Inflatable Dinghy

Hi Everyone,
We have a 10 ft Avon Inflatable Dinghy. The question is; is it common for the dinghy to become somewhat deflated over night and then get hard again during the day. Should I pump it up in the morning?
We live in Florida where the temperature fluctuates.

Thanks
Gordo

I have an older AB rib and I find the temperature has a large impact on the level of inflation. I generally have to reinflate the boat the next morning if I used it the previous day.

If you pump it up in the morning you do take a risk of overinflating it and possibly causing some damage unless it has a relief valve built in as mine does (Grande).

Gordon B said:

Hi Everyone,

We have a 10 ft Avon Inflatable Dinghy. The question is; is it common for the dinghy to become somewhat deflated over night and then get hard again during the day. Should I pump it up in the morning?

We live in Florida where the temperature fluctuates.



Thanks

Gordo

Click to expand...

You want it at the proper pressure when you use it. If you aren't using it at night when it is cold, you don't need to worry about it not being as hard then. If you are going to use the dinghy in the morning, add some air to get it to pressure, but you might want to let some out before it gets hot and risk over inflation.

An inflatable dinghy, like some other things, only needs to be hard when you are about to use it. The rest of the time it can be a bit flaccid.

This is a subject that Tom Brady and almost everyone in New England is well versed on. Don't forget to pump it up!!! ��

Gordon B said:

Hi Everyone,
We have a 10 ft Avon Inflatable Dinghy. The question is; is it common for the dinghy to become somewhat deflated over night and then get hard again during the day. Should I pump it up in the morning?
We live in Florida where the temperature fluctuates.

Thanks
Gordo

Click to expand...

Yes, though it would be easy to say "warm air expands, cold air contracts", some physicists will be quick to point out about how it's actually the movement of the air molecules as they get warmer, and that in colder temps there is less movement of the air molecules, therefore they take up less space......yadda, yadda, yadda.

As stated, avoid blowing it up in the morning, unless you're going to use it. If you do, be prepared to release some air pressure as the day warms up.

Our nights are getting down to 9c C. and my dingy goes down by 11pm at night thats when I do the last dog pee run .The dingy is the same at 6am in the morning for the morning dog pee run and by 10am its inflated back to 90% and 2pm its 100% .I just live with it otherwise Id be pumping up and deflating every time I use it

Most of us do not bring our dinghies up to full pressure as we should. We are afraid of damaging it from over pressure. If you were to use a pressure gauge for a while you will learn the "feel" of proper inflation. With proper inflation, the dinghy should be useable day and night, with very occasional topping off. If the dinghy is underinflated in the cool of the night, it was probably not fully inflated during the heat of the day. There is more damage done to inflatables by underinflation than by over inflation. Worked at Zodiac/Avon customer service and rib engineering for many years.

Thanks for the info tadhana.

I've been inflating all kinds of tenders large and small for decades and never worried about over inflation.

Nor have I every seen one get damaged from it. In fact I don't know if it's possible to truly over inflate one with a manual pump.

Capt.Bill11 said:

I've been inflating all kinds of tenders large and small for decades and never worried about over inflation.

Nor have I every seen one get damaged from it. In fact I don't know if it's possible to truly over inflate one with a manual pump.

Click to expand...

I think all inflatable dinghy's have a safety relief valve in every chamber so you cant over inflate

gaston said:

I think all inflatable dinghy's have a safety relief valve in every chamber so you cant over inflate

Click to expand...

Yep, mine does, but one chamber has a non standard pressure relief system I`m about to try to fix.

Capt.Bill11 said:

I've been inflating all kinds of tenders large and small for decades and never worried about over inflation.

Nor have I every seen one get damaged from it. In fact I don't know if it's possible to truly over inflate one with a manual pump.

Click to expand...

gaston said:

I think all inflatable dinghy's have a safety relief valve in every chamber so you cant over inflate

Click to expand...

No they don't, actually, but as pointed out by Tad Hana & Capt Bill, above, and stated categorically in the manual that came with my inflatable dink, if you only use the foot operated pump that comes with the dinghy, it is virtually impossible to over-inflate them, even when they then expand/firm up a bit more in the sun. So be happy, pump it up in the am if needed, and don't worry.

The only overpressure valves I've seen in inflatables have been in the military boats we built for the USCG and US Navy when I was at Zodiac/Avon. The ones we installed were bulky and expensive bronze fittings. I have not seen an O.P. valve in a recreational RIB. If someone has such a device in their RIB, I would be most interested to learn more about it and know who built it. I was in the inflatable boat industry with Zodiac until 2008. As of that date, there were no inflatable recreational ribs with an O.P. valve. We cruise full time, and so we see a lot of dinghies, I have not seen a dinghy with an O.P. valve in my wanderings.

#11



https://www.google.com.au/search?q=...2RwMnTAhVKpJQKHcYKDSoQsAQIKA&biw=1680&bih=888

Thank you, I had not realized they were now available. I wonder what manufacturers are using them as standard equipment. From what I have just read, it seems that it is an optional fitting, but if someone has it as standard that is great.

tadhana said:

Thank you, I had not realized they were now available. I wonder what manufacturers are using them as standard equipment. From what I have just read, it seems that it is an optional fitting, but if someone has it as standard that is great.

Click to expand...

They have been around since 1943 and most if not all inflatables have had them standard for as long as I can remember and thats a long time

I read somewhere where wasn't actually the air but the moisture in the air that cause the expansion and contraction. That's why they fill car tires with nitrogen it is dry and does not expand or contract

motion30 said:

I read somewhere where wasn't actually the air but the moisture in the air that cause the expansion and contraction. That's why they fill car tires with nitrogen it is dry and does not expand or contract

Click to expand...

By volume, air contains 78.09% nitrogen

Greetings,
Mr. 30. From my poor recollection of physics 101, everything expands and contracts due to temperature change. The use of nitrogen in tires for the average motorist is mainly a marketing gimmick BUT pure nitrogen does expand and contract less than air by a small amount. I don't think moisture content has all that much to do with it, again, for the average motorist/inflatable user.

There is more to using nitrogen than marketing.
USN uses nitrogen in our aircraft.

"I was in the inflatable boat industry with Zodiac until 2008. As of that date, there were no inflatable recreational ribs with an O.P. valve. We cruise full time, and so we see a lot of dinghies, I have not seen a dinghy with an O.P. valve in my wanderings."


Both of my Nautica's had them - my Zodiac came with a manometer which we used as well.
The pressure for the PVC tubes was different than the pressure for the Hypalon tubes.

"They have been around since 1943 and most if not all inflatables have had them standard for as long as I can remember and thats a long time."

These lightweight O.P. valves have not been in the US market until very recently. According to all of the US inflatable boat shops, these are not available as standard item in any of the main line boats built today. They are not available in Zodiac, Achilles, Avon, AB or Walker Bay. It is available as a separate part sold by some inflatable boat shops. It must separately purchased and must be installed separately into an inflatable. The O.P. valves which have been around since 1943 are the heavy duty bronze valves seen in military and commercial craft.

Thanks to everyone.

"They are not available in Zodiac, Achilles, Avon, AB or Walker Bay. It is available as a separate part sold by some inflatable boat shops. It must separately purchased and must be installed separately into an inflatable"


Halkey-Roberts valves installed by Nautica as a listed option on both my 2002 and my2010 inflatables. One OP valve per side in a 5 segment tube system.

"I have not seen an O.P. valve in a recreational RIB. If someone has such a device in their RIB, I would be most interested to learn more about it and know who built it."
I thought this was your original question so just pointed out that you could/can get them from some manufacturers.
There are other types of OP valves that are available as well as aftermarket.

A fully inflated dinghy has a pressure of about 3.2 psi. For every 35 degree F temperature rise, the air pressure rises about 1/4 psi. So if you fully inflate your dinghy at 70 degrees and then pull it up onto a tropical beach where the temperature gets up to 140 degrees, the tube pressure is only 3.75 PSI. A well built hypalon boat won't rupture till 17 PSI.

Defender does sell an OP valve, but don't recall that they have ever yet installed one for a customer, and they don't see the need for it. I checked with some other big dealers in Lauderdale and Tampa. They have not seen them in recreational boats. Novurania has a big dealer in Lauderdale. They have do not recall having seen OP valves in Novuranias.

So the short answer is that yes you can buy a valve and have it installed. About a two hour job. But you would need one in every chamber so you are looking at 6 hours of labor to fit the valves. Which according to the manufacturers and dealers are not really necessary anyway. Inflatable boat repair shops report that they see far more damage from under inflated boat than from over inflated boats.

Tadhana - which RIB dealer did you work for? I dealt with many of them on the East coats all the way down to Florida where I bought 3 of my RIBS.


"A fully inflated dinghy has a pressure of about 3.2 psi. For every 35 degree F temperature rise, the air pressure rises about 1/4 psi. So if you fully inflate your dinghy at 70 degrees and then pull it up onto a tropical beach where the temperature gets up to 140 degrees, the tube pressure is only 3.75 PSI. A well built hypalon boat won't rupture till 17 PSI."


Perhaps the math works out like that (I do not really know) but for those who have had pressure gages installed on the tubes we see pressure changes from right about 3 psi in the mornings to over 4 psi in the mid day sun. That is a 25% change and it is not advised to go to 4 psi with many "well made hypalon' boats". Some specs are even lower so check your owners manuals please. Now that static pressure needs to also account for people sitting jumping and otherwise straining the tubes and seams as well as the effects of hitting objects both sharp and not so sharp. Many high quality RIBS (Hypalon and PVC) are tested to 5-6 psi static at max.

"But you would need one in every chamber so you are looking at 6 hours of labor to fit the valves"
I agree with this 100% if you are filling by a compressed air tank - I have never done a fill with my dive tanks so I do not know. For typical use you fill each chamber part way (per the manual) and the baffles keep the pressure in the individual tubes separate. But as each tube is completely 'topped' off for pressure each adjacent tube affects the pressure of the next tube. So in normal situation (no compressed tank fill) having the OP valves in lead tubes 2 & 4 they protect pressure overfill in all 5.

I do not have my Nautica or other manuals handy anymore but there is an excerpt from a Novurania manual below...

If anyone wants to get some real great feedback on RIBS and inflatables by folks that are fanatics and very seriously involved post over at Rib.net - great stuff over there.






Below is straight from the Novurania owner's manual:


RECOMMENDED PRESSURE 3 PSI
Inflate all tube compartments to maximum pressure of 3 PSI. If a pressure gauge is not
available, check by depressing the tube with your finger. When the tube cannot be
depressed by finger pressure, the approximate working pressure has been reacted.
CAUTION
The foot pump provided with your Novurania will not allow over-inflation of the tubes.
NEVER use dive tanks, air compressor etc., to inflate tubes; over inflation can occur
causing damage to the tubes and seams. Under-Inflation can cause excessive stress on
the tubes and hull, always maintain proper inflation pressure while operating your boat.
IMPORTANT
If the boat will be exposed to direct sunlight for a long period of time, slightly deflate the
tubes to compensate for expansion due to heat.

The Achilles manual also recommends adjusting the pressure as ambient temperatures change, suggesting that the pressure could double in some circumstances and possibly damage internal seams.

This is especially a concern if your dinghy is a darker than usual colour like mine (orange on top and black on the bottom). I usually inflate it to it to 80% of recommended pressure and leave a bit of room for expansion, unless I'm inflating it in the midday sun. It does have a very slow leak, so that is my safety valve.

"The Achilles manual also recommends adjusting the pressure as ambient temperatures change, suggesting that the pressure could double in some circumstances and possibly damage internal seams."


The low pressure gages from Zodiac and others have a long sweep on a low pressure range and do a great job telling you exactly what pressure yo do have - I wish we bought one 30 years back rather than 10 years back.
For not so much money you know if you are low or high and can be sure whether you are in range for your particular boat.
The zodiac ones could stay in the fil valve if you wanted to but we typically just popped it in when we wanted to check the pressure.