So far there has been no mention of moulds. Making moulds of this size suitable for prepreg or infusion for that matter will be costly, especially given that your basement workshop prevents the use of polyester.

Carbon Copies Ltd

I'm following warren and ChrisR on this one,

Quite a few marine builders still use poly resin as they know how it works from the old CSM & wet lay days. (And it's cheaper) Also, don't forget one of the primary benefits of using poly resins is the fast cure time and people don't tend to get reactive to poly resins like you do with epoxy

Perhaps I have misunderstood. From the outset weight and strength have been the criteria. Fumes from polyester were quoted as reasons for not using infusion. Why would you want to use polyester given all its disadvantages?

Guys, I'm not sure where the confusion is? I've used polyester infusion resin before so I don't think he is confusing resins.

I have to admire your confidence. It's an ambitious project and will require an equally ambitious budget. Not knowing the difference between polyester and epoxy resins suggests more research is needed.

Epoxy isn't polyester. There is no smell issue, certainly not when infusing.

If that Gurit stuff is low temp curing you could most likely use it together with the Easypreg.

I did give infusion a good deal of thought - it is a process we use at work and I know well, although we inject the (polyester) resin as well as drawing it through with the vacuum. The largest parts that I am looking to make would be a maximum 6m long by 0.5m wide by 0.2m deep (i.e. half an 18' hull), so we are not talking about a huge item to lay up & it is a pretty simple laminate; so the out life of the prepreg should not be a factor.

I'd still need an oven to post cure the infused laminate, although it might be at a lower temperature, just to avoid the inevitable core block print through. The oven would still need controls, etc. so not much saving there either. I was woring on a scalable design for the oven so that I could build it in sections, say 2m at a time. I could then "practice" on some smaller parts - rudders, etc. - before working on the larger parts. This would at least give some confidence in the controllability of the oven and reduce the likelihood of scrap parts.

I could go down the route of the Gruit SE84 prepreg with the associated / compatible surfacing resin, adhesive layers, etc. This is an 80 degree C cure. Additionally, there would be no open resin mix and hence a much lower smell issue (I am looking at working in my garage in a residential area!).

Thanks for the continued contributions, all food for thought!

This is not me being critical but I have to agree with Matthieu. Out of autoclave pre pregs need carefully controlled heat cycles to perform well. It is not an easy task building a DIY oven of that size and to be able to control very accurately the temperature evenly throughout it and achieve temperatures in excess of 100 degrees C.