Tube pressure, do you use a gauge?

[acraw]

Hi all
Last week I put some more air in the rib tubes as they were slightly baggy.
Do people use a pressure gauge or just use the push test?
I know there is always a lot of warnings about over pressuring them?

[two stroke mick]

Too low a pressure will also do a lot of damage to tubes

[Maximus]

Originally Posted by two stroke mick

Too low a pressure will also do a lot of damage to tubes

Yep....and quickly!
Never used a Gauge... you soon get to know the "sweet spot" and can Top up or deflate as conditions (Mainly Tempreture) dictate.

[office888]

Bravo 12 BST HP

[Last Tango]

Just tried a gauge a couple of weeks ago to check pressure. Quite surprised how hard 2PSI (100mmHg) is.
I use bellows to pump up the tubes and I'd be surprised if you could get them much harder without bursting the bellows

[SixtyNorth]

Yes. As mentioned, the correct pressure is usually far higher than you think. Better to be sure to avoid damage. Pump up the tubes to what you think feels right and then check the actual pressure... you will probably find you need to add more air.

[willk]

Originally Posted by acraw

Hi all
Last week I put some more air in the rib tubes as they were slightly baggy.
Do people use a pressure gauge or just use the push test?
I know there is always a lot of warnings about over pressuring them?

So I think the important question here is "do you have overpressure valves?"

If you don't - you'll do well to know how much pressure you pump to and what happens when things warm up in the sun. Once you get close to 2psi, things looks/feel very similar as the pressure rises from there.

[knewfie]

I'm new to ribs and also wondering how to judge correct pressure by feel. I see alot of posts that say "when you can't depress with finger pressure." So does this mean when you can't depress at all? We've pumped up ours pretty hard but you can still depress a few millimetres. We are using a foot pump so I also have read that you can't over inflate with a this. Is this correct? Thanks!

[Last Tango]

Originally Posted by knewfie

We are using a foot pump so I also have read that you can't over inflate with a this.

What do you mean by a "foot pump"..... not a tyre inflation foot pump.
That could massively over inflate it. They are also low volume pumps so will take forever.
If it's bellows then I'd guess you're unlikely to over inflate very much with that. I find they get quite difficult as you get to near to 2 PSI

[beamishken]

Reading this thread prompted me to look at pressure gauges we have a few ribs in the family with different valves so I guess a universal gauge will be best but I'm wondering if it's just a push fit or a pump through gauge how is the valve depressed to get a reading? Do you test with the valve open then close it quickly before it loses to much air or do the adapters that come with the universal gauges depress the valve
What are people using?

[sydneyribber]

Following this

I too am very cautious about over inflating, as what seems fine in the morning on the trailer drastically changes when the temp creeps up, which in Sydney can be 10 degrees before the sun comes up and 35 or more in the mid day sun.

Thus I find myself constantly adjusting, am I being paranoid.

Also I tend to deflate the tubes quite a bit when I leave it on the trailer for a few days. Again it's left outside and on my way to work they can be soft and on the way home pretty firm.

Is it a big job to fit pressure release valves?

[jeffstevens763@g]

Bravo 7M Foot Pump With Pressure Gauge - Foot Pumps - Discount Marine Chandlery and Sailing Equipment. Bargain Boat Spares and Clothing

not worth the risk if you dont know for sub £30
without gauge i pump up solid slap the tube it has a steely ring is my best explanation if you havent pressure relief valves leave the dust caps off

[BogMonster]

Overpressure valves are best and usually I pump it up till it rings when you bang your hand on it. Depending on your location, the temp (and thus pressure) of the air in the tubes between sitting at rest in the sun and being sprayed with cold seawater can vary considerably, particularly on the rear chambers.

Because I am operating in very cold water (about 4 C for most of the year) one little trick I developed is to pump up the aft chambers first, then middle, then bow, then the baffles in the chambers are biased towards the forward chambers, so when the aft chambers go cold in the water they can 'steal' a little bit of pressure from the middle chambers.

[Maximus]

Originally Posted by sydneyribber

Following this

I too am very cautious about over inflating, as what seems fine in the morning on the trailer drastically changes when the temp creeps up, which in Sydney can be 10 degrees before the sun comes up and 35 or more in the mid day sun.

Thus I find myself constantly adjusting, am I being paranoid.

Also I tend to deflate the tubes quite a bit when I leave it on the trailer for a few days. Again it's left outside and on my way to work they can be soft and on the way home pretty firm.

Is it a big job to fit pressure release valves?

It sounds like you may be a obsessing somewhat about Tube pressure...then again I do have pressure release valves fitted on my RC ....which I would have thought would be ubiquitous "Down under"??!!

It's not a huge job (compared to some )to fit them...but it's not a quick cheap fix either,you could shop around for quotes.
I tend to keep the Tubes a pretty constant pressure...deflating and inflating IMO just adds unneeded stress....I've had/been messing with inflatables of different types for over Forty years.

[jeffstevens763@g]

Charles law

do the maths % increase isn't that great i might be wrong but i asked the late paul tilley re test pressures on inflatables all manufacturers differ he said but i think it was around 25% over inflation pressures was about the norm thats not till destruction which al depends on condition dont forget whilst afloat they are cooled i agree with maximus and have done the same for 40 + years

[GuyC]

Originally Posted by BogMonster

Because I am operating in very cold water (about 4 C for most of the year) one little trick I developed is to pump up the aft chambers first, then middle, then bow, then the baffles in the chambers are biased towards the forward chambers, so when the aft chambers go cold in the water they can 'steal' a little bit of pressure from the middle chambers.

One thing I've read is that you should generally inflate from the front to the back. The internal divisions are glued in with the 'bearing surface forward of the division. If you pump from the back, it is possible to unpeel the division. Happy to stand corrected though.

On the subject of gauges, it is probably a good idea to use a gauge until you have learnt what the pressure feels / sounds like.

[Max...]

Make a very accurate one for a few quid, old topic but mine is still going strong:

http://www.rib.net/forum/f50/adaptin...sib-42375.html

[GuyC]

Isn't that funny - I'd originally included a paragraph about using a decent quality calibrated gauge but I decided I'd get flamed for suggesting it.

I'd agree entirely at least until you have calibrated your hand with the correct feel / sound of the tube.

[jeffstevens763@g]

Originally Posted by GuyC

One thing I've read is that you should generally inflate from the front to the back. The internal divisions are glued in with the 'bearing surface forward of the division. If you pump from the back, it is possible to unpeel the division. Happy to stand corrected though.

On the subject of gauges, it is probably a good idea to use a gauge until you have learnt what the pressure feels / sounds like.

i understand what your saying guy if i am right the convex side facing forward and the concave side facing the stern cut edge ( stern ] bow peel easer ) in that case wouldn't the convex side peel easier as there is no cut edge on the material and the convex turns into a concave?
personally i have always pumped up equally to keep the pressure equal on the baffle from both sides.
happy to be corrected

[spartacus]

Throw my tuppence worth in.

Tube pressure is important. On a Zodiac SIB - I used to use the pressure gauge religiously. The inflatable keel was critical as this stopped the aluminium floor flexing and gave the boat rigidity.

Now onto RIBs and the gauge is just as important especially for tube longevity. Before launching, normally during boat preparation (and generally faffing about) I check each chamber for a pressure reading. Ribcrafts have pressure release valves fitted as standard which gives peace of mind.

Once the boat is in the water it will lose a little pressure due to temperature fluctuations. I don't tend to check the pressure again unless it's left overnight afloat.

It should be on your list of things to do before every trip. I takes literally minutes to do.