Unsinkable Yacht Project

[JonathanCole]

Basics of flotation:
1. A gas atmosphere such as air is lighter than water. If you enclose a gas atmosphere in an container/enclosure it will float. If you breach the enclosure water can flood in. If total weight of the enclosure and any cargo is greater than the weight of water of an equal volume, then it will sink.

2. If you make multiple enclosed sections such as the Titanic, then if one or several are breached then the vessel may still float. The more the separate enclosed sections the less likely the vessel will sink when some are breached. In the case of the Titanic there were not sufficient enclosed sections and the sections were not completely enclosed (they were open at the top). That is why closed cell foam is a popular flotation material. Tens of thousands of small enclosures per cubic meter.

3. However the walls of the enclosure have weight so the more material it takes to enclose the volume, the more weight you have. You need power to push that weight. So closed cell foams and structures use very thin walls on the cells. The problem is that water can leak through thin walls with small imperfections and the the flotation becomes waterlogged and may not hold the loaded ship above water. It is also very difficult to remove if poured in place.

The best solution may be to use something like HDPE ping pong balls that are contained in flexible net bags made of something like Kevlar and put into the hull below the water line. Multiple flotation chambers in a loosely bound array would have the least likelihood of being breached. These net bags of flotation elements would need to be secured to the underside of the deck well away from the exterior hull surface so that they could not be released from the hull by a breach.

[icetreader]

What about an inflatable floatation system that's automatically activated in emergency situations, when the boat cannot be salvaged by other means?
There are personal floatation devices (PFD) that work this way.

The advantage of such an approach is that it would save space under regular conditions.

Yoav

[Guillermo]

Originally Posted by icetreader

What about an inflatable floatation system that's automatically activated in emergency situations, when the boat cannot be salvaged by other means?....

This idea already was put to work. There was a company in the USA comercializing flotation bags. The system was named Yachtsaver, but the comapny run out of business.

Happy New Year to everybody.

[CapGeorge]

Look at the attached Carolina skiff picture: boat cut into three parts with two people in each part. Interesting but notice the calmwater and nobody's rocking the boat. Problem with all the floatation being below the water line is that the boat is just as stable upside down as rightside up.

[JonathanCole]

Originally Posted by icetreader

What about an inflatable floatation system that's automatically activated in emergency situations, when the boat cannot be salvaged by other means?
There are personal floatation devices (PFD) that work this way.

The advantage of such an approach is that it would save space under regular conditions.

Yoav

That is an interesting idea. The only downside I can see is that it is an active system with the extra costs of an active system. Since flotation will hopefully be rarely used to avoid sinking, an active system may be neglected in terms of maintenance. A passive system that is bulletproof and cheap is a better design approach even if it takes some hull space. Most boats have some space that is difficult to access. An alternative would be to make the hull a GRP-ping-pong ball composite sandwich!! Which actually makes me wonder what kind of high durability closed cell materials there are.

[safewalrus]

Trouble with all this unsinkability is the fact that the unsinkable stuff drastically reduces the payload! so you are either safe and won't drown (you can't get into the boat) or you can have lots of goodies on the boat and be comfortable but MAY drown! there is an alternative

Go buy a car

[safewalrus]

And yes Guillermo I am serious, never more so

10/21/1805

[Guillermo]

Originally Posted by safewalrus

And yes Guillermo I am serious, never more so
10/21/1805

Great guy, Nelson.

[kach22i]

Originally Posted by Robert S

You might look at the norwegian Navy's SES boats. They are supposed to be unsinkable even if both hulls should be destroyed. Basically there should be enough boyancy in the sandwich construction.

Robert S, I just noticed your response in this thread.

I've owned a hovercraft for 15 years and have been aware of their existance (40 years ago) when I was only six years old.

If you happen mention SES or hovercraft again you can expect to get a favoriable response from me.

Very few people, including "boating enthusiast" in America even know what hovercraft and SES are.

I've found very few people on this board interested in hovercraft/SES despite the fact they are posting from all over the world. Not a shot at anyone here as I'm aware this is a boating forum not a hovercraft forum.

RE Boats:
I've noticed that with composite construction becoming the norm, many boats on the market have foam cores. This is a good thing. However be warned that if constructing something yourself that extruded polystyrene rigid insulation can melt away when exposed to gasoline and can leave a void under the fiberglass sandwich which may fill up with water without you ever knowing it.

[Windvang]

Etap in Belgium makes unsinkable yachts.
See for a description:
http://www.etapyachting.com/index.cf...=Unsinkability

[D'ARTOIS]

In theory all very nice and well.

Gas included stations, unpractical and and environmentally wrong; the same counts for the application of all the foams: they can provoke all sorts of illness because of the ultra-poisoness components the foams are made off. Has been discussed here thoroughly, in SA as well, some time ago.
Etap has had a dew incidents as well - carefully kept from the press, nontheless one came in the open and that was not a nice case.

You can make a ship unsinkable if you make it impermeable to water. Secondly you can make watertight comparments from bottom to keel with watertight doors; it make a small boat impractical but there you go.

In an open boat, like that Carolina Skiff, the foamcore is an intelligent solution. Not in sailing yachts and boats with a bigger volume. See the Etap problems for example.

Careful sailors will be seldom confronted with the threat of immediate sinking.

If so, for example if you are endangered to be run over by a 20.000 ton freighter, what is the use of being unsinkable.

[Windvang]

I am not a fan of the Etap system, it won't save you frome a fire also.

The foam issue was about particles of crumbling foam if I am correct. In Etap's case the foam is between 2 layers of fiberglass so no particles can escape. Fiberglass is also virtually airtight so even outgassing of the foam should not be much of a problem.

[D'ARTOIS]

Not really - first of all, it was not directly a fault of Etap - let's put that on front. It was a side effect of one of the components in the foamstructure self that made the crew of this yacht sick. Just like the sick building syndrom but then on a different platform. You know that it is there but you cannot measure it.
Besides the incendiary effects, IMO it is an overvaluated measurement. very few yachts sink. Bigger threats are fires and collisions. It is the typical topic of armchair sailors - not to meant to offend some body in particular but basically there are no unsinkable boats neither are planes/aircraft that cannot crash.

[JonathanCole]

Originally Posted by D'ARTOIS

very few yachts sink. It is the typical topic of armchair sailors - not to meant to offend some body in particular but basically there are no unsinkable boats neither are planes/aircraft that cannot crash.

Quite a few sink. Often when boats sink it is an act of nature with no one on board. If they sink they are much more difficult to retrieve and because they are likely to be immersed longer, there is greater possibility of total loss. Keeping a disabled boat on the surface is definitely desirable if the flotation is cost effective and does not take too much useful space.

[D'ARTOIS]

Well, I wouldn't park my boat just there, too wet!