View Full Version : Fibreglass?????

hovercad - n/a
24-Mar-07, 07:27 PM
Hello all,

Well ive done the usuall left it to the last minuite to do anything with the flying pig.(oops my craft or im just coming out of hibernation from the winter.)Although meant to be a racing craft thought would ask here as its relavent to cruisers as well as racers.(He he he is there such a thing as slowers. Last time out the beer tent was faster than me.)

Have to replace 2/3 of the bug infested wood that makes the underneath of the hull.The rest is fibreglass.

Havent done any fibreglassing before.

Have measured up the amount of material I need.

The material mostly avalible seems to be 450g/sqr mtr chop strand mat.

From what i have read over the years on here is that 2 layers will be adequate.Reading else where should work on the base's same weight of resin as material.ie 2 sqr meters of 450grm mat would need 900grms of resin.

So by my calculations I would need 10 sqr mtrs of 450grm.(10 x 450g = 4.5kgs of resin.)

As the underneath will not be seen.(Hopefully) the finish is not importent.Pva realise agent on smooth boared.

Any major flaws in my thoughts.

Will be ordering the materials soon.(I hope)


team black - n/a
24-Mar-07, 08:31 PM
Hold on there.

Chopped strand mat absorbs approximately 2.5 times its own weight in resin. A woven fabric will absorb about its own weight. Give a little more detail- if you're planning on using board for the planing surface then you don't necessarily need to cover the whole board, just tape the seams. I used to use 4mm ply for my planing surfaces, with 3x 1oz tapes over the seams.


hovercad - n/a
26-Mar-07, 08:27 AM
Hello Ewan,

I was going to use that smooth white boared to act as a simple mould.(PVA realise agent to get it off after dry.)

Just a surface to make fibreglass panels.

I was going to replace the wooden planing surfaces with fibre glass one's.

But thinking about it.It would be quicker to just replace with ply.Like you have (thats whats almost there apart from one side which is fibre.)

Did you coat your ply with resin.

Or as its for racing and the suspected life will be less than a cruiser just leave untreated.

Would the B&Q cheapy stuff be adequate.

I suspect the craft will only be servicable for this season as its very very old and has had a harsh life previously.


team black - n/a
26-Mar-07, 08:10 PM
I've always used the ordinary WBP plywood ("exterior ply") and simply taped the joints. Using kevlar and epoxy was no better cheap old polyester. I would put extra reinforcement where the closest points between feedholes will be, as this tends to be the weakest point.