Laying Fibreglass

[Jonny Fuller]

Originally Posted by boatster_sr4

Gelcoat is just polyester resin. You can use a thick celophane to keep the resin from air while it cures, this is called Vacuum bagging.

Vacuum bagging, doesn't really describe laying cellophane over un-cured gel to stop it getting a sticky surface.
Vacuum Bagging is exactly as it says.
For the best possible strength & lightness, the main laminate in any composite structure should have the highest fibre to resin ratio possible, as the resin is only the medium that holds & bonds all the fibres, whatever they may be, in place and to each other, too much reduces the strength and flexibility.

Vacuum bagging is the process of covering the uncured laminate in celophane, with vacuum pipes attached at various points both in the celophane itself, and also at points around the mould. A vacuum is applied to these points decreasing the pressure tween mould & celophane to a level considerably less than that of the surrounding atmospheric pressure (approx 14.5), this causes all the excess resin within the lay up to be queezed out, and compresses the laminate to a very efficient, dense structure.

Most carbon fibre structures are made this way, but are also submitted to a greater pressure from the outside by pressurising the vessel that it's cured in, which is also an oven, as in most cases, C-F is cured with the aplication of heat to the resin pre impregnated fibre matt, so no catalist.

lots of 'suck', lots of 'squash', and a bit of 'warm', and you have a wing, or a tailplane, or a race boat.

Not trying to steal the thread, just wanted to point out that VB-ing is a little more involved that just draping a bit of selotape over some gel.

jf


PS. just realised this has already been covered, sorry to repeat.

[Dirk Diggler]

Originally Posted by slimtim

Can the cracks not be filled with that stuff in a tube (name escapes me) that uses capillary action to penatrate deep into hairline cracks and seal them tight?

Captain Tolleys Creeping Crack Cure! No it can't.

I've just "vacuum bagged" me cheese and pickle sandwich. Well, wrapped it in cling film.

A little knowledge is such a dangerous thing.

[boatster_sr4]

Ok forgive my loose verbage of the term "vacuum" bagging but it is still a legitimate method of laying thick celophane over the resin/gelcoat to help it cure and mold to the surface. This method is discussed in the West System boat repair manual just before the process of vacuum bagging. Its the same concept except applied for smaller repairs which is what Biggles' type of job requires.

[boatster_sr4]

Originally Posted by Dirk Diggler

A little knowledge is such a dangerous thing.

Vacuum bagging, celophane, gelcoat, oh so dangerous! Watch out!

[jwalker]

Originally Posted by Dirk Diggler

I've just "vacuum bagged" me cheese and pickle sandwich.

Good one Dirk, I'm still laughing.

[Gav]

Originally Posted by boatster_sr4

Gelcoat can come as straight pigmented resin, so gelcoat at times is in fact resin.

??? so what you are saying is you can use gelcoat instead of resin to laminate if they are one and the same???

[boatster_sr4]

Ah shucks, I might be wrong about the gelcoat as well. I do know that straight laminating resin is used with the fibreglass layup. You guys really know how to stick it to ya when someone gets it wrong. What a friendly bunch.

As far as any of the advice I gave in the original subject to Biggles it was purely from my own experience. I even stated it as such. Just trying to help a fellow out with a minor blemish on his boat. If you read my posts alot of the info is correct and helpful. Whats with all the snobbery?

[Gav]

Originally Posted by boatster_sr4

Ah shucks, I might be wrong about the gelcoat as well. I do know that straight laminating resin is used with the fibreglass layup. You guys really know how to stick it to ya when someone gets it wrong. What a friendly bunch.

As far as any of the advice I gave in the original subject to Biggles it was purely from my own experience. I even stated it as such. Just trying to help a fellow out with a minor blemish on his boat. If you read my posts alot of the info is correct and helpful. Whats with all the snobbery?

oh stop bleeting! lol! i got the general idea with the celophane idea.... and the wax additive(4% styrene solution) is a far more widely used thing over here....

you say tamayto, i say tomartow.............hehe!

[Biggles]

Thanks for all the replies folks.

I've been working over the weekend and haven't had chance to catch up on the forum.

I'm going to read this well over the next couple of days and then do the work maybe tuesday or wednesday. So long as the rain pi__es off.

[Pete7]

If you need a large workshop for a fortnight you could do worse than have a chat with Rogue Wave, I am sure he do you a short term deal with light and power available to work on the boat in Drivers Wharf. I watched him do a couple of scratches on his Avon 4.7m, very impressed with the results he achieved.

Pete

[The Garfish]

Originally Posted by Pete7

I watched him do a couple of scratches on his Avon 4.7m, very impressed with the results he achieved.

yus butt de iydea iz too gett de fkin scrachis owt, nott putt dem inn yew nobbur


gArf

[Rogue Wave]

Originally Posted by The Garfish

yus butt de iydea iz too gett de fkin scrachis owt, nott putt dem inn yew nobbur


gArf

I think we shouldn't talk about putting scratches into boats now should we!

[Biggles]

Well I've ordered some Gelcoat with hardener and pigment from the place Tim suggested in Cornwall.

I shall be giving it all a go when the weather picks up.

One last question would using a Dremel with small grinding stone dig out a big enough hole for the Gelcoat to adhere to.

In fact one last question if the Gelcoat was applied straight on to old gelcoat that had been rubbed down would it hold well.

[Hightower]

In my view a dremel is Ideal for routing out the cracks, you've got far more control!

[The Jackeens]

Originally Posted by Biggles

Well I've ordered some Gelcoat with hardener and pigment from the place Tim suggested in Cornwall.

I shall be giving it all a go when the weather picks up.

One last question would using a Dremel with small grinding stone dig out a big enough hole for the Gelcoat to adhere to.

In fact one last question if the Gelcoat was applied straight on to old gelcoat that had been rubbed down would it hold well.

Certainly lots of useful advice on this thread. Be interesting to see how it all turns out Biggles.

Rogue Wave, is the 'workshop' idea (i.e. a space for hire to work on boats) going to be a permanent feature of the new premises?

Us

[Cookee]

Originally Posted by boatster_sr4

Ah shucks, I might be wrong about the gelcoat as well. I do know that straight laminating resin is used with the fibreglass layup. You guys really know how to stick it to ya when someone gets it wrong. What a friendly bunch.

As far as any of the advice I gave in the original subject to Biggles it was purely from my own experience. I even stated it as such. Just trying to help a fellow out with a minor blemish on his boat. If you read my posts alot of the info is correct and helpful. Whats with all the snobbery?

Boatster - Please don't take what I said as being personal - I was just correcting what you said as I knew it to be incorrect, and if statements like that are left then some people might believe them to be correct, and that's when things go wrong - admittedly it wouldn't do anyone any harm, but those before you have given out quite dangerous advice and they were "corrected" as well!

[Biggles]

So far I've managed to touch up some bad bits with Gelcoat mixed with pigment and and I'm slowly rubbing it all down.

I'll be finishing off with 1200 Wet and dry and then using some rubbing compound to get the final finish ready for polishing.

Can anybody suggest a polish to get the GRP nice and shiny.

I'm tempted to use Mer as I have found it to be good in the past but would like some suggestions of any one that has had good results with readily available polishes.

[Rogue Wave]

Originally Posted by The Jackeens

Rogue Wave, is the 'workshop' idea (i.e. a space for hire to work on boats) going to be a permanent feature of the new premises?

Us

Yeah that's the plan! I started to put the Sound system into the workshop today and was pretty pleased with the results.

The idea rests on getting insurance for everybody to use our tools. I have a feeling it may have to become a club t get insurance.

where are you?

[The Jackeens]

Originally Posted by Rogue Wave

Yeah that's the plan! I started to put the Sound system into the workshop today and was pretty pleased with the results.

Haha cool dude Stu
Walter Trout blaring down the Itchen then

where are you?

We're back. Church on Monday night if you can drag yourself away from the new sound system

Us

[Rogue Wave]

Originally Posted by The Jackeens

Haha cool dude Stu
Walter Trout blaring down the Itchen then




We're back. Church on Monday night if you can drag yourself away from the new sound system

Us

Well my little Dixie Chicken

At the moment I am into Poppa Chubby, Little Feat and Proffesor Longhair and of course Westlife and the Sugababes not forgetting whoever wins the Xfactor

No church for me I am at sea as of 05:00 monday towing a small tanker
from Hull to Southampton. To any ribbers in the area you've been warned!

to put the thread back on track when you have filled the cracks and yu needd to rub down the surplus do it gently when you get to the finer grades , very gently, if you put to much arm into it it takes longer and isn't as good! The Dremmel with a mop will also be good for final polishing.