Reply
 
Thread Tools Search this Thread
 
Old 13 January 2008, 21:30   #1
Member
 
Country: Other
Town: San Carlos, Mexico
Boat name: INDE
Make: LOMAC 730
Length: 7m +
Engine: 200 Merc.
MMSI: Please press 1
Join Date: May 2006
Posts: 1,688
Send a message via Skype™ to Limey Linda
Topping up da toobs

Has anyone used a CO2 for topping up the tubes. I have a few paintbal gun cylinders that I can refill from a large tank at home. Any comments would be welcome. I know you cannot do it too fast without freezing.
Thanks
__________________

__________________
Running around like a head with it's chicken cut off.
Limey Linda is offline   Reply With Quote
Old 14 January 2008, 02:33   #2
Member
 
Country: Ireland
Town: South East
Make: Valiant DR520
Length: 5m +
Engine: Yamaha 75
Join Date: Mar 2005
Posts: 53
Often did it from dive bottle, just keep the jet about 3 inches from the valve then when the tube gets hard the pressure equalizes and valve lets no more in. The only thing about CO2 is the fact that it becomes a weak acid when disolved with any salt water that may be in the tubes, so may rot the tubes from the inside.
__________________

__________________
keelhauled is offline   Reply With Quote
Old 14 January 2008, 15:24   #3
Member
 
Country: Other
Town: San Carlos, Mexico
Boat name: INDE
Make: LOMAC 730
Length: 7m +
Engine: 200 Merc.
MMSI: Please press 1
Join Date: May 2006
Posts: 1,688
Send a message via Skype™ to Limey Linda
Quote:
Originally Posted by keelhauled View Post
Often did it from dive bottle, just keep the jet about 3 inches from the valve then when the tube gets hard the pressure equalizes and valve lets no more in. The only thing about CO2 is the fact that it becomes a weak acid when disolved with any salt water that may be in the tubes, so may rot the tubes from the inside.
That is could to know, thanks. I assume there would no problems using nitrogen.
__________________
Running around like a head with it's chicken cut off.
Limey Linda is offline   Reply With Quote
Old 14 January 2008, 15:27   #4
Member
 
Tim M's Avatar
 
Country: UK - England
Make: Avon Searider SR4
Length: 4m +
Engine: Yamaha 50
Join Date: Jan 2004
Posts: 5,796
I don't see why not - afterall liferafts are filled with CO2 very quickly.
__________________
Tim M is offline   Reply With Quote
Old 17 January 2008, 05:22   #5
Member
 
Cookee's Avatar
 
Country: UK - England
Town: Salcombe, Devon, UK
Boat name: BananaShark
Make: BananaShark
Length: 10m +
Engine: 2xYanmar 260 diesels
Join Date: Mar 2003
Posts: 4,225
Quote:
Originally Posted by Limey Linda View Post
That is could to know, thanks. I assume there would no problems using nitrogen.
I seem to remember that nitrogen is preferred as it is less likely to leak (bigger molecules or something) and expands less in heat - might be wrong though! I think they might fill tyres with it as well for a similar reason?
__________________
Cookee
Originally Posted by Zippy
When a boat looks that good who needs tubes!!!
Cookee is offline   Reply With Quote
Old 17 January 2008, 05:45   #6
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 12,908
RIBase
Quote:
Originally Posted by Cookee View Post
I seem to remember that nitrogen is preferred as it is less likely to leak (bigger molecules or something) and expands less in heat - might be wrong though! I think they might fill tyres with it as well for a similar reason?
Someone on Iboats.com forums suggested filling the tubes with nitrogen for exactly that reason-apparently it's common in the USA to fill tyres with it.

Quote:
Originally Posted by Tim M
I don't see why not - afterall liferafts are filled with CO2 very quickly
Not sure the comparison to liferafts really counts though-they aren't left inflated for years at a time. It's an interesting question though.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 17 January 2008, 07:48   #7
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,910
Quote:
Originally Posted by Nos4r2 View Post
Someone on Iboats.com forums suggested filling the tubes with nitrogen for exactly that reason-apparently it's common in the USA to fill tyres with it.
Surely our tubes have 79% Nitrogen in them anyway?

Pete
__________________
.
Ribnet is best viewed on a computer of some sort
Pete7 is offline   Reply With Quote
Old 17 January 2008, 11:55   #8
Member
 
Country: UK - England
Town: cookoo land
Boat name: tba
Make: ribcraft 595
Length: under 3m
Engine: Suzi 140
Join Date: Sep 2007
Posts: 316
Boom

Hows about hydrogen! The positive bouyancy must reduce fuel consumption! Maybe thats what they use in them french ribs?


Seriously though........what about helium? Anyone done any experiments? Very expensive though.
__________________
BassBoy is offline   Reply With Quote
Old 17 January 2008, 12:00   #9
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,910
Helium costs about 1p per litre, now work out how many litres you would need to fill your tubes. The other problem is helium is a very light gas and would leak out past valve seals and through the material seams.

Oddly enough ordinary air seems to be quite a cost effective solution

Pete
__________________
.
Ribnet is best viewed on a computer of some sort
Pete7 is offline   Reply With Quote
Old 17 January 2008, 12:06   #10
Member
 
Country: UK - England
Town: cookoo land
Boat name: tba
Make: ribcraft 595
Length: under 3m
Engine: Suzi 140
Join Date: Sep 2007
Posts: 316
Cheaper than I thought!

My question was really...... has anyone ever tried it?.
I'm sure some crazy naval architect has had access to the required seaming/valve technology and budget to give it a go.
__________________
BassBoy is offline   Reply With Quote
Old 17 January 2008, 15:39   #11
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,183
Quote:
Originally Posted by BassBoy View Post
Cheaper than I thought!

My question was really...... has anyone ever tried it?.
I'm sure some crazy naval architect has had access to the required seaming/valve technology and budget to give it a go.
Ignoring the problems of sealing. The weight difference is tiny. In a typical 6.5 m rib the tubes will (roughly) have a volume of 3000-4000 L. So at best would save you about 4 kg of weight. Thats about the same as one small spare (car sized) fuel can, or everyone on the boat going to the toilet before they leave, or probably completely drying the inside of the boat and bildge.
__________________
Poly is offline   Reply With Quote
Old 17 January 2008, 17:05   #12
Member
 
Country: Other
Town: San Carlos, Mexico
Boat name: INDE
Make: LOMAC 730
Length: 7m +
Engine: 200 Merc.
MMSI: Please press 1
Join Date: May 2006
Posts: 1,688
Send a message via Skype™ to Limey Linda
I did some digging around in the garage and found a 1 ltr. nitrogen tank rated to 3000psi. It has a regulator on it bringing down to 800psi, a pressure gauge and safety valve. If I can fill it to 2000psi this would seem to give a useful volume of gas at 2psi. Any math. whiz kid want to run a sanity check on this?
__________________
Running around like a head with it's chicken cut off.
Limey Linda is offline   Reply With Quote
Old 17 January 2008, 17:11   #13
Member
 
Country: Other
Town: San Carlos, Mexico
Boat name: INDE
Make: LOMAC 730
Length: 7m +
Engine: 200 Merc.
MMSI: Please press 1
Join Date: May 2006
Posts: 1,688
Send a message via Skype™ to Limey Linda
I did some digging around in the garage and found a 1 ltr. nitrogen tank rated to 3000psi. It has a regulator on it bringing down to 800psi, a pressure gauge and safety valve. If I can fill it to 2000psi this would seem to give a useful volume of gas at 2psi. Any math. whiz kid want to run a sanity check on this?
__________________
Running around like a head with it's chicken cut off.
Limey Linda is offline   Reply With Quote
Old 17 January 2008, 17:39   #14
Member
 
Country: UK - England
Boat name: Ribell
Length: no boat
Join Date: Oct 2006
Posts: 195
Could well be wrong here, but i think at atmospheric pressure (14.7 PSI) you would get 130L (ish) from the full tank. (you get 660L from a 5L oxygen tank)

Not sure what you would get at 2psi - 1000 ish

Tim
__________________
v666 is offline   Reply With Quote
Old 17 January 2008, 18:15   #15
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,910
Quote:
Originally Posted by Limey Linda View Post
want to run a sanity check on this?
I think you will need about 30 of them to pump your tubes up from flat.

Pete
__________________
.
Ribnet is best viewed on a computer of some sort
Pete7 is offline   Reply With Quote
Old 17 January 2008, 18:43   #16
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,183
Quote:
Originally Posted by Pete7 View Post
I think you will need about 30 of them to pump your tubes up from flat.

Pete
I got 20 of them but it obviously depends what assumptions you make about limey's tubes. (I was assuming 50cm diam and total 15m long).
__________________
Poly is offline   Reply With Quote
Old 17 January 2008, 19:13   #17
Member
 
Country: Other
Town: San Carlos, Mexico
Boat name: INDE
Make: LOMAC 730
Length: 7m +
Engine: 200 Merc.
MMSI: Please press 1
Join Date: May 2006
Posts: 1,688
Send a message via Skype™ to Limey Linda
Quote:
Originally Posted by Polwart View Post
I got 20 of them but it obviously depends what assumptions you make about limey's tubes. (I was assuming 50cm diam and total 15m long).
That's about right and as already stated I only intend to use nitrogen tank to top off rather than carry a 12v. pump. I carry a stirup type pump also but the ally tank would be a lot easier. Just found out I can fill the tank for about 2 bucks at the paintball range at the end of my road. Thanks for the input. BTW, if the tubes are totally flat I use my big arse compressor to fill them. Just a tip if using a compressor you need to make an expansion chamber in the fill tube as high pressure air will damage the tube valve and do not use a fixed attachment just a push fit so you have to hold it in place. Otherwise a small distraction could end up with burst tubes.
__________________
Running around like a head with it's chicken cut off.
Limey Linda is offline   Reply With Quote
Old 18 January 2008, 04:27   #18
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,910
Quote:
Originally Posted by Polwart View Post
I got 20 of them but it obviously depends what assumptions you make about limey's tubes. (I was assuming 50cm diam and total 15m long).
Yep plus I added the pressure to raise above atmospheric and a fudge factor because there will be some leakage changing over cylinders.

Still think a foot pump is a better solution, its free with unlimited supply of gas and good exercise which some of those colonists could do with

Pete
__________________

__________________
.
Ribnet is best viewed on a computer of some sort
Pete7 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 -5. The time now is 02:41.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.