Worst Case Scenario: Hitting A Sunken Container - What To Do!??

[LakeSuperior]

Originally Posted by skipmac

Problem is a container is pretty solid. Very rough calculations a 20' container has a volume of about 10,000 gallons, a 40' container double that.

Even if the container is 80% full of cargo that leaves c. 2000 gallons of water to fill a 20' container or about 8 MT. Add the weight of the container (2-3 MT) and the cargo (up to 25 MT) at a min you will be running into a 12-15 MT object. Max could be over 30 MT. That much weight will be the same as hitting something very solid.

The great thing is that in the collision momentum would be conserved. Some of the available energy will be consumed by the damage to the hull (tearing of the fiberglass or wrinkling of the metal).

[transmitterdan]

Originally Posted by LakeSuperior

The great thing is that in the collision momentum would be conserved. Some of the available energy will be consumed by the damage to the hull (tearing of the fiberglass or wrinkling of the metal).

And some day you can explain to me how that's a comfort.

I agree with others that the odds of hitting a rogue floating container are minuscule. The shore lines seem to be littered with abandoned recreational boats that washed ashore but not many containers.

[rgscpat]

For me, an unlit fishing vessel or smuggler would be more of a worry.
But if you want scary, try some port and government authorities.

[skipmac]

Originally Posted by transmitterdan

And some day you can explain to me how that's a comfort.
.

Hmmm. I'm guessing some element of humor was intended?

Originally Posted by transmitterdan

I agree with others that the odds of hitting a rogue floating container are minuscule. The shore lines seem to be littered with abandoned recreational boats that washed ashore but not many containers.

Depends on how you define minuscule but in any regard, odds I agree are very, very small. Certainly not enough to deter me from crossing oceans, but certainly enough to motivate me to a higher level of preparedness for possible sinking.

[LakeSuperior]

Originally Posted by skipmac

Hmmm. I'm guessing some element of humor was intended?

There are laws of physics, which do not need a governmental entity (man) to enforce as they cannot be violated. Then there are rules of man. The rules of man are not laws and can be broken at whim. I was pointing out basic law of physics that is learned in the sophomore year of college.

[hellosailor]

Andy, your steel rib would need to be a custom made (bent in 3D) beam capable of sustaining an impact load without deforming and crushing or splitting the hull behind it. I'm going to guess it would add 10-20 grand to the cost of the boat, and a couple of thousand pounds. Structural steel is damned heavy.

So, who's going to buy it? No one. Because if you hit the container off-center, you're still going to punch a hole in the forward quarters and sink the boat. Might as well just buy a steel or aluminum boat.

There were some comments from one of the cruising authors decades ago about adding in steel tire belting and fiberglassing that inside the bow as a retrofit. Steel belting (in the pre-kevlar age) being a good way to reinforce things that might crack, but at least keeping them more or less in place and slowing the water ingress. Don't know anyone who's been tempted to do that either, personally.

[Atraxia]

I don't know about containers these days. I found one half-floating in the Med quite some years ago and had a brush with a barrel off the Croatian coast as well. Two years ago while crossing the Atlantic, west to east, a whale came and brushed him/her self along the hull. Probably wanted to scratch but last year was the first time we had a bad experience with a USFO (Unknown Semi Floating Object). While sailing along the north-west coast of Australia, we hit a whale (or he/she hit us) and caused some damage that forced us to haul the boat out. Not an easy task along that part of Australia and only thanks to a great couple, Gayle and Bruce from Canarvon, we managed to get the boat out at their yard and fix it so we could continue on our way across the Indian. The skeg was totally torn off and the rudder was crushed a bit.
Here are some pictures taken right after the "bump". Unfortunately, we never got to see the whale but we saw a few others in the distance.

[Atraxia]

Oopsss

Here are the pictures

[Andy73]

Originally Posted by hellosailor

Andy, your steel rib would need to be a custom made (bent in 3D) beam capable of sustaining an impact load without deforming and crushing or splitting the hull behind it. I'm going to guess it would add 10-20 grand to the cost of the boat, and a couple of thousand pounds. Structural steel is damned heavy.

So, who's going to buy it? No one. Because if you hit the container off-center, you're still going to punch a hole in the forward quarters and sink the boat. Might as well just buy a steel or aluminum boat.

Thanks HS... I guess I was thinking more of using the rib as a structural foundation for the ship itself... a steel keel I guess.

Your point of the off center hit is certainly valid. Probably contributes to why this isn't common. Still, it would be interesting to see a ship with a steel bow section with fiber flowing aft. Weight and balance would be a challenge I guess... but still interesting.

Andy

[jeanathon]

Apparently they do wash up on beaches.
Strangest Things That Washed Up on Beaches - weather.com

[garyohv]

Make some bulkheads watertight with watertight doors. I wonder if spray urethane foam (insulation) would seal a hole, or be glue to hold a patch?

[boatman61]

Don't Panic.....!!

[hellosailor]

Urethane foam & urethane glues actually set up faster when damp, they tell you to make sure the wood has been dampened if you want the best bond. So they should set up well underwater. Problem is, the water pressure may blow out the patch, or squeeze out the glue, until it has set up. And water pressure would prevent it from expanding normally, you'd want the high-expansion stuff to hedge that bet.

[RaymondR]

The urethane foam in cans is great stuff. One of my techniques for finding whether corroded spots in the hull are sound is to try to knock a hole in them with a chipping hammer. I was doing so one day and found a bad spot (sudden water ingress) a tube of Knead It, small piece of plywood and a prop fixed the small hole and then to subdue my paranoia I got loose with a can of urethane. When I came to fix the thin spot one of the more difficult parts of the job was the removal of the urethane foam.

Whilst I was in the boat yard a 70' fiber glass cray fishing boat was hoisted out with about four feet of its bow missing at the water line. It had run into a previously unidentified rock off the NW coast of Australia. It had a collision bulkhead which was unaffected so they screwed some thin alloy plate over the hole and filled the volume between bow and bulkhead with expanding polyurethane foam. Apparently a lot of boats in that part of the world carry the stuff for emergencies.

Steel is ductile and tough which tends to allow it to absorb a lot of energy before tearing. If the welding is done properly it should be as strong, and perhaps even stronger, than the parent metal.

If I suffered a collision in my steel boat similar to that which caused the damage represented in the images in post #158 it would probably only scratch the paint because the bottom of the keel is 1 1/4" plate and the front 3/8" wall thickness round tube.

In general I would say that all else being equal, in a collision with a floating object a reasonably well built and maintained steel boat is far more likely to survive. The difference between the materials is that the steel boat is going to require more maintenance, be considerably heavier and not look as near as pretty.

If you want your boat to look good all the time and/or don't want to have to do much maintenance (mainly worry incessantly about the coatings) and/or be nice and light to beat the other guy around the buoys buy plastic.

If you are of a careless or over adventurous nature, don't mind caring for your paint work (inside and out) diligently and are paranoid about running into things in the ocean and want the greatest probability of a non fatal (for the boat) collision, buy steel.

And when you have done all you practicability can or want to, to ensure survival, stop worrying about it and go sailing.

[heres hoping]

ive never heard of a floating container killing anyone ok you may lose your boat but youll be ok if your prior preparation is up to scratch liferaft,epirb, sat phone and a grab bag.... concentrate on the 5 P's