This!
Thank you; very helpful.soma said:Weight IS a factor in the gelcoat vs paint debate, but the bigger issue is the resin choice that gelcoat demands. Gelcoat is polyester, meaning the whole boat has to be built in polyester/vinylester. No epoxy construction. That is a big technological step back if you're trying to build a light, stiff, carbon boat. That's not to say that vinylester/polyester boats can't be fast, but you DO give up a lot performance-wise (extra weight/decreased stiffness). Also, gelcoat comes in very basic colors. No sexy metallics with gelcoat.
During the design phase of the 68 some members within the group kept mentioning gelcoat. We tried to squash that debate right away. Gunboats just should be epoxy boats.
For your purposes, though, I'd think that a vinylester/gelcoat boat would be the way to go (if you were designing a custom production boat). I think it's safe to say that fairing/painting represents a 20% price premium over gelcoat. Epoxy, as well, represents a huge price increase compared to vinylester (though the % of the total cost of the project is tiny).
I think about weight savings a lot, and how every gram adds up. Chase every gram. If you flip the debate, though, and chase cost then there are a LOT of ways to save a lot of money. Fiberglass ($) vs carbon ($$$), infusion ($) vs wet-layup ($$$), gelcoat ($) vs paint ($$$), vinylester ($) vs epoxy ($$$), foam ($) vs nomex ($$$). I think that's where the TS guys have it right. Spend on the stuff that matters, save everywhere else. Yeah, you may be giving up 5% on the performance, but it frees up a lot of money to spend elsewhere to get that performance back. And you'll sell a helluva lot more boats.Gunboat have sold 2 boats in the time it's taken TS to sell 30.
Wait, maybe I'm misunderstanding something, is wet-layup better than infusion? For all the other items you mentioned, the expensive option is obviously better (other than price), hence the trade-off, but I thought infusion meant less resin, better resin/fiber ratio, less weight, etc.??soma said:
You can split the build process and avoid the excess weight gains, you can achieve very good skin/resin ratios, it’s the core bonding with infusion that adds to the weight, however it comes down to $$$$ as always.soma said:
Could you create a legal structure where an LLC or Corp entity could own the work in progress including the hull, purchased parts etc? The builder could have a contract with the llc to perform work etc. The LLC could buy parts and materials directly and/or the builder could be paid monthly based on work done (man hours) and parts needed for next months work etc. If the builder goes belly up, you'd own the LLC including all of the work and inventory of parts and materials etc.
This seems like a logical way to approach a custom build. Not sure if production builders would be willing to go that route....
that doesn't solve the problem i mentioned above...
It's only heavy if the infusion is done badly. If there are no gaps between core panels, the core is flat, simply curved or heat bent (ie, not contour cut) and the edges treated so there is no accumulation of resin then 2:1 fibre:resin is a given. Consequently, it is only "cheap and fast" if the hulls shapes are simple. Lots of cored compound curves really slow things down.soma said:
2:1!? By volume or weight? Carbon or glass?
I read this to mean 2 parts fibre 1 part resin or 33.33% resin so you guys appear to be in "violent agreement"...
Really depends what you are building and how ! We build nice light hulls using infusion but the secret is you MUST thermoform the plain foam and not have cuts or score marks in it that suck up the resin . It also must fit well and you need a perfect vacume or forget it !soma said:
Well don't forget that you also to have consider the building materials & method too. An all carbon, nomex boat will be much lighter than a glass one of similar size but labor hours would be similar. Ian's chart was for people building his style of boats (one-off glass/male molds)
Most of our boats are infused Vinylester and we always put a vinyester skin coat against the gelcoat . BUT we only use epoxy prepreg and a lot of post taping reiforcing is done with epoxy with no issues .
Don't even need to go that way. You can structure a contract that title to the work in progress is not held by the builder, but by the owner as progress payments are made. Normally the builder owns the boat until completion.
I understand this
This I don't understand. I can understand post taping reinforcing INSIDE a vinyl laminate where there is an exterior gelcoat layer - but then you say you use epoxy pre-preg laminates when you say you're infusing Vinylester.
Yes , we use Vinylester for the hulls behind gelcoats . But some parts are are taped in with epoxy . For instance epoxy prepreg chainplate bulkheads, that are made in our Autoclave are taped in to hulls made with Vinylester, using epoxy resin ! Daggerboard cases , made with epoxy prepreg , are taped in and reinforced with epoxy ! Rapido Trimarans are complex pieces of equipment and require lots of careful boat building to build ! Hence the price , you do get what you pay for ! As for hours quoted by some guys on here , they are living in fantasy land and no wonder some of them go broke building boats ! Costs , volumes , labor hours rise expotentially as a multihull gets longer !
Cored glass, by weight. ie, the weight of the finished laminate, minus the dry weight of the core. 2:1 fibre:resin is 66.6:33.3 35% resin is 65:35.
My 2nd hand experience with infusion is that it tends to be heavier because the resin will fill all those little gaps in the foam, and the edges of foam where transitions to solid glass occur. Somehow all the very top builders still think pre-preg makes a lighter boat (F1 car/fighter jet/hypercar) - because you never start with excess resin anywhere.
