Plastic BP

[kavka]

I just bought Aqua3 Pionir wing (30 kg). Till now I used Al bp.
For this wing I intend to make plastic (20 mm polypropilen) bp.
Anyone tried this?

 

[jplacson]

Hmmm... my thoughts are on the actualy durability of the plastic. The sun and sea water may make it brittle.

I'd probably only trust carbon-fiber or polycarbonate, but unless the polycarbonate is Lexan, I have seen these break as well. Oakley lenses do crack... these are pretty tough already... and I've seen (and broken some myself) Delrin crack too...and not under that much pressure either. That's why these are used in thick grades, and in small structures; flashlights, canisters, etc.

20mm? That's pretty thick for a BP... almost an inch... that may be thick enough to resist cracking... BUT the weakest structural points would be the slots you'd have to drill for the webbing to thread through. These areas would be significantly weaker than the rest of the BP and may snap and the whole BP may break away from the harness itself.

Although I am surprised that I haven't seen any carbon-fiber or titanium BPs yet...

My ideal BP construction would probably be a Halcyon style wing, but Kevlar shell instead of nylon...and a Titanium BP... but then again... that would probably cost as much as a car already! :lol:

 

[detroit diver]

kavka once bubbled...
I just bought Aqua3 Pionir wing (30 kg). Till now I used Al bp.
For this wing I intend to make plastic (20 mm polypropilen) bp.
Anyone tried this?

The AL BP only weighs about one lb (less than 1/2 kilo), so why are you even thinking of switching to plastic?

 

[HammerNoMore]

detroit diver once bubbled...


The AL BP only weighs about one lb (less than 1/2 kilo), so why are you even thinking of switching to plastic?

Because plastic causes less damage to the webbing.


Kavka,

Dive Rite has a plastic plate: http://www.diverite.com/products/bcd/bkplt_harn.htm

 

[jplacson]

Hmmm.. very interesting James! Thanks for the link! Ok, here's my concern.. see the 2 slanted slots where the webbing goes through from the shoulder to the waist area? The thin panel between the 2 slots is the weakest point on the BP, and if that little section breaks off... your waist webbing slips through it completely...granted, you'll still have the shoulder straps, but the space from the top to the first shoulder slots are very thin as well, and these could break off just as easily. (Believe me, it's not that difficult to break ABS or Delrin plastic...even by accident)

I'd actually think that a plastic BP would go well with something like the IQ Pack where it would just slip in.

Oh well... anyone with plastic BP experience? We'd all like to hear comments.

James, with regards to metal BPs damaging webbing... I was thinking of putting Duck tape (or plumbing tape) around the slots to cushion the webbing, wouldn't this reduce wear on webbing as well?

 

[HammerNoMore]

jplacson once bubbled...
James, with regards to metal BPs damaging webbing... I was thinking of putting Duck tape (or plumbing tape) around the slots to cushion the webbing, wouldn't this reduce wear on webbing as well?

I've heard of some people doing this. I'm sure it would extend the life of the harness some. Personally I don't really worry about it because a new harness costs about $6.

I dive an SS plate. If I wanted a lighter plate I would probably use plastic over AL. The other big advantage to plastic is that you don't have different metal corosion problems. I cannot personally attest to it but I have heard from others that they are quite strong, I don't think breaking it would be near as easy as you think.

James

 

[detroit diver]

James Goddard once bubbled...


.......because a new harness costs about $6.

.....
James

That was kind of my point. I didn't see where buying another plate solved a financial issue, and it certainly didn't solve a technical one.

 

[jplacson]

James Goddard once bubbled...


I dive an SS plate. If I wanted a lighter plate I would probably use plastic over AL. The other big advantage to plastic is that you don't have different metal corosion problems. I cannot personally attest to it but I have heard from others that they are quite strong, I don't think breaking it would be near as easy as you think.

James

I know plastic offers much better resistance to corrosion... uhm..zero chance of corroding? This is the first I've ever heard of a plastic BP... I'm very intrigued. I'm sure it's cheaper than my idea of a Titanium BP.

Although, I would feel safer if the webbing areas were reinforced by a metal frame or something... even if it was just glued on, it would strengthen the weakest areas of the plastic plate. But, if none have broken so far... then I guess they're ok. I'd still love a Kevlar outer shell though... :lol: Something that could resist a chainsaw. (Like the Kevlar chaps for lumberjacks)

 

[HammerNoMore]

jplacson once bubbled...
I'm sure it's cheaper than my idea of a Titanium BP.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3619006005&category=16053

 

[jplacson]

Wow James! You find a lot of cool stuff!!!

Next you'll show us a BP made of glass!!! :lol:

The Titanium link was cool... and just as expensive as I thought it would be... although it's heavier than AL.. hehehe... I forgot about that.

By any chance have you heard of any Kevlar outershelled wings? If not, I'm surprised cave divers haven't developed these yet... having a Kevlar outshell would make your bladder knife-proof... and literally puncture proof...at least from rocks, and any sharp objects that you may scrape against.