More liferafts

Think you mean Newtons...

Think you mean N (Newtons) not kN (kilo Newtons)!! Just in case people get even more confused. Amazing how few seem to have actually read your original question.
 
On parting painters

Bought a reel of 4mm Liros 8 plait to use for mousing halyards. Was amazed to see that the reel end gave the breaking strain as 150 kg. So any thin stuff in a painter would have to be pretty thin.

Also, article in one of the current mags states categorically that there is no breaking potential in the painter, but that rafts have a knife secured close to the doorway to allow the crew to cut the painter; and that the knife doesn't necessarily look like you'd expect a knife to look.

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Err - No.

The buoyancy of the uninflated canister is enough against the resistance of the attached painter to inflate the raft underwater. The inflated raft, now having greater buoyancy than the canister - thus more force - causes the second line to part. I guess, just specify a line that has a breaking load between the canister and inflated raft buoyancy load?

Seems simple enough to me, don't you think?

This is not my 'unproven' idea. According to the lecturer at the Fleetwood Naval College, this is the way commercial shipping set-up their liferafts.

Cheers

Wayne


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Fleetwood Naval College is good enough for me but then your word was too. There was no side or sarcasm to my question. I just thought this piece of rope or small stuff would need to be very closely specified to be both strong and weak enough. I wonder if it's a professionals only thing, and I suppose the context was that had me wondering wast that yacht mysteriously lost in the north sea a couple of years ago which everyone presumes was run down. It's a subject very much on my mind, since I just spent £1200 on a new liferaft!

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Sorry John, perhaps I over reacted.

I also have just spent £1000 on a raft and after spending so much, though it would be a good idea to learn how to use it. This prompted my wife and I to do the course at Fleetwood (very good BTW). Although I’ve a cradle mounted on the transom, the idea of auto deployment had completely passed me by, as I would imagine most Yachtspeople. This is something I’m now going to sort out, as you say, if you’re run-down, you run the risk of sinking quicker than you could deploy the raft. This is why keeping a raft in a cockpit locker, I feel now, is not the best way to go and any deck mounted storage should have an auto deployment system.

All the best

Wayne

(PS after doing the course, my views on lifejackets has been turned on it’s head also – but that’s another story!)


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The hydrostatic release unit (hru) has been required on Coded yachts for some time now.
They are readily available through your liferaft servicing station or supplier. The only minor difficulty is when you need to put your liferaft away for security when leaving the yacht unattended, but it is not a serious problem.
Everyone should have one if they have a liferaft. Locker stowed valise types are practically useless in an emergency.
Can I here do a bit of advertising? Get a RNLI SEACheck - it's FREE.

.....back to wrecking!

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The liferaft canister will float. Then the painter will pull tight and inflate the raft. Then the boat will pull the liferaft underwater.

Normal plan is for the occupants of the liferaft to use the knife just by the door to cut the painter. Every liferaft has one.

Many yachts (all teaching yachts, also ferries etc) have a hydrostatic release unit on the mounting strap. As the boat sinks this pops at about 2m underwater and releases the raft. The cannister floats up and painter pulls tight.

The release unit (essentially a blade on a spring) also has a weak link that the painter is attached to. This breaks when the raft is inflated and the boat is sinking. Correct fitting is critical to avoid the liferaft being pulled down.



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(a) As the boat sinks the canister will float, with the painter paying out as She goes down. There is enough buoyancy in the packaged raft to ensure the raft is deployed when painter at full stretch.

(b) Depends upon what it is tied to. 10mm line could well hold your pride and joy suspended with a little help from trapped air and buoyant contents. The effect this scenario could have on the raft is not good to contemplate.

For just a few scheckels more strap it down with a hydrostatic release that will cast the raft off when submerged about 3m, and the painter is attached by a weak link, strong enough to ensure the raft is deployed, at which point it parts easily.

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".......container is enough to set off the inflation, which in turn breaks the relatively thin painter. "

NO;NO;NO;

The painter is 14 meters of strong braid. The hydrostatic release has a weak link which snaps.



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Absolutely correct. The painter will not break of its own accord, and logically this is just about the last thing wanted in most circumstances. One of the things I learnt on my original offshore survival course was a mnemonic for initial actions on entering a liferaft. This applies more to an offshore platform on fire or in similar life-threatening mode but it largely applies. The mnemonic is the "3 Ps".

* Cut the painter
* Paddle - hard, away from the danger
* Have a pee. Apparently sitting in a liferaft with a cold floor causes bladder/prostate problems and relieving oneself can become impossible, with very painful results.

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surely the painter is attached to a hydrostatic release.


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Answers?

Shall not offer my opinions as they are not backed up by any real experience, but if you are on the south coast this saturday have a look at the following "http://www.messengermarine.co.uk", as mentioned before on this forum. A chance to see, do and have your questions answered by the people who should know the answers.

Need to get my life raft serviced, so I intended to be there.

Jeff.

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Not immediately - the hydrostatic release releases the liferaft from the deck, so enabling it to float. The painter must stay attached to the boat so that the buoyancy of the canister triggers the inflation.

Note that for ORC approved liferafts it is a requirement that the breaking strain of the painter is such that it parts should the boat sink with the liferaft still attached.

From other people's posts it would appear that some hydrostatic releases also have a weak link for the painter, but this would seem to be unnecessary if the liferaft complies to ORC standards

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