Inflation - Hot/Cold Changes

ninjah · 06 November 2014, 16:26

Greetings!

With the fall season upon us here in northern California we're getting 20+/- temperature ranges almost daily. In the morning it's in the 50's and in the afternoon it's getting up in the 70s. The pressure on my boat reacts accordingly going from barely inflated in the morning to "back to normal" in the afternoon.

I'm taking the boat ocean fishing (crab season!) this Saturday and I'm trying to figure out a plan of attack to deal with this. I'll need to pump it up to launch in the early am (when it's fifty degrees) and likely take air out as the day goes. What I'm concerned about is doing this in the ocean. As easy as it might be I'm somewhat nervous about cracking open a valve while in the boat on the water a couple miles out. Also, how do I address the bottom valve while the boat is filled and on the water? There is no way I'll be able to tell what the pressure is...?

Can anyone share any tips on how to best approach this?

JAH

chipko · 06 November 2014, 17:39

I can sympathise, real pain monitoring tube pressure!
Based in UK so temp extremes less but pressure variations still an issue.
I tend to store my sib at 0.15 bar, pump up to 0.24 bar at the beach immediately prior to launch. Check pressure after 20 mins on water, re inflate to 0.24 bar (typically drops by 0.05 bar) and as tubes are partially in water, pressure remains fairly stable throughout the day. Tubes on mine are light grey but darker colours will have more extreme temperature issues. I also use an integral battery powered electric pump (Genova GP80BD although Bravo favourite on here) which although pricey has proved invaluable.
As soon as boat come out of water I let some pressure out back to 0.15 bar approx.
As mentioned, a real pain but boat performs so much better with tubes at max. recommended pressure without risk of over pressure in the sun.
Good luck!

Peter_C · 06 November 2014, 17:42

The water is really warm right now, and in fact warmer than the air in the mornings. I set mine at home in the morning for the speed tubes and center tube, but leave the larger tubes just a little low. Then once in the water I bring them up to their proper pressure. If the sun comes out strong and it is hot, I will adjust as needed on the water. The water will do a pretty good job of keeping the temperature fairly constant inside the tubes. Do not fear opening valves on the water as it is no different than on land.

captnjack · 06 November 2014, 20:56

Quote:

Originally Posted by Peter_C

The water will do a pretty good job of keeping the temperature fairly constant inside the tubes.

^^^^
This, particularly for any under floor tubes. They won't overpressurize to any dangerous degree.

jyasaki · 06 November 2014, 22:42

I typically don't worry about temp changes on the water (I pump tubes up after launching.) The convective cooling keeps pressures fairly stable. It's when you have the boat sitting on the trailer that it becomes an issue.

One other thing: If you are highway trailering on warm days, take note of the tube pressure when you stop. The air going by at 60MPH will help cool the tubes, and when you stop you lose that cooling.

jky

ninjah · 06 November 2014, 23:44

Thanks everyone! Sounds like a shouldn't be too overly concerned and I hadn't thought about the water temp factor.

m chappelow · 07 November 2014, 10:48

Even though you may top the boat up after its been in the water a while for post immersion pressure drop , once underway if you start going through waves & your getting cold water sloshing over the bow & tubes you will also get another pressure drop .

jyasaki · 07 November 2014, 15:23

Probably true, but as water pulls heat 26 times faster than air, just sitting in the water for a while will cool the tubes pretty effectively. The added cooling of running and splashing won't, IMO, make all that much of a difference, as the air inside is already well on its way towards equalization (though that does depend on the length of time it's been in the water, how much of the tube is in contact, and a host of other variables.) It's the big changes that are going to affect performance and safety, not so much the little ones.

jky

philpot · 10 November 2014, 11:07

My Excel has an automatic over pressure release valve fitted to one tube, perhaps fitting some of these on your boat would help with extreme temperature changes that you have. I must say that I don't really know why only one is fitted, I would prefer to have them on each tube and may look into that for next year.

Phil