# Damage from Altitude Change?



## Kendarflugen (Jan 31, 2006)

I know tubes expand as altitude increases.

Has anyone actually had or heard of damage from, say, driving over Vail Pass?

Same with cool to hot... anyone had a tube blow?

I'm curious how fragile tubes are with regard to expansion.


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## Schutzie (Feb 5, 2013)

Kendarflugen said:


> I know tubes expand as altitude increases.
> 
> Has anyone actually had or heard of damage from, say, driving over Vail Pass?
> 
> ...


A WalMart air mattress might have an issue.
No worthwhile raft is going to have an issue with either a change in altitude or temp.

Once, I had a Udisco blow a seam but it went from cool morning pump up to full sun for several hours out of water before it blew. And, it was an old boat to start with.

I'd be more worried my girlfriend would.............

Never mind


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## Osprey (May 26, 2006)

I usually stop at one of the chain up areas this side of the tunnels going up from Denver and it's pretty solid hard by then. I'm not sure the relative change going over Vail is as great, I usually don't stop for that one. Coming home my raft will be pretty damn near flat by the time I get home. It can probably handle it going up but that's what I do.


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## Kendarflugen (Jan 31, 2006)

Schutzie said:


> I'd be more worried my girlfriend would.............
> 
> Never mind


Thanks Schutzie... no doubt my girlfriend is going to blow a tube going over Vail Pass.


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## Andy H. (Oct 13, 2003)

The outfitter my buddy and I bought that first raft from warned us about the tubes popping while driving out into the hot desert with an inflated boat. I've always wondered about whether overinflation stresses the seams and looked into it once. I found a table saying the pressure difference from Denver to the Tunnel is 2.5 PSI.

So if your boat is supposed to be at 2.5 PSI, and you drive it up to the tunnel the pressure in the tubes there is then 5 PSI. 

I always try to leave Denver with just enough air in my boat that it's not totally soft, it's hard as a rock at the Tunnel, and then I top off again in Eagle or Glenwood.

Maybe it won't pop, but I can't imagine it's good for the seams and all to have a rock hard boat.

Anyone that's got some better data on pressure difference over the passes would be greatly appreciated.

-AH


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## jakebrown98 (Mar 4, 2008)

Even if the main tubes would be fine, you might want to think about the floors. I know they are supposed to have relief valves that are supposed to work but I've met Murphy before. I pulled my Hyside out of a rather warm Klamath River and set it up on its side without bleeding it. Less than five minutes later I watched an I-beam start to zipper. Stupid move, I know, and I don't blame the boat. I think with floors in particular, the pressure can change too fast for a relief valve when it comes to temperature shifts. I don't know shit about altitude, but I suspect the math is more complicated than it sounds.


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## mbrookins (Jan 27, 2012)

jakebrown98 said:


> I don't know shit about altitude, but I suspect the math is more complicated than it sounds.


lets make some assumptions
1. there is no humidity changes 
2 there are no temperature changes 

then the math is simple 1.2 kPA change in atmospheric pressure per 100 m or 

1.2 kPA/100 m*(.145 PSI/kPA)*(.304m/ft)*1000 ft= .53 PSI/1000 ft


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## kengore (May 29, 2008)

Yes I have seen/heard a ducky blow. It was an internal bladder style boat and one of the side chambers popped as we topped the pass. Made a noise as loud as a gun! To be fair, I live up in the hills (8700 ft.) and there are there are several 3000 ft passes between me and the river.

It's not just the change in altitude, change in temperature contributes a lot. The inflated tubes experience large temperature swings; from parked in a hot asphalt lot while you fetch ice to chilled by a 60 mph breeze on the highway.

For me popping the boat wasn't as big an issue as tying it down. The changes in pressure meant that if the boat was tied in nice and snug at the top of the pass it was sliding around and the tubes flopping in the wind when I got to the valley. If I made them snug in the low lands they got way too tight as I climbed high. A got tired of adjusting straps.

I,m also concerned about the beating the rubber might take in a trailer bouncing along gravel roads. The leading edge of my trailer shows some significant damage from previous dessert shuttles.


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## Learch (Jul 12, 2010)

I live at about 200 ft above sea level and go over a 4000 ft pass to hit the Deschutes, I make sure the raft isn't topped off. We usually stop at the summit going both directions, and the raft feels pretty stiff (like it was topped off) at pass level. I run on the theory that if some flying road debris hit the raft while on the trailer, it is less likely to get punctured by it if the material is able to conform to it, rather than hit a super stiff tube that a sharp edge has an easy time pushing in to. More luck probably goes into it than that lol.


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## [email protected] (Jun 1, 2010)

I measured one trip over Vail and had gained 3 lbs. of pressure from starting point of 5200 ft. It had gotten slightly warmer also.
I have had more problems with my cooler sealing tight when I come off the pass. It took me a while on the river before I figured out I needed to pull the drain plug to open it.


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## Osprey (May 26, 2006)

Haha yeah, that's like trying to open a pelican case without knowing about the pressure valve. That's a dang good sealing cooler.


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## miker (Jan 26, 2006)

*Blowout*

Oh Yea! 

I pretty much ruined my first raft. It was an older Riken. I topped it off on a cold Denver morning. Then drove down to BV. While it was at the put in warming up in the hot sun on concrete it exploded. Blew out a chamber separator and the side of the raft. Never do that again. 

It was a great tool for Zach to learn how to repair at Raftfix.com. He did a great job.


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## BoilermakerU (Mar 13, 2009)

[email protected] said:


> I measured one trip over Vail and had gained 3 lbs. of pressure from starting point of 5200 ft. It had gotten slightly warmer also.
> I have had more problems with my cooler sealing tight when I come off the pass. It took me a while on the river before I figured out I needed to pull the drain plug to open it.


I make that drive a lot, and I always start with a pretty soft boat at home. On warm days, I'll stop somewhere along the way and check and even let air out if I have to. I'd rather have to work harder on the other end topping it back off than get there and not have a raft to run with!

Maybe I've been lucky so far, but no issues to date (*knocks* on wood)


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## Schutzie (Feb 5, 2013)

Kendarflugen said:


> Thanks Schutzie... no doubt my girlfriend is going to blow a tube going over Vail Pass.


Well, then you want to make sure she's a little soft when you start out, and you will need to check for stiffness as you go over the passes. It might also help to check the straps along the way. You won't want anything popping out or flapping loose.

*Schutzie puts himself in time out for shameless humor*


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## miker (Jan 26, 2006)

Schutzie said:


> Well, then you want to make sure she's a little soft when you start out, and you will need to check for stiffness as you go over the passes. It might also help to check the straps along the way. You won't want anything popping out or flapping loose.
> 
> *Schutzie puts himself in time out for shameless humor*


Where is the thumbs up button???!!!:razz:


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