Where can I buy replacement o-rings for the vent screws?
I bought an o-ring pack from Masters for about $3 and 2 out of 8 were ok but slightly thinner than the original.
Surf Sail Australia has them......just got some posted to me.
Sure you could get some from a plumbing store but the online option is pretty easy.
The standard size is Ø8x1.5mm cross section
You can get 2mm 2.5mm 3mm cross sections
These larger cross sections are better as rather than sealing between 2 faces, ie the plug and the bottom of the hole they also seal on the inside of the hole.
The Pros.
It stops any sand getting underneath the Oring which creates a leak path and also over time shreds the Oring.
By contacting the inside of the hole it stops the Oring from extruding out from underneath the plug if over tightened.
The Seal is Vastly superior.
When traveling the Oring resists the plug vibrating out better.
The con
The Plug sits up a ****tenth above the deck of the board, which is not a problem even if the mast base sits on top of it.
O'rings can be purchased from
Hydraulics shops (mining and Hydraulic supplies)
Oring suppliers (Lodowici's , Transeals)
Bearing suppliers.
Buying in bulk (1000's) these generally cost $0.02 each but because you are buying low qty's (for the shops it is best to ask for $10 or $20 worth and you will have enough to keep a trailer load of boards happy for quite a few years and your boards watertight.
If you have access to verniers measure the ID of the hole (they do change) or just get a range of cross sections
Select to expand quoteelmo said..
The standard size is Ø8x1.5mm cross section
You can get 2mm 2.5mm 3mm cross sections
These larger cross sections are better as rather than sealing between 2 faces, ie the plug and the bottom of the hole they also seal on the inside of the hole.
The Pros.
It stops any sand getting underneath the Oring which creates a leak path and also over time shreds the Oring.
By contacting the inside of the hole it stops the Oring from extruding out from underneath the plug if over tightened.
The Seal is Vastly superior.
When traveling the Oring resists the plug vibrating out better.
The con
The Plug sits up a ****tenth above the deck of the board, which is not a problem even if the mast base sits on top of it.
O'rings can be purchased from
Hydraulics shops (mining and Hydraulic supplies)
Oring suppliers (Lodowici's , Transeals)
Bearing suppliers.
Buying in bulk (1000's) these generally cost $0.02 each but because you are buying low qty's (for the shops it is best to ask for $10 or $20 worth and you will have enough to keep a trailer load of boards happy for quite a few years and your boards watertight.
If you have access to verniers measure the ID of the hole (they do change) or just get a range of cross sections
who are you wise man of science? anyone would think you knew something about this? 
it'd be the equivalent of me talking about wankin 
Elmo I think you mean 10mm I.D :)
My vent plugs are a smidge over 10, so I recon probably 3/8 is closer.......... but 10mm won't fall off.
Anyway here is my chance, its another thing that sh!ts me about Bunnings. You can't buy a 10mm o-ring anymore. noooooo you have to buy a mixed pack of about 100 all the way up to 50mm, and 4 of them fit. Kinda.
G'day Mark,
Just got my little baggy of vent plug Oring goodness out of my ashtray and they are definitely 8mm.
O'rings are measured: Inside Diameter x cross section
Just go to a bearing supplier up your neck of the woods, if not PM me
My vent plugs are 10.5mm on the thread major dia, and the head is 13mm
so a 10x1.5 works nice........
Didn't realise the factory ones were 8mm ........ must be tight and why they snap so easily
seems we are both kinda right, as both will work...
Any bearing supplyer they stock all sorts of O rings. I bought a packet or 20 fo $7.00
Select to expand quotewindaddict said..
What about these o-rings from eBay?
It says the inside diameter is 8mm and 1.8mm thick ? $3.27 for 20 free delivery
Any good ?
Thanks for all the helpful advice .. and thanks for the link.
I measured the o-ring from a recent board from Cobra factory and it was 8mm ID.
I'll make the big $3.27 investment and give them a try! :)
every hardware store should sell them... while you are at it buy some vaseline. This is a tip someone gave me a few years ago. Apparently a small amount of vaseline in the vent while prevent any water from entering should the o ring be leaky but any air will be able to escape.
I always go to the seal and gasket shop and use the 8 ID x 2mm. same as cobra use.
I also check that the 3/8 bsw hole is tapped nice and square and that the o-ring will seal with out to much tightening, I had a brand new board once that leaked badly through the vent plug because of an out of square thread also check that the shoulder where the o-ring contacts is nice and smooth with no lumps.
In most applications o-rings are only supposed to be compressed about .2 -.25 mm what we do with them under the vent screw is pretty ugly so pays to check them every now and then.
