hydrostatic release on deck mounted liferaft

[BlueSkyNick]

One of the main recommendations in the Ouzo report is that a liferaft should be carried, with a hydrostatic release. The supposition is that she was either capsized or swamped by the Pride of Bilbao and had they a raft, the crew might have survived.

On Lechwe, the raft is deck mounted just foreward of the mast. It is strapped down with webbing, which I would cut off with a knife if I didnt have time to undo the buckles.

I am now planning to fit a hydrostatic release, but not quite worked out how. One idea is to cut the straps short, then sew a large loop on the end. Then feed a length of shockcord through the loops, and close the circle with the H-S release. Theory is that if the boat sinks, release operates, shockcord runs loose, allowing enough of the straps to be freed and the raft to open up.

A better option will be to replace the deckmounting with a proper cradle.

One thought in all this though - if the boat has sunk to the extent that the H-S release opertates, isnt there a chance that the raft itself will have blown open - or tried to - first?

It worries me that the whole thing could go pear-shaped (almost literally).

Ideally, the raft needs to be launchable by the weakest member of crew on their own.

What is the perceived wisdom for a deck mounted raft?

 

[Steve Clayton]

Hmm! can't quite see it on this picture (but the manual release is visible)

and it's just out of shot on this one:

Ahh! this is better:

Nick, this is the best shot I can find. Just above the release is an adjustabe strop which easily fitted into the cradle strap and the H-S. (Got it in a UK chandler for about £6.00 in 2004). Just above the whole lot is the cradle quick release catch for manual operation if required.


Just found a better one

(The mobo in the background is Alinghi)


www.seraph-sailing.com

 

[BlueSkyNick]

took me at least 5 viewings to even see a life raft - great deck tinsel !

Seraph benefits from a proper cradle which we dont have on Lechwe - guess I'd better move it up the shopping list.

 

[Twister_Ken]

Nick,

There are raft-specific cradles made (or at least marketed) by the raft manufacturers at tooth rattling prices, but there are also generic, adjustable ones at something like 2/3rd to 1/2 the price (depending on your raft manufacturer).

 

[Richard10002]

I'm considering a new canister liferaft, (perhaps next year, but we'll see), and see the sense in the release...

I used to maintain the safety gear on merchant ships, but cannot quite see, nor remember, how the whole thing works.

e.g. the boat sinks, the hydrostatic release releases the canister.... does the canister then float to the surface.... to be found and opened or..... is the lanyard of the canister attached to the hydrostatic release by a line of a breaking strain which will break when the raft inflates, and the inflated raft floats to the surface.

the above relies on the canister breaking/floating free from the cradle, and having the buoyancy to either float to the surface, or to float and unwind the lanyard to inflate the raft etc...

from the weight of our valise, and from what I have felt with canisters, I would have thought they would sink like a stone.
Also think they might be better placed towards the stern where there is less stuff to impede their trip to the surface, or to make it easier for the less able bodied to launch them.

If ours was on the coachroof or the sunbathing terrace foreward of the mast, it would go over the side right there, as there is no way even I could get it to the stern without a lot of hassle.

Just a few thoughts

 

[fisherman]

The raft will not inflate until it has floated up and pulled out all the painter. Ideally you need a couple of eyebolts, some rafts are rigged with a Senhouse slip for manual release, I bought a hydro release yesterday that has a manual release built in. £38 I think. (Newline Fuels, Newlyn).
The hydro goes off between one and four metres deep. Raft floats off, and painter is extended by the sinking of the vessel, until the raft fires. Then the weak link on the hydro parts to release the painter.
safety surveyors don't like to see rafts strapped down without a hydro.

My only worry about all this is the unlikely event that the raft is temporarily snagged and reaches a depth such that the air spaces in the canister are compressed and buoyancy is lost.

 

[Daedelus]

Can't say for all of them but mine has a cradle on the aft rail. Age related weakness means SWMBO and I never thought we could throw the thing overboard if it was midships in case of fire or collision.

There is a sort of clip device which provides the manual release and the hydrostatic is connected to the strap holding the whole lot together. There is a separate trigger line (about 30 feet long) connected to the boat. Should your vessel sink, at a predetermined depth the hydrostatic triggers, and a sharp blade cuts its rope, the canister then floats towards the surface and if it reaches the full length of the line is triggered to inflate. If it doesn't, pull the line. There is weak link in the rope so that if the boat is going way down it doesn't take the life raft with it.

You have to replace the release every few years and when I last did that I played with the old one to see how the blade worked: simple circumsions would be a doddle. Fortunately the blade is fairly well hidden so you can't get your finger by accident.

I proved the canister floated when I was trying to fit the wretched thing in the cradle and it slipped out of the straps I thought I'd got holding it as I moved it to the cradle. It floated gently off down the marina and I had the humiliation of asking them to get their dory and bring it back. Happily I hadn't then connected the firing rope to the boat so it didn't trigger and inflate.

If you do get a hydro release you'ld probably be better off forking out for the strap that goes with it and also note that the releases come in different sorts. (Red and Yellow or maybe green) and they are for different size of craft. No-one seems to care much but it might be comforting to have the right one: I can't remember which is which but it tells you on the box.

 

[wafu77]

I have sailed a Westerly Fulmer which had the life raft strpped to the coachroof with a hydrostatic release unit. Twice, when sailing in heavy seas, we shipped a large wave over the side, the release unit 'let go' and we were then towing a nice bright orange tender behind us. Took some explaining to the coastguard about the EPIRB signal!!!

 

[tangofour]

[ QUOTE ]
I'm considering a new canister liferaft, (perhaps next year, but we'll see), and see the sense in the release...

from the weight of our valise, and from what I have felt with canisters, I would have thought they would sink like a stone.


[/ QUOTE ]

A typical 6 man canister liferaft measures 80cm * 50cm * 28 cm thats a volume of 112 litres. It weighs 38 kg's so theres about 70 litres of bouyancy. Surely the internal CO2 bottle, the raft itself and the waterproof seal on the canister ensure that the unit has masses of excess bouyancy!