FAQ Friday #28 - Why does all the air hiss out of my inflatable boat as soon as I disconnect the pump?

Whether you have a small SIB, large RIB, paddleboard or other inflatable, it is really frustrating to pump it up to the correct pressure, disconnect your pump and hear "HISSSSS" ....especially if you've worked up to a high pressure or your tubes now have less air in than when you started.

Typically, the reason this happens is the valve is in the open rather than closed position. Most valves have a spring loaded plunger with a diaphragm which seals against the back of the valve.

When the plunger, which often has a cross or star shaped top to it, is in the lower position, the diaphragm is away from the valve back enabling you to deflate your inflatable.

When the plunger, is in the most proud position, the diaphragm should be against the back of the valve and form an air tight seal. Some valves will still weep without the cap at this stage.

It's always worth checking your valve is set to closed before commencing the inflation process to avoid frustration and extra work. 

If you're certain the valve was in the closed position and you're using an adaptor with an adjustable screw in the centre, you may need to adjust the position of the screw.

If you're certain the valve was in the closed position and you're using an adaptor with a straight plastic bar across it internally, I would suggest snapping this bar off. From personal experience, pumping up a paddleboard to about 18psi three times in quick succession is somewhat tiring!