Hull protection for floating objects

[ShinyHappy]

Originally Posted by Midnight Son

I know the Caliber LRC sailboats have Kevlar reinforcing in the bow laminates. They have it in their brochures and the website, last I looked.
Best wishes

Interesting. If I go pre-owned, this is on the short list. Thank you, I will look for that info.

[Belezar]

Several of the higher end ocean going boats both reinforce the area and or use watertight bulkheads. I agree that although worrisome, if it was much of an issue smart folks would be selling us a fix.

[Scorpius]

Originally Posted by ShinyHappy

I'm hoping to keep my record of no buoys hit intact.

Everytime I think I've excluded steel and aluminum boats from my wish list, you guys tell stories like this and make me reconsider.

There's a story from many years ago of an Aussie in a steel boat (about 45' I seem to recall) who was crushed during a hurricane between a cargo ship and a big tug that was trying to keep the ship off the beach. The "incident", in La Paz, Sea of Cortez, Mexico, narrowed his sailboat by about six feet! but didn't hole it.

Apparently he sailed his boat back to Australia before fixing (or probably scrapping) it. He said it sailed just fine and pointed higher than before because of the narrower sheeting angles!

[ShinyHappy]

Originally Posted by Clivevon

You've heard about the Titanic, right? Steel boat, hit iceberg a glancing blow which ripped all along its side? Scaled down, a container is iceberg size to a cruising boat, & your reinforced bow is not going to help at all if you hit the corner of one of those a glancing blow. A collision bulkhead might help or at least buy you time - depends where you hit.
You could buy an "unsinkable" boat like a Sadler 34 which has a thick foam filled gap between the inner & outer hull which is proven to stay afloat even when full of water.
I reckon most of us just trust to luck & "keep our powder dry" (liferaft, epirb, carefully thought out grab bag & water bottles....).

And really, your last statement is what it's about, be prepared.

I understand anything is fallible. And this isn't something keeping me awake at night but i figured there must be an answer.

[Scorpius]

Originally Posted by ShinyHappy

And really, your last statement is what it's about, be prepared.

I understand anything is fallible. And this isn't something keeping me awake at night but i figured there must be an answer.

I totally agree! But I also like the added security of a steel boat.

[hpeer]

Originally Posted by Martkimwat

Unfortunately most containers float up and down level or just below the surface and often the impact is vertical as the container bobs back up towards the surface. a foot or to of motion may not seem much but bear in mind it is a forty ton item and that equates to a lot of inertia/momentum depending on what it is doing. It's just as likely to be a glancing blow as well rather than an impact straight on so might miss the bow all together. I have considered using a forward looking sonar which can have a 600 foot detection range in deep water,(Interphase) or 300 feet (Echopilot) but at 6~7 knots that's only going to give you 60 seconds (30 seconds with an Echopilot) at best. May be enohttps://www.sailnet.com/threads/2021-sailing-the-chesapeake-bay.336547/ugh if you are quick to respond if the warning is recognised straight away without the hesitation that is likely with a warning alarm that may not be immediately recognised for what it is. After all it's not likely to be going off regularly.

A point to consider,
Water is about 62 pounds per cubic foot,
A 40’ containers weight, for contained water alone, is roughly 40x8x8x62 or 158,000 pounds.

That is 77 tons or there abouts. Plus the weight of the container. THAT is the momentum resisting you.

A year or two ago there was a steel super yacht (about 130’ IIRC) , a couple of years old, that went down suddenly. Somewheres near Malaysia. I think that could have been a container strike.

I don’t want to test my steel boat against a container. I may have a edge over a glass boat, but I am not guaranteed to survive.

Ditto bergy bits and growlers. One day I see a bit of ice floating so I go over by it and look it over. Its submerged volume is nearly as much, perhaps more, than my boat. Yeah, no. I moved on.

[duncan_ellison]

Before Hunter went down (pun intended), they did put a reinforcing layer of Kevlar from the bow to the keel of their larger sailboats (45ft+) - including mine.

Saw them actually doing it in the factory. I wouldn't like to hit a container either, but at least it might help (a bit).

[boat driver]

sometimes insurance is there for a reason- mines in the red sea come up as a thought

[wingssail]

We hit a 40' (1' diameter) log perpendicular to our bow while motoring at about 6.5 knots. It banged the bow, rolled under to the keel, banged the keel, rolled under some more, missed the propeller, but hit the rudder. Very noisy, and by that time my daughter, who was on watch and driving, was wide awake. I stuck my head out the hatch and saw the log come to the surface behind us.

There was little damage, superficially actually, fixed at the next haul out with bog and paint.

But that is not a 70 ton water logged container with metal corners. I doubt that many boats could hit that without damage, serious damage. And I am not interested in driving around in an icebreaker anyhow. At higher speeds no one is safe.

So the solution is to keep the containers onboard the ships. The way to do that is make it illegal and levy huge fines to ships which return without their containers. Right now there is no penalty except to the hapless mariner who hits one, just a minor insurance cost and that's it. Not enough.

Also, make them sinkers, with water soluble plugs. And if filled with floatable cargo, add weight.

And add short range AIS transmitters.

As it is there is little incentive to do anything. Make it expensive and the problem will be solved.

[Paul L]

Originally Posted by boat driver

sometimes insurance is there for a reason- mines in the red sea come up as a thought

Acts of war or piracy are generally not covered

[Scorpius]

Originally Posted by hpeer

A point to consider,
Water is about 62 pounds per cubic foot,
A 40’ containers weight, for contained water alone, is roughly 40x8x8x62 or 158,000 pounds.

That is 77 tons or there abouts. Plus the weight of the container. THAT is the momentum resisting you.

A year or two ago there was a steel super yacht (about 130’ IIRC) , a couple of years old, that went down suddenly. Somewheres near Malaysia. I think that could have been a container strike.

I don’t want to test my steel boat against a container. I may have a edge over a glass boat, but I am not guaranteed to survive.

Ditto bergy bits and growlers. One day I see a bit of ice floating so I go over by it and look it over. Its submerged volume is nearly as much, perhaps more, than my boat. Yeah, no. I moved on.

Somewhat faulty calculations: Because a container is made of steel (denser than water) if it was completely full of water (40 x 8 x 8) it would sink. And you can't add the weight of the contents because they would displace water - at 62 pounds per cubic foot. Only if the contents were sufficiently less dense than water and there were enough of them to displace quite a lot of water, or if there was air trapped in the container (unlikely as most are vented right up near the roof) would the container float - and it's total weight would be considerably less than your calculations.

Still, even though I have a steel boat, I don't want to test it's strength hitting the corner of a floating container! (There are also lots of reasons other than container strikes that could have sunk that superyacht - including a failed through hull, pirate attack, insurance fraud, etc. Note too that even if it was container strike, he was probably traveling A LOT faster than we would be, thus increasing his momentum substantially, and increasing the force with which he would have hit the container. And, how big was the super yacht? As a boat gets bigger, the ratio of hull plate thickness to vessel weight drops dramatically. A small steel boat is MUCH more resistant to hull strikes than a big one).

[Scorpius]

Originally Posted by wingssail

We hit a 40' (1' diameter) log perpendicular to our bow while motoring at about 6.5 knots. It banged the bow, rolled under to the keel, banged the keel, rolled under some more, missed the propeller, but hit the rudder. Very noisy, and by that time my daughter, who was on watch and driving, was wide awake. I stuck my head out the hatch and saw the log come to the surface behind us.

There was little damage, superficially actually, fixed at the next haul out with bog and paint.

But that is not a 70 ton water logged container with metal corners. I doubt that many boats could hit that without damage, serious damage. And I am not interested in driving around in an icebreaker anyhow. At higher speeds no one is safe.

So the solution is to keep the containers onboard the ships. The way to do that is make it illegal and levy huge fines to ships which return without their containers. Right now there is no penalty except to the hapless mariner who hits one, just a minor insurance cost and that's it. Not enough.

Also, make them sinkers, with water soluble plugs. And if filled with floatable cargo, add weight.

And add short range AIS transmitters.

As it is there is little incentive to do anything. Make it expensive and the problem will be solved.

I'm happy to hear that log you hit did so little damage. You were probably lucky it was fairly small (for around here anyway) and probably pretty waterlogged so it didn't quickly bob up aft of your keel (assuming a fin keel) and take out the propellor.

Good luck with trying to do anything to penalize ships that lose containers - or do anything to make them less dangerous when in the water. The reason there are so many logs in the water around here is that loggers don't have to pay the government (who owns most of the land and therefore the trees) for the trees/logs until the they get to a scaling station - usually in Howe Sound just outside of Vancouver. Thus when logs are lost from booms the finacial loss is not that great - so they are not all that careful about making sure they can't get loose.

If you hit one of those logs (and it happens all the time) it's considered an act of God and no one is accountable. However, if you try to SALVAGE one, then sell it to a sawmill, sorry, that's stealing. That log is owned by somebody (there's a stamp on the end), can only be salvaged by a licensed beachcomber, and MUST be sold to the log salvage co-op at a fraction of the market price. Welcome to big company legalese. I doubt you would have any more success with containers than we have suing logging companies for log strikes.

[coopec43]

As far as fiberglass is concerned an Airex cored hull handle an impact much better than a solid glass hull as the Airex will absorb the impact and as it has a memory it will go back to its' original shape.

[Midnight Son]

Originally Posted by wingssail

We hit a 40' (1' diameter) log perpendicular to our bow while motoring at about 6.5 knots. It banged the bow, rolled under to the keel, banged the keel, rolled under some more, missed the propeller, but hit the rudder. Very noisy, and by that time my daughter, who was on watch and driving, was wide awake. I stuck my head out the hatch and saw the log come to the surface behind us.

There was little damage, superficially actually, fixed at the next haul out with bog and paint.

But that is not a 70 ton water logged container with metal corners. I doubt that many boats could hit that without damage, serious damage. And I am not interested in driving around in an icebreaker anyhow. At higher speeds no one is safe.

So the solution is to keep the containers onboard the ships. The way to do that is make it illegal and levy huge fines to ships which return without their containers. Right now there is no penalty except to the hapless mariner who hits one, just a minor insurance cost and that's it. Not enough.

Also, make them sinkers, with water soluble plugs. And if filled with floatable cargo, add weight.

And add short range AIS transmitters.

As it is there is little incentive to do anything. Make it expensive and the problem will be solved.

You will hit the law of diminishing returns. People WILL LIE, and payoff their customers under the table. Thus increasing bribes and crooked/unscrupulous companies, of which I think we have enough of already.


Sorry we need strenuous inspections before the ships leave. THEY HAVE to secure the containers before leaving port. That will be greatly fought, as that is usually the deck crews job, immediately after casting off lines.



In The St. Laurence River in Canada, a year or so ago a third officer, I believe, was supervising removal of container lashings, before coming into Montreal Harbour! He didn't make it.
So lots of room for improvement.


Best wishes, stay safe

[ShinyHappy]

Originally Posted by Martkimwat

Unfortunately most containers float up and down level or just below the surface and often the impact is vertical as the container bobs back up towards the surface. a foot or to of motion may not seem much but bear in mind it is a forty ton item and that equates to a lot of inertia/momentum depending on what it is doing. It's just as likely to be a glancing blow as well rather than an impact straight on so might miss the bow all together. I have considered using a forward looking sonar which can have a 600 foot detection range in deep water,(Interphase) or 300 feet (Echopilot) but at 6~7 knots that's only going to give you 60 seconds (30 seconds with an Echopilot) at best. May be enough if you are quick to respond if the warning is recognised straight away without the hesitation that is likely with a warning alarm that may not be immediately recognised for what it is. After all it's not likely to be going off regularly.

Interesting Stuff. I recall reading about the forward facing SONAR not being very effective for floating objects from those who use it. I read that awhile ago but it was from a search here.