hey kit
basically they are manufactured by goretex
there is an australian distributer of goretex products
goretex vents are used in electronics, consumables and chemical containers
food container,weather proof cases etc etc
the cheapest type of goretex vent is prolly only worth 2 bucks or so
the guy trying to sell sailboard type vents for 50$ nz is pulling your chain
he probably buys them for a 1/4 of that
from what i understand
goretex clothing craps out after a couple of seasons in salty windy conditions
the vents would need to be replaced eventually
i believe that the plastic screw vents to be cheap and excellent
and easily replaced
and easily tightened with a fingernail if you forgot to close it and notice it down at the waters edge or something
a hole with wax in it works in a similar way
if the board gets hot enough to balloon and delam
the wax will melt and push out like a little sausage
releasing the build up of air
the vents should be placed on the deck at eye level
that way you never forget to close it
vents are an outstanding idea for a surfboard
i can crack my vent and leave my board in a hot car
and never have to worry about a delam
i post cure my boards at about 50 degree celsious
so it will be thermally stable up to around 55 to 65 dc
pu/pe will eventually deteriorate under this sort of abuse
i vent my plain eps boards as well
it removes any stress about leaving a board in car or hot sun
and creates an easy way to remove any absorbed water through a hole
so makes a board easier to repair
it is also great for high temp postcures without having to use a vacuum bag
and can be used to check the board for leaks when finished and during maintenance checks
i remove all wax from my boards every month or so and check it over
i check the bottom and rails over once a week
each to there own eh
some kids leave there bikes on the lawn
some kids leave theres in the shed
some people maintain there cars
others drive them till they die
the reason why we have classic cars is because of the people that looked after them