forward cockpits and picture windows

[44'cruisingcat]

So boats should be built so that having the rig come down does no damage?

[tp12]

Originally Posted by jmh2002

In theory I agree with you, but then there are unexpected possibilities like I posted earlier in the thread:



So the hatch itself may have been seaworthy enough, but damage to the structure around it prevented it from performing it's job correctly. And probably nobody thought about that, or at least not enough.

I think in conclusion all that can reasonably be done is to take a belt and braces approach and consider, "what if" and after "what is my plan for that"?

On regulated vessels these type of events and the action you should take is (in theory) foreseen, and stipulated. But even then it doesn't always go to plan, and the most unbelievable messes occur from a simple original event.

In the past it was always normal and common to carry equipment to somehow patch a hole, wherever that may be, and on larger vessels it is normal to have metal storm shutters which are fixed to 'picture windows and hatches' before ocean crossings.

Possibly such thinking needs to also apply to some of the yachts we are talking about too.

I also mentioned earlier in this thread that designs could consider these windows to not be critical and that damage only impacts comfort rather than safety.

Eg: this could be achieved with additional 'companionway hatches' that make the hulls watertight in the event of the main salon windows being breached.

My statement still stands. You may not like the compromises you'd have to make to ensure that's the case. And generally people don't but to say it's not possible is incorrect.

They didn't make those compromises on Rainmaker and I wouldn't mind betting that Gunboat changed their design after that experience. I also wouldn't mind betting that risk management played a part in the original design.

[boatman61]

Originally Posted by 44'cruisingcat

So boats should be built so that having the rig come down does no damage?

Inflatable carbon fibre masts.. if it breaks the air escapes and the mast deflates causing minimal damage..

[44'cruisingcat]

Originally Posted by boatman61

Inflatable carbon fibre masts.. if it breaks the air escapes and the mast deflates causing minimal damage..

Helium filled, so the mast just floats away?

[boatman61]

Originally Posted by 44'cruisingcat

Helium filled, so the mast just floats away?

Hey..!!! Even better.. and it'd improve speed.. lighter boat.

[Painless]

Interesting thread....I believe Nordhavns are a pretty well thought out hull although powered, they are ballasted to survive a knockdown and a rollover so they have made allowances for storm plates to be installed for “crossings”. I don’t think this implies their windows are poorly made but is realistic about the forces water can make on all parts of a boat, sail, power, mono or multi.

James Theodore of Friday Harbor, WA asks:

How well would the 40 survive a knockdown or even worse a rollover?

Jeff Leishman responds:

You bring up a good question on the basic design parameters of a true ocean going boat. As the chief designer of the Nordhavn 40, and all of the other Nordhavns, it is my job to ensure that these boats can survive a knock down or worse yet a complete 360 deg. roll over. On paper the N40 does show a positive righting moment through 180 deg. So a knock down is something that would not present a problem assuming that a window or windows didn’t get blown out. That is the reason for the storm plates that we suggest for the side salon windows. The Diamond Sea Glaze windows that the N40 comes standard with have welded sockets on the corners of the salon windows, which allow the storm plates to be easily attached when going to sea.

Occasionally we get reports from owners on N46s or other Nordhavn models that claim they took a knock down without any significant damage or trouble. A knock down, while quite scary, is unlikely to be catastrophic if the boat and crew prepared for such an event. A 360 deg. roll over is another matter. Theoretically on paper the N40 would easily right herself in a roll over. However, in real life, a roll over would be a very violent event that would undoubtedly cause some type of damage to the boat and the crew. Unsecured objects get tossed about increasing the likelihood of windows being broken from the inside, which could cause severe flooding. Antennas and rigging would likely be lost or damaged. Provisions and other stores get shifted which cause the center of gravity to shift hindering the ability of the boat to come back up. All of these things would contribute to a very dangerous situation that is difficult to predict. The same waves that will put a boat upside down will also put the boat right side up and the negative righting curve of the N40 is quite small compared to the positive righting curve, meaning that it would take a lot less of a heel angle for the boat to get back to a positive righting moment that it took to get it into the negative realm. A very important element of surviving a roll over would be how well the boat is prepared to handle it. If everything is tightly secured, storm windows are in place and the crew doesn’t get too beat up, then a roll over could be survivable with the boat continuing on.

This subject has so many variables and the sea is such a dynamic force that it makes it almost impossible to predict any outcome.If I had to pick a motor yacht to try a roll over in the N40 would be high on my list. Let’s hope we never know the answer.

[jmh2002]

Originally Posted by 44'cruisingcat

So boats should be built so that having the rig come down does no damage?

No I didn't mean that of course (even though everyone had a good laugh), only that as I mentioned in my earlier post some thought should be given to a belt and braces approach and consider, "what if" and after "what is my plan for that"?

Especially for critical construction parts like hatches and windows.

eg: what will I do if for some reason that critical opening hatch doesn't close properly anymore and now the interior is open to the sea? This would be especially relevant on the gunboat open type design.

There was another thread here about Giot escape hatches failing. I would sure want to have a 'just in case' plan about how to shutter a hatch that is under the boat and just above the waterline...

Shxt happens, and things still can and do go wrong, even with the best thinking, planning, and construction.

[LeeV]

Originally Posted by Painless

Interesting thread....

As the chief designer of the Nordhavn 40, and all of the other Nordhavns, it is my job to ensure that these ---------------snip-------------

A 360 deg. roll over is another matter. Theoretically on paper the N40 would easily right herself in a roll over. However, in real life, a roll over would be a very violent event that would undoubtedly cause some type of damage to the boat and the crew. Unsecured objects get tossed about increasing the likelihood of windows being broken from the inside, which could cause severe flooding. Antennas and rigging would likely be lost or damaged. Provisions and other stores get shifted which cause the center of gravity to shift hindering the ability of the boat to come back up. All of these things would contribute to a very dangerous situation that is difficult to predict. The same waves that will put a boat upside down will also put the boat right side up and the negative righting curve of the N40 is quite small compared to the positive righting curve, meaning that it would take a lot less of a heel angle for the boat to get back to a positive righting moment that it took to get it into the negative realm. A very important element of surviving a roll over would be how well the boat is prepared to handle it. If everything is tightly secured, storm windows are in place and the crew doesn’t get too beat up, then a roll over could be survivable with the boat continuing on.

This subject has so many variables and the sea is such a dynamic force that it makes it almost impossible to predict any outcome.If I had to pick a motor yacht to try a roll over in the N40 would be high on my list. Let’s hope we never know the answer.

Great perspective, and a pleasure hearing from a designer!
When I sailed aboard the Pride of Baltimore II in 2000, we visited Baltimore, Ireland during a terrible storm that actually dragged the Pride across the harbor and kept the entire crew working most of the day. As it turns out, that harbor is also home to one of the steel rescue boats used throughout the British Isles. Unfortunately that storm caused the sinking of two freighters who couldn't get to safety. I was ashore and was invited to ride along and take photos in the rescue boat when it went out.

I was TOTALLY unprepared when I saw this rolly polly steel thing that looked half like a boat and half like a toy sub sitting on a railway that looked to be at a 120 degree angle. Just getting into it was interesting. Everybody inside wore 4 point harnesses, and since I was standing behind the pilot's seat, I was strapped in first. Apparently when we were ready, somebody outside used an enormous sledgehammer to drive out the pin and release the "boat" which flew down this railing and into the harbor we went!

The worst part was getting out of the harbor with 22' seas; that was my first and only experience at a rollover. I hope I NEVER experience that again. The pilot warned us all that it would probably happen, and had told me the vessel is designed to handle it. Even so, when it happened it was unsettling, to say the least. Almost everything had been lashed down or stored, but some small items were being tossed around. I cannot envision a rollover in any boat, sail or power, and have great sympathy for those who have done so.

Unless the design calls for a vessel to do just that, I can't imagine any boat or sailor/Captain coming through a roll over unscathed, physically or mentally.