FoamStream...

[eaglesdare]

hey i don't even know how to text yet.

i'll be looking forward to the drawings steve.

i hope you don't mind me taking your foamstream idea and running with it gpw but the more and more i think about it, the more and more i love this!

[Fishingtomatoseed]

This may have already been brought up, but watch a couple of the videos of the building of the Bailey Blade Car on youtube. May give you some ideas. I like using the wood cut to shape then shaping the foam to it.

[eaglesdare]

man i wished i could clean my house as fast as he cleaned that garage!

cool vid, and yes, it does give ideas to ponder.

[atahoekid]

Cutting ribs out of ply like that could use up a lot of wood, but I was looking at your diagram and I'm thinking that you probably don't have to make the ribs too wide. I think that arch is a naturally strong shape and as long as the wood or the joints don't snap you should be good. Maybe 1 1/2" to 2" at the widest? You should realize that this is using the "seems about right to me" type of engineering... Maybe strengthening the joints would be a good idea?

[GPW]

The formers actually serve to keep the stringers in place , and once the foam is attached , it should be pretty strong , once canvas skinned , even Stronger... The formers could be made of foam , but would have to be a bit wider , taking up valuable space inside ... Just thinking, with the right layout I could cut all the former pieces out of a single sheet of ply ... maybe ?
I was hoping that my buddy could cut them all out on his CNC machine , making this process Quick and accurate ... That would make the rest of the assembly pretty simple ... The formers would be braced at the joins by a small doubler plate ...

While not as nice and “clean” as a steam bent wagon "bow “ , it is easy for most folks to do ... even cutting the ply with a small jigsaw... Assembly would be easy too ... Stand up the formers , plumb, pop in the stringers and there’s a frame ... For a 12’ FS I only need 5 full formers....not so bad ...

[Wobbly Wheels]

The formers actually serve to keep the stringers in place , and once the foam is attached

That's exactly how we built this boat:


The hull and deck are 1 1/2" foam and the the layup was epoxy and S-glass/kevlar/carbon.
A flat deck arrived one day loaded with laser-cut MDF forms like in the video.
We mounted them upside down on a strongback and ran stringers into precut notches. The foam was ripped into 3" wide 'planks' for rough fitting and spiled (tapered) as needed, then a cove was routed along one edge and a bead along the other.
We then screwed through the stringers and into the foam from the inside so we could pull them after the outside layup was done. Drywall screws were the best for that because the threads are coarse enough to get a good bite on the foam.

Given how easy it seems to be (for those more skilled than I) to use readily available software like SketchUp to come up with a design, and the proliferation of shops offering CNC cutting, it's probably even more feasible now for the home builder than 10 years ago when we built Melina.

[GPW]

W2 , CNC rental time is really cheap around here ... ~$75/ hr, but in that hour you can cut most everything you’d need , saving Hours of tedious hand cutting , and with the machine all the pieces are Exactly the same size ... Money well spent for replicating many pieces... IMHO Better fit when you start assembly ... Precise alignment of the parts means the foam fits better over it , no “fudging” with spray foam needed... The “fit” is the detail that makes the difference between homemade looking or a Professional looking job ... Although I can’t say the RV industry does this , they just cover over their sloppy work ... causing many problems later... grrrrrr !!!!

Luckily , my buddy Vinnie has a CNC in his guitar making shop, and I might be able to talking him into cutting my ribs ... Who knows , he might even want to make one too ...

[Wobbly Wheels]

Hehe...I'm sure we must have kicked at this can before, but it sounds like we've had similar experiences with so called 'professionally built' RVs.

You see the same sort of garbage in production boats as well: anything to save a buck on the production line. It's not as bad because you can't just pull a boat over to the side of the road if something goes wrong, but it still happens.

Done a couple stick-and-staple RV restos and...wow, it's a different world.
A lot of people think that they could never build something that's as good as a 'production' unit, but I'd stack up what I've seen on here against showroom-fresh RVs any day. Amateur builders' conscientiousness more than makes up for not knowing about so-called 'proper' construction techniques. Plus, you know every inch of your rig and have a fistful of ideas on how to make the next one better.
Production builders often don't seem to give a rat's arse.

Alright, back on topic...
If you figure 5 forms at 6' long (high) plus a bit to allow for the curve, you should certainly be able to nest them in a single sheet if they're in 4' length that you join during assembly. That's 20 strips 4' long and, at 4" wide you've got room left for waste. Another advantage is that he can add lightening holes or slots at the same time. You could glue on wood edging to finish it.
The forms that came for Melina had 'jigsaw puzzle' cuts on along their adjoining edges so that they would go together only one way and the alignment would be perfect (and quick !). Thanks to CAD and CNC, you could incorporate that into the joined ends of the ribs and they would fit tightly enough that your eye probably wouldn't pick up the line, even under a clear finish.
Hmm....

[GPW]

W2, That would be Cool , precise fitting pieces , and the thought of lightening holes is thrilling .. So I could use 1/2” ply instead of the 3/8” and end up with about the same weight with the lightening holes ... and as a bonus , the rib holes would be great places to hang things up ...

[eaglesdare]

hey steve, did you get a chance to do that drawing? looking forward to seeing it.

[GPW]

... and while we’re waiting , here’s a pic (drawing ) of the FS rib , with the lightening holes ... All this could easily be done with a jig saw and hole saw for the holes ...

[eaglesdare]

here comes the technical stuff....what are those holes for?

[GPW]

Removing weight , and hanging stuff from ... Lights , cargo nets , laundry ... anything

[GPW]

Contacted Vinnie, going over there Thursday ... going to see if it’s feasible to cut these on his CNC ... That would sure speed up the process... Also going to see if he can kerf my foam on the CNC ... That would be nice cause’ he has a dust collection system hooked up to the CNC , avoiding all that foam dust in my yard... again ... All the blu foam dust is gone from last years build ... Schmaybe’ the hurricane blew it away , or just covered it with fresh debris...

[eaglesdare]

that would be great if someone could do the shapes for you.