Lifejacket. Tying a double bow.
 

After teaching safety stuff for nearly a decade I was challenged yesterday as to what constitutes a double bow, as required by our company to tie a lifejacket round the waist.
I've always assumed that a double bow is the simplest tie that you use for shoes whereby one tug on either straight section will release the lifejacket whereas the other opinion voiced was that a 'double' bow was the same knot I use plus another knot added on top to prevent the first knot coming undone.
Isn't the idea that the knot should be able to be untied even with cold hands?

Would have thought that the double bow was to prevent the thing comming undone.You wouldnt really want your lifejacket comming off in the water having been snagged on something during an evac or by a panicked passenger pulling at everything in sight.Scarry thought.

Then why not just tie a simple knot without loops on it. Surely you'd be even less likely to get snagged? We teach smokehoods to be tied without loops so as to prevent you getting snagged on armrests etc so why not lifejackets?

My understanding is:
1. Shoelace bow knot.
2. Take bows and tie in overhand knot.

Like this.

Edited to mention that, yes, the overhand knot will be difficult to undo when wet and with cold hands. Use a ballpen as a spike to open it. (I hear they can also be used for emergency tracheotomy.)

Err... Just SLF here, but bow? Double bow ? On all my flights over the last five years, both within Europe and half way accross the world, all the lifejackets which I have seen demonstrated have plastic clips to fasten the lifejacket, which you attach, then pull the excess strap to tighten... No mention of tying bows :confused:

I thought I was paying attention...

Maxbert

Well, just goes to show.
In all the flights I have done over a considerable time, I've never seen a commercial airline demo carried out with anything other than tapes.

As far as the "double-bow" is concerned, can't see the problem. Tie a bow then grab hold of both ends of the bow and tie another one.

And if there are no clips a follow up question: why tie (the double bow) at the side?

Rwy in Sight

I regularly fly with Flybe. They always tie the tapes under the lifejacket with what I would call a reef knot. As SLF I've often wondered why both the knot and its position are different from other airlines.

But then maybe I should get out more!

RHRP

Reason for tying it to the left side is that the lanyard you pull to inflate is on the other side. As to clips, we bought a load of the clip type but the CAA mandated their replacement with tape type.

The question still remains...why a double bow and not any old knot? There HAS to be a good reason, surely?

Perhaps so it is easily undone for whatever reason.

One of my previous airlines did the double bow thing and we were supposed to get people in a loop and link each other with the tapes but I can think of situations where you may need to break that link. A double bow would be easier than a knot.

Good question, though.

Spoken to the CAA. "No idea. I'll get back to you". Called the Coastguard. "No idea. I'll get back to you". Phoned the manufacturers. "No idea. I'll get back to you". Tried the Royal Yachting Association. "Not a boat? Sorry". Emailed the Royal National Lifeboat Institute. "404, file not found".

One point that might be of interest is from the CAA Safety Sense pamphlet. After the SAR Helo picks you up they need to get the old jacket off and give you a new uninflated one. How would they get an old one off??? Knife?

Any SAR types on here?

I would think that part of the reason we use bows rather than any old knot are because the tapes on some life jackets are extremely long. With just a random knot, you'd run the risk of tripping over the tapes on the way to the door but the bows take up some of the excess tape. I couldn't say that that's definitely the reason, but it seems to make sense. Also, if you do have to have to remove the old jacket for a new one as per the SAR helo, the width of the tapes make double bow knots fairly easy to undo, although it'd obviously be trickier when wet. But I may be completely wrong on all of those points!

Would be interested in the answers from those in the know if they ever come back to you!

blue up,

I will probably meet some SAR guys on Sunday. I will ask them about the removing issue.

Rwy in Sight

It's like Jetset lady mentioned, it's to do with the length of the tapes.

It's easier to tie a bow than a knot, given of the length of the tapes you have to feed through tying the knot. Also bear in mind it will probably be dark with panic setting in so you don't want to be struggling with 6 feet of tapes, a double bow is unlikely to slip therefore allowing your life jacket to ride up when floating in the water or worst still come off over your head.

One would imagine that most would know how to tie a bow, so perhaps that is the reason. Although with our shoeless brethren the newer style clips would be better.

No need to remove the lifejacket in the helo, just deflate it using the valve in the mouthpiece.

the reasoning my airline trains bow rather than knot is you may have to get it off quickly ie to swim under water to avoid a hazard and a bow is far easier to untie than a knot.

Gordon Bennet! A ditching, evacuation, and now we are into sub aqua......
Words fail me.
It really wouldn't be a good day, would it?
Do they provide the snorkel as well?

Hi Maxbert...

Indeed, you were paying attention and are correct. The minimum performance standards for the design of life preservers approved for use on board aircraft in North America (and many other parts of the world that have adopted a similar standard, such as EASA) requires the following:
Typically, in order to meet this performance standard (one attachment and one adjustment), a plastic clip is used by the manufacturers. You can see a typical example of this type of life preserver and attachment at the following links:
Eastern Aero Marine EAM XF-35
Eastern Aero Marine EAM UXF-35 - photograph
Switlik AV-35H - photograph

I spoke with a SAR captain and he said he does not care how a life jacket is done. Even if it is with a knot, the SAR crew can use a knife to cut the life jacket and give a new one.

Rwy in Sight