Dinghy life-raft

pmagowan said:
I am thinking about this because I have become more and more convinced that a life raft is an unnecessary temptation to abandon ship. Survivability seems to be poor in them and in most cases the reason for abandoning ship could have been foreseen and prevented. The reasons for needing to abandon ship seem to fall into two categories;
1) Sinking
2) Fire
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That may have been the case years ago but these days I think we have better training / understanding. I can't think of any recent occasions when people have suffered through taking to the liferaft too early (although I can vaguely remember one case a few years ago).

The cases around UK when liferafts have been used, or would have been useful, have either been as a result of collision or where the boat has been wrecked on rocks
 
bedouin said:
The cases around UK when liferafts have been used, or would have been useful, have either been as a result of collision or where the boat has been wrecked on rocks
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Handful of fires as well. Two I can think of are Sybarite's Frenchman in the North Sea, and a brand new big mobo that was engulfed in seconds, there were photos of the crew just making it to a transom-stowed raft ahead of the flames.

Pete
 
prv said:
Handful of fires as well. Two I can think of are Sybarite's Frenchman in the North Sea, and a brand new big mobo that was engulfed in seconds, there were photos of the crew just making it to a transom-stowed raft ahead of the flames.

Pete
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This idea of a boat being engulfed in seconds seems odd to me. Either the boat is made out of something ridiculously flammable or it is hyperbole. I am used to lighting fires and even relatively flammable things take quite some time to get going. There is a significant period whereby any reasonable fire detector should pick up on the small fire at a stage where it is easily extinguished. Then there is just the basic sense of taking into account fire retardancy at the design and construction stages. Fire needs a material to burn, air and heat. The sources of the later on a boat are normally limited to the wiring, cooking, heating and engine. The later two can have dedicated compartments that resist fire and have automatic extinguishers. The wiring can be designed in such a way as to make fire very unlikely and with flame extinguishing sleeves on the wires and cooking simply requires a basic level of vigilance. An out of control fire on a boat is a pretty devastating thing but it should be possible to avoid this or at least reduce the risk to negligible.
 
bedouin said:
That may have been the case years ago but these days I think we have better training / understanding. I can't think of any recent occasions when people have suffered through taking to the liferaft too early (although I can vaguely remember one case a few years ago).

The cases around UK when liferafts have been used, or would have been useful, have either been as a result of collision or where the boat has been wrecked on rocks
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It is hard to get good stats. The US coast guard have some and the risk seems to be very very low. I would like to know hoe many life raft deployments were necessary. How many were avoidable by simple precautions. How many would a tender have been equally suitable etc

One of the main points I am making is that a liferaft is the final safety net once a whole range of failures have occurred. I wonder if these failures could be better targeted so that you never get to the liferaft stage and also if a liferaft is the most effective final solution.
 
prv said:
Is the CO2 in a liferaft bottle in liquid form? I have no idea, but I assume that would take up much less space than the same amount as gas, and I believe the pressure needed for CO2 is not excessive.

Pete
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Is it actually CO2 or just ordinary atmospheric air.
A leak in an enclosed liferaft might be quite dangerous if it was CO2
 
The two people I know who had to get out in minutes, were from hitting something and a fire. Both were a while back.
Something not mentioned often is how the family that spent 170 odd days adrift, found the rigid dinghy more useful that the LR, as the latter deteriorated quickly.

A friend modded his rigid as a LR, but found that the extra weight made it clunky as a tender and he doubted being able to launch it extreme conditions. He did lose his boat after a collision, but was able to radio for a pick up from a passing cargo ship.
 
DownWest said:
Something not mentioned often is how the family that spent 170 odd days adrift, found the rigid dinghy more useful that the LR, as the latter deteriorated quickly.
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That sort of epic drift should be a thing of the past nowadays, though. Light off an EPIRB or PLB and even in mid-ocean somebody ought to be able to reach you in three or four days max. In European coastal waters that's down to a small number of hours.

Pete
 
pmagowan said:
My assertion is that you can make a boat that doesn't burst into flames and burn to the waterline in 10 minutes. :)
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Sure, but Bedouin was talking about "cases around UK when liferafts have been used". The self-immolating motorboat off Calshot was one of those, which is why I listed it.

Pete
 
bedouin said:
The cases around UK when liferafts have been used, or would have been useful, have either been as a result of collision or where the boat has been wrecked on rocks
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Not quite. If you carry out an analysis of the MAIB (and Irish equivalent) reports involving yachts that founder over the last 20 years or so you will find 3 main causes. First extreme weather, usually capsizes close to shore or on the continental shelf (think Fastnet 1979). Second structural failures (mostly racing boats) and third collision. The last explains founderings where both the boat and occupants are lost, but in most cases a liferaft would not have helped as either the boat destroyed on impact or no time to launch a raft. Fire at sea is very rare and rarely results in a raft being launched.

Relating this to the subject of this thread, there are few incidents where a modified dinghy would have been better than a liferaft, although some where it might have been equally effective.

The important thing to remember in our local waters is that the purpose of the raft is to keep you safe until rescue arrives. Given the type of communications now available and the extensive coverage by rescue services, this is likely to be hours.

However, if you are venturing to more remote places then the ability to have some control over where you are going makes a lifeboat rather than a raft more attractive, hence its popularity in the past with some blue water sailors. Now, though with the advent of EPIRBs even that is now questionable.
 
pcatterall said:
Must look for the table I saw recently where the tramp compared quite well to dedicated life rafts. We are still considering a tramp, as a tender, as a bit of fun with sails and as a something better than standard tender when fitted with the liferaft kit.
Yes you have to prepare it before hand if you may have to deploy as a raft in a hurry but it could work as a compromise and you only need to store one item. If you are using the tramp regularly as a tender you also KNOW it will inflate!
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For the reasons I explained in post#32 the attraction of a dual purpose boat like the Tramp is no longer there. It is a compromised tender and a compromised liferaft - and does not meet some of the basic requirements of self righting and stability. Where you sail can see no advantage in it over a good tender and a standard liferaft - plus your EPIRB.
 
Tranona said:
third collision. The last explains founderings where both the boat and occupants are lost, but in most cases a liferaft would not have helped as either the boat destroyed on impact or no time to launch a raft.
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A raft with hydrostatic release ought to launch itself in that case, though, and pop to the surface ready for any survivors floating in the water to climb into.

Not aware of any incidents where this nice theory has played out in practice, but I think that's mostly because catastrophic collisions that splinter the boat to matchwood are quite rare. Ouzo didn't carry a raft.

Pete
 
prv said:
A raft with hydrostatic release ought to launch itself in that case, though, and pop to the surface ready for any survivors floating in the water to climb into.

Not aware of any incidents where this nice theory has played out in practice, but I think that's mostly because catastrophic collisions that splinter the boat to matchwood are quite rare. Ouzo didn't carry a raft.

Pete
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Yes, you are right - it should work. It was mentioned in the MAIB report on Ouzo - but only as a possibility.

However, they are effective on fishing boats, but many fishing boats capsize either through loads shifting or snagging nets.

Hydrostatic releases are recommended for coded boats, but arguably based on theory rather than any empirical evidence. If you read the accounts of when rafts have actually been deployed you find they are almost always problematic and difficult to see how either a hydrostatic release would have helped or, pertinent to this thread how a rigid tender with a canopy would have been any better.
 
I don't know what was in cylinders I had always thought they worked like large life jacket cylinders but they were much smaller than a dive tank and there were 2 much the size of a fire extinguisher so much easier to stow even in a centaur coffin berth with the Avon and its long oars
 
There have been enough instances when a liferaft did the job, I know of several, forty hours in the channel in NE gales in Feb is one when having the canopy was essential. Also my brother had to leave a burning yacht in a hurry, thought to have been accumulated fumes from battery charging, next start up it went, (petrol mind). He went for the Avon on the foredeck and didn't have time to even reach it. The other crew had the liferaft over by then.
 
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