Mary

I have looked at most of the new boats. The only boat, that I think might sink if both hulls are holed, is a monoque carbon A-class. The hulls are ~ 2mm stressed skin carbon and nothing else in the hulls. For a race I would probably risk it. For everything else, I would probably want 10-20 liters of airbags in each hull.

Recently a lot of my packages have been padded with little half liter airbags. They are permanently sealed plastic bags. They are pretty tough. I would probably use them for floatation

Attached is a photograph of an Auscat MkV A-class under construction. This photo came from the Australian High Performance Catamarans Website:

http://www.ahpc.com.au

You will notice in the picture that the cross members (if that's what they are called) are made largely from polystyrene. It is partly this use of polystyrene that enables these boats to be built so light. The polystyrene of course acts as positive floatation.

I'm not sure about the A-class rules but the Taipan 4.9 rules (which have a similar construction) suggest that each hull can support 50kg when swamped.

Rob Wilson
Taipan 4.9 AUS175

I lost my first cat about 2 months after I bought it. It was a '78 NACRA 5.2 with solid glass construction (no foam core). The previous owner had done a very poor job of installing ports just forward of the cross beams after doing repairs. We were about 2 miles of Va Beach when we flipped it for the first time (big lesson learned). It began to take on water and we could not right as every time we hiked out, water would run to the back and it would just roll over backwards. Finally a power boat spotted us and took us under tow. The towing only exacerbated the leakage rate and it began to sink. The Coast Guard finally showed up and took us on board. They also took on the task of towing the boat for about 15 minutes, but my crew began to show signs of hypothermia and the Coasties decided the best thing to do was to cut the boat loose and get my crew back to shore. Meanwhile, some of my friends who had been sailing out from the beach to check on our status witnessed the NACRA slip into the deep, never to return. The only thing to float was one daggerboard which they rescued and I still have as a reminder. We were very lucky that everything turned out OK. I was undeterred and within two weeks had purchased another 5.2, this time I spent twice the peanuts to get an ’83 (also solid glass) which I have put many miles on and still have today.

The Tornado and the Marstrom A-cats has a 10 mm thick nomex layer between the carbon skins. That volume gives a lift of about 50 kg / hull!

/hakan

i figured it out= i guess if you are really, really bored, on a wind less day with nothing else to do, and want to put your boat thru unnecessary stress and strain this is how to 'conrol sink' your boat= (this only works in tidal areas). at high tide anchor your boat in about 2' to 3' of water near shore. secure it so it want move around with 2 or more anchors. undo the drain plugs and watch her go down. you probably need to screw out the inspection holes to hasten process. you can even act like you are brave and 'go down with the ship'. oh, the beach goers will think your are wacko. as the tide goes out, she's on the hard again and should naturally drain! brilliant, huh?

Just thought I would bring this thread back to the top for possibly more debate, now that there seems to be some pictorial evidence that a Jav 2 hull will sink when holed. See attached photo that I borrowed from a post on the Old Forum. It is the Jav 2, sailed by Matt Struble and W.F. Oliver, that was T-boned at the Alter Cup.

Of course, it may be some sort of optical illusion. But there were verbal reports, as well, that the holed hull did indeed sink below the surface.

remember, it was believed the Titanic was unable to sink! Where is she now?

It's simple; I have a Hobie Cat with foam blocks. I'm glad the 1000 was cancelled now that we have all seen what one Jav218HT hull full of water looks like in flat water. Lord knows with heavy seas the outcome of the sailors!

BC

I thought the USCG requirements for small boats require enough flotation to keep a swamped/holed boat afloat and stable to a certain level. It appears that if both hulls were breached, this boat could sink completely, or at least deep enough to persuade sailors to abandon. What are the USCG specs? Does the Jav 2 meet them somehow? This reminds of the situation that ended up in a major lawsuit for NACRA...

Mary and others,

>>>I have recently heard that some of the newer, lighter, more high-tech cats, partly because of their hull construction, can definitely sink.

Well it will be easy enought to establish which class designs will sink and which won't, just check the class rules.

Formula 18 rule B.1.2

Each hull shall carry at least 110 litres of flotation by solid closed cell foam, air bags, sealed air compartments in hulls and at least one inspection hatch.

source http://f18-international.org/Complete%20Formula%2018%20Class%20Rules%202003.pdf

Formula 20 rule B.1.2.

drijflichamen Niet van toepassing.

Literallt translation from Dutch: Flotation devices not applicable.

Source : http://www.formula20.org/


Formula 16 rule 1.5.2

"Each hull shall carry at least 50 liters of flotation, either by solid closed cell foam, solid blocks of compacted foam granulate, air bags or sealed air compartments."

Source : http://www.geocities.com/f16hpclass/F16HP_class_rules_section_A_box_rule.html

Similar rule as the F16 rule in the Taipan 4.9 class rules.


The A-cats don't have floation rules and mostly don't have use garanteed floatation in teh shape of foam or sealed air compartments. For this reason they can not obtain an European CE quality mark. The F18 class has such a CE quality mark and the F16 class is working at getting it. Alot of paper work ! But we will get it. If we have to increase our floatation to get it then we will.

I know that the Hobie Fox as an F20 design has foam block in the hulls to get positive floatation. I assume that they still have that since the F20 no longer require each F20 design to have it. It has been the hobie way to do that and I assume that they will keep doing that.



>>So if you have any doubt about whether your boat would float, do you stuff it full of styrofoam -- how do you know how much is enough?

Styrofoam will work by I'm told it is an open cell foam that will absorp water over time and make your craft needless heavier. Closed cell foam is better. Or if you use styro foam or even foam granulated (can be molded) than pack it tightly in a sealed back. Perferable vacuumed to make it hold shape.

Best is to fix (!) low in the hull to make it work even when the hull is partly flooded. Also fix it always. There is no use when it just rests in the hull only to float the your stern on top of the water surface. You'll be riding high with your sterns out of the water and you bows pointing down. No good sailing that way.


Wouter

Now, I must say that I take a different approach to class rules and how to do things than the F18HT class but a crew can just as well survive on the remaining hull that still floats.

And I know that sailing an F18 or F20 (inter 20) with a holed hull is no picknic either.

But then again there is a distinction between surviving and limping back to shore yourself.

But this problem can easily be solved but adding a floatation rule to the F18HT class rules.

Wouter

Before a problem can be solved, people have to be convinced that there is a problem in the first place.

Indeed Mary.

Wouter

It will be interesting to see whether the F-18HT class now will require positive flotation to be added to their boats.

But requirements by a class association to add flotation to boats (if it is not inherent in the construction or at least added within the hulls by the manufacturer as independent flotation materials) is not going to work for the people who buy a boat just for fun, recreational sailing.

Those people do not join class associations, but they do buy boats, both new and used. And they probably assume their boat will float even if it is full of water. They do not have access to the information that we do.

Some racer decides to remove flotation inserts from his hulls to reduce weight. Some "cruiser" sailor buys the used boat later and does not even know that there was supposed to be flotation in the hulls.

So how do we protect a guy who innocently buys a boat that can't float if the hulls are compromised when he is out there on a beach-camping trip with his wife and two small children?

Heck, even for the BIG multihulls, the big selling point is that they may capsize, but they won't sink and it will be your liferaft.

And who would have thought that a little beach-cat would sink? I mean REALLY sink? I suspected it was possible for certain boats. But how do we know WHICH boats?

P.S. And for those who bring up that long-ago lawsuit about the Nacra that supposedly sank, it is not true. The boat did not sink and was still floating quite well, upside down, when it was recovered and towed in. The manufacturer prevailed in that lawsuit.

That is not say that I trust any boat to float unless I know there has been testing and unless I know that there is some kind of flotation that guarantees the thing will keep floating even if both hulls are ripped open. Aren't there any laws about this to protect the blissfully ignorant among us?

Well,

The are some things to be said for those class rules that enforce garanteed floatation.

With respect to the F18 and other classes the boats are weighted before racing and reduction in weight that might be from removed floatation will void the boats race permit.

In some boat type like the Taipan the floatation requirement is satisfied by having foam bulkheads instead of timber or glass bulheads. It is pretty hard to remove those without losing hull integrity.

The fact that those bulkheads are made out of (glassed) foam blocks is the direct result of the Class rules.

In short when designers are faced with a garanteed floatation rule as the one in the F18 rules than they tend to try and incorporate that in the overall design as a element that does more than just take space. Of course not always. Hobie Fox is an exception.

Also from the perspective of the builders they have to sell a fully compliant boat and they can't really know wether a buyer will race to boat or not. Ergo they can't assume that the boat will never be measured and checked for compliance. They will then always assume that it will be measured and checked and be forced in practical sense to sell the boat with floatation.

Of course the class needs to take this rule up in her compliance checks / pre race checks. I know that the F16 will do that. We don't have the rule on having inspection hatches for nothing do we ? I know that we will have a serious word with the builder who sells boats which are not compliant with rule B.1.2.

Can a second hand boat builder be absolutely sure ? Only when teh boat has a current measurement certificate. But even then the buyer must check these things for himself. And when lacking floatation he or she can add it him or herself. Nothing is full proof.


With respect to laws protecting the "ignorant"
Well yes there are. the CE (Communion European) is one of those quality marks that concerns herself with issues like these in all areas and products. I haven't looked into the US version yet but I'm sure that I will soon enough after we that CE norm sorted out.

All buyers have to do is look for these marks. For example All Hobie Tiger owners will be able to find such a metal plaquette or sticker on their beams or hulls that deplays boat information and the CE logo.

Wouter

I mentioned the NACRA lawsuit NOT to make the claim that the boat sank. If I remember the story right, one hull did flood somewhat due to a leaking port cover. Supposedly this led the sailors to think the boat was sinking (or in danger of) and they decided to swim for shore, when indeed the boat stayed afloat and they should have stayed with it. They violated several common sense rules, and they paid a price for it. If I remember right, however, part of their lawsuit did make the claim of inadequate flotation. I mentioned it because I would think that such things would still be a sore subject in the industry, and that to produce a boat without some sort of positive flotation might be asking for it these days. Even my roto-molded sea kayak has expando-foam in the bow and stern for flotation. Again, I thought the USCG reg for small boats included a flotation requirement. Maybe a sealed hull counts, and breaches don't enter enter in the equation. In a high-speed sailing craft, a compromise to the hull is possible.

Floatation Suggestion:
Big foam "noodles" into the hulls. They weigh almost nothing and will support a lot of weight. They're also good for stuffing into the mast and beams.

Sol Cats:
I bought my yellow Sol 18 in New Orleans in '77. Sold it in Houston in 1983. Never had a problem with it. It was a great boat. I miss those old durable, solid boats.

I still feel that the cleanest, easiest solution for many boats would be to install a pair of kayak flotation bags. Just slip them inside the hull and inflate. They're light, and they don't absorb water. You can even get double-walled models that can be used to store gear (or beer).

Oops, I posted a reply but somehow put it as a new thread... it is at:

other thread

The story I heard was that 4 people had gone out on this cat into the Atlantic, with one port cover actually missing. When capsized, therefore one hull filled, but did not sink. Sadly, they did not stay with the floating boat.