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| Need advice on leak test http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=157 |
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| Author: | devnull [ Tue Jun 17, 2003 8:10 pm ] |
| Post subject: | Need advice on leak test |
Hi, I've inherited responsibility for a club Hobie 16. It's about five years old. The hulls are leaking water, one hull very badly. On its most recent sail, with light crew, low-medium wind, and little splash, quite a bit of water got into the hulls. I don't think it's the pylons because these conditions seem to rule out water leaking into the pylons. I've inspected the rudder and plug fittings, and for the most part, they seem to be well-seated in silicone (although I do wonder about the rudder fittings). Seems like I need to do a leak test. I've never had to do this before, and in my searches have stumbled across a couple of references to leak tests involving soap & water, blowing air into the hulls with a hair dryer, etc. I don't suppose by any chance anyone is aware of any websites which document this. Any suggestions for the best way to do a leak test? Any help would be appreciated. Cheers, d. |
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| Author: | mmiller [ Wed Jun 18, 2003 11:23 am ] |
| Post subject: | Leak Test Technique |
There is not a website on this that I am aware of. The technique is simple though. You need to force air pressure inside the hull in some way. There are many possible ways to do that. By mouth, hair drier, vacuum exhaust, tire pump... whatever. DO NOT put more than a couple pounds of pressure into the hull. I prefer the vacuum exhaust. Direct the flow into the drain hole, but do not seal it tightly. Any positive pressure inside the hull will try to escape. It will escape through possible leak locations. Mop, sponge or spray soapy water around fittings and seams that are suspect. Bubbles will be formed by the air escaping from the hull. On the 16, look at the keels. Are they wearing through? Look at the drain plug gasket. Is there one? Is it crushed and out of place when the plug is installed? Look at the bow tang fitting and shroud anchor pin. Holes drilled through the hull may have pierced the inner hull cavity. Look at the gudgeon screws, deck to hull lip seam and, of course, the pylons. |
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| Author: | Nigel H17#6424 [ Thu Jun 19, 2003 6:00 am ] |
| Post subject: | Vent tube |
There is a vent tube in each forward pylon, to vent each hull so the hulls can "breathe" with changes in temperature i.e. internal pressure. |
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| Author: | mmiller [ Thu Jun 19, 2003 10:20 am ] |
| Post subject: | There should always be a vent... |
Good point Nigel. The hulls are designed to vent with changes in temperature and altitude pressure. Hulls need to "breathe". Without the vent, the hulls will flex when pressure changes inside as compared to outside the hull. This can cause damage to the structure of the hull. If you hear a puff of air when removing a drain plug, that is not "a good thing". |
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| Author: | devnull [ Thu Jun 19, 2003 10:41 am ] |
| Post subject: | |
Thanks for the helpful advice. However a leak test may not be necessary. Funny story follows. I found out that the boat had been previously sailed by novices who forgot to install the plugs. After the expected misadventures, they managed to return the boat to shore. I'm guessing that they did not completely drain the hulls before returning that boat to its usual horizontal storage position. Am I correct in assuming that if a swamped Hobie is not completely drained (by raising the bows until all the water runs out), and is then left in a horizontal position, a significant amount of water will remain in the hull? I figure this is what happened: The first crew took the boat out without the plugs in, returned with swamped hulls, did not drain the boat properly, and left the boat stored in a horizontal position. A week later, the second crew rigs the boat, puts the plugs in and unknowingly takes the boat out with water already in the hulls. After returning from sailing, they remove the plugs, note water coming out, and report that the boat is taking on water. Note that the second crew had trouble launching the boat... it wouldn't seem to float off the dolly, which leads me to suspect the boat already had water in the hulls... |
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| Author: | avlahcevic [ Sun Jun 22, 2003 8:57 pm ] |
| Post subject: | Matt Miller Follow Up Question... |
Hi Matt, My 16 sometimes gets "pressurized" while sailing as you describe, so obviously, the vent tube isn't venting at it once did. I have tried to clear silicone out of the track in the frame post, but that hasn't hasn't fixed it entirely. Further, my '83 boat frame was epoxied for added stiffness. I store the boat with the plugs out, but what action would you suggest I take? Would installing ports help to provide a natural air escape? |
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| Author: | waldorf [ Mon Jun 27, 2011 9:31 pm ] |
| Post subject: | Re: Need advice on leak test |
it seemed like yesterday ... the first time i read this.... time goes... |
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