Dinghy tube pressure - under or over?

[TPG]

Curious how everyone determines the correct pressure to keep their tubes inflated to, especially when you're dealing with temperature swings. I've seen my tubes deflate somewhat overnight but once the sun warms them up we're fine.

[robert sailor]

Many of the dinks I’ve seen around on average are under deflated. Using a foot pump it’s near impossible to over inflate them.

[GordMay]

The optimum pressure for an inflatable boat is specified by the manufacturers.
It generally lies between 200 and 250 millibars* [2.9 ➛ 3.63 psi].
This pressure must be measured when the boat is in the water, as contact with the water causes the pressure to drop with the temperature difference. It is therefore best to avoid inflating your boat on land, and to inflate it once it is in the water.
If you inflate your boat in the morning when it's cool, you can expect the pressure to rise with the afternoon heat. You should therefore under-inflate your boat slightly in the morning, leaving a margin of 10 to 20 millibars [0.145 ➛ 0.218 psi] over the standard pressure. So be careful and under-inflate your boat or depressurize it slightly at the hottest part of the day.

* 1 millibar ≈ 0.0145038 psi
* 1 psi ≈ 68.948mb

USCG Marine Safety Alert
INFLATABLE BOAT SAFETY: DO NOT OVER-PRESSURIZE!
➥ https://www.dco.uscg.mil/Portals/9/D...m_352cAA%3D%3D

Originally Posted by robert sailor

... Using a foot pump it’s near impossible to over inflate them.

True.

[JPA Cate]

We had an Achilles inflatable that had suffered a wound to its bow, and was properly patched, but one day, it was left in the shade while we had gone for a walk and when we returned, it was in the sun, and the bow had blown out. We had gone with friends, who kindly rowed us to the mother boat, where we got the repair materials, and returned, to re-do the original repair..... Maybe it wasn't properly repaired the first time, after all.

Ann

[Don C L]

I bring my pump with me when we go ashore. If its going to be in the sun I let some air out and reinflate when I get back.

[JPA Cate]

How very beforehanded of you, Don!

Ann

[Don C L]

Originally Posted by JPA Cate

How very beforehanded of you, Don!

Ann

Yeah... ask me how I know to do that now!

[Pete7]

I do a thump test. Hand fist slapped on the tube. Does it deflect a little? if yes that's fine, if too much then add more air. You can buy a tube pressure gauge, but it's just another expensive accessory to loose on board:

https://www.rib-shop.com/professiona...ressure-gauge/

After a life time of diving from ribs, I prefer light coloured tubes. Black is a nightmare even in England. Way too hot to sit on during a sunny summers day and go really soggy at night. With a light colour the tubes still go softer at night but are still useable.

Pete

[Don C L]

Originally Posted by Pete7

You can buy a tube pressure gauge, but it's just another expensive accessory to loose on board:
Pete

I was just thinking yesterday how many things are on my boat SOMEWHERE. My boat is so small, how can they be lost?