Scuba backplate thoughts

General Composites Discussions Engineering Talk
#1

Hi all!! First post, thanks in advance for any help.

I’m looking to make a flat “plate” for use in scuba diving. The plate will mount to my back and be held on with 2" wide strapping, and will hold 2 small canisters and a small tank. For the final iteration of this idea, it may curve to conform to my back properly. This is for personal use, not for commercial production.

The current plate is made of ABS and is flat, and IMO it’s oversized.

I don’t think I need to do any Kevlar since there’s no impact issue, and I’m thinking carbon fiber will lighten it up and let me beef it up pretty strong.

Any cons to this idea? Thoughts on materials to best use and layup ideas?

#2

Will carbon fiber laminate break down in sea water? This may sound dumb but I would consider sealing all trimmed edges with a coat of gel coat or epoxy. Just a thought.

#3

That’s the kind of input I’m looking for, thanks!

I was thinking an epoxy resin might be best for this application.

#4

I feel this is stiffness related plate, so a core of some sort might be nice. I would probably do a small amount of layers of carbon (2x200 gr/m2) then a Soric core, or a thin foam, then 2 layers of carbon again.

The holes should be designed in single skin laminate, or reworked with epoxy putty. The shape can conform to the body, with ridges to hold the gear in place.

#5

Not sure if buoyancy/overall density is an issue, but adding a foam core may create the tendency for this panel to float. Just another thing to think about.

#6

you could also do a flat plate that’s thin with some sort of hat stiffeners. They’re fairly easy to make and give great rigidity as well as not needing to use a core that could add flotation.

#7

Hi,

my first infusion part was a Scuba Backplate for my Apeks WTX Jacket. It is a copy of the original steel plate which was too heavy for traveling by plane.
The plate is not used to bolt the tank to it, my jacket can hold a single tank without a plate but have a “back pocket” to carry a plate to have more stability.

The layout is 2 mm Soric core with 1x 200g Carbon and 1x 160 g Aramid on each side. It’s made with Epoxy resin. Total weight is 240 gr instead of 2,3 kg of the original.
Aramid was used because I wanted to do a part with Aramid and also because I wanted to have it better withstand rough handling.

The mold was in a way that the Soric core is inside the fiber and fully “wrapped”, the core is at no place without being covered with carbon. Also the wholes for the belt and bolts are done in this way. Unfortunately I made no pictures of the production.

So far I did with the plate ~15 dives up to 30m in sea water.
It is quiet rigid, the core is totally stable to this depths. For sure it is does not have a perfect surface, but it fully fulfills my needs.

I had the impression that somehow at first the epoxy was getting white fog due to the sea water, but this stopped and for a technical part I do not care.

I did not test if the plate is floating. If so use a small extra weight and it’s fine. I have 2 kg more weight in the jacket instead of the 2,3 kg original steel plate.

Hope that helps
Thomas

#8

SO did you just make this?

You had asked for opions to verify your work?

Looks like you did pretty much the right thing. Looks nice too.

I don’t see the kevlar, so it’s inside? A surface ply of kevlar is useful for that rough handling.

nice work

#9

Hi Sammymatik,

I’m not the thread starter, I just posted what I had done when I did a similar part.

Yes, I put the Kevlar inside under the carbon. I did not want to use Kevlar on the outside due to strength degeneration and the risk that it drains water.

Thomas