Vinylester vs. Isophthalic Resin in Oz Goose Construction with Fillets

Hello!
I'm from Uruguay, and here it's not possible to get the nautical epoxy resin recommended in the boat plans. The only types available are epoxy resin for crafts or flooring.
I was advised to use ISO resin, but after doing some reading online, Vinylester resin seems to be a better option.
What would you recommend? Any advice is welcome, as this is my first sailboat.

 

Use the epoxy even if it's for flooring, just make sure it's not diluted, somewhere in the technical data sheet it should say 100% solids epoxy, or something similar. For fillets you can also try the thickened epoxy used for anchoring bolts in concrete.
Buy a small quantity and do some tests, glue two pieces of wood with it and laminate some fiberglass. If the wood breaks before the glue you are good to go.

 

Vinylester is a step up from Iso, and epoxy is often overrated.
You can build a very solid boat using ISO, it is the industry standard, and there are very strong boats built with it that are over 50 years old.

 

I'd assume the laminate is designed around epoxy, the reinforcement would have to change with vinylester or poly. At the very least your going to need csm between layers. My guess is the variable strength difference would need some additional engineering.

 

I would suggest known additives for making fillets (glass spheres and fumed silica, wood flour if you have it) and light weight +45/-45 stitched biaxial for the seams.

I did a boat with 6oz plain weave tape and it eventually split in some locations where the fiber crossed the seam in only one direction . I did another boat with screened shop sawdust replacing part of the filler material for fillets and they were less easy to work. That boat is getting the +45/-45 biaxial once the weather improves enough to glass.

I do like the trick where mixed fillet material is piped into the seam with a plastic bag and then smoothed.

 

Guys, the Oz Goose is a 12 ft plywood box. It has two construction methods, ply on frame and stich&glue. The ply on frame version uses fiberglass in form of 50mm bands over the chine for waterproofing. The rest of the epoxy is for glueing and coating.

Andres, use wood battens with nails or screws instead of fillets (saves on expensive epoxy) and if you don't trust the flooring epoxy for glueing them on, use something else. Any glueing epoxy will do, as well as other waterproof adhesives like polyurethanes. Then you can coat and laminate with the flooring stuff.
But really, glue two pieces of wood with thickened flooring epoxy and try to break them.

 

Ah.... I should have looked that up

 

I have built a Puddle Duck Racer, which is the same as a Goose but without the 4 extra feet in the middle.
My biggest issue/regret was not painting over the epoxy on the outside of the boat and leaving it upside down and uncovered in harsh weather (snow and sun), leading to checking of the epoxy and deterioration of the plywood.
The taped seams did better than most of the rest of the boat but the fiber direction was not ideal, leading to some cracking.

I just got in the -45/45 tape for the next boat. It looks good for fiber direction over seams but will be a little more effort with its thickness and rough edges.

If the OP does not have epoxy on hand, it could be an expensive buy-in for a test unless a sample quantity can be sourced.

I got in a batch of general purpose epoxy in off Ebay. It is a nice water-clear 2:1 formula (edit: and inexpensive)... but needs warm temps and longer time to set and cure than the other epoxies I have gotten previously for boats or surfboards.

 

Two additional tips for taped seams. Lay out your tape on a strip of polyethylene (visqueen) and wet it out there and then transfer it to the boat and lift off the visqueen. Apply a layer of peelply and peel off after resin has set, eliminates a lot of sanding/filling.

 

One more tip,cut a very shallow bevel on the outer surface of the ply,say 1/16" deep and tapering to nothing about an inch and a half in.It will take a lot of the work out of fairing and finishing the boat,with no noticeable loss of strength.

 

Carpenters ...

 

Did I miss something here?
Some of the replies above seem to know what boat, method and materials are involved, maybe my crystal ball is smudged?

 

A 'Goose' is an extra long Puddle Duck Racer (PDR).

Puddle Duck Racer - Easiest Sailboat to Build and Race https://www.pdracer.com/
Oz Goose Sailboat, easy to Build. Excellent Family or Club Sailing Fun - Oz Goose Sailboat - Cheap Simple Plywood Boat https://www.opengoose.com/

 

Some flooring epoxies have solvents in them to improve the flow, this type isn't what you want for building a boat, it will drain out of the glass and the physicalproperties of the epoxy will be lower. Craft epoxies tend to be thicker and clearer, thicker means it won't drain out of the glass as quickly, being clearer may or may not make a difference depending on the look you want.