View Full Version : kombat air vent leak - need help - roger...?

21st January 2009, 06:08 AM
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

21st January 2009, 07:34 AM
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,

21st January 2009, 08:29 PM
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

22nd January 2009, 05:55 AM
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,

22nd January 2009, 09:28 PM
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.


22nd January 2009, 11:26 PM
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/dremelocs-uk/Category.jsp?ccat_id=479) but feel a bit wary of operating it


Brian S
23rd January 2009, 02:26 AM
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/products/asst_repair.php

23rd January 2009, 11:04 AM
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,

23rd January 2009, 10:58 PM
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

23rd January 2009, 11:25 PM
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

27th January 2009, 05:52 AM
Hi again guys

sorry for bothering again with my questions on how to treat my board after some water leaked in ... I've orderer a thread repair for the surface the vent plug sits on, while leaving my board permanently at rest in a very dry and warm environment with the vent fully opened. Now I have a doubt: some water might have entered anytime in the past few months and I began the treatment only recently, leaving the vent only slightly unscrewed and not fully opened. Is there any risk it started a delamination process or other damages?

I 'sucked' some air from the vent hole and noticed a slight flavour of epoxy in my mouth. Is this normal, or is it a sign my relatively new board (from 2008) might have started delaminating?

from the outside it has no such signs and looks perfect and has no soft spots or any bubbles, but the doubt remains... cheers and thanks again for your precious help

27th January 2009, 08:16 AM
Hi Dom,
I think your board is probably very dry on the inside.
You didn't have that bad a leak, and you worked the vent plug
each time you sailed, so if the pressure ever tried to build up, it
was released after the session.
As far as the epoxy smell/taste, that's probably quite normal, but
I do wish to know how you know what epoxy tastes like.... ? Just
kidding here.
I think you will find that after you get the surface of the vent plug
O-ring seat smoothed out, you will have no further issues.
Once you are pretty sure the O-ring is sealing well, you can leave it
tightened up all the time unless you change temperature or altitude
Hope this helps,

27th January 2009, 10:11 PM
Definitely helps, as any of your golden tips! thanks again ROger!

I should just get on the water and enjoy a nice ride shouldn't I? btw that epoxy stink, did some epoxy repair on a larger boat ... buon vento, dom

28th January 2009, 09:57 AM
Hi Dom,
I couldn't resist the crack about the "taste of epoxy".
Yes, when doing board repair or boat repair, the true craftsman normally
experiences the taste, smell, and feel of whatever resin they are using
(epoxy/polyester/other). It's just part of doing the job.
And you soon get so you can tell the difference between cured resin and
uncured resin.

17th February 2009, 06:01 AM
Hi again Roger, how are you? followed your instructions with the air vent and it seems to work now. I sailed it once and it appears dry. I also have applied a slightly larger o-ring, I think 2.5 mm instead of 2. the new o-ring fits very well inside with no strains when I screw the plug.

ANyways, I have one more question that's related: the wood deck in my 2008 Kombat shows some discoloration located in the nose of the board near the SB sticker, and around the mast box along two lines left and right of the track. just parts of the deck that look pale compared with the rest of the deck.

is this common? or does it mean the moist that had accumulated into the board might have leaked from some invisible cracks/loss of epoxy in the wood deck? or perhaps the marks might be the result of water leaking from the vent and pushing its way towards the wood... ? thanks thanks thanks again... good winds, dom

18th February 2009, 05:04 AM
Hi Dom,
Sometimes, the wood of the deck does not get fully saturated when they are finishing the board.
So, the wood layer on the outside is sometimes a little prone to "soaking" up a bit of water which can cause some discoloration.
The fix?
Get some 2 part polyurethane floor varnish.
Lightly sand the areas you think are absorbing some water, and then let them dry out
(preferably in the sunlight...to restore the original golden patina).
Then coat the exposed areas with the polyurethane floor varnish.
Only better product would be a penetrating epoxy, which is very hard to obtain.
After the poly o epoxy cures, the deck should remain the same color virtually forever....
except for UV yellowing of the original finish.
Hope this helps,

18th February 2009, 05:29 AM
thanks ROger. My only worry was that this soaking of the wood layer could cause water leaking inside the board. From your words I understand this only affects the outside layer), SO I am quite happy with the board as it looks, as long as this soaking is not letting any water penetrating the inside... am I right?