More about Tube Pressures

[smallribber]

Up until yesterday when I used my new Bravo electric pump with gauge I had always pumped up the tubes one by boats by feeling the tubes. Yesterday I pumped up my SIB with the new electric pump set at 2.5 bar as the plate said.

When I got the tubes to just over 1.5 bar they felt firmer than I had previously pumped them so I stopped. Used the boat 2 up with my 9.8 hp and it planed fine

This boat is a 3.2 m Ali floor with blow up keel

I also did not pump the keel to the pressure it said to

Do others feel the pressures as the instructions seem rather high

Dennis

[Searider]

psi or bar?

2.5 bar is almost 40psi!

[jeffstevens763@g]

yep not bar 1 bar = 15 psi roughly tubes around 3 psi it tells me on my valve what pressure.

[chipko]

Originally Posted by Bigplumbs

Do others feel the pressures as the instructions seem rather high

Dennis

We always ran our sibs fully pumped up to the manufactures pressures (typically 0.24 bar/3.5psi) even to the extent of topping up pressure after 20 mins on the water. A firm believer in 90% of a sibs performance is achieved in the final 10% of pressure.
Acknowledge you need to be reasonably confident the pressure gauge is ok, but in my opinion at the correct pressure the tubes should feel absolutely drum tight. Far more stress on the tubes/joints if run under pressure.

[Mikefule]

Originally Posted by chipko

Far more stress on the tubes/joints if run under pressure.

Slightly ambiguously stated but I think you meant at less pressure than recommended. I agree. I like my tubes to ring slightly if I tap them sharply with my finger tips. I've never used a gauge, and of course the pressure varies throughout the trip as they cool with immersion, then heat up when you anchor in the sun, and so on. I once ran my first ever SIB on too low a pressure and I hit a wave and the floorboard from the bow slipped under the second board.

However, an earlier post referred to 2.5 BARS pressure and I am hoping that was a typo. That's the sort of pressure you put in a car tyre or bike tyre.

[smallribber]

Sorry typing on iPad divide by 10 I meant 0.25 and 0.15 bar etc

[lightning]

My Zodiac 2.85m SIB performs better when the tubes are fully inflated to the recommended 3.4psi.
Although it is a bit scary watching the wooden floor creaking and distorting as you inflate the keel.
lnflated to 2psi or less (l discovered that my previous Rule branded pump was only inflating the boat to around 1.2psi) the boat looked OK but crashed and bashed on waves, plus the transom would move with engine thrust.