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Old 16 January 2019, 16:40   #1
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Composite floor vs ply? Deck replacement: Pro530

I'm replacing an original floor on a 1985 Pro530 and was planning on using glassed ply. One company suggested the following composite panel that is glass skinned polyurethane. The website has data on strengths etc which makes no sense to me. My concerns are being able to fix the centre console into it when comparing screwing into ply vs this material. And how much the screws are fixing into the ply vs glass on top of it, ie where the strength comes from. And for that matter how much the sicoflex goop around the centre console does too.
The guy selling it to me assures me that will be fine to fix into as it's really dense, no surprise there really.

It's more expensive than ply, but much less labour than glassing both sides of ply so I can live with that with the weight saving also.

I'm going to add a few stringers laterally under the floor so I don't see stiffness being an issue so this makes me wonder how thick I would need this material.
And how it compares to ply based on the figures.

material is here:
Multiple Application Bluewater Panels - Coosa Composites
Data is also there but here it is:
http://www.coosacomposites.com/image..._Data_0412.pdf

I can't seem to find any like data on ply so I'm not sure how to compare apples for apples.
The composite panel is coming from another state so I can't 'see it' or test it. I'll ask if I can get a sample in the mean time.

Does anyone have any experience with these panels, thoughts, suggestions etc.
Thanks
Craig.
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Old 16 January 2019, 18:37   #2
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No expert on coosa. Never used it. Personally Id choose non wood any day on a wish list. However the cost v ply deck has to be offset. Ply decks are not my cup of tea. However properly installed, will cost a shed load less and last for years. Your choice of resin is another factor. Polyester does not stick to ply naturally. Although there are ways round it, epoxy is my choice when blobbing something on wood. However you then need a painted deck as epoxy is not uv stable.

The guys on boat design.net that are worth listening too seem to still glass both sides of coosa to eliminate water ingress. Even the smartest closed cell foams can absorb 1-3%. I removed trapped water in closed cell foam stringers in my last refurb. The foam was fragile and semi disintegrated. So I am not happy letting water get to closed cell foams.

You could add ply implants in console area to ensure the coosa deck is firm enough for console fixings. Or oversize the holes and epoxy fill, or make an inspection hatch and through bolt with large backing washers to distribute the consoles load. If you dont see the console ever moving use 5200 rather than silka. Al this is extra effort thus cost.

The trick with a boat is to keep it roughly as it was out of factory or it will stand out when you come to sell it and the tyre kickers will rip it to bits.
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Old 17 January 2019, 05:20   #3
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A lot of boats these days are using glassed Nidoplast for the stringers and the decking.

Mega strong, very light and will outlast Ply by a very considerable margin.
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Old 17 January 2019, 07:01   #4
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RIBase
http://www.robbins.co.uk/Pdf%20Files..._technical.pdf

has some strength data for plywood. I'd have to have a bit of a think about it before I could say whether there was any equivalence.

It's an interesting / good idea though.

My Pacific 22's plywood deck survived 26 years before it needed replacing.

The Coosa Bluewater panels are structural panels with a core and laminate skins that give it strength and you would use it a bit like plywood. Nidaplast appears to be just a core panel so you need to add skins to it to gain any strength.

I was about to sing the praises of Sika 292i, which is their structural adhesive but looking at the spec's of 3M 5200, I might have to try some of that.
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Old 17 January 2019, 11:51   #5
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The chop strand on the backside increases the stiffness.

By omitting, you're going to alter the properties of the boat which may lead to a hull failure.
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Old 17 January 2019, 17:05   #6
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Thanks for the replies everyone, very helpful and further food for thought. I'm getting a sample of coosa in the mail which might help my final choices also. Whatever I use for the floor I'll be adding stringers under it. I'm a long way off doing this job, I'm still very much in the planning phase.
Cheers.
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Old 23 January 2019, 07:36   #7
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I'd go ply again. Your current deck has lasted nearly 30 years. If fitted properly, there is no reason why you shouldn't get another 30 years from a replacement ply one. Doing that you know the hull design intent isn't altered and you can still screw stuff to the deck.

Phil M
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Old 04 February 2019, 06:31   #8
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I received a sample in the mail, it's an interesting panel product.
I screwed two different screws into it and left enough hanging out to get the pry bar under them. The thinner pulled out reasonably easily with a pry bar, the larger screw took a fair bit of force to finally pop. I'd be confident either would be ok after going through the fibreglass on top of it as well as the product.
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