GRP Core Material

[justanothersailboat]

I really do have a strong impression that Westerly were a bit more fastidious with the Fulmar in terms of pads on load items, glassing over more of the backs of things and so forth... than on older or smaller or lower end models. Which would make sense given higher loads. But then, most of the Westerlys I've seen in pieces are older or smaller ones.

The practice of glassing over the undersides of nuts and pads is a bit "what on earth were they thinking" - it must have cost a lot in labour, it makes stuff hard to fix, and each prevented drip is a trapped drip slowly wrecking the pad. I replaced a few ply pads without re-glassing, but would use G10 next time, or build new solid glass myself as I have elsewhere.

They certainly didn't glass over *everything* in every model. I think they must have been pretty inconsistent - in another thread here someone described faults in his dad's old Griffon that mine certainly never had, but mine has different ones. And later Merlins, Tempests etc have loads of detail design differences.

As you say, it's pretty good that these boats are able to be kept going aged 40-50. They're pretty malleable.

 

[justanothersailboat]

Nidaplast - you mean this stuff? Nidaplast®8 15mm sheet 2.5mt x 1.22mts – GRP UK LTD that looks fantastic, thanks for the heads-up Trident. But does it have to lay flat or will it take up a gentle one-directional curve?

 

[potentillaCO32]

Take your pick from these Core Materials - Pro Quality - Fast Delivery - ECF

ECF are great suppliers.

 

[rakaaw]

Thank you for all the advice and recommendations. Perversely I have made Ann about turn and am going with plywood and will adopt the techniques described by Refueler and Justanothersailboat.
The synthetic materials do appeal but I do not have hands-on experience of any of them and therefore cannot compare one to another.
Thanks all for your time and attention. It has been very enlightening.

 

[ducked]

Nidaplast - you mean this stuff? Nidaplast®8 15mm sheet 2.5mt x 1.22mts – GRP UK LTD that looks fantastic, thanks for the heads-up Trident. But does it have to lay flat or will it take up a gentle one-directional curve?

Try Nidaplast - it's an octagonal plastic core bonded with fabric each side. No worries with water or drilling, comes in a nice 20mm depth , very light and dimensionally stable. Leaking holes only ever allow one 8mm honeycomb cell to get water in - its can't go further -

So, what would happen to the structure if that water were to freeze while it was sitting around not going further, (which it certainly would in Scotland)?

I suppose with polypropylene there is a chance it would just distort and expand into adjacent cell space, possibly partly reversibly, but I'd guess it might lift too. Then it might cycle repetitively.

""The polypropylene honeycomb structure composed of 95% vacuum uses little material while ensuring high mechanical properties."

Nature abhors a vacuum.

(Though I'd be surprised if that description is in fact accurate).

 

[justanothersailboat]

So, what would happen to the structure if that water were to freeze while it was sitting around not going further, which is what would happen in Scotland?

Probably bend the cell wall rather than break it, but I still think it would be worth bothering to build solid grp patches for bolts/fittings. It's a relatively small amount of additional work when building from scratch. Even retrofit isn't always all that bad.

We don't know enough about the OP's project to really weigh up what is nice-to-have and what is necessary, structurally. Seems they've made a decision that is probably sound.

 

[ducked]

Probably bend the cell wall rather than break it, but I still think it would be worth bothering to build solid grp patches for bolts/fittings. It's a relatively small amount of additional work when building from scratch. Even retrofit isn't always all that bad.

We don't know enough about the OP's project to really weigh up what is nice-to-have and what is necessary, structurally. Seems they've made a decision that is probably sound.

Being a cheapskate, if I ever had to deal with such issues, which is probably unlikely, I would be very tempted to try concrete, with a lightweight aggregate, and additivels which might include 10% epoxy, so its probably just.as well I have no core that I know of.

 

[rakaaw]

Probably bend the cell wall rather than break it, but I still think it would be worth bothering to build solid grp patches for bolts/fittings. It's a relatively small amount of additional work when building from scratch. Even retrofit isn't always all that bad.

We don't know enough about the OP's project to really weigh up what is nice-to-have and what is necessary, structurally. Seems they've made a decision that is probably

Probably bend the cell wall rather than break it, but I still think it would be worth bothering to build solid grp patches for bolts/fittings. It's a relatively small amount of additional work when building from scratch. Even retrofit isn't always all that bad.

We don't know enough about the OP's project to really weigh up what is nice-to-have and what is necessary, structurally. Seems they've made a decision that is probably sound.

I am replacing 25mm teak combing..

 

[Keith 66]

I have used a number of core materials, these days i tend to use PET foam cores, easy to use & bond well with Polyester, Vinylester & Epoxy resins. Its cost effective too.
East coast fibreglass is my go to, Epoxy Armacell PET Foam - Pro Quality - Fast Delivery - ECF,