Air permeable watertight membrane

Discussion in 'Materials' started by DogCavalry, Sep 7, 2021.

  1. BlueBell
    Joined: May 2017
    Posts: 1,782
    Likes: 501, Points: 113
    Location: Victoria BC Canada

    BlueBell "Whatever..."

    Okay, I get 18% increase in pressure over a 50C range (0.0C - 50C)
    So, if you seal it up on a 20C - 25C day of average atmospheric pressure,
    that's going to give you a working range of +/- 9%.
    14.7 x +/-9% = +/-1.3 psi worst case scenario.
    Likely less than 0.5 psi fluctuation each day (or cycle).

    If the boat's in the 9C water ( 15C in Alaskan waters! ) then it's tending towards
    a negative chamber pressure. I would rather have a compression situation (negative press.)
    than tension (positive press.).

    You could consider the pinholes from the other thread I posted to balance the compartments.
    And running the vent to a balloon in the wheel house to evaluate and monitor,
    eventually leaving it open to the atmosphere.
     
    DogCavalry likes this.
  2. fallguy
    Joined: Dec 2016
    Posts: 5,258
    Likes: 1,006, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    The pressure doesn't add.

    I will say one thing. There doesn't seem to be a very sound direction for builders.

    Pretty artsy to surg tube all the chambers and run to a balloon in the cockpit. Just sayin..

    What about these?McMaster-Carr https://www.mcmaster.com/vents/connection-style~threaded/for-use-with~air/fitting-material~plastic/system-of-measurement~inch/gender~male/pipe-size~1/

    It doesn't look like these would keep water out.


    John, I can send you mcmaster
    Products no returns if you pickup ship and pay me up front. I have an account and buy 316 hardware from them every week..
     
    Last edited: Sep 9, 2021
    DogCavalry likes this.
  3. BlueBell
    Joined: May 2017
    Posts: 1,782
    Likes: 501, Points: 113
    Location: Victoria BC Canada

    BlueBell "Whatever..."

    "The pressure doesn't add" what?

    Where did I say surg tube all the chambers?

    I would have suggested a gauge but I thought a balloon would be easier, cheaper, and disposable.

    If they look like they wouldn't keep water out, why would you recommend them?
     
  4. fallguy
    Joined: Dec 2016
    Posts: 5,258
    Likes: 1,006, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    The pressure doesn't add for each chamber. John used 50 square feet.

    someone on the other thread suggested the balloon (it isn't always about you bb)

    I only mentioned that vent as conversational. I'm trying to understand what vent John saw at McMaster.

    Again, such an artsy affair for something that seems to straightforward. I have 1.5" or 1.25" pvc female adaptors, but I didn't seal them, so they are also not waterproof and my watertights got water in them last year after 10" of rain and some bad leaking unfinished.

    Seems strange the industry d9esn't have a go to is all.
     
  5. Blueknarr
    Joined: Aug 2017
    Posts: 1,233
    Likes: 290, Points: 83
    Location: Colorado

    Blueknarr Senior Member

    Check the product's spread sheet. Each unit probably has a maximum volume it can protect. Large chambers may require multiple vents.
     
  6. Barry
    Joined: Mar 2002
    Posts: 1,491
    Likes: 280, Points: 83, Legacy Rep: 158

    Barry Senior Member

    submersible breather vent - Google Search https://www.google.com/search?source=univ&tbm=isch&q=submersible+breather+vent&sa=X&ved=2ahUKEwjuutWx5vTyAhXTLH0KHTtqDR4Q420oAHoECCMQPA&biw=1536&bih=750

    Attached should be the image search for "submersible breather vents" There are more manufacturers than McMaster and Grainger in Canada is noted as a supplier of alternatives.
     
    DogCavalry likes this.
  7. DogCavalry
    Joined: Sep 2019
    Posts: 1,757
    Likes: 909, Points: 113
    Location: Vancouver bc

    DogCavalry I aim to misbehave.

    Got a box of the goretex breather vents from Mcmaster-carr by courier today. Wouldn't send to an individual. Identical order to a business name, aok! So now we are Serenity Marine Services. Needed to do the gubment legal stuff anyway. So stopped putting it off.

    Thanks everybody for helping with this. You all are invited to a trip on Serenity, some day soon.
     
  8. DogCavalry
    Joined: Sep 2019
    Posts: 1,757
    Likes: 909, Points: 113
    Location: Vancouver bc

    DogCavalry I aim to misbehave.

  9. DogCavalry
    Joined: Sep 2019
    Posts: 1,757
    Likes: 909, Points: 113
    Location: Vancouver bc

    DogCavalry I aim to misbehave.

    The Mcmaster-carr breather vents don't have that information included. I'll follow the original suggestions, vent one to the next, and the last with multiple vents to the inside of the cabin. All told there are 9 separate areas. My bg worry was the entire cockpit floor pressurized on a scorching hot day. Maybe not a worry: Bluebells point about water remp is well made. But landed on a beach for a day....
     
  10. fallguy
    Joined: Dec 2016
    Posts: 5,258
    Likes: 1,006, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

  11. DogCavalry
    Joined: Sep 2019
    Posts: 1,757
    Likes: 909, Points: 113
    Location: Vancouver bc

    DogCavalry I aim to misbehave.

    Yes, exactly. But why feel dumb?
     

  12. fallguy
    Joined: Dec 2016
    Posts: 5,258
    Likes: 1,006, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Just had vent confusion.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.