Cockpit deck fibreglass

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Cockpit deck fibreglass

Postby SMHolmans on Sun Oct 25, 2020 5:18 pm

I'm 'glassing out the cockpit and wondering if more than one layer on the decks is a good idea. Strength versus weight. Any views, please?
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Re: Cockpit deck fibreglass

Postby TassiePete on Sun Oct 25, 2020 11:43 pm

Hi Steve,

One layer of glass (on both sides) gives enough stiffness - there is also plenty of support underneath. The only bit I did re-enforce with an extra strip of glass tape (bi-axial) is the joint between deck and rear cabin. The deck 'hangs' on the rear cabin panel, and this is where people usually step/jump down onto the boat.

Cheers,

Peter
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Re: Cockpit deck fibreglass

Postby doug@dougbraun.com on Mon Oct 26, 2020 12:31 pm

The most recent version of the manual doesn't say to glass the underside of the deck.

Doug

TassiePete wrote:Hi Steve,

One layer of glass (on both sides) gives enough stiffness - there is also plenty of support underneath.
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Re: Cockpit deck fibreglass

Postby SMHolmans on Mon Oct 26, 2020 2:54 pm

The most recent version of the manual is the ONLY version of the manual, and as you say Doug it specifies a single layer of 'glass on the upper side of the cockpit deck. I put three layers on the forward deck, as suggested by the manual - I'm wondering if the same approach might be appropriate in the cockpit.

Views welcome!
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Re: Cockpit deck fibreglass

Postby doug@dougbraun.com on Mon Oct 26, 2020 3:06 pm

Three layers of glass cloth, or three coats of epoxy?

SMHolmans wrote:The most recent version of the manual is the ONLY version of the manual, and as you say Doug it specifies a single layer of 'glass on the upper side of the cockpit deck. I put three layers on the forward deck, as suggested by the manual - I'm wondering if the same approach might be appropriate in the cockpit.

Views welcome!
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Re: Cockpit deck fibreglass

Postby SMHolmans on Mon Oct 26, 2020 4:45 pm

Three layers of glass cloth.
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Re: Cockpit deck fibreglass

Postby riverron on Mon Oct 26, 2020 8:50 pm

I put 1 layer of glass on each side of the cockpit deck to strengthen it. I had concerns with my 235 weight walking around. It feels solid with the extra layer underneath.
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Re: Cockpit deck fibreglass

Postby TassiePete on Tue Oct 27, 2020 4:57 am

Glass really only works in tension, which means that glass underneath the cockpit helps to support the weight of things. As the ply bends by loading up the cockpit, the glass underneath is under tension, while the glass on top is under compression. Glass on both sides gives stiffness to panels (e.g. bulk heads and hull) by putting glass under tension for loads (bending) in either direction - it stops excessive flexing. I have glass underneath the heavy traffic areas i.e. cockpit, foot-well and front deck, where people stand, step and jump around, although that might not be as per manual. The glass on a surface (e.g. cockpit) will also help to protect the plywood from penetration by things like flying shackles, dropped beer cans, booms, etc., but not from abrasion. Glass will wear away easily - protection against abrasion is the job of the epoxy, as we know when sanding into the glass by accident ;) .
Regarding the original question, one layer glass of on the top is sufficient against serious dings, combined with some really good (two-pack) paint later.
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Re: Cockpit deck fibreglass

Postby SMHolmans on Tue Oct 27, 2020 8:56 am

Thanks Pete That's really helpful!
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Re: Cockpit deck fibreglass

Postby SMHolmans on Thu Oct 29, 2020 2:52 pm

Actually Pete, that's more than helpful. It's the most informative piece of information about building with glass fibre cloth that I've come across in the last two years. I now intend to retro-fit a layer of cloth under my cockpit deck when the boat is upside down.

Thanks again!
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