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Carbon Fiber Backplates?

Discussion in 'Wreck Diving' started by WWoody, Jan 1, 2020.

  1. WWoody

    WWoody Angel Fish

    # of Dives: 0 - 24
    Location: Mons
    All thank you for your insights and some very strong opinions. Even know the CF plate I’m looking at is only €9 I think I will stick with something that has a long and reputable history. I think I will start looking for a good travel rig in aluminum. Thanks again for all your inputs.

  2. Diving Dubai

    Diving Dubai Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: Dubai UAE
    It was also written on an iPad late at night :)

    So CF (or more correctly called cfc Carbon fiber composite) 101 and this will be very simplistic

    CFC is a fab material, but its not a miracle material. It has strengths and weakness like any other.

    One weakness is poor tensile performance. E.g. If you hit a sheet of metal with a hammer. on one side you'll get a concave dent (compressive) on the underside, you'll have a convex bulge, (tensile)

    Do the same with a sheet of CFC and you may get a concave dent on the top side, but the tensile side will delaminate, even splinter. Bad. Very bad.

    Product you see advertised as Carbon fibre, often just have on layer of Uni direction (the famous herring bone pattern). Its not doing much (but looks pretty)

    A proper lay up would comprise of many layers. Generally. one at 0-180 degrees another at 90-270 and others at +/-45 degrees

    The precise layup is determined by what you want the component to do. Lots of expertise and a big dose of witchcraft involved

    CFC is electrically conductive. It also loves absorbing moisture. So it generally has a glass fibre final lay to protect and isolate it

    If you were to use it as a back plate, one way to prevent damage by over tightening bolts would be to have metal inserts. If the glass layer were to wear, then the CFC become a battery with moisture, add the metal inserts and they'd corrode and fail incredibly quickly.

    If water gets to the resin then it can fail

    While CFC is great, a CFC back plate is plain stupid. I'm sure a Titanium plate would be cheaper and allow similar bragging rights.

    Other CF is used as a marketing tool for the gullible, much like the constant adverts claiming something is made from Aircraft grade Aluminium (don't get me started on that fraud.)

    Hope that's informative
    Johnoly, BlueTrin, RyanT and 2 others like this.
  3. jale

    jale Barracuda

    CF plate are a bad idea but if you insist of diving one, please make sure you don't forget to put a large washer between the plate and the head of the bolt for the the double bands. Indeed, if not done and if you inflate the wing, the head can go through the plate and then good luck :(
  4. NothingClever

    NothingClever Manta Ray

    # of Dives: 200 - 499
    Location: Red Sea and Atlantic Ocean
    Exceptionally informative. Thanks for sharing your expertise.

    Thus far I’ve fought off the temptation to purchase too many CF race bits for my Ducati track bike.
  5. Joneill

    Joneill ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: New Jersey, USA
    I’ll let you know how it holds up - got a CF plate before heading to French Polynesia in October. So far it held up fine even in the BC piles on the RIB’s heading back to the dive shop.

    I love it so far - no STA needed so my tank is closer to my back. Time will tell, but saving 5.5 lb while traveling is a major positive for me!
  6. jadairiii

    jadairiii Solo Diver

    CF is great if you want to spend lots of money and impress other divers. But at the end of the day, Aluminum, for a light weight BP, is just about perfect.

    And even though CF is "stronger" than Aluminum, CF fails "catastrophically" that is, it dont bend, it breaks, maybe a little, maybe a lot. Alum bends, and can be bent back. I can not even image an application in diving that would require CF material(s).

    But it will look great with a titanium 1st stage and titanium knife!!
    Diving Dubai and rongoodman like this.
  7. Jonn

    Jonn ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Alberta
    What if I spent so much on my ultralight CF plate that I can’t afford the extra lead to sink it?
    NothingClever likes this.
  8. Manatee Diver

    Manatee Diver Stop throwing lettuce at me! ScubaBoard Supporter

    # of Dives: None - Not Certified
    Location: Tampa Bay, FL
    I think carbon fiber has its place, a single tank travel BPW rig for those that can't stand soft backplates. It is a half pound lighter than the lightest AL backplates (Mares XR 3mm AL), and a full pound lighter than most of the AL backplates. Using cambands you don't have the issues of the bolts and the single stress point.
  9. Johnoly

    Johnoly ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    CF is a common spearfishing gun material. It's light weight makes it very easy to 'sweep' sideways underwater to follow a moving target.
    But I do agree with you that for a backplate with all those holes & slots, the failure points are un-forgiving and it's not suitable.

    If the original poster is proficient with a drill and file, Kydex sheets of all different sizes and colors can be bought on amazon. You can then easily heat it in your friends kitchen oven(it smells) and design your own BP.
  10. Tienuts

    Tienuts Instructor, Scuba

    I always respect an engineer's knowledge. But for what it's worth, I was given a Halcyon carbon fiber plate by someone 3 years ago. I'm a dive instructor and I absolutely beat the crap out of that thing. It has about 1000 saltwater dives on it, regularly gets chucked in a truck with tons of customer gear, weights and tanks banging on top of it. It's held up perfectly well. I'm not sure I would buy one, as was pointed out, the difference in weight between the carbon fiber plate and an aluminum plate is about half a pound. But aside from price I can't say anything bad about it.

    Also worth noting many BoneX scooters have a carbon fiber hull, and so do SF2 rebreathers. My KISS rebreather frame is carbon fiber as well. I have not heard of any stories of premature failure on any of these.

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