Maritime NZ report into the loss of the yacht Essence, October 2019

[rslifkin]

In my mind, a drouge is a trade-off between potential problems. You'll slow the boat down (should only be needed if you're having control problems due to excess speed which should be less likely on many modern hulls). But because the boat can't be pushed forward as easily, the boat will see higher forces from waves and you're more likely to be pooped.

[fxykty]

Originally Posted by rslifkin

In my mind, a drouge is a trade-off between potential problems. You'll slow the boat down (should only be needed if you're having control problems due to excess speed which should be less likely on many modern hulls). But because the boat can't be pushed forward as easily, the boat will see higher forces from waves and you're more likely to be pooped.

Note that in Essence‘s case they were struck from the side and the boat was knocked down and possibly rolled. That is one of the risks of actively sailing in extreme conditions (though the conditions were not generally that bad according to their report). They did have control problems in so far as they had to hand steer due to the auto pilot not being capable. The author commented that the fin keel, broad stern and spade rudder of Essence had much less directional stability when quartering the seas than his own full keeled and relatively narrow boat.

In any case, there is a difference in behaviour between a speed limiting drogue and a properly sized series drogue.

The first limits the top speeds of the boat to prevent uncontrolled surfs and enables the boat to be actively sailed. It is a response to a conditions that are severe but not yet extreme (with the possibility of overwhelming the boat). In a breaking wave the boat will still surge forward with the breaking water, so no particularly high loads nor pooping likely (unless the conditions are worsening towards extreme) compared to having no drogue. And uncontrolled surfing resulting in striking the trough of the wave at speed and a bad angle is dangerous for pretty much any ocean-going small boat.

A series drogue effectively stops the boat and is a passive response - no sailing is needed. Just as with a sea anchor, the boat still moves with respect to the water, although stern to the waves instead of bow on. During a breaking wave the boat initially will be swept forward by the wave, so not necessarily experiencing greater wave strike loads than if it had deployed a speed limiting or no drogue at all. The difference is that as the wave passes the boat the series drogue will stop the boat and prevent it surfing into the trough - in fact it will pull the boat onto the back side of the wave. Neither a speed limiting nor no drogue will do that in severe let alone extreme weather.

But being stern to does present a generally weaker part of the boat to waves that break over the boat. Whether this is worse than being driven backwards onto a rudder(s) during a wave strike is up to the skipper of any particular boat to decide and generally informs the decision of whether to use a series drogue or sea anchor.

[fxykty]

Originally Posted by goboatingnow

…
I’ve not read the book but has it explained the open forward hatch issue. !

…

The author saw that the forward hatch over the v-berth was open after the knockdown/roll over. It had been locked shut.

He speculates that it may have been the same force that blew the cabin windows out (the windows blowing out was witnessed by the other crew, who was in the salon at the time).

[goboatingnow]

Originally Posted by fxykty

The author saw that the forward hatch over the v-berth was open after the knockdown/roll over. It had been locked shut.

He speculates that it may have been the same force that blew the cabin windows out (the windows blowing out was witnessed by the other crew, who was in the salon at the time).

I can’t believe compressive forces would be sufficient to blow a hatch open

[noelex 77]

Originally Posted by fxykty

He speculates that it may have been the same force that blew the cabin windows out (the windows blowing out was witnessed by the other crew, who was in the salon at the time).

The security of some modern boat windows is a concern.

The NZ authorities seem to place their faith in storm coverings. While these are a good idea, in practice they are very rarely carried, particularly in a ready made form that could be quickly fitted in adverse conditions over multiple windows.

[hpeer]

I am curious as to why "hatches" are considered differently than "windows".

Is it because hatches are stronger?
Or because they are fitted in a different plane?

What comes to my mind are the escape hatches in catamarans. They would seem as big a liability as windows and in a more vulnerable spot.
For that matter what about the large doors found on many cats and I have even seen them on some power boats.

And a second question is the boats material a consideration? Do aluminum and steel constructions have the same requirements. Surely the flex is much less in these builds.

[Adelie]

Porthole - opening or non-opening “window” on a vessel.
Hatch - means of ingress egress for people and material.

My sense is that hatches are usually significantly bigger which means that need to be made beefier to be as strong as a port light.

[JPA Cate]

Originally Posted by Adelie

Porthole - opening or non-opening “window” on a vessel.
Hatch - means of ingress egress for people and material.

My sense is that hatches are usually significantly bigger which means that need to be made beefier to be as strong as a port light.

Unfortunately, they are not always as beefy as they should be--just a sheet of maybe 10 mm acrylic, and plastic handles-- and sometimes the latches are really substandard. I suspect the boat was under built for $$ reasons. The modern standards could be seen as inadequate when the crossover is made from harbor hopping to offshore passages.

Ann

[JAFO]

Originally Posted by Paul L

First hand account of the loss of Essence and the rescue of the crew. Harrowing account.
https://www.yachtingmonthly.com/sail...Q0l47vq2S20zHM

Interesting comment in the lessons learned section:

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.

After breakfast on Tuesday we raised the anchor and stowed it under a bunk down below, thinking that our next stop would be a customs wharf in Tauranga, New Zealand, nearly 1,400 miles south – this action was to impact our decision-making during the fateful storm six days later.

When I took a turn on the wheel, I noticed the touchscreen chartplotter was no longer functioning due to the continuous rain. We had a choice of a digital or magnetic compass to steer by.

As we approached the Northland coast, Stuart and I discussed the idea of turning west to seek shelter in Whangaroa Harbour or the Cavalli Islands. I concluded that it would be risky to close the coast without the chart plotter to indicate hazards, and without the anchor being immediately available to drop.
It would have been a 20-minute job in calm water to refit the anchor; impossible in those conditions.

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.

[GordMay]

Originally Posted by JAFO

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...
... 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.

Indeed!

[noelex 77]

Originally Posted by JAFO

Even 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 weakness in the windows would not have been revealed, but the weakness would still have been present.

[goboatingnow]

Originally Posted by noelex 77

The security of some modern boat windows is a concern.



The NZ authorities seem to place their faith in storm coverings. While these are a good idea, in practice they are very rarely carried, particularly in a ready made form that could be quickly fitted in adverse conditions over multiple windows.

The Bavaria ocean range has very small windows in comparison to modern designs especially deck saloons

[rslifkin]

Originally Posted by goboatingnow

The Bavaria ocean range has very small windows in comparison to modern designs especially deck saloons

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).

[goboatingnow]

Originally Posted by rslifkin

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).

I’m of the view we still don’t understand the failure mechanism or even the exact event cascade

Until that is understood it’s very hard to place blame on a given component

[rslifkin]

Originally Posted by goboatingnow

I’m of the view we still don’t understand the failure mechanism or even the exact event cascade

Until that is understood it’s very hard to place blame on a given component

Agreed. 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.