Mike
I find myself agreeing with you again. One
point and one question though.
Rudders: since the cat was thrown backwards or
sideways the kick up feature probably wouldn't have
helped.
Rigs: Rob what do you think of the swing-wing
rig (see http://www.youtube.com/watch?v=m25fBUaz43g )
as an option to your designs? In theory and without
any experience with such rigs they seem like a
promising option.
Regards,
Arto
On
Monday, February 3, 2014 11:07 PM, Mike Crawford
<mcrawf@nuomo.com> wrote:
Luc,
Interestingly, a new Aeroyacht 42 ( http://www.aeroyacht.com/sailing-catamarans/aeroyacht-alpha-42-catamaran/ ) recently had to be abandoned due to damage to rudders sustained in a storm:
http://www.sailfeed.com/2014/01/helicopter-evacuation-abandoning-be-good-too/
QUICK SUMMARY
Jib sheet tore, making it tough to use the headsail, and batten pockets/cars were damaged, making it questionable to hoist the main. The genset and motors stopped charging the batteries, and eventually all three stopped working.
The biggest problem, though, was that both rudders became useless after the boat was thrown back by a rogue wave.
Both rudders broke their set screws, allowing them to turn independent of the steering system, and one rudder's stock bent, freezing it in place. They tried to sail and steer the boat after the weather calmed down, but no combination of sails and motors allowed them to go in a straight line, even after they semi-fixed the steering.
While the boat itself was floating fine, it was too far from land to request a tow in such conditions, and being unable to make any progress, the skipper and crew abandoned her.
Some questioned the design of the boat, but other than being a normal catamaran with spade rudders, I can't find fault with much.
One person commented that the rudder stocks should have been linked with something beefier than the set screws that were used, but that's a tough call. Another mentioned that one actually /wants/ the set screws to break. Perhaps there should have been spares fastened to the steering arm, along with instructions, but how many boats are that well prepared?
DESIGNING SAFETY
The problem is that the boat had standard features that most sailors have come to accept as normal, and perhaps even desirable. The problem has nothing to do with the Alpha 42, and everything to do with failures that would have plagued most 42-foot catamarans.
While the safe harryproa I mentioned the other week could potentially have been disabled by the same storm, I'll make the argument that it could have escaped relatively unscathed. Something that put a half-million dollar performance cruiser out of commission could have instead just been an annoying few days.
Here's how the proa might have made it through:
- Torn jib sheet. No jibs = no torn jib sheet. Okay, that's an oversimplification, but it's worth noting that the sheets on the proa would have been much more lightly loaded than the jib sheet on the catamaran, particularly if they used a 2:1 purchase. The mainsheets also wouldn't have to be routed across various bits of deck hardware, having nearly a straight shot back to what might be a single winch.
- Blown batten pockets. With a Wharram soft wing, or a swing-wing junk rig, there are no highly-loaded battens to fail, or have their pockets fail, or have their links to the cars fail, or have their cars fail, or have the track fail. No battens, pockets, links, cars, or track. Lots less to fail.
- Flexible reefing. Without blown pockets, the mainsails could have been used, and with these two rigs, it's easy to build in many reef options. They could have had just the right amount of sail area up.
- Ease of reefing. Dump the sheets, mess with the halyards while looking /downwind/, finish reefing. That's a much less stressful process than reefing a big cat in a storm.
- Rudders 1. Kick-up rudders probably would have kicked up. Maybe they'd break a fuse and have to be reset, but that's the most likely outcome of something that wants to wrench the rudders from their normal alignment.
- Rudders 2. But let's say that the rudders did somehow fail, and the fuse couldn't be easily reset. What then? Raise the rudders from the water, and/or remove them from their mounts. Now the boat can be steered again by the remaining rudder. Or a long oar. Or the sails.
- Rudders 3. Or perhaps things as things were getting really ugly, the crew could have raised the rudders, paid out the series drogues, and went below for some tea.
- Rudders 4. And with that schooner rig, there would have been some nice sail-steering options, even if both of the rudders had to be removed.
We could go on, but the basic idea remains the same: design away the risks that can be designed away and the boat becomes a lot safer.
Regardless of what I spend, I'd rather have a boat that can sail its way back home, and then sail it home, than to have to call the coasties and get a lift. I have no idea what that costs, but it can't be cheap to get a helicopter ride that far from land, nor to abandon such a nice boat.
- Mike
Interestingly, a new Aeroyacht 42 ( http://www.aeroyacht.com/sailing-catamarans/aeroyacht-alpha-42-catamaran/ ) recently had to be abandoned due to damage to rudders sustained in a storm:
http://www.sailfeed.com/2014/01/helicopter-evacuation-abandoning-be-good-too/
QUICK SUMMARY
Jib sheet tore, making it tough to use the headsail, and batten pockets/cars were damaged, making it questionable to hoist the main. The genset and motors stopped charging the batteries, and eventually all three stopped working.
The biggest problem, though, was that both rudders became useless after the boat was thrown back by a rogue wave.
Both rudders broke their set screws, allowing them to turn independent of the steering system, and one rudder's stock bent, freezing it in place. They tried to sail and steer the boat after the weather calmed down, but no combination of sails and motors allowed them to go in a straight line, even after they semi-fixed the steering.
While the boat itself was floating fine, it was too far from land to request a tow in such conditions, and being unable to make any progress, the skipper and crew abandoned her.
Some questioned the design of the boat, but other than being a normal catamaran with spade rudders, I can't find fault with much.
One person commented that the rudder stocks should have been linked with something beefier than the set screws that were used, but that's a tough call. Another mentioned that one actually /wants/ the set screws to break. Perhaps there should have been spares fastened to the steering arm, along with instructions, but how many boats are that well prepared?
DESIGNING SAFETY
The problem is that the boat had standard features that most sailors have come to accept as normal, and perhaps even desirable. The problem has nothing to do with the Alpha 42, and everything to do with failures that would have plagued most 42-foot catamarans.
While the safe harryproa I mentioned the other week could potentially have been disabled by the same storm, I'll make the argument that it could have escaped relatively unscathed. Something that put a half-million dollar performance cruiser out of commission could have instead just been an annoying few days.
Here's how the proa might have made it through:
- Torn jib sheet. No jibs = no torn jib sheet. Okay, that's an oversimplification, but it's worth noting that the sheets on the proa would have been much more lightly loaded than the jib sheet on the catamaran, particularly if they used a 2:1 purchase. The mainsheets also wouldn't have to be routed across various bits of deck hardware, having nearly a straight shot back to what might be a single winch.
- Blown batten pockets. With a Wharram soft wing, or a swing-wing junk rig, there are no highly-loaded battens to fail, or have their pockets fail, or have their links to the cars fail, or have their cars fail, or have the track fail. No battens, pockets, links, cars, or track. Lots less to fail.
- Flexible reefing. Without blown pockets, the mainsails could have been used, and with these two rigs, it's easy to build in many reef options. They could have had just the right amount of sail area up.
- Ease of reefing. Dump the sheets, mess with the halyards while looking /downwind/, finish reefing. That's a much less stressful process than reefing a big cat in a storm.
- Rudders 1. Kick-up rudders probably would have kicked up. Maybe they'd break a fuse and have to be reset, but that's the most likely outcome of something that wants to wrench the rudders from their normal alignment.
- Rudders 2. But let's say that the rudders did somehow fail, and the fuse couldn't be easily reset. What then? Raise the rudders from the water, and/or remove them from their mounts. Now the boat can be steered again by the remaining rudder. Or a long oar. Or the sails.
- Rudders 3. Or perhaps things as things were getting really ugly, the crew could have raised the rudders, paid out the series drogues, and went below for some tea.
- Rudders 4. And with that schooner rig, there would have been some nice sail-steering options, even if both of the rudders had to be removed.
We could go on, but the basic idea remains the same: design away the risks that can be designed away and the boat becomes a lot safer.
Regardless of what I spend, I'd rather have a boat that can sail its way back home, and then sail it home, than to have to call the coasties and get a lift. I have no idea what that costs, but it can't be cheap to get a helicopter ride that far from land, nor to abandon such a nice boat.
- Mike
lucjdekeyser@telenet.be
wrote:
http://www.john-shuttleworth.com/Articles/NESTalk.html is about seaworthiness in different types of catamarans. Some of this is applicable to proa's. Again, the relative importance of any option is the difficult part. Luc
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