Reply
 
Thread Tools Search this Thread
 
Old 19 May 2015, 15:02   #1
Member
 
Country: USA
Town: Chicago
Make: N/A
Length: no boat
Engine: N/A
Join Date: Jan 2015
Posts: 75
Inflation Questions

A few questions for the more experienced SIB'ers out there... Having trouble planing, and just want to rule out the apparent #1 cause of SIBs not planing (underinflation).

1. Is it safe to inflate Zodiac tubes 0.5psi higher than the stated 3.5psi inflation pressure? Would doing so offer any extra ridgidity?

2. I inflate my buoyancy tubes with the valves in the closed position, since they are one-way and will let air in when closed. I find that with the cross bars still in the adapters, the valves will stay open more often than not, letting the air out. I removed those bars at the recommendation of my dealer. Is inflating like this going to make my Bravo BTP12 Manometer electric inflator read a higher pressure than what's actually in the tube?

3. Can one tell if their tubes are underinflated or overinflated by the "feel" of the tubes?
__________________
kestrel452 is offline   Reply With Quote
Old 19 May 2015, 15:13   #2
Member
 
The Gurnard's Avatar
 
Country: UK - Scotland
Town: Stirling
Boat name: The Gurnard
Make: Quicksilver
Length: 4m +
Engine: mariner 25hp 2s
Join Date: Jul 2013
Posts: 1,653
Quote:
Originally Posted by kestrel452 View Post
3. Can one tell if their tubes are underinflated or overinflated by the "feel" of the tubes?
Hi..I have a Quicksilver 4.3m inflatable SIB..and have never put a pressure gauge near it.

I just top it up with the hand pump..until it passes the "thump test" In other words..I give it a thump with clenched fist..and it bounces off when righ pressure is achieved. Nothing so scientific as PSI or millibars. Its 10 years old now and the previos owner just did a thump test on it...so no harm has ever resulted in it.

It is a wooden floor though..not a new fangled air floor that needs pressure tested.

It planes no problem at all. It has an inflatable keel under the wooden floor..which I deflate if Im hauling up a shore for a while. If I forget to inflate it again..it still planes easy..but causes a bit of a bow wave.

Perhaps that answers some of your question.. unless its an air floor SIB.. IMO..its not critical

Engine is 25HP for this SIB
__________________
The Gurnard is offline   Reply With Quote
Old 19 May 2015, 15:16   #3
Member
 
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,653
1) I wouldn't. And no, probably not. Underinflated show up with the boat sort of arching in the middle as you try to climb out of the hole; or flexing as you hop over swell and chop. Put as much weight as you can forward, whack the throttle open, and see if you climb out.

2) No idea. My Bravo 12 (the box-like grey job with the adjustable shutoff - don't remember the model) specifically says valves should be open to inflate (though I suspect that's to allow the squirrel cage high volume stage to run.) Can you open the valve and allow the pump to inflate it and feel how taut the material is?

3) Experience helps, but you need to get a feel for what "correct" feels like. Which means you have to be pretty sure of the pressure.

jky
__________________
jyasaki is offline   Reply With Quote
Old 19 May 2015, 18:05   #4
Member
 
chipko's Avatar
 
Country: UK - England
Town: Up North and right a bit
Make: XS500/Merc340/Bic245
Length: 5m +
Engine: Mar 60/20/3.5/Hon2.3
Join Date: Sep 2013
Posts: 1,055
Inflation Questions

Theoretically shouldn't do any harm to inflate to 4psi, but also wouldn't offer any performance benefit. Zodiac recommend .24 bar (3.5 psi), but also give a range between .22 and .27 bar (3.2 to 3.9 psi) as an operating range. Just be careful of any pressure increase caused by temperature rise/hot sun if running at 4psi.

I also inflate with the one way valves in closed position with both Bravo and Genovo battery pumps and no cross bars in the adapters.

Properly inflated tubes feel rock hard and offer a nice ping when flicked. In my experience people who don't use a gauge (at least initially) are amazed how hard a correctly inflated tube feels. I also contribute to the theory that 90% of a sibs performance comes with the last 10% of pressure.👍
__________________
chipko is online now   Reply With Quote
Old 20 May 2015, 19:15   #5
Member
 
Country: USA
Town: S. Carolina
Boat name: D560
Make: Avon
Length: 5m +
Engine: 2016 Merc 115hp CT
Join Date: Aug 2013
Posts: 1,277
Quote:
Originally Posted by chipko View Post
Properly inflated tubes feel rock hard and offer a nice ping when flicked. In my experience people who don't use a gauge (at least initially) are amazed how hard a correctly inflated tube feels. I also contribute to the theory that 90% of a sibs performance comes with the last 10% of pressure.👍
Amen to that.

My FC470 RU performs like a wet noodle once the pressure is below 2.8 psi.
__________________
Richard
Gluing geek since 2007
Opinions and intepretations expressed are solely my own and do not express the views or opinions of my employer
office888 is offline   Reply With Quote
Old 21 May 2015, 01:48   #6
Member
 
Country: Australia
Town: Dalmeny
Make: zodiac
Length: 5m +
Engine: outboard
Join Date: May 2015
Posts: 1,200
Being new to ribs and having tubes black at the front and grey at the back temp makes a huge difference to my tubes.

Its now winter so my Zodiac sits in my garage cooling down to 0-10c, when the sun comes up it quickly rises to 22-24c and the black tubes obviously warming well above that.

Question is should I be constantly checking throughout the day and what harm can come from driving home on dark or during cold cloudy days when the tubes become a little soft?

Even summer with temps in the high 30's we can get a sudden hale storm dropping temps dramatically.

Cheers Jon

__________________
jonp is offline   Reply With Quote
Old 21 May 2015, 10:49   #7
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Excel 435
Length: 4m +
Engine: Suzuki Outboard/25/4
Join Date: Oct 2011
Posts: 7,443
RIBase
as gurnard says pump up solid job done trouble with psi is pump up on trailer put in the ogin psi changes pump up on dull day sun comes out pressure changes. i have pressure relief valves on mine pump to recommended pressure and leave they stay good all year might have to top up when its a really cold day
__________________
jeffstevens763@g is offline   Reply With Quote
Old 21 May 2015, 11:01   #8
Member
 
Lee argyle's Avatar
 
Country: UK - England
Town: Porchfield
Boat name: Katie
Make: Stingher
Length: 10m +
Engine: Verado 350 x 2
Join Date: Jan 2011
Posts: 695
A mate has I think a humber? Yellow and black tubes and she blew a seam on one of the really hot summer days last year, its an old rib and I guess the extra pressure found a weak spot
__________________
Fully fledged member of the ‘Bordering negligent and very irresponsible club’.
Lee argyle is offline   Reply With Quote
Old 21 May 2015, 15:55   #9
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Excel 435
Length: 4m +
Engine: Suzuki Outboard/25/4
Join Date: Oct 2011
Posts: 7,443
RIBase
Quote:
Originally Posted by Lee argyle View Post
A mate has I think a humber? Yellow and black tubes and she blew a seam on one of the really hot summer days last year, its an old rib and I guess the extra pressure found a weak spot
you can not beat the pressure relief valves lee well worth the money but in the old days we use to undo the dust cap which is the last seal for the air and if they looked a bit hard we just touched the valve to let a bit out.
__________________
jeffstevens763@g is offline   Reply With Quote
Old 22 May 2015, 01:57   #10
Member
 
Country: Australia
Town: Dalmeny
Make: zodiac
Length: 5m +
Engine: outboard
Join Date: May 2015
Posts: 1,200
Does anyone know if these are relief valves? (doesn't say in the book)

If the rib is up on the plane how can slightly soft tubes effect performance, surely the tubes are skimming above or only slightly touching the surface?

Sorry for my ignorance Im new to owning a rib and also living in an area they are not popular due to the harsh conditions. This site also states to search for an answer rather than starting a new thread on something already covered.

Jon

__________________
jonp is offline   Reply With Quote
Old 22 May 2015, 02:34   #11
Member
 
Country: USA
Town: S. Carolina
Boat name: D560
Make: Avon
Length: 5m +
Engine: 2016 Merc 115hp CT
Join Date: Aug 2013
Posts: 1,277
Quote:
Originally Posted by jonp View Post
Does anyone know if these are relief valves? (doesn't say in the book)

If the rib is up on the plane how can slightly soft tubes effect performance, surely the tubes are skimming above or only slightly touching the surface?

Sorry for my ignorance Im new to owning a rib and also living in an area they are not popular due to the harsh conditions. This site also states to search for an answer rather than starting a new thread on something already covered.

Jon
The pictured valve is the new Zodiac push-push valve that was introduced in about 2009.

It is only a toggle-able one-way valve. It does not act as a pressure relief valve.

A reduction in tube pressure can cause high frequency oscillations in the tube set which can cause premature wear on the sterns, especially the stern-most perpendicular seam before the cone.

In SIBs, low tube pressure can cause a lack of rigidity in the vessel, which can cause the bow to drag, increasing the friction to the water, and reducing performance.

RIBs aren't affected as much, but you can really trash your tubeset running it underinflated.

Bottom line, check the pressure after putting the boat in the water. It should be 3.5 psi.
__________________
Richard
Gluing geek since 2007
Opinions and intepretations expressed are solely my own and do not express the views or opinions of my employer
office888 is offline   Reply With Quote
Old 22 May 2015, 04:39   #12
Member
 
Country: Australia
Town: Dalmeny
Make: zodiac
Length: 5m +
Engine: outboard
Join Date: May 2015
Posts: 1,200
Thanks for that, I will certainly need to put a little more pressure in then and maybe look at getting some relief valves especially on the black tubes.

Thanks Jon
__________________
jonp is offline   Reply With Quote
Old 22 May 2015, 06:29   #13
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Excel 435
Length: 4m +
Engine: Suzuki Outboard/25/4
Join Date: Oct 2011
Posts: 7,443
RIBase
that's an inflation valve Jon in your book or boat spec it will tell you how many chambers your boat has i.e. three chambers three valves if you have relief valves as well not far away from the inflation valves when you take the cap off all you see is a flat rubber mushroom valve which you can not press as the air pushes past it when at the required pressure.
__________________
jeffstevens763@g is offline   Reply With Quote
Old 22 May 2015, 07:06   #14
Member
 
Country: Australia
Town: Dalmeny
Make: zodiac
Length: 5m +
Engine: outboard
Join Date: May 2015
Posts: 1,200
Quote:
Originally Posted by jeffstevens763@g View Post
that's an inflation valve Jon in your book or boat spec it will tell you how many chambers your boat has i.e. three chambers three valves if you have relief valves as well not far away from the inflation valves when you take the cap off all you see is a flat rubber mushroom valve which you can not press as the air pushes past it when at the required pressure.
Thanks mate, Ive got 5 chambers just wasn't quite sure if those small green plastic bits on the end were some sort of release valve (obviously not). The guy I bought the boat off had only done 47 hrs on the water and claimed to of never checked the air pressure since buying it

After checking with the gauge I first thought the gauge must be faulty but after hearing how hard they should be on here when properly inflated I was way under (not even registering on the gauge). Ive just pumped each section up in my garage in cool conditions to 1.5 psi and they now feel very firm, next trip out I will carefully check Im closer to the 3.5psi.

All ribs seem to be hard to get info on over here (apart from this site), I contacted the closest dealer who only gets boats or parts to order and is 5hrs from where I live, he couldn't give me any prices on a 12 volt pump, step ladder, fuel tank size (pretty much everything). Still waiting for him to get back to me (3 weeks). By the way Ive since found a label on my underfloor tank stating 97lt.

Thanks again Jon
__________________
jonp is offline   Reply With Quote
Old 22 May 2015, 07:25   #15
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Excel 435
Length: 4m +
Engine: Suzuki Outboard/25/4
Join Date: Oct 2011
Posts: 7,443
RIBase
Quote:
Originally Posted by jonp View Post
Thanks mate, Ive got 5 chambers just wasn't quite sure if those small green plastic bits on the end were some sort of release valve (obviously not). The guy I bought the boat off had only done 47 hrs on the water and claimed to of never checked the air pressure since buying it

After checking with the gauge I first thought the gauge must be faulty but after hearing how hard they should be on here when properly inflated I was way under (not even registering on the gauge). Ive just pumped each section up in my garage in cool conditions to 1.5 psi and they now feel very firm, next trip out I will carefully check Im closer to the 3.5psi.

All ribs seem to be hard to get info on over here (apart from this site), I contacted the closest dealer who only gets boats or parts to order and is 5hrs from where I live, he couldn't give me any prices on a 12 volt pump, step ladder, fuel tank size (pretty much everything). Still waiting for him to get back to me (3 weeks). By the way Ive since found a label on my underfloor tank stating 97lt.

Thanks again Jon
to be honest Jon i can believe he hasn't pumped them up i only do mine once a year mine should be at 3 psi which seems to be the norm apart from high pressure floors there should be a plate showing pressure somewhere on the transom.
zodiac have a good website with all the info you require with costs for all there kit if not there will be info for a dealer near you.i bought a bravo pump over here in the UK cost was about £100 i do know that takakat over in new Zealand sell 12v pumps and ship world wide have a look at them.

cheers jeff
__________________
jeffstevens763@g is offline   Reply With Quote
Old 22 May 2015, 08:54   #16
Member
 
Country: Australia
Town: Dalmeny
Make: zodiac
Length: 5m +
Engine: outboard
Join Date: May 2015
Posts: 1,200
Plate states 3.4 but will try for 3 (temp depending), no pricing online here with Zodiac but I get a rough idea going off the UK site.

Jon
__________________
jonp is offline   Reply With Quote
Old 22 May 2015, 09:49   #17
Member
 
Country: UK - England
Town: Sussex
Boat name: Bombard
Make: Aerotec 380
Length: 3m +
Engine: Mercury Mariner 15hp
Join Date: Jul 2010
Posts: 3,398
Every SIB owner unless they are plodding along the river needs a decent pressure gauge. Tubes are generally 3.4 psi and the last 1/2 psi makes all the difference. This is especially true with HP air floor SIB's where inflating to say 9 or 10 when they should be 11.2 to 11.4 means they handle like a wallowly waterbed.

Easy to make a very accurate pressure gauge for a few £'s.

http://www.rib.net/forum/f50/adaptin...sib-42375.html
__________________
Max... is offline   Reply With Quote
Old 22 May 2015, 10:46   #18
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Excel 435
Length: 4m +
Engine: Suzuki Outboard/25/4
Join Date: Oct 2011
Posts: 7,443
RIBase
inflate to what it says on the plate as a maximum Jon pic of my plate 3 psi

cheers
Attached Thumbnails
Click image for larger version

Name:	pics of all aspects of the boat 038.jpg
Views:	233
Size:	97.4 KB
ID:	105518  
__________________
jeffstevens763@g is offline   Reply With Quote
Old 22 May 2015, 16:56   #19
RIBnet supporter
 
bartiny's Avatar
 
Country: UK - England
Town: Accrington
Length: no boat
Join Date: Oct 2012
Posts: 451
This is the type that I used on my Humber SIB, Took no more than half hour to fit 3 of them.

NEW A 6 Leafield Air Pressure Relief Valve Boat Rib Inflatable Marine Sib PRV C7 | eBay

__________________
bartiny is offline   Reply With Quote
Old 22 May 2015, 17:18   #20
Member
 
Country: USA
Town: S. Carolina
Boat name: D560
Make: Avon
Length: 5m +
Engine: 2016 Merc 115hp CT
Join Date: Aug 2013
Posts: 1,277
Most Zodiac Products = 240 millibar - 3.48 psi.
__________________
Richard
Gluing geek since 2007
Opinions and intepretations expressed are solely my own and do not express the views or opinions of my employer
office888 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT. The time now is 17:52.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.