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Advice on Raft Jumps

 

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jclalor  (B 33202)

Jun 19, 2010, 12:18 AM
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Advice on Raft Jumps Can't Post

Was looking for any advice on launching a 2 man raft out of a SkyVan.

--Thanks --


sundevil777  (D License)

Jun 19, 2010, 5:02 AM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

If you're going to have a rope going around/through the attachments surrounding the raft, make sure that each section of rope is independent - so if it is pulled in one area, it can't tighten up somewhere else. That can make it possible to grap on to someone, trapping them. Make separate pieces of rope for each section and that can't happen.

It helps if the pilot can do a little bit of a push down to lighten everyone, but of course not so much that you get tossed up to the ceiling.

It might need to be deflated a bit as you go up, so don't fill it too much on the ground.


monkycndo  (D License)

Jun 19, 2010, 5:51 AM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

A 2 man raft often doesn't have the best attachment points for rope. A group down in Belize came up with some ideas. Look me up at the boogie and I'll help you with it. Most important thing is no loops where a hand/foot can get caught.


mircan  (D 32291)

Jun 20, 2010, 7:37 AM
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Re: [monkycndo] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
Most important thing is no loops where a hand/foot can get caught.

+1

My buddy got his hand through loop, the jump was fckup from the start and the raft started spiraling. His hand got caught by the line of the spinning raft. At some time he went for the hooknife, but the line broke before he got to the cutting part. With every rotation the pressure was getting bigger. Just before the line broke the line was pressing soo tight on his finger that he thought it was broken. He did not feel his fingers for several days later.

Funny thing is that, just before this jump, I found post on dz.com what to do and what not to do on raft dive, but on the actual dz, nobody wanted to listen. Unsure


ZigZagMarquis  (D License)

Jun 20, 2010, 8:56 AM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

Leave the oars on the ground.

Wink


JohnRich  (D License)

Jun 20, 2010, 4:57 PM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
Was looking for any advice on launching a 2 man raft out of a SkyVan.

Search, read, heed:
http://www.dropzone.com/...p;sb=score&mh=25


theonlyski  (D License)

Jun 20, 2010, 5:33 PM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

Clicky

"If the rest of the people let go of the raft, dont try to save it!"


Rick  (D 28557)

Jun 21, 2010, 9:58 AM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

VERY IMPORTANT noone should ever be above the raft. If the raft gets loose or the riders get dumped out the raft WILL KILL YOU IF YOU ARE ABOVE IT.


Jumpah  (D License)

Jun 21, 2010, 10:11 AM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

Get someone who has done one before to go on the jump and help you organize.

As someone else posted, never get over the raft. Very dangerous.


Morne  (B License)

Jun 21, 2010, 11:07 AM
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Re: [Rick] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
VERY IMPORTANT noone should ever be above the raft. If the raft gets loose or the riders get dumped out the raft WILL KILL YOU IF YOU ARE ABOVE IT.
Why ? or How?
Sorry not doubting you , just want to learn something


JohnRich  (D License)

Jun 21, 2010, 11:21 AM
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Re: [Morne] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
In reply to:
VERY IMPORTANT noone should ever be above the raft. If the raft gets loose or the riders get dumped out the raft WILL KILL YOU IF YOU ARE ABOVE IT.
Why ? or How?
Sorry not doubting you , just want to learn something

A raft without it's riders will decelerate very rapidly, to about 20-30 mph. If you hit that at a freefall speed of 120 mph, it's going to smash you very violently, possibly breaking bones and knocking you unconscious.


Beachbum  (B License)

Jun 21, 2010, 3:05 PM
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Re: [JohnRich] Advice on Raft Jumps [In reply to] Can't Post

120?? I wonder how many rafts ever get going that fast? The one we did yesterday, my Protrack showed an average of 97 for the first half of the jump (I stayed with the raft the whole time). Even from "just" that though, a 60+ mph decelleration is still a large enough difference to cause a lot of damage!!!


wmw999  (D 6296)

Jun 21, 2010, 3:11 PM
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Re: [Beachbum] Advice on Raft Jumps [In reply to] Can't Post

Quote:
my Protrack showed an average of 97 for the first half of the jump (I stayed with the raft the whole time)
Didja have to go head-down to reach that speed Angelic

Wendy P.


happythoughts  (D License)

Jun 21, 2010, 7:07 PM
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Re: [Beachbum] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
120?? I wonder how many rafts ever get going that fast? The one we did yesterday, my Protrack showed an average of 97 for the first half of the jump (I stayed with the raft the whole time). Even from "just" that though, a 60+ mph decelleration is still a large enough difference to cause a lot of damage!!!

Most rafts seem to fall about 110. When he mentioned
120, I suspect he meant a jumper diving out after the raft and approaching it.

As far as impact, I saw a raft dump about 10-15 ft under someone.
The contact seemed to be instant, even in slo-mo.

The rubber handle on the front hit his face, splitting his goggles, and stunning him. He was wrapped for 3-4 seconds until some people holding ropes pulled it
off of him. From about 7,000 to 3,000 ft -
he was dazed.

On the ground, his forehead and nose were bleeding.
He said that he suddenly realized he was still in freefall
and dumped around 2,000.

If it had hit his head differently, it would have snapped his neck easily.

"Do not get above the raft" seems like an obvious safety rule. There doesn't seem to be a value in doing it either.


happythoughts  (D License)

Jun 21, 2010, 7:11 PM
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Re: [Rick] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
VERY IMPORTANT noone should ever be above the raft. If the raft gets loose or the riders get dumped out the raft WILL KILL YOU IF YOU ARE ABOVE IT.

Thanks for throwing that in. Never gets repeated enough.
Smile


Beachbum  (B License)

Jun 22, 2010, 7:56 AM
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Re: [wmw999] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
Quote:
my Protrack showed an average of 97 for the first half of the jump (I stayed with the raft the whole time)
Didja have to go head-down to reach that speed Angelic

Wendy P.

nah ... I wore my weights!! LaughLaugh


azureriders  (D 28830)

Jun 22, 2010, 8:20 PM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

obvious, but it is not funny to reach into the raft and deploy for your friend! The PC and bridle will dance around in the burble of the raft, wrapping up the heads of everyone on board.


(This post was edited by azureriders on Jun 22, 2010, 8:21 PM)


JohnRich  (D License)

Jun 23, 2010, 7:40 AM
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Re: [azureriders] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
obvious, but it is not funny to reach into the raft and deploy for your friend!

And why would that be necessary? Because (answering my own question) the altimeters of the people inside the raft are giving false high readings due to the fact that they are sitting in a giant low pressure burble. On one raft dive I was an outside rope-holder in front. The people inside the raft didn't exit when they were supposed to. I started signaling for them to get out. They ignored me. My signals got more frantic, and they finally rolled out, but about 1,000' lower than what was planned.

Please don't do that. You may find your raft holders abandoning you, leaving you to be cocooned inside a giant mass of rubber.

Plan the dive with several people to give break-off signals to the raft-sitters. Raft sitters: Heed them.


kkeenan  (D 22164)

Jun 23, 2010, 8:34 AM
Post #19 of 29 (1222 views)
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

Jeez - After reading all this, one wonders that all raft jumps don't end in horrible mass fatalities. Crazy


JohnRich  (D License)

Jun 23, 2010, 11:06 AM
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Re: [kkeenan] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
Jeez - After reading all this, one wonders that all raft jumps don't end in horrible mass fatalities. Crazy

Most people look upon raft jumps as just simple harmless fun. Fortunately, most of the time they are. But there is also a LOT of extra risk and things that can go wrong with them. And most of the people doing them aren't even aware of those factors. I don't like the idea of highly inexperienced people getting involved in such jumps. I believe we are fortunate that raft jumps don't go bad more often.
"What fools these mortals be."
- Shakespeare



(This post was edited by JohnRich on Jun 23, 2010, 11:10 AM)


Premier billvon  (D 16479)
Moderator
Jun 23, 2010, 11:12 AM
Post #21 of 29 (1184 views)
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Re: [JohnRich] Advice on Raft Jumps [In reply to] Can't Post

>the altimeters of the people inside the raft are giving false high
>readings due to the fact that they are sitting in a giant low pressure
>burble.

Not by much. 200-300 feet is about the worst error I've seen. Agreed on the everyone-exit-on-the-signal tho.


stayhigh  (F 111)

Jun 23, 2010, 5:25 PM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

you need couple people to stablize the raft out the door
or
85% of the time you'll be rafting upside down..


(This post was edited by stayhigh on Jun 23, 2010, 5:27 PM)


happythoughts  (D License)

Jun 23, 2010, 6:04 PM
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Re: [stayhigh] Advice on Raft Jumps [In reply to] Can't Post

In reply to:
you need couple people to stablize the raft out the door
or
85% of the time you'll be rafting upside down..

The major point of failure is immediately out the door.
The raft flips forward. The back comes over the front.

The two ways to fight that are:
- The people in the raft lean back on exit.
- On the back of the raft, one person helps launch it, but hangs on.
As the raft starts to flip forward, the person on the back will
feel the shock on his arms. They can stop that forward flip. (It may stand them up vertically and almost put them in the back of the raft)

Do those two things and your chances of success increase a lot.

The people on the side are essentially there as launchers.
All the launchers should be good RW belly-flyers.
Dress for success. Rafts fall slow, probably 110.
If someone starts to sink out, they should let go.


VideoFly  (D 25621)

Jun 23, 2010, 7:19 PM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

I use climber’s tubular webbing instead of rope. Use short separate pieces for each anchor point, knotted tight enough to get a good grip, but not have spaces big enough to get a finger through. I use different colored webbing to be slot specific and avoid confusion.

Choose your jumpers carefully, looking for good flying skills and some raft experience on the load.

Rehearse the jump on the ground.

Do not fully inflate the raft on the ground. It will expand as you gain altitude and lose firmness as you descend.

Don’t let the passengers get stuck in a “clam shell” when descending as the raft becomes less inflated.

Plan each jumper’s break-off to maintain stability until letting go.

Have fun—Be careful!
Attachments: Raft.jpg (211 KB)


GLIDEANGLE  (D 30292)

Jun 25, 2010, 6:21 AM
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Re: [jclalor] Advice on Raft Jumps [In reply to] Can't Post

BEWARE OF THE "ZERO-G" EXIT.

I have seen video of one which occured last year where the pilot mis-judged and ended up launching the raft and passengers into the overhead of the CASA. There were injuries and some scary moments in freefall.


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