Hypothetical (and daft) idea

BogMonster · 11 September 2006, 09:51

What would happen if you filled the tubes on a RIB with helium?

Surely as you would get "lift" from the tubes there would be less drag in the water and performance would improve?

Not that I have any helium, it was just a

moment

floater · 11 September 2006, 10:05

i have often though the same usually after the fluid stuff !

would you not have to work out the volume of the tubes and then the amount of lift that would be created by said volume of helium deducted from the overall gross weight then what ?

Andy

Pete7 · 11 September 2006, 10:38

Quote:

Originally Posted by BogMonster

What would happen if you filled the tubes on a RIB with helium?

You would be wasting a lot of expensive gas. Helium in the UK costs about 1p per litre. Do some sums to see how much you would need to inflate your tubes. Then how are you going to keep it in? Helium being much lighter will leak out past the valves and through the tube seams even if they are tight enough for Nitrogen.

If you want to go faster you need more power or less weight, so fewer pies

Pete

Poly · 11 September 2006, 10:50

I just did a back of envelope calculation:

25 cm radius tubes, 6 m long on each side of a boat is about 2,350,000 cm3 of gas.

With air - this weighs roughly three and a half kilos. Helium therefore can save you no more than 3 kg! Even if you could keep it in your tubes.

Matt · 11 September 2006, 11:55

I guess there could be an argument for using nitrogen though, same points as using nitrogen on car tyres.

Pete7 · 11 September 2006, 12:02

Quote:

Originally Posted by MadMat

I guess there could be an argument for using nitrogen though, same points as using nitrogen on car tyres.

Mat, most of use are already using 79% Nitrogen

Hightower · 11 September 2006, 12:11

One advantage of Helium is that you can detect leaks easier

. Everyone starts talking like "Chip and Dale" (Chipmonks).

Jus · 11 September 2006, 12:22

I once filled a SIB with expanding foam (stuff builders use), worked a treat and stopped all the leaks.

Matt · 11 September 2006, 12:27

I heard old spice is filled with a mix of CH4 & various sulphides.

Quote:

Originally Posted by Pete7

Mat, most of use are already using 79% Nitrogen

Pete7 · 11 September 2006, 12:31

Quote:

Originally Posted by MadMat

I heard old spice is filled with CH4

Nah, it's a very efficient clean burning diesel running on Haslar Marinas finest red

Mephane might be useful to cook on but I don't have a stove on O/S. How do you get on with it in Distant Fumble ?

codprawn · 11 September 2006, 12:38

Even better why not fill the tubes with nitrous oxide? You would get a hell of a perfomance boost - trouble is your tubes would go down the faster you went!!!

BogMonster · 11 September 2006, 15:20

Quote:

Originally Posted by Polwart

I just did a back of envelope calculation:

25 cm radius tubes, 6 m long on each side of a boat is about 2,350,000 cm3 of gas.

With air - this weighs roughly three and a half kilos. Helium therefore can save you no more than 3 kg! Even if you could keep it in your tubes.

OK so the whole idea was silly but if I hadn't asked I would never have known the answer

Pete7, less pies for me, correctly noted - I am a fat barsteward

I'll get to 40kt yet

Next question is whether or not if I bounce up and down on the jockey seat, whether the intermittent weight saving of [something over 100kg actual figure strictly classified] would get that last knot

Nos4r2 · 11 September 2006, 15:52

Quote:

Originally Posted by BogMonster

Next question is whether or not if I bounce up and down on the jockey seat, whether the intermittent weight saving of [something over 100kg actual figure strictly classified] would get that last knot

It worked when I was a kid on a skateboard

BogMonster · 11 September 2006, 19:26

Quote:

Originally Posted by Nos4r2

It worked when I was a kid on a skateboard

Cool. The other thing I could try (just occurred to me) is get to max speed and then jump over the stern with the kill cord attached to me using 400 yards of nylon twine, hopefully the weight loss would allow a speed increase, when it got to the end of the twine the engine would stop and I could then swim back to the boat and check the maximum speed on the GPS. Though on re-reading that idea and considering the current sea temperatures here, I think maybe I am getting too obsessed with 40kt

jyasaki · 12 September 2006, 07:19

Stephen;

I think you need to get hold of a couple of JATO bottles*.

Bolt 'em up to your radar arch, run up to WOT and light em off. You'd probably get a *lot* more than 40 kts.

jky

JATO = Jet Assisted Take Off; essentially a couple of solid fuel rockets which were attached to a plane, and lit to generate extra thrust for a short run takeoff or a high climbout rate, or both. Current examples can be seen by Fat Albert (the Blue Angel's support C-130 Hercules), who uses them at select airshows.
http://www.blueangels.com/fatalbertairlines.shtml

BogMonster · 12 September 2006, 09:40

Quote:

Originally Posted by jyasaki

Stephen;

I think you need to get hold of a couple of JATO bottles*.

Bolt 'em up to your radar arch, run up to WOT and light em off. You'd probably get a *lot* more than 40 kts.

jky

Yeah I've seen the Darwin award (where the guy fitted them to his car) too and you don't get rid of me that easily

Here for anybody who doesn't know what I am talking about...