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Old 06-06-2022, 18:12   #166
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

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The weakness in the windows would not have been revealed, but the weakness would still have been present.
Agreed. Which is why I never claimed otherwise.
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Old 06-06-2022, 19:06   #167
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

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We know the windows failed, so they're obviously not as strong as some use cases may want or need them to be. But we don't know exactly how or why they failed. So we don't know what changes would have made them strong enough to avoid the failure.
Actually, we do. Make them smaller. A lot smaller. It's a pretty safe bet that a smaller overall surface area would go a long way towards mitigating the problem, simply because it would significantly reduce the maximum amount of force nature could apply to them. Which is why some of us, myself included, keep harping on about the importance of keeping windows small.

According to physicists, a breaking wave can apply a pressure of between 250-6,000 pounds per square foot (1,220-29,294 kilograms per square meter), depending on its height.

In other words, that's up to a potential maximum of around 40 pounds per square inch. Given that the windows on Essence each had a surface area of approx. 574 square inches, that comes to a little under 24,000 pounds of force that could possibly be applied to one of those windows. That's only a couple of thousand pounds less than the entire boat weighs. In other words, about what you'd experience if you dropped the boat off a wave.

For an 8" porthole in the same circumstances, on the other hand, we're talking about a much more reasonable 2,000 pounds of force. Make that a 10" porthole, and we're looking at 3,000 pounds.

So at the end of the day, it's simple. Less square inches, equals less chance of it all going horribly wrong.
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Old 07-06-2022, 00:43   #168
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Maritime NZ report into the loss of the yacht Essence, October 2019

Modern trends have customers that demand deck saloons with associated larger windows. Itís unlikely we are returning to tiny portholes any day soon

The point is Essence has suffered two previous significantly violent knockdowns , one trashing the starboard solar panels.

This was a yacht that had now suffered unknown damage before the violent final knockdown occurred


The point being is probably unlikely this yacht ( or any yacht ) would have survived this type of abuse without damage.

When I read this report I see a failure of the command structure. Little effort was made protect the boat both via storm shutters but also heavy weather sailing techniques. Itís imperative that knockdowns are prevented as at this point you are merely throwing dice.

The fact that a particular piece of the boat failed isnít in itself a reason just to make that bit stronger you must understand the failure mode. Otherwise the whole boat ends up like Skip Novaks Pelagic with a matching price. ( or a chieftain tank to go shopping )

Itís unlikely any modern ( or older ) production ( or semi production )boat would survive multiple knockdowns including falling off a big wave .

I think if the window hadnít failed , something else would have anyway.
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Old 07-06-2022, 01:13   #169
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

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But of course, while size is a factor, it's not the only thing that determines how strong a window is. The design and material choice matters a lot (although a smaller window is easier to make strong enough).
Agreed. Also the amount of flex in the material around the windows is a factor. The flexing of the cabin structure around the windows for this boat was mentioned in the accident investigation.

ďThis is also likely to have caused pressure within the cabin which, combined with the flexing, may have caused the windows to blow out. It is noted that prior to the final knockdown, a crewman observed the cabin flexing due to wave pressure.Ē

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The Bavaria ocean range has very small windows in comparison to modern designs especially deck saloons
Agreed. This is part of my concern. If some boat builders cannot adequately secure what by todayís standards are reasonably small windows, are we going to see problems with larger windows, especially when the boats age and glue is subject to UV and fatigue cycles. Windows or port lights on the hull sides close to the waterline are of particular concern.
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Old 07-06-2022, 01:42   #170
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

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A couple of other things are mentioned in the account and the 'lessons learned' section, that are worth mentioning. Apparently, even before the fatal knockdown, they had discussed seeking shelter, but were unable, for two reasons.

As some, even here in these forums, advocate for long passages, they had removed their primary anchor and stowed it below, not expecting to need it again before landfall. Also, rain and spray had rendered their chartplotter inoperable.

I'm one of those who maintain that the primary anchor should always be ready for use, and the fate of Essence is an excellent case in point. Had they been able to divert to shelter and anchor, this entire tragedy could have been averted.

But the more serious failing was that, astonishing as it sounds for such an experienced skipper and crew, apparently they had NO backup system for the chartplotter! No backup unit below deck, and no paper charts covering alternative destinations along their route.

Essentially, due to these two failures of imagination, they had destroyed their only 'plan B' option, and thereby painted themselves into a corner.

The other lessons, about the oversized windows, the EPIRB, the liferaft mountings, and so on, are equally valuable in their own light, but if they'd simply been able to head for shelter in Whangaroa Harbour or the Cavalli Islands, those weaknesses might never have even been revealed, and the whole sorry misadventure could have become merely another tale to tell over the yachtclub bar.

The YM article is a woefully deficient source to draw the conclusions that youíve made as it is a fraction of the information in the bookís lessons learned chapter.

First, they had decided to divert their course to seek earlier shelter. They chose Bay of Islands as that is the only wide and relatively safe entry on the N coast.

Cavelli Islands are completely exposed in E and NE weather - there is nowhere safe there in those conditions.

Whangaroa Harbour has a narrow entrance - 200m - and is relatively shallow for several miles offshore (<20m for several miles). It is a very difficult entry in strong E and NE conditions, and deadly with high swells and an ebbing tide. Even had they decided to take their chances with the entry to Whangaroa, their final knockdown took place well short of there too.

Second, they had a chart on an iPad, but it presumably wasnít waterproofed for use outside. There was no mention of whether or not there were other charts. Cat 1 does require enough paper charts of ocean, coastal and harbour scales to provide a safe backup in case of e-chart failure, so those should have been on board.

Third, they could have entered a harbour and then rigged their anchor - not having it rigged did not prevent them from using it as there were no exposed safe anchorages that they could have used in the prevailing conditions.
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Old 07-06-2022, 02:16   #171
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

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Originally Posted by goboatingnow View Post
Modern trends have customers that demand deck saloons with associated larger windows. Itís unlikely we are returning to tiny portholes any day soon

The point is Essence has suffered two previous significantly violent knockdowns , one trashing the starboard solar panels.

This was a yacht that had now suffered unknown damage before the violent final knockdown occurred


The point being is probably unlikely this yacht ( or any yacht ) would have survived this type of abuse without damage.

When I read this report I see a failure of the command structure. Little effort was made protect the boat both via storm shutters but also heavy weather sailing techniques. Itís imperative that knockdowns are prevented as at this point you are merely throwing dice.

The fact that a particular piece of the boat failed isnít in itself a reason just to make that bit stronger you must understand the failure mode. Otherwise the whole boat ends up like Skip Novaks Pelagic with a matching price. ( or a chieftain tank to go shopping )

Itís unlikely any modern ( or older ) production ( or semi production )boat would survive multiple knockdowns including falling off a big wave .

I think if the window hadnít failed , something else would have anyway.

Both knockdowns, neither to 90*, were not necessarily a result of any sort of impact. The first knockdown tore the solar panel from its stored position on the lifelines adjacent to the cockpit (presumably as a sort of lee cloth) and the bookís author only mentioned excessive heel. The second knockdown wasnít mentioned in the book.

Failure of command structure? The boat was prepared for heavy weather to the usual standard. A reasonable decision was made to keep sailing for a relatively near safe harbour - the Maritime NZ reportís admonishment to change course out of the dangerous quadrant would have had them heading NW, directly away from potential shelter and flirting with the N coast to leeward.

Setting a drogue or heaving to could have been done, but the decision to continue sailing was not unreasonable even in the words of the Maritime NZ report.

The biggest lesson was about storm shutters for windows and having them mounted is now part of Cat 1 requirements. Iím certainly looking at our salon windows and wondering how to make shutters for them - in our case perhaps curved lexan sheets mounted with through bolts? At least that would preserve visibility and make it more likely that we would use them.

Nobody mentions shutters for deck hatches, so presumably even had they mounted storm shutters for the windows, the forward hatch could still have opened. Very weird still.
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Old 07-06-2022, 04:50   #172
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

I think this is a weird thread, it seems to me a lot of things are amiss and that is probably because of the kind of boat we have. I try to see how all this would apply to me or some others.

1- It strikes me that a lot of good argumnt has been put forth indicating why the new regulation is not really helpful. My guess is that it was an attempt to "do something so something was done, even if likely ineffectual.
2- my boat is steel built in 1987. NO windows. But 14 opening port lights. I just replaced all of them because the original were done, some were badly corroded but it was not visible. The legislation does not address that, but maintenance is an issue. Was it an issue here?
3- I have 4 hatches, just saying.
4- How does this apply to catamarans? They have huge sliding doors?
5- And I would think those bottom Catamaran escape hatches would be an issue. Can they take the pressure?
6- I can't imagine sailing on a boat that flexes like that. We never flex, at least not noticeably. Doors always shut just fine.
7- Maybe they didn't use a drouge because they would have been pooped more? Did transom design effect stratrgy?

So report does not conclude WHY the wi dos poped, just noted that they AND the hatch posed open. Could be pressure, could be flex. I have eyeglass lenses pop out because of frame flex. Which then begs the question of why boars over windows and not hatches? Both failed.

And if flex is the problem then why not regulate boats flex? Lots been said about how "heavy" that boat is. Not to me, it is (or was) 47' and 24,000 pounds, I am 44' and 40,000 pounds. Now THATS heavy. It strikes me this new rule is a pretty silly knee Kerkorian reaction. Not terribly bad for most, but an annoyance and it doesn't help the credibility of the rule makers. A new rule should be driven by some demonstrable improvement, they don't even know, and do not state with certainty why the windows and hatch poped. AND then, if boards are called for, there should be some indication of the performance required, a performance standard.

I have met brand new sailors whose first boat was a big cat. One a gun boat. The other was racing off to a round the world rally because he thought it would be a good way to "get his feet wet." How do you legislate stupid?

I really would like to hear about how cats are dealt with, especially those BIG doors.
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Old 07-06-2022, 06:54   #173
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

Heavy in itself isnít any Indication of anything. Itís not necessary safer or better. All you know is itís heavier !
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Old 07-06-2022, 07:28   #174
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

Agreed, it was the report that brought it up that the boat was "heavy". To what end? Where they trying to imply "quality of build"?

They cloud have said the boat was white, but did not. Which implies "heavy" has some bearing.

Then on the hull structure they repeated some marketing blurbs, nothing quantitative.
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Old 07-06-2022, 14:37   #175
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

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I really would like to hear about how cats are dealt with, especially those BIG doors.
our boat is not NZ registered so they can have whatever silly rules they like, however i suspect this rule may not be applied to a catamaran as cats don't get knocked down

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Old 07-06-2022, 14:44   #176
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

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our boat is not NZ registered so they can have whatever silly rules they like
The concern is they have applied these rules to foreign boats visiting NZ waters.

This was challenged and I am not sure of the current situation.
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Old 07-06-2022, 15:09   #177
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

Current situation is that Sec. 21 was overthrown by a triumvirate of judges, long ago. Vessels from other countries are now required to meet whatever standards their country of registration has.

Ann
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Old 07-06-2022, 15:32   #178
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

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Current situation is that Sec. 21 was overthrown by a triumvirate of judges, long ago. Vessels from other countries are now required to meet whatever standards their country of registration has.

Ann
Thanks for the update.

Glad to see they have dropped their bureaucratic legislation at least for foreign boats.
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Old 07-06-2022, 17:59   #179
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Re: Maritime NZ report into the loss of the yacht Essence, October 2019

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Ö
I really would like to hear about how cats are dealt with, especially those BIG doors.

Only the windows are covered in the current Cat 1 requirements; no mention of the cockpit doors for multihulls. For multihulls it does include storm coverings for escape hatches but does not say they need to be fitted, unlike for salon windows.

From the current regulations summary of changes https://www.yachtingnz.org.nz/sites/...202021-24.pdf:

ď13.10 (M)
On all multihulls a readily usable safe method of entering and exiting from the inverted vessel must be provided to allow a fully clothed person to pass through this entry/exit which must be clear of the water at all times, upright or inverted. It is required that skylights and hatches must be fastened from below to allow exit in case of emergency. If this is not possible a cutting line shall be clearly marked - Escape Cut Here, and appropriate hull cutting tools kept secured nearby for instant use adjacent to the intended cutting site.
Add:
If hatches are used for this purpose, a storm board must be carried that can be used to rapidly over the hatch should it fail.
13.11 (K)
Change from:
Storm coverings are required for all windows more than 1852 cm2 (2sqft) in area
Change to:
Storm coverings shall be fitted for all windows more than 1858 cm2 in area
13.12 (M)
Change from:
Storm coverings for exposed windows more than 1852cm2 (2sqft) in area shall be provided or it shall be demonstrated that the window material as installed will withstand severe blows and remain intact. In the case of curved glass windows, properly positioned and secured, very heavy covering material, may (as the only practical solution) be permitted as a substitute storm shutter.
Change to:
Storm coverings for exposed windows more than 1858cm2 in area shall be fitted.Ē

And for clarification, the Cat 1 regulations ONLY APPLY to New Zealand-flagged ships.

ďNew Zealand-flagged ships departing New Zealand require a Yachting New Zealand category 1 Safety Certificate to complete New Zealand Customs documentation requirements prior to departure.Ē
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