Inflatable leak

Discussion in 'Materials' started by valvebounce, Oct 2, 2016.

  1. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    I have a 9ft infatable made of Hyperlon.There are two tubes,each with a valve.
    The deck is inflatable and of a different material.
    The deck doesn't leak,but the tubes slowly deflate.
    I have been over it carefully with washing up liquid to find the leak,to no avail.
    I am thinking of using PVA let down 3 to 1 and pouring it in the valves,then rolling the boat around to let it run into the seams.Then bringing the pressure back up to normal,hoping the
    PVA will set in the leak.(a bit like the temporary tyre repair material.)
    Anybody tried this?
    The boat is taking up space,and I intend to sell it,but I can't sell it with a leak.
    The boat wasn't expensive,but is like new.I have fitted a stainless steel transom bracket and a ply floor.Be a shame to scrap it.
     
  2. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Hypalon is porous, so it slowly looses air. But the advantage is that it can be repaired successfully with the proper glue. Other materials like PVC need welding.
    If no leaks show with washing up liquid I guess there is nothing wrong with your boat.
     
  3. CatrigCat
    Joined: Jul 2016
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    CatrigCat Junior Member

    If both tubes slowly deflate, maybe you dont have a leak because its rare for both tubes to leak the same.

    With the boat out of the water, never fully inflate the tubes because under the hot sun tube pressure will rise above the recommended pressure.
    Also, at night when its cold, the boat will look underinflated.

    The deck never looks underinflated, only when you step on it.
     
  4. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Hello CDK,
    The boat held air for about a year (up and down with the temperature and external air pressure.)
    It takes a couple of days to deflate at present.
    Both compartments deflate equally,there are two compartments,the procedure is to blow up compartment one first.I have changed the valves for more reliable ones.
    If I sell it on,the buyer would have the same problem.
    I've looked on the net,and other people are having the same problem.
    In the USA,there is a fluid they pour in,but the price is well over the top,almost what I would sell the boat for.
    That's why I was considering using PVA.
     
  5. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Hello CC,
    The blow up deck stays inflated indefinately,the material it's made of is similar to
    the cheaper inflatable boats on the market.
    It sounds like Hypalon doesn't stand the test of time.
     
  6. Petros
    Joined: Oct 2007
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    Petros Senior Member

    if it noticeably looses pressure overnight, you should be able to find the cause using the soapy liquid. try a mix that makes lots of bubbles (experiment with different soaps and mix ratios), and than look for it again. check all the seams and around inlet valve.

    My limited experiance with hypalon is that is is fairly durable and holds up well. If it is leaking because of a break down of the air tight fabric, than I am not sure anything can be done. It means the fabric has outlived its useful life.

    Sealing it from the inside is an interesting idea to try, any number of adhesives could work, as long as they are compatible with hypalon. Just make sure it is liquid enough to spread out evenly, and it will cure inside the inflated chamber, and cures flexible so it does not crack and peel off.

    It is something I would try if indeed there was not a particular point of leak, but rather due to porous fabric.

    good luck.
     
  7. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Thanks for your interest Petros,
    I imagine that a liquid that needs Oxygen to cure is likely to work,mainly because of the air
    that is under pressure in the tubes.
    I suspect the temporary tyre repair liquid uses the same principal.
    A decent PVA liquid that is a bonding agent and porous sealant,let down just enough to
    roll round completely inside the tubes would find and seal the leaks.
    There is no doubt that once cured,PVA is waterproof.Decorators use it on porous walls prior to wallpapering.Used in a mortar mix for pointing it seals the mortar/sand and cement.
    There is nothing in PVA that would react with Hypalon,so the end result would be to block
    any micro leaks with cured PVA.
    This is my theory of course,not a proven fact.
    I suppose the proof of the pudding will be in the eating,Haha:D
     
  8. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Look up sodium silicate or water glass in Wikipedia.
    I've used it successfully to treat all kinds of porous surfaces.
     
    hoytedow likes this.
  9. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Thanks CDK,I'll check that out.
     
  10. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    Worth checking the sealing cap (fill/deflate) non return flaps and O rings. These DO degrade on most RIB tubes regardless of tube material. Most are designed so the valve can be replaced, mostly the newer ones are a lot easier than the really old ie Avon ones.
     
  11. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Hello again SS,
    I'll give that a try.I upgraded the valves about 18 months ago.The boat isn't that old,but wasn't expensive.
    The original valves were poor quality.
    I've got too old for scrambling in and out of inflatables,and it's taking up space.I'd rather give it away
    than dump it.
    I've been having probs with my 1964 18hp Evinrude,it's on a 14ft fibreglass semi speedboat.
    I took it out for the first time last week,and it wouldn't get on the plane.I think the prop on it is for a heavy boat.The transom height is spot on,and the engine ran like a dream.It churned out a huge wake,
    but wouldn't get above about 8mph.It did the same speed at 1/2 throttle.I dropped the spare 5hp yammy in to test it,and the speed was more or less the same.
    I have been struggling to find what dia and pitch prop was standard on it when it was new.
    The guy I bought it of had it on the river Trent,so it may have been on a house boat or a barge.I should have asked at the time,but didn't.
    I can't find any ID numbers on the prop,which is part of the problem.
     
  12. Barry
    Joined: Mar 2002
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    Barry Senior Member

    There are many inflatable paints on the market that will cover hypalon and deal with small pinholes etc It is flexible and will not crack when you roll it up
    it would take about a quart to do a 10 foot boat

    Obviously inflating and checking the entire surface and valves with a soapy water solution might find that you have one or more leaks that you can focus on.

    Hopefully this might jog some other contributors brains.

    There is product that I used maybe 25 years ago, water based that skinned over a bit when it dried. So for a leak test, you brushed this on, the surface would skin. Over say 24 hours the slow air leak would just create a noticeable bubble which would identify the leak. An extremely slow leak then would become evident. After you could just wash the surface off

    The problem of putting liquid into the tubes is that you might need quite a lot to ensure that the entire tube is coated as you will not have a mechanical means to move the liquid around. Ie as compared to brushing the outside

    So if you need a lot to ensure the coating, what will the weight penalty be?

    How do you know if all compartments are deflating equally?
    The baffle, or end of each compartment is flexible and if you have all the compartments at the same pressure and one compartment loses pressure, then the adjacent compartment will appear to have lost air but may not have lost air, only pressure.

    Ie the baffle moves toward the leaking compartment, which increases the volume on the higher pressured compartment, and then it look like it has also lost air.

    To see if you have a leak in a specific compartment, just blow one compartment up to design pressure, check it after a day or so to see if it is leaking. Do the same with the other compartments.

    If there are three compartments you can do two the first day, leaving the middle compartment unpressurized, then the middle compartment another day.

    You might find then that you only have one compartment leaking and can focus your efforts to find a specific pin hole or a few, to repair
     
  13. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Thanks for the advice Barry,it's a logical way to tackle it.
    There are only 2 main tubes,the floor is of a different material,and stays up indefinately.
    The boat stays up all day,maybe a łittle added air later on with the hand pump.
    When the boat is first put in the cold water,it sometimes needs a pump or two because of the difference in temperature.
     
  14. SukiSolo
    Joined: Dec 2012
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    Location: Hampshire UK

    SukiSolo Senior Member

    On occassion we borrow an old inflateable about 10 feet long. It planes one up with 3.5 Hp...
     

  15. KoruCaptain
    Joined: May 2020
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    Location: Crofton, BC

    KoruCaptain Junior Member

    I'm curious if you followed through on your PVA 'repair'. I have a PVC Zodiac C240, that I have discovered some porous fabric leaks... just very fine bubbles out of one tube. In the past, with an older inflatable, I have painted on an exterior coating recommended for just such a problem... but invariably the air pressure 'bubbled' the coating and leaks reappeared. I have found the product online that I can pour into the tube... but it is at least a week away, and it is not particularly inexpensive when shipping and duty are considered. This inflatable came to us for free... so my 'investment' is currently minimal. I can't help but think that a diluted PVA, applied in the manner you describe, from the inside, would be a good solution... and then an external coating of recommended product to 'brighten' the tender up.
     
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