull side wall stiffners and I have a question about which resin to use, is it ok to use the US composite polyester resin 700, any use it?? The reason I ask is because I have read that you cant put polyester on-top of epoxy resin but you can put epoxy on-top of polyester.  What was the 270xf made of??? I hope polyester cuase its wayyyy cheaper per gallon.  Plus the 700 polyester resin is made to be comparable to epoxy in strenght.  opinons very welcomed!

[seabob4]

Guaranty you the 270 used poly throughout.  You only get into epoxy's in rebuilds.  Polyester was the norm until vinylester came into play, and even then only the better brands use it...$$$, you know.  Even Intrepid (yes, I did work for them for a bit) didn't use epoxy...

[captseasick]

Fantastic!! 5 gallons for 180 is sooo much better then 2 lol.  Thanks for the fast response!!  Pics of the build will be no my 270 rebuild thread!

[RickK]

If you're not going to gelcoat the area when finished I would go the extra $$ and go epoxy.  It will be much stronger that the bonding of poly.
I pay less that $100 for a 5 of Poly BTW, not sure where you are getting your supplies - I get my poly locally.  Check the prices of epoxy at USComposites.com.  With epoxy the stiffeners will become part of the structure, with poly it will be stuck to the original poly somewhat but not as strong as the original.

[Georgie]

^^^^^^^^^^^^ X2

For structural purposes that won't need coatings or finishings, use epoxy (in spite of the price difference).  Adding new poly onto old poly results in a much weaker bond and you'd be asking for delamination issues down the road.  Epoxy has many times the adhesive bonding strength of poly.

[saltfly]

Like Bob said poly is what was used on your boat. If  structural  strength is of concerned to you, then why not use vinyl ester. It is only a few dollars more per gallon then poly and a hole lot cheaper then epoxy. I use vinyl ester on everything I do.  don’t like the cost of epoxy for the small amount of strength difference between it and vinyl ester. All so what is never discussed is the stiffness of epoxy verse vinyl ester. there are places on a boat where epoxy should not be used. A hull has to flex. If it doesn’t in some places, it will crack, on the weaker part. Most epoxy’s are  stiffer then vinyl ester, but only a little stronger. There is a difference between, stiffness and strength.

[kaptainkoz]

im no expert but I have done alot of research and I went with vinylester on my build. Although everything said above is true and all products have their strengths and weaknesses, in the end you have to ask yourself are the properties of the product overkill or appropriate for the application. I would sure like a set of military grade hardened titanium tupperware bowls, but is it cost effective, overkill and/or practical?
The way I approached my rebuild is that if its all made with poly, then poly is fine.... BUT... vinylester is compatible and a bit more expensive but much better properties so why not??? Epoxy has alot of fans and for good reason, but i am not a fan simply because gel coat wont stick to it and I do not want to keep track of what went where and what wont stick to what. In fact, I will switch back to polyester for cost savings to build my pilothouse as it is purely cosmetic in the sense that it isnt holding the boat together. God help you if you are applying enough force to the stiffeners to pop polyester let alone vinylester or epoxy.
Also check different suppliers' pricing. By the gallon at your marine supply is brutally expensive. 5 gallons of vinylester at my local fiberglass supply is $242, $48 a gallon. I spent $38 for a gallon of polyester at Home Depot and the stuff was the worst to work with.

[CLM65]

For what it is worth, I originally planned to go with vinylester on my rebuild, but a very reputable boat builder who does a lot of these rebuilds (who is also a member here), as well as a local shop that does rebuilds, both convinced me that poly is more than adequate.  I get quality poly in 5 gallon buckets (I provide the buckets) for just under $20 per gallon.  I can't find VE or epoxy for anything close to that.  Now, with that being said, I did end up splurging on about 5 gallons of epoxy for some "piece of mind" when I joined the tops of my stringers to the bottoms, as well as a portion of where I tabbed in the insides of the existing stringers to the hull beneath where the tower will go.  I think these joints will be about the most heavily stressed.  I also purchased a gallon of VE that I intend to use on the joints where the transom cap meets the existing cap.   Note that I do intend to use gelcoat.

Between the poly and epoxy, I really haven't had any difficulty with either, but to me the poly seems a little easier to work with.  I know others feel the opposite.  Oh, and I think one of the keys to getting a good bond, especially with poly, is surface prep.  Make sure the surface is clean and adequately roughed up for good adhesion.  And one of the builders mentioned above recommends using a layer of 3/4 oz mat as the first layer when bonding to old fiberglass.  This is in addition to the built-in mat found in 1708, 1808, etc.

[fishinonthebrain]

X3 on the vinylester. Wish I knew about it before I started redoing my transom with epoxy.

I am using vinylester on everything now.

[gran398]

It's a function of need.

Best example is Rick's deluxe 170 rebuild.

Rick used epoxy minimally...mostly for adhesion purposes. New stringers to hull, cross-members to hull, etc....set in place to tab later.

Vinylester for bagging if remember correctly.

Poly for the rest.

[captseasick]

Well guys im sorry that i miss posted.. the original question was about 700 Vinyl Ester Resin by us composits vs epoxy... the vinyl ester is 180$ for 5 gallons and its supposed to be almost as strong according to UC composites website..... so from what yall have said the vinyl ester is plenty strong for boat hull side stiffners every 3 feet or so just to stiffen the sides up a little and to use on the transom for making it stronger to support a 4ft long, 10ft wide dive platform.  Thanks again everyone.  Cant wait to get started on the 270 and get her on the water!!

[Aswaff400]

ive been using vinylester throughout my entire rebuild but any brand New parts(deck, console, casting deck) have been made from poly.

[RickK]

Admin Edit: I changed the name of the original topic so that members will know the real question.

[wingtime]

The big question here is primary bond vs a secondary bond.  Poly has a terrible secondary bond strength (laminating to already cured fiberglass).  

For what you are doing I'd personally use epoxy.  It smells considerably less.  Little to no VOCs. You can control the cure time better.  The secondary bond is is very high.  My second choice would be vinylester resin.

I would only use poly for new layups since that is all primary bonds.  (curing to still wet layers)

[seabob4]

As all probably realize, the key to to use of ANY adhesive/bonding agent is proper surface prep, including adhering to all the manufacturer's application instructions.  I work on many an older boat, built entirely with polyester resins, both higher end and run-of-the-mill, with quite often no signs of delam, saturation, bond joint integrity issues, and some of these boats are pushing 25 years old.

While epoxy resins and vinylester resins are indeed superior products in regards to comparisons with polyester, done right, polyester has proven to be a reliable, durable material when it comes to laminating fiberglass.  It can be a VERY cost effective means for producing a desirable product for those on a somewhat limited budget.

Just my 2 pennies from someone who has seen literally thousands and thousands of boats laid up.  Yes, there will be times when the lay up was poorly done, and that has been shown by the number of threads we have all read, even regarding newer boats, where lamination issues and failures have reared their ugly heads.  But most definitely the exception, not the rule...