600 GSM Biaxial Fiberglass

[Meanz Beanz]

Hey Jeff,

Tony at themultihull.com has done it and reckons you don't need stringers plus I am going heavier on the bottom than he went. I guess that's an experiment.... they can always be added.

Hey Brian,

Nah... this is only a few hundred bucks worth of stuff, its as much to play with the material as it is to solve the problem. I have watched impact tests on the 15mm Polycore and 600 gsm Bi Ax, they are quite impressive. I have also heard stories of truck being driven over sample panels... it has me intrigued. The edge treatment is the biggest bug bear with the stuff as far as I am aware... cost wise it compares with good quality ply but the weight savings are big, possibly down to a third of the current set up. Given the SW24 was designed for tramps and not hard decks this is a good thing!

The Nupol guy's offered me 600gsm Double Bias as well... better... worse???

Cheers
MBz

[Meanz Beanz]

Originally Posted by waikikin

Meanz, if your using foam...

I should cost it in foam... I will need stringers then, I think! What about impact resistance? What about foam edges just to form the tapers?

[masalai]

Just a stupid thought from a know nothing (with regard to what you are trying), I gather there is some concern between the strength of the edges to hold the whole in a "groove" in aluminium mast. Why not glass in edges of wood or plywood and give that to be threaded into the mast section and the glass onto the ply is bonding as it should and the lighter foam or whatever is in the middle where that stuff is good? Does that make sense?

[Meanz Beanz]

The current ply is rotting so I don't want to go back there with timber. I might but, not convinced its a good idea yet. What I could do is use harwood (or???) as a denser solid core for the transition to the solid glass lip. That way it the glass will stick, I can get it say 10mm into the core and it ***should*** never see moisture as there will not be holes through that part. I will draw it up latter and post a pic... but for the moment I'm still trying to avoid timber.

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Nice pic you auld artist you

[masalai]

When I have a brain fart I need to get it down quick or I loose it...... try western Red cedar (wear a nose bag as the dust is not good for your health) a little carbon or something for impact/pressure load carrying and general epoxy (west system is it that is less toxic to breathe) and a bit of triaxial cloth to hold it and join it all together....

[Meanz Beanz]

That might be the go Mas, still light enough, does not have to be that impact resistant... I will draw later.

Cheers
MBz

[Meanz Beanz]

Whaddya reckon?

[TeddyDiver]

Nice'n solid I'd make the upper edges of the core (cedar edge) a bit tapered too, maybe 1/3 of the edge thickness, to carry loads evenly to both sides of the sandwich..
Does that make sense?

[Meanz Beanz]

Yeah it makes sense, I'm trying for a flat surface on top to fit carpet. You think its a must?

[masalai]

Good one Heinz, but, - - - don't use the chopper use woven - less epoxy more fibre = better strength - You will get to much epoxy with chopped strand and take the join further out for better load distribution & bonding, then cover with peel-ply and squeeze it with a little steel wheeled roller to force out all air bubbles.

I have seen it done and I would strongly suggest you seek professional advice too

--------------------------- With a v to the wood and glue/bog stuff to fill the holes
. . . . . . . . . < . . . . . . . . .then clamps to squeeze it all together whilst laying the
___________________ . . .strips of cloth to finish the whole join and that fiddley bit in a mould using only wet cloth to make it strong ...

[AndrewK]

Meanz Beanz

1. to determening laminate thickness in (mm) for your typical stitched fabric multiply the weight of your glass in kg/m2 by 1.2 for hand laminates and by 0.9 if using 80+% vacuum.

2. I am guessing that the old ply decks are lashed in place, if so then an option for you is to bond a round section (conduit, aluminium tube, glass rod) to the perimeter of the core and glass over. The 600g glass (DB would be better) will easily go around the 15mm diam edges. Then simply lash through this reinforced edge to the existing points on the beams and hull sides.

Cheers
Andrew

[Meanz Beanz]

Hey Andrew,

They are screwed into the top of the old tramp bolt rope tracks. That's the normal "solution" for a Seawind 24. The tracks themselves are a drainage problem so they are going and are to be replaced with brackets mounted at about 500mm centers.

Thanks for the formula... so about .72 mm is around the mark for 600 gsm hand laid? That would be good... cheers!

[waikikin]

Meanz, Masalai is correct if using epoxy resin, however as your using poly & seeking thickness at the perimeter choppy is a pretty good way to get it especially if sandwiced between your stitched fabric layers at lower cost in resin compared to epoxy, if you tear the chop on one edge & stagger the edges it will kinda blend & taper into the main laminate nicely. One issue that Masalai has touched on is the use of epoxy, even though its more expensive per liter/kilo, an epoxy job often can come out the same cost & lighter than the poly job as it can be constructed with no chop & therefore less resin, chopstrand mat is a requirement for poly lamination to a core of stitched or woven fabric particularily over 400gsm, the beauty of poly/styrenated resins is for gelcoat finish & also the speed of process. All the best from Jeff.

[Meanz Beanz]

Originally Posted by masalai

I have seen it done and I would strongly suggest you seek professional advice too...

Mas, I live in Couta Boat country, the pros down here consider kauri and copper composite construction, they get a nervous tick when they try and say fibe...fiber...fibergl....

Must try and find some one building modern boats!

[Meanz Beanz]

Originally Posted by waikikin

chopstrand mat is a requirement for poly lamination to a core of stitched or woven fabric particularily over 400gsm

Hi Jeff,

Are you saying that I can't laminate the 600gsm onto the polycore with polyester without a layer of chop? Do I understand that right? I was going for polyester to keep the cost reasonable but will happily use epoxy if there is no real saving or if I have to use a whole bunch of chop to make it work.

Cheers
Mbz