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Old 21st January 2009, 06:08 AM   #1
dominic72
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Default kombat air vent leak - need help - roger...?

Hi ROger

sorry to bother with one more air-vent related set of questions. I bought a '08 Kombat last year (105L) for onshore wave sailing and bump & jump stuff. Just loved it.

I kept sailing it over the winter here (Italy) til a month ago, when a gust just tossed it away onto the beach from my car roof, causing a few dings. Nothing serious, took it immediately to a retailer after loosening the air plug, as I always did each time after sailing with air vent rigorously closed.

Got the board back from the repair after a few weeks and, as soon as I opened the air vent, inside my well-heathed home, to my great surprise I heard it hissing a bit with a little humidity gurgling near the air vent. it lasted one or two hours, with no water leaking, just very small air bubbles in the vent hole. the material just beneath the air vent, though, was a bit humid for a few days.

SO I read your posts and followed your advice of keeping it in a warm and dry environment (not under the sun sadly, being winter here). the board is now apparently dry and, without footstraps, it weights 7 kilos which seems in line with company specs and with previous measurements I did.

is it possible that the hissing was due to just a bit of humidity or does the board interior really need to get washed to hear the board hissing? I am quite sure I closed the vent every time I sailed the board. it had not a single ding til it flew from my car roof.

To test the board, I had to put it outdoor at a temperature of some 10 celsius degrees with loose vent, than took it back inside home (around 24 celsius), closed the air vent, let it warm a little bit and checked vent plug, fin and mast box for possible leaks with soapy water. can I rely on my such leak test or do I have to take the board back to a repair guy before I can ride it?

I am keeping testing it this way, and storing the board with the plug removed in the warmest room I have here, but do I risk damaging it from sudden changes of temperature?

thanks so much for your help, just can't wait til I go back riding. Cheers from Roma, all the best -- dom
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Old 21st January 2009, 07:34 AM   #2
Roger
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Hi dominic72,
Sounds to me like you are doing all the right things to ensure the interior of your board is as dry as possible.
The O-ring under your vent plug may have "seeped" a bit of moisture (especially if you had it heated up on the beach and then put it in cold water, creating a vacuum inside the core of the board that the O-ring may not be able to seal totally.
If there were no "drips" of liquid water when you first opened the vent, then chances are your boards core is as dry as it's going to get.
If you take it outside (not in really cold temps) and allow it to cool off thoroughly, then close the vent and bring it inside, you can test it as it warms back up.
If you get a little "hiss" the vent plug is working as it should.
Using the soapy water test is good around the footstrap inserts and the fin box, but I wouldn't use that method on the vent plug as there's a good chance some of your soapy solution will run into the board when you open the plug to test it.
Sudden changes in temperature are OK, as long as the vent is open.
Same with sudden changes in alititude.
If the core of your board can "breathe" (equalize the internal pressure/vacuum with the ambient outside atmospheric/barometric pressure, there is no chance for damage.
It's when you suddenly change the temp with the vent closed that the pressure can build up or if going from hot to cold, that the internal vacuum can develop enough to cause an issue. As long as it's dry when you do this, it's not an issue, but if you put a hot core board, into cold water and it chills quickly a significant vacuum can result in the core and this can pull water past the O-ring seal and vent plug.
Best to place your board near the water if it's hot, then slide it slowly into the colder water with the vent plug up and kept dry, until the temps equalize.
Also, in winter, be careful taking the board outside as if there is significant moisture somewhere in the core or between the core foam and the skin, the moisture could condense and then form ice which can damage the core or the core/skin bond.
Hope this helps,
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Old 21st January 2009, 08:29 PM   #3
dominic72
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Thanks so much Roger, couldn't ask for a more thorough advice. Will do as you suggest. The only thing that doesn't square with my board is, after exposing it to a higher temperature with the vent closed, I can't hear the 'hiss' as soon as I open it. Maybe I should check the o-ring, which looks good though it may be a bit 'flatetned'. Or I should do the test my accurately. Cheers, dom
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Old 22nd January 2009, 05:55 AM   #4
Roger
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Hello Dom,
Yes, it's a good idea to change the O-ring.
Some boards seem to come with spares.
Also take a look at the flat surface where the O-ring "seats"
in the plastic fitting in your board.
It needs to be very smooth and flat.
Also, I use a bar of soap on the threads to lubricate them
and use a bit of moistened soap on the O-ring.
Also most sailors tend to think that the tighter you get the
plug the better it will seal.
Actually just as long as it's fully seated and compresses the
O-ring at least 20% it will seal better.
Overtightening the plug just flattens and distorts the O-ring,
which makes it less likely to provide a positive seal.
I usually install the O-ring in a new board, and tighten the
plug until it's snug, then make a mark with a Sharpie indelible
pen on the head of the plug to give me a good quick "visual"
way to tell if the plug is tightened.
I do not remove the plugs (except for an occasional "test")
unless the board is going to be flying or it's had some damage.
Hope this helps,
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Old 22nd January 2009, 09:28 PM   #5
Crash
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Hi Iím having very similar issues with both my SB 160 and Apollo, its seems the air vent is nearly always closed when the air temp is warmer than the water temp creating quite a vacuum. Even with a new seal I have had problems so now I always get the board as cold as possible before closing the air vent and a SMALL amount of silicone sealant in the threads finally gives a seal. I bet if more people brought their boards into a warm environment, took the air vent out and roll up a fine piece of tissue to act as a wick they would find some moisture, the seals are not good.

Crash
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Old 22nd January 2009, 11:26 PM   #6
dominic72
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Hi Roger and Crash
thanks a lot for your feedback. Very useful actually.

Roger, you got it just right: I was looking carefully inside the plastic fitting of the air vent yesterday, and the flat surface where the O-ring "seats" isn't perfectly flat. Is looks a bit uneven. This might explain how the board managed to seep water in when I made sure the vent was closed (possibily overtightening).

wondering whether I should try to flaten that surface, I have a 'Dremel' precision drill (http://www.dremeleurope.com/dremeloc...sp?ccat_id=479) but feel a bit wary of operating it

cheers
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Old 23rd January 2009, 02:26 AM   #7
Brian S
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Default Damaged vent plug seal

I had this problem with my 12'6" SUP. I "flattened" the vent plug countersink landing with the Permatex thread repair material suggested by Roger, and referenced on the repair section of this site: http://star-board.com/2009/pages/pro...sst_repair.php
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Old 23rd January 2009, 11:04 AM   #8
Roger
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Hi Brian and Dom,
Yes, you could easily repair (as I have done several times when repairing damaged vent plug threads) with the Permatex thread repair kit.
Simply get another vent plug and coat it with the blue release agent.
Then mix a small amount of the 2 part thread repair epoxy, and put it carefully on the
flat horizontal surface of the counterbore where the O-ring seats.
Then simply screw the vent plug down into the hole (without the O-ring installed) and it will create a nice smooth hard epoxy surface for the O-ring to land on.
Allow the 2 part epoxy to set up and back the vent plug out of the hole.
Allow it to cure for the full period suggested by the manufacturer of the kit,
put a new O-ring on plug and you will have a better seal than the original.
Hope this helps,

Last edited by Roger; 24th January 2009 at 07:27 PM.
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Old 23rd January 2009, 10:58 PM   #9
dominic72
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thanks once again for your tips Roger. Will do as you suggest. First off I'll have to look for Permatex products in Italy/Europe ... cheers
--dominic
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Old 23rd January 2009, 11:25 PM   #10
dominic72
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ROger, Brian, Crash et al., thanks a lot for your tips. fyi just ordered the stripped-thread repair on ebay from UK. looks like I won't be sailing over weekend, BUT better now than over the summer!

cheers, very useful indeed
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