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"Gybe Draulic" Preventer on SY Gefion


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In the thread about lusting yachtworld boats, there's a mention of a 74 foot sailing yacht (SY Gefion) listed in northeast Europe which has a very interesting and esoteric system for controlling the boom swing in a gybe. There is what looks like a second, massive Vang structure that connects to a very beefy large steel shaft extending down to the bilge where there's a very large cog mechanism with a rack and pinion on either side attached to hydraulic pistons. It appears that the system is intended to slow down the motion of the boom and by all appearances the engineering is robust and it looks like a very interesting solution for larger boats were boom brakes don't work due to size.  

I've been reading a very long thread on another website about the Platino disaster over a decade ago which focuses predominately on the pros and cons and mathematics of different preventer arrangements for boats above 50 feet. My current boat and next boat are in this category and I'm very interested in safety.  I'm wondering if anyone has ever seen this mechanism or one like it?  In one of the listings they describe it as "Gybe Draulic" or sounds like a brand name but there's nothing online suggesting that this was made only one time?

If I were to have my druthers, there would be some way of slowing down the motion of the boom but not completely arresting it causing a back winded situation.

For those not familiar, SY Platino was a 66 foot sloop which had undergone a massive refit which included installation of a furling boom which weighed around 1.600 lbs. There was an issue with leaking hydraulic pressure in the auto pilot ram causing the boat to wander heading during a deep down-wind run in a confused sea state. Waves from coming three directions and wind gusts up to 48 knots.  The boat gybed and the inadequate preventer mechanism broke causing the traveler to explode killing the helmsman and caused a second fatality when another sailor got knocked off the boat by the swinging mainsheet/traveller.

https://www.yachtingworld.com/news/new-zealand-death-mob-tragedy-76516

https://www.yachtbroker.se/baat/sailing-yacht-gefion/4759

image.thumb.png.adb171ee5a3cdf5b8df2e1c5a1ecdd4b.png

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Man, I tried to go down the rabbit hole for you... best I could come up with was that there was a Danish patent filed for it around 2001..

And then this article in WELT that mentions "With the new "Gybe-Draulic" from Denmark, which is sold by the mast manufacturer Nordic-Mast"... but Southern and Nordic merged a decade ago, and I don't see anything on Southern Spars' site...

https://www.welt.de/print-welt/article423475/Sicherheitstechnik-gefragter-denn-je.html

So, TL;DR.... I didn't help at all! :lol:

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53 minutes ago, suider said:

Man, I tried to go down the rabbit hole for you... best I could come up with was that there was a Danish patent filed for it around 2001..

 

Reading it now. Thanks.

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There are more and more rich novices buying or hiring 50'ers to take their family on, these are people much to important to take the time to learn how to do something properly, and much to clever to hire someone who knows how to do it and make them look bad.  The world needs more of this complicated expensive heavy shit to make these sailing boats seem more foolproof.  Joystick parking.  Intelligent passage planning.  All furling rigs.  Just need docking clamps, and auto watchkeepers.  Complex systems built and maintained by marine professionals really do take the pain and risk out of sailing.

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17 minutes ago, maxstaylock said:

Complex systems built and maintained by marine professionals really do take the pain and risk out of sailing.

And most of the fun.

These fully automated luxury sailing caravans are mobile cocktail platforms, which seem to be targeted at people who have no comprehension of the joys of a well set-up small boat where the wind and the waves talk to you through all the things you tweak.

At its best, sailing is the nearest thing to being alive.  Automation reduces it all to being behind glass.

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21 hours ago, Student_Driver said:

There was an issue with leaking hydraulic pressure in the auto pilot ram

At the worst possible time, there would be an issue with leaking hydraulic pressure in the GybeDraulic mechanism. Crew expecting the boom to be prevented would be clubbed/swept overboard when it suddenly gybes. Hydraulic systems on sailboats are not famed for dependability.

21 hours ago, Student_Driver said:

The boat gybed and the inadequate preventer mechanism broke causing the traveler to explode

There exists a dynamic loading situation in which the GybeDraulic would also prove inadequate and break, causing large heavy things to fly across the cockpit area.

Thanks for posting this topic and the story behind it. It is a fine illustration of the way our human mind works to solve problems. Sometimes the results are amazing and revolutionize how we live, fixing issues that have menaced us for decades (bread mold and penicillin;  shoulder harness belts and auto crashes). Other times, we end up with overengineered Rube-Goldberg solutions to simple problems which introduce more failure points than they obviate. I'd put GybieD firmly into the latter bin.

An adequately strong hard point and energy-absorbing preventer line is the simpler answer. When you meaningfully alter a rig (like doubling boom weight with roller furling), you need to chase down every component attached to it and ensure the hardware meets the new loading requirements. Amazing how often even trained engineers fail to follow this rule; boat yards and we owners are even less apt to think of that one shackle that wasn't upsized to cope with the new fathead mainsail.:(

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I don't mind complexity, I just want to understand it. It seems to me that whenever you add complexity and automation to the boat you expect higher expenditure, more rigorous and extensive maintenance with the risk that the system fails precisely when you need it most. For me the best example of this is the auxiliary which fail with unfortunate frequency during storms and while docking.  Nonetheless we accept that trade off and we do our best to maintain our auxiliary so that we have the highest chance that it will work when needed. On the other hand, prudent sailors have back up plans and know how to operate manual back up systems.

Sailors tend to be very slow at adopting technology and often eschew technology being used successfully offshore by racers and record setters.  Sometimes technologies are rejected simply based on cost. Clearly, this device has not been adopted broadly which suggests that it was not a resounding success or complexity and cost make it impractical.

Without hijacking my own thread,  there are debates over best practice with regard to preventers. Unless I am mistaken, the divide seems to be between having a preventer with a given and predictable stretch or breaking point (a.k.a. "fuse") versus massive and unbreakable and no stretch. Whilst I've seen some arguments about placement of the preventer on the boom (many seem to suggest a third of the way back from the end or all the way to the end depending on how much pressure your gooseneck to take) and the placement of the turning point or attachment point of the preventer at or near the bow. These arguments seem less controversial and opinions are more aligned.

I personally don't like the idea of a massive and unbreakable preventer. I'm not really a big fan of the fuse strategy either. Next season I plan to re-rig the boat and will need to do some work on the exact amount of stretch and rigging for a new preventer system. The hydraulic system in question is not on the shortlist but it does seem intriguing and could the ability to scale in size to absorb larger loads (vs a boom brake) at a cost measured in: weight, effort, risk and burnt money. Horses for courses.

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@Diarmuld, I think I misled you. The base of the GD is not linked to a dynamic/controllable hydraulic system but rather to hydraulic shocks like on the suspension on a big truck... Think of a massive truck. 

In my experience, sealed hydraulic pistons don't fail frequently but do have a finite life.

Having said that, I agree generally with your assessment that there would be multiple failure points and it's probably not practical or reliable..

OTOH, Gefion is 22 years old and the system has not been removed. Am guessing that it 'does no harm' at least. 

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@Tylo sent me this photo. That geared cog is at the base of the shaft which in turn is attached via the strut to the boom.

 

From what I've read, the gears on the cog drive the hydraulic piston shafts which dampen the motion of the boom.  

Gefion_Preventer.jpg

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23 minutes ago, Raz'r said:

Ok, dumb question but how does a centerline ram slow the boom from swinging?

I agree.  The moment arms (at the base of the mast) are too small to be reliable, given the very large forces involved.  Might work fine in a 5 knot apparent wind, but anything greater, not on my watch.  Add that to the attachment point on the boom and all bets are off, IMHO.

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2 minutes ago, jamhass said:

I agree.  The moment arms (at the base of the mast) are too small to be reliable, given the very large forces involved.  Might work fine in a 5 knot apparent wind, but anything greater, not on my watch.  Add that to the attachment point on the boom and all bets are off, IMHO.

I was thinking that the 2 little ears that go around that pin might not be up to an accidental gybe in breeze/waves, but I ain't no engineer nor did I stay at a Holiday Inn.  what's that, a 25' lever arm concentrating down onto 2, 1/2" tabs? yikes.

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2 hours ago, Student_Driver said:

I don't mind complexity, I just want to understand it. It seems to me that whenever you add complexity and automation to the boat you expect higher expenditure, more rigorous and extensive maintenance with the risk that the system fails precisely when you need it most. For me the best example of this is the auxiliary which fail with unfortunate frequency during storms and while docking.  Nonetheless we accept that trade off and we do our best to maintain our auxiliary so that we have the highest chance that it will work when needed. On the other hand, prudent sailors have back up plans and know how to operate manual back up systems.

Sailors tend to be very slow at adopting technology and often eschew technology being used successfully offshore by racers and record setters.  Sometimes technologies are rejected simply based on cost. Clearly, this device has not been adopted broadly which suggests that it was not a resounding success or complexity and cost make it impractical.

Without hijacking my own thread,  there are debates over best practice with regard to preventers. Unless I am mistaken, the divide seems to be between having a preventer with a given and predictable stretch or breaking point (a.k.a. "fuse") versus massive and unbreakable and no stretch. Whilst I've seen some arguments about placement of the preventer on the boom (many seem to suggest a third of the way back from the end or all the way to the end depending on how much pressure your gooseneck to take) and the placement of the turning point or attachment point of the preventer at or near the bow. These arguments seem less controversial and opinions are more aligned.

I personally don't like the idea of a massive and unbreakable preventer. I'm not really a big fan of the fuse strategy either. Next season I plan to re-rig the boat and will need to do some work on the exact amount of stretch and rigging for a new preventer system. The hydraulic system in question is not on the shortlist but it does seem intriguing and could the ability to scale in size to absorb larger loads (vs a boom brake) at a cost measured in: weight, effort, risk and burnt money. Horses for courses.

Just use three strand nylon, not too thick, it’s a long strong bungee cord...

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I picked up a slightly oversized and older model Walder Boombrake for my boat but have yet to try it out. Pip Hare (I now know who she is because of the VG), gave it 8/10 in a review on Yachtworld. Somewhere between the above contraption and a simple rope preventer.

https://www.yachtingworld.com/yachts-and-gear/tested-boom-brakes-and-preventers-65517

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Seems crazy that they haven’t removed it. Sounds like a 22 year old ticking time bomb.  When R’zer explains it the forces are magnified by the ratio of 25’/2.5” or about 120:1.  Wow.  

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2 hours ago, Student_Driver said:

Seems crazy that they haven’t removed it. Sounds like a 22 year old ticking time bomb.  When R’zer explains it the forces are magnified by the ratio of 25’/2.5” or about 120:1.  Wow.  

No cardboard there.

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12 hours ago, jamhass said:

I agree.  The moment arms (at the base of the mast) are too small to be reliable, given the very large forces involved.  Might work fine in a 5 knot apparent wind, but anything greater, not on my watch.  Add that to the attachment point on the boom and all bets are off, IMHO.

Steel is strong....

I wouldn't add this contraption on a boat, nevertheless I think that a competent engineer can make this work. The design is very inefficient but IMO it is a matter of throwing enough material at the design and not caring about weight. A shaft this size would be at the end of a pretty substantial engine and the "moment arm" is quite hefty. Anyway if it has lasted 20 years, assuming that the boat has been sailed, the thing works.

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21 hours ago, Student_Driver said:

@Tylo sent me this photo. That geared cog is at the base of the shaft which in turn is attached via the strut to the boom.

 

From what I've read, the gears on the cog drive the hydraulic piston shafts which dampen the motion of the boom.  

Gefion_Preventer.jpg

That'll make for some crazy round-ups unless the main can get over fast enough.  There are times when you want that main over NOW, and the only issue is preventing damage when it stops on the other gybe.  I found a small dent in my boom yesterday from the PO obviously allowing a crash gybe causing the boom to hit the cap shrouds.  This gives some pause for reflection on how to prevent this from happening again.

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Well I'd start by not letting the main sheet out that far. As you probably already have a main sheet and some form of cleating arrangement that seems like a simple and cheap solution. Some people will go to great lengths to avoid simple and cheap.

If you want fool proof you could put a knot in the sheet so it can't go out too far. That's what we do for the smaller oppie kids when it's windy.

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  • 2 weeks later...

IMHO this is a demonstration on anti-KISS principle...

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