How can I keep it hard longer?

R

Rick486

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Oct 1, 2007
1,865
Boston Whaler Super Sport Pt. Judith
Hi all:
I have a 10 ft AB inflatable about 12 years old. It has been trouble free but has always seemed to be temperature sensitive. Whenever the temperature drops, the tubes soften. Of course the density of the air inside will decrease with lower temperature, which will tend to soften the tubes, and vice versa. However, the dinghy next to mine on the dinghy float is a brand new AB, same model as mine. I noticed that his dinghy seems to be less temperature sensitive than mine such that his stays hard and mine softens.
So, the question is am I doing something wrong here? Maybe I don't pump it up enough initially? How hard should it be? Or is there something else? How do you maintain your inflatable?
I'd appreciate your thoughts.
Thanks
Rick
 
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jviss

jviss

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Feb 5, 2004
7,089
Tartan 3800 20 Westport, MA
I don't recall the exact figure for AB inflatables (I have one, the VS9), but the tube pressure should be 2.5 to 3 psi. You need a special gauge for this.

Age makes a difference. the fabric seems to become less elastic, and also develops otherwise undetectable leaks. Naturally, the more elastic, the less susceptible to the phenomenon you describe.
 
Rich Stidger

Rich Stidger

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Feb 10, 2004
4,070
Hunter 40.5 Warwick, RI
Just a thought- perhaps in hot weather the air expands and pressure rises. The increased pressure causes some air to leak past the cap gaskets. Then as the temperature cools, the boat becomes soft.

When was the last time you replaced/cleaned the o-rings or gaskets at the cap?
 
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FastOlson

FastOlson

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Apr 8, 2010
2,040
Ericson Yachts Olson 34 28400 Portland OR
We finally decided to junk our great old Zodiac after about 20 years due to near-undetectable seam leaks. dealer said that there was a way to put a liquid sealant inside and slowly rotate the inflated boat for a number of hours to allow the thin sealant to be drawn into the tiny leaking areas, but that it was sometimes ineffective.
The scheme seemed too unreliable (kind of like the fix-a-flat stuff you inject into your flat tire to get you home... and then throw away the tire).
We bought a new dinghy instead.
Whether we made the 'right' decision is another discussion. Inflatable Dinghies have a lot of advantages, but also a limited useable life. This opinion worth only 2 cents on a good day! :)

ps: as Rich points out, do check on the valves and caps!
 
capta

capta

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Jun 4, 2009
4,876
Pearson 530 Admiralty Bay, Bequia SVG
On a hot tropical sunny day our Zodiac is about as hard as a basketball and it stays hard at night, even in the winter. But we don't have the temperature changes you have up there.
I firmly believe that keeping an inflatable hard is the reason we get such a long life from ours. An under inflated dinghy will flex when in use which I think is very bad for the seams.
 
rgranger

rgranger

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Jan 19, 2010
12,548
Hobie 16 & Rhodes 22 Skeeter Charleston
It is all I can do not to let my inner 13 year old out.:oops:




But on a serious note. Pressure (P) and temperature (T) can be related by the equation

PV=nRT. V= volume (constant) and if you don't have a leak then n (number of moles of gas) is a constant (and R is the "gas constant") so... P = cT where c is the combined constants. You should expect the pressure to change with temperature so if you do not have a leak then I suggest you fill it firm on a cool day. It should get ridiculously hard around noon but then "soften" back up to just plain old hard in the evening. If that does not happen and it gets soft again, then you have a leak.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
22,224
CAL 35 Cruiser #21 moored EVERETT WA
rgranger said:
It is all I can do not to let my inner 13 year old out.:oops:
Click to expand
I had refrained comment as all of the responses had been so helpful. Then you go and do it.
Thanks...:laugh:
 
Richard19068

Richard19068

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Jun 11, 2004
1,700
Oday 31 Redondo Beach
Rick486 said:
Hi all:
I have a 10 ft AB inflatable about 12 years old. It has been trouble free but has always seemed to be temperature sensitive. Whenever the temperature drops, the tubes soften.
Click to expand
If it softens when it's cold does it re-harden when it warms back up?
If so it is probably just underinflated from the start.


FastOlson said "dealer said that there was a way to put a liquid sealant inside and slowly rotate the inflated boat for a number of hours to allow the thin sealant to be drawn into the tiny leaking areas."
I did that once with an old Achilles and it worked very well to cure slow leaks.
 
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Bob S

Bob S

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Sep 27, 2007
1,780
Beneteau 393 New Bedford, MA
Just have to get used to it soft, just don't jump into it to quickly!
 
Scott T-Bird

Scott T-Bird

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Oct 26, 2008
6,216
Catalina 320 Barnegat, NJ
I'm guessing that nobody actually ever puts a gauge on the inflation. I've been wondering about it. How are you supposed to know how inflated it should be? My brand new Zodiac labels the chambers from 3.5 psi to 11 psi for the air floor. How are you supposed to know without over inflating?
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
22,224
CAL 35 Cruiser #21 moored EVERETT WA
On my boat, Scott, the valve and the pump do not have a way to install a gauge. I suspect it could be engineered.
 
Richard19068

Richard19068

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Jun 11, 2004
1,700
Oday 31 Redondo Beach
Scott T-Bird said:
I'm guessing that nobody actually ever puts a gauge on the inflation. I've been wondering about it. How are you supposed to know how inflated it should be? My brand new Zodiac labels the chambers from 3.5 psi to 11 psi for the air floor. How are you supposed to know without over inflating?
Click to expand
Something like these?

shop.inflatableboatparts.com

Bravo In-line Inflatable Boat Pressure Gauge - Manometer - Inflatable Boat Parts

Bravo Inflatable Boat pressure gauge for Achilles, West Marine, Nautica, and Highfield Inflatables. Reads pressure while inflataing your boat. Up to 14 PSI. Works on Halkey Roberts Valves.
shop.inflatableboatparts.com shop.inflatableboatparts.com

www.inflatableboats.net

Achilles Inflatable Boat Parts | Bravo 9 HP Pressure Gauge - E136

Boat Specialists stocks fiberglass and inflatable boats from top brands like Zodiac, Sea Fox, Achilles, AB Inflatables, Avon and Inmar Inflatable boats; Outboards from Yamaha, Honda, Tohatsu, Mercury and Torqeedo.
www.inflatableboats.net www.inflatableboats.net
 
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dLj

dLj

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Mar 23, 2017
3,844
Belliure 41 Back in the Chesapeake
Way over-thinking things here. But hey, toys are fun!

You could also use like a basket ball, pump it up. Use a tire gauge on the needle valve and put it in and feel how it feels at 3 psi, pump it up to 11 psi and feel that. It will be noticably different. Then you have calibrated you hand... No more gauge needed...

dj
 
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