Questioning The Infusion Of 33¨boats

jiggerpro, your boat hull will made with a sandwich construction no? like a balsa core or similar?

If you use a sandwich construction, your hull laminates i doubt would go beyond 10mm solid laminate thickness in the chine areas? 10mm of solid infused glass laminate is around ~13,000gsm of reinforcement so thats in excess of 20 layers of 600gsm fabrics... if you want your boat to go super fast, your going to have to keep the weight out of it. I dont see a problem infusing this much laminate using a VE resin...

you cant base your information simply on wht yellowfin are doing, they may be doing something really stupid and not realize whats going on, we just dont know... using a low exotherm resin you should be fine. Also, you may have to hand lay a skin coat first in order to deal with the print though issues, this is not much work as it only has to be a light csm laminate to block the print. It will also hide other surface blemishes if you make small mistakes with your infusion.

When start infusing things, especially sandwich cored laminates on gelcoated tooling, you cant see the tool side of the part during the infusion, nor after the part is completed. It is not uncommon, to have blemishes in the laminate on the tool side which you will not notice after demolding. You will find the problem (or your customers will) some time down the road when it starts to show thru the gelcoat. This is why you MUST have your process well figured out before you attempt to infuse your hulls or there may be problems you dont know about until its too late... i would start to play around with infusing small flat panels on a table to get familiar with your materials, laminates and discover solutions to the problems which arise. You will also find the answer to the question in this thread and the exotherm and gelcoat print etc... theres no other way other than to start trying things out for yourself and simply talk to resin suppliers and ask for a low exotherm and low shrink resin to avoid the gelcoat problems your worried about.

 

Hi Groper, yes our boat will have corecell as the sandwich core, and yes the weight has to be kept as low as possible for efficiency and performance reasons, in regards to Yellowfin boats, I am not basing my information only on the owners opinion on the subject, but nevertheless the source, the owner, should be a quite respectable one since the man himself has a very good reputation of a serious builder of well constructed boats, but thinking about his statements I have the theory that he may have some " obscure reasons " to say what he has said, when I say obscure, I mean commercial rather than technical reasons for his statements, I do not know for sure but there is a chance that the man says what he says because his larger boats molds of which he has 6 size models where probably made in the pre-infusion ages and now he "can not" when a new model is introduced and a new mold is made to do it with infusion because probably then this new model among his 32-42 feet range of boats might "embarrass" the other models in his range because of having better performance due to lighter weight, maybe even making the sale of the non infused large models difficult due to comparison to the only large model infused, but this is only a "conspirative" theory.

Naturallly, we have plans on making several infusion tests off course applying a strong hand laid skin coat and to get assesment from people with vast infusion experience, but the man is not talking about small surface imperfections like printhorough he is mentioning heat distorted pieces, and there a re places like the keel area where unavoidably, the two laminates of the two sides of the "v" of the hull will be overlapped, and since we will not use a sandwhich in the submerged parts of the hull, there, at the keel due to the overlapping there might be a solid thickness of maybe around an inch (25 mm) or even a bit more maybe 35 mm.

 

Landlubber, if the provider of the resin of your Nowegians shipyard was Gurit then for sure the resin was an epoxy for infusion, which is probably a very good resin but being an epoxy, it would need to be heat postcured in a low temp oven to achieve better properties than a good vynilester resin without postcuring this making the use of epoxy quite complicated due to the size of the (low temp and low tech) oven needed.

I had plans to infuse my boats with Gurit´s Prime 20 LV epoxy before discovering this, and arrived to the conclussion that a good vynilester resin would be much more practical: no oven needed, Vynilester does not soften with high temps as non postcured epoxy does and the mechanical properties of the laminates are very very close to those made with postcured epoxy ..... and no need to oven the pieces so I decided that the use of epoxy was not worth

 

An oven is simply a plastic bag or sealing the room the boat was infused in (we had both), as the temp was not all that high from memory. You could walk into the room whilst it was going on, very hot but not unbearable.

 

Yes Landlubber, its a very simple low tech oven, but just a single layer of plastic will not provide enough isolation since a thin plastic film practically all it does is avoid ventilation, not really providing any kind of heat isolation, if two plastic layers with an airspace in between are used things would be quite different, but still the oven should have some heat sources (domestic heaters) and some air moving devices ( fans ) to get an even uniform temperature inside the oven, and then maybe 48 hours ( of surveillance of the oven) at 50-70 celsius, off course it can be done, but what for ? just to get 3% better mechanical properties when compared to Vinylester resin ???

Not to mention the fact that vinylester infusion resins are more fluid or less viscous than comparable epoxys and slightly cheaper.

I have been in contact with Herman via e-mail and it seems that the key is the choice of the right initiator but it seems that definitely is doable regardless of what the Owner of Yellowfin boats might say.