Preventer Rigging -- Lessons from the Platino Disaster

[Dockhead]

Originally Posted by Breaking Waves

. . . DH - jfyi - if you had a ketch, you probably would not have been flying the mizzen in those conditions (angles and strength). The main would be smaller, but still big enough on these size boats to create large loads. I would have preferred to have just headsails even/also with a ketch in this particular situation. net net - I'm not sure a ketch makes much difference to this particular case.

You're damn right I wouldn't be. And never have in a lifetime of sailing.


I will use the mainsail reaching in a F8 -- some good sailing possible like that. But I will not go down wind in F8 or above with the mainsail in use.



In such conditions the main is put away and the boom is secured with a pennant to the windward rail.


There's a reason why storm trysails don't use the boom.


Not just the risk of backwinding it, or dipping the boom -- you also sure as hell don't want the center of effort to be aft, in such conditions -- you want it as forward as possible. I don't even use the staysail -- I use a scrap of the jib, to keep the center of effort all the way forward.

[Kenomac]

Rejoining the discussion for one final comment which I feel is vital.

Please everyone... read the entire report, much can be learned about cascade events such as this regarding equipment and human behavior. Nothing can be gained by endless speculation by those who haven’t even bothered to read the entire report.

Lots of valuable insight and knowledge in the report.... its not just about preventers or who thinks they have the best preventer, many, many equipment choices and decisions lead up to the disaster.

An absolute must read. https://www.maritimenz.govt.nz/comme...eport-2016.pdf

[Don C L]

Originally Posted by Hardhead

I'm sure this is also a silly question - but couldn't an attempt been made to bring the boom under control, after the preventer failed, by drawing in on the mainsheet? Or was it that the hydraulic sail controls were smashed, and therefore, with the loads of that large boat, the main sheet could not be brought in otherwise? I know the mainsheet & traveler were pulled out eventually by the free slamming, but I thought maybe an attempt would have been made to draw in the main sheet before it was ripped out. Apparently, there were enormous issues in controlling the steering of the boat as well, and that must have prevented lessening the loads on the mainsail I would imagine.

Ordinarily, yes, but I think the situation was bad enough that they couldn’t do it or didn’t think of it, before things got worse.
Some other things: bigger boats tend to engender more confidence and security than they may deserve. Running downwind never seems as dramatic as even reaching in the same conditions so we may leave too much sail up for the conditions. And APs can seem infallible, or at least reliable. Those three to me seem to play the major roles here, less so the preventer, though it was inadequate, IMhumbleO.

[Kenomac]

All the answers are in the report, if only everyone commenting would take some time to actually read it.

The doomed yacht was on a steady and controlled beam reach, with a partially furled main... not running with the wind behind them... in 30-35 knot wind. Nothing out of the ordinary for a 36 ton sailboat, until the hydraulic steering leak caused an auto pilot malfunction.

A classic cascade effect... It’s all in the report.

[Don C L]

Executive summary claims broad reach and gusts to 48kts stated too. I did not see where it says how much of main was up, have to re-check, but jib was already partially furled . In a “confused sea” hard to know how stable and steady she was.

[Breaking Waves]

Originally Posted by Kenomac

The doomed yacht was on a steady and controlled beam reach,

hmmmm....NO... "sailing downwind on a broad reach2" and the report even defines that: "2'broad reach' is a course sailed further away from the true wind than a beam reach" - more specifically 120-degree apparent wind angle (thus deeper true angle - probably more like 140) with the wind continuously backing behind the boat. It is the exact sort of conditions where a boat can be squirly in ocean-sized waves and if being driven hard with can back a mainsail even with a working autopilot.

in 30-35 knot wind. Nothing out of the ordinary.

hmmm . . . . "gust noticed had been 48 knots." So a true gale, which they had never seen anything close to in this boat before.


A classic cascade event.

Yea, true, as with most incidents; As I pointed out in post above #1 crew/owners/Skipper not taking the voyage seriously. #2 poor seamanship with sail management. #3 Really **** preventer set-up. #4 super heavy boom, difficult to control after preventer failure, which rips the mainsheet hardware out of the deck to act as a flail. #5 Crew probably in shock after deaths.

breaking wave

[Don C L]

I’d like to hear more about the AP, and it’s upgrades, from folks who have similar AP and similar boat. It seems that AP was overwhelmed by the conditions too, likely leading to the leak of hydraulic fluid.

[fxykty]

Originally Posted by Don C L

I’d like to hear more about the AP, and it’s upgrades, from folks who have similar AP and similar boat. It seems that AP was overwhelmed by the conditions too, likely leading to the leak of hydraulic fluid.

Ummm, read the report. Cause of the hydraulic leak was prior to the passage.

Gust of 48 knots does not mean the conditions were full gale. They were broad reaching in 30-35 knots of wind with commensurate sea state and they were experiencing gusts of up to 50%. Normal early winter conditions on the passage north from NZ and perfectly fine.

It seems they were over powered during the gusts and were too slow to reef down (probably because reefing would have been a pain on that wind angle and they were unwilling or delaying making a turn towards the wind to reef further).

But nothing that the autopilot couldn’t handle, until it lost pressure on one side. Had the autopilot been working fine there likely would not have been any trouble.

[Breaking Waves]

Originally Posted by fxykty

Had the autopilot been working fine there likely would not have been any trouble.

Perhaps not at that instant.

It is common in incident investigation. You can conclude that this particular incident might not have happened if this particular thing (like the autopilot) had been fixed or changed or improved. But you also have to conclude that particular thing was not, in fact, the true root cause of the incident, and something else/slightly different bad would very likely have happened.

This boat and crew were 'an accident waiting to happen'. They were going to back that mainsail sometime, and it was going to break that preventer, and the weight of the boom was then going to rip the traveler out, acting as a wrecking ball, and be very very difficult to bring under control.

As you correctly describe the conditions should not have been unanticipated. But the crew had not sailed the boat in anything like them, were not taking it seriously enough, and the boat was not adequately prepped for it.

[cyan]

Fascinating report. One has to wonder if the attitude was too casual regarding the preventer rigging, not understanding the forces.
When racing downwing on a much smaller (35ft) boat, we would sometimes use human-preventers, leaning on the boom for short legs in rolling seaas with maybe 15-20 knots. Dangerous, sure, but also maybe breeding contempt for the exponential scaling of the forces on larger boats.

These points stood out to me in the report...

Equipment:

1. preventer at very bad angle - leverage multiplied forces more than 10 times
2. insufficient (and old, history-unknown) extender line connected to the preventer pennant
3. insufficient preventer extender connection method (2 bowlines, weakening line strength by 70%)
4. autopilot hydraulic leak (not detected)- no low fluid alarm in system
5. bad hydraulic ram installation with plastic block on un-reinforced GRP that partially failed
6. undersized padeye installed by mistake- installer even noted it looked too small

Humans:

1. bad call: large main, decent winds, on super heavy boom broad reaching in very confused seas
2. too much relying on autopilot in rough conditions
3. didn't notice that the crippled autopilot system was occasionally failing to hold course at times during 3 hours before accident
4. noted the preventer angle was not ideal but assumed they had to do it that way apparently due to pennant length
5. survivors collectively very surprised that traveller gave way on crash gybe, clearly not understanding the forces involved

[Joli]

Haven’t posted here in a long, long time.

That said. It’s foolish to push a large boat in heavy conditions with a small crew. A sixty some foot boat in 35 true will easily sail at 12 knots with just a staysail. No reason to push the boat unless it’s fully crewed with capable sailors.

[Maka]

This is food for thought regarding my own boat and considering unimagined possibilities for disaster.

[DumnMad]

Originally Posted by Kenomac

Rejoining the discussion for one final comment which I feel is vital.

Please everyone... read the entire report, much can be learned about cascade events such as this regarding equipment and human behavior. Nothing can be gained by endless speculation by those who haven’t even bothered to read the entire report.

Lots of valuable insight and knowledge in the report.... its not just about preventers or who thinks they have the best preventer, many, many equipment choices and decisions lead up to the disaster.

An absolute must read. https://www.maritimenz.govt.nz/comme...eport-2016.pdf

Thanks for the insistance Ken

Tragic.
My take;
If none had left the cockpit they'd all have been OK.
Being keen helpful types they tried to get to the wheel before the danger was fully appreciated.
If the wheel was in the cockpit they would have been OK.

[Kenomac]

Copied from previous post by Breaking waves

The doomed yacht was on a steady and controlled beam reach,

hmmmm....NO... "sailing downwind on a broad reach2" and the report even defines that: "2'broad reach' is a course sailed further away from the true wind than a beam reach" - more specifically 120-degree apparent wind angle (thus deeper true angle - probably more like 140) with the wind continuously backing behind the boat. It is the exact sort of conditions where a boat can be squirly in ocean-sized waves and if being driven hard with can back a mainsail even with a working autopilot.

in 30-35 knot wind. Nothing out of the ordinary.

hmmm . . . . "gust noticed had been 48 knots." So a true gale, which they had never seen anything close to in this boat before.


A classic cascade event.

“Yea, true, as with most incidents; As I pointed out in post above #1 crew/owners/Skipper not taking the voyage seriously. #2 poor seamanship with sail management. #3 Really **** preventer set-up. #4 super heavy boom, difficult to control after preventer failure, which rips the mainsheet hardware out of the deck to act as a flail. #5 Crew probably in shock after deaths.”


Response:

I wrote “beam reach” in error, I meant to write broad reach. Otherwise, my assesment is accurate and I completely disagree with yours. I seriously doubt you read the entire report to come to your conclusions.

Had the hydraulic steering not failed, it’s highly unlikely any of the other cascade events would have happened, and the crew would have likely continued on a nice sail. The conditions were not out of the ordinary for a 36 ton sailboat to easily handle.

One of the many lessons I’ve learned from the report is to always have someone behind the helm, which is easy to forget under seemingly controlled cirumstances.

[Kenomac]

Originally Posted by Don C L

I’d like to hear more about the AP, and it’s upgrades, from folks who have similar AP and similar boat. It seems that AP was overwhelmed by the conditions too, likely leading to the leak of hydraulic fluid.

Don,

I have a similar 36 ton boat, hydraulic steering and similar auto pilot. I’m trying.... but nobody seems to be listening, instead only criticizing and comparing the situation to smaller sailboats and their own equipment. I’ve already previously given up twice attempting to explain myself.