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GRP leak detecting. Idea i had and worked.


W+T

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A few folk have seen this idea I had have been asking about it more so I thought I would share it here.

 

For a good while on my GRP boat refurb I found a slow drip on the inside when it rained hard or for long periods. I was finding if difficult to find though where it was getting in.

GRP leaks work on a capillary action so where the leak is on the inside it could be getting in many feet away.

There are a few ways to find leaks like this, one using a smoke bomb in the cabin, but that needs a clear route out so if water is in the laminate then how does the smoke get out, and then there is spotting the smoke from the outside.

Well my idea was that if water can get in air can get out.

 

I made a pressure plate as here using a 1/4BSP male air line fitting and i cut down a brass fitting to make a lock nut to suit as i was having difficulty in getting a lock/half nut to fit. Plenty of PTFE was used aswell. 

 

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3mm spacer was sealed down with sikalfex and then the fitting and nut sealed in.

The pressure plate would of been flat but where the water was getting in is on a corner.

 

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The plate was held in place with sikaflex to make a seal and left for 6 days to set. It can take this time due to so much being used. 

 

 tn_20170311_125824.jpg

 

Once set i just pushed on the air line and set the air regulator to 0 and bit by bit raised the pressure, when it got to 5psi i heard air hissing from somewhere.

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I got a soap solution and dapped it first around the rail fittings and over here and there, where ever i thought it would be coming from.

I found it was about 2-3 foot from where the internal leak was coming in.

Here we have the pin hole that was causing so much hassle,

 

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What i have done up to now is blow air through for a while to get as much water out as possible then made a dam around the hole with Blue Tac and used Creeping Crack to seal it a little, there was no need to as it will be filled properly asap by counter sinking and resin filler used.  I was going to try and pump resin into it but going to far i think.

 

I hope this helps out others if they find the same situation which is real hard work to find the leak.

Wolly :)

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12 hours ago, rasputin said:

already posted on a different thread

As not many look at my build blog then i thought it would be better to have its own thread. 

 

Edited by W+T
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You can do something similar with an inner tube and an electrical enclosure. Cut the valve and surrounding area of rubber from wheelbarrow or car inner tube. Drill a hole in the back of the enclosure (something like this) for the valve to poke through. Put the inner tube in the enclosure and wedge in place around the leak with some sealant where it contacts. Then pressurise with a car tyre inflator; or even bike pump. Handy if there's a second person checking for bubbles as there's not much of a reservoir for the air.

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5 hours ago, stegra said:

You can do something similar with an inner tube and an electrical enclosure. Cut the valve and surrounding area of rubber from wheelbarrow or car inner tube. Drill a hole in the back of the enclosure (something like this) for the valve to poke through. Put the inner tube in the enclosure and wedge in place around the leak with some sealant where it contacts. Then pressurise with a car tyre inflator; or even bike pump. Handy if there's a second person checking for bubbles as there's not much of a reservoir for the air.

just the valve with a few inch left around the base and then glued over the hole will work, no need for any reservoir. 

Today i finished the job and from the outside ( as now i know where the hole is ) i used a ring of 6-8mm thick Blue Tac around the  hole and pressed it in place and then pushed the air line fitting i used bolted to the original pressure plate into it and it took 5psi easy, i reckon it could of took more. 

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1 minute ago, W+T said:

just the valve with a few inch left around the base and then glued over the hole will work, no need for any reservoir. 

Today i finished the job and from the outside ( as now i know where the hole is ) i used a ring of 6-8mm thick Blue Tac around the  hole and pressed it in place and then pushed the air line fitting i used bolted to the original pressure plate into it and it took 5psi easy, i reckon it could of took more. 

Yeah. The enclosure is more of a means to be able to prop the rubber in place without having to be dependent on glue alone. Just happens to create a small reservoir.

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