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-   -   Leopard 46: Leopard 46 sinks after collision (https://www.cruisersforum.com/forums/f151/leopard-46-sinks-after-collision-99295.html)

transmitterdan 14-03-2013 13:45

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by s/v Jedi (Post 1185142)
Well, I'm with DOJ on this one. While a bilge pump might cope with a leaking valve or fitting, it won't do for a complete failure of one.

I think I am in violent agreement with Jedi and DOJ. The pumping system becomes important as a delaying tactic and ultimately to make the boat livable after the flooding is a trickle. Arguing about how big or how many bilge pumps to carry becomes a bit silly when you look at the flooding charts such as the one Evans has posted on his web site. I would guess less than 0.1% of cruising boats have a bilge pump system capable of staying ahead of the smallest thru-hull if broken off and left unplugged.

transmitterdan 14-03-2013 13:51

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by Boatguy30 (Post 1185175)
Any decent offshore multihull should have positive buoyancy when flooded. no need for the fire hoses.

I am not trying to be cute with this post. Apparently sometimes that isn't clear.

I truly don't understand the benefit of positive buoyancy when flooded as it pertains to safety of life at sea. My questions:

In 15 foot waves is the crew safer on the deck of a flooded boat or a life raft?

Why is a flooded boat that is still technically afloat not a hazard to navigation?

Cotemar 14-03-2013 13:55

Re: Leopard 46 sinks after collision
 
The benefit of positive buoyancy is that you have a big target to find in an infinite ocean. You want to be bigger than a postage stamp.

s/v Jedi 14-03-2013 14:42

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by transmitterdan (Post 1185262)
I think I am in violent agreement with Jedi and DOJ. The pumping system becomes important as a delaying tactic and ultimately to make the boat livable after the flooding is a trickle. Arguing about how big or how many bilge pumps to carry becomes a bit silly when you look at the flooding charts such as the one Evans has posted on his web site. I would guess less than 0.1% of cruising boats have a bilge pump system capable of staying ahead of the smallest thru-hull if broken off and left unplugged.

Exactly and only monohulls should come with a crash pump as multi-hulls have enough time with the missing ballast of a monohull.

To all: Instead of all the wooden plugs (take some of those too!) I would recommend to bring some of those big size epoxy sticks that cure under water. These can be used to plug partial thru-hull failures, unlike the wooden plugs. Just don't forget to knead them before use :thumb:

gbanker 14-03-2013 15:06

Re: Leopard 46 sinks after collision
 
Interesting article about a Nordhavn that sank.

Plumbing failure sinks $4.5 million yacht in its slip


There are bildge pumps installed in all boats and most boats do not have "crash" pumps because folks can't agree on what is "reasonable" as to size, number, flow rates, power sources, etc. So, most boat manufacturers install just enough to pass some standard, certification requirement, etc.

Sort of similar thinking to the vehicles we drive on our highways. We have about 35,000 deaths due to driving each year but none of us that I know drive around in Sherman tanks.

virgincapt 30-03-2013 05:33

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by smj (Post 1183313)
From what I read the capt. Got a view of the "foam core" while under the boat trying to save it from sinking. Probably an honest mistake.

I was the delivery captain on this boat, and this is true. I had a quick glance underwater and saw the core, assumed foam, but maybe it was balsa.

Also, and very important, is that I never saw nor stated that the boat sank. Most likely she turned turtle and drifted back down wind to Roatan or other Honduran shore. When we abandoned her, she was heavily down by the stbd stern with both eng rooms flooded.

In all these cases of a breached, cored hull, if the production process does not include vacuum bagging, then the interstices of the core are open and so will allow water to travel throughout the core, thus seriously altering flotation qualities of the foam. Thus a cat can surely sink.

Boatguy30 30-03-2013 06:46

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by transmitterdan (Post 1185266)
I am not trying to be cute with this post. Apparently sometimes that isn't clear.

I truly don't understand the benefit of positive buoyancy when flooded as it pertains to safety of life at sea. My questions:

In 15 foot waves is the crew safer on the deck of a flooded boat or a life raft?

Why is a flooded boat that is still technically afloat not a hazard to navigation?

if you're afloat there's hope. When the weather clears you can likely make repairs. :popcorn:

Palarran 30-03-2013 07:12

Re: Leopard 46 sinks after collision
 
Hello Virgincapt. Thanks for joining the CF and posting about your experience.

boatman61 30-03-2013 07:30

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by Palarran (Post 1198328)
Hello Virgincapt. Thanks for joining the CF and posting about your experience.

I'll second that..:thumb:

mcarling 31-03-2013 15:22

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by virgincapt (Post 1198285)
In all these cases of a breached, cored hull, if the production process does not include vacuum bagging, then the interstices of the core are open and so will allow water to travel throughout the core, thus seriously altering flotation qualities of the foam.

Foam can be either open-cell or closed-cell. Open-cell foam is like a sponge. Closed-cell foam is more or less waterproof.

s/v Jedi 31-03-2013 15:48

Quote:

Originally Posted by mcarling (Post 1199216)

Foam can be either open-cell or closed-cell. Open-cell foam is like a sponge. Closed-cell foam is more or less waterproof.

But still little blocks just like balsa for parts that are rounded, right?

mcarling 31-03-2013 15:56

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by s/v Jedi (Post 1199234)
But still little blocks just like balsa for parts that are rounded, right?

It doesn't have to be. Many types of foam can be sprayed into oddly shaped spaces.

See for example:
GREAT STUFF 16 oz. Gaps and Cracks Insulating Foam Sealant-162848 at The Home Depot

s/v Jedi 31-03-2013 16:00

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by mcarling (Post 1199240)
It doesn't have to be. Many types of foam can be sprayed into oddly shaped spaces.

See for example:
GREAT STUFF 16 oz. Gaps and Cracks Insulating Foam Sealant-162848 at The Home Depot

:confused: :confused: :confused: :confused: :confused: :confused:
You use that for a fiberglass hull as core material?!

mcarling 31-03-2013 16:05

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by s/v Jedi (Post 1199244)
You use that for a fiberglass hull as core material?

No, but it could be used for adding buoyancy. Filling nooks and crannies with closed-cell spray foam will prevent water from entering those spaces.

SVNeko 31-03-2013 16:09

Re: Leopard 46 sinks after collision
 
Quote:

Originally Posted by mcarling (Post 1199249)
No, but it could be used for adding buoyancy. Filling nooks and crannies with closed-cell spray foam will prevent water from entering those spaces.

Man, I can just see the mess this would make in a saltwater environment after its adhesion breaks down and it starts to disintegrate into a powder.


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