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post #126 of Old 02-24-2018
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Re: Multihull Popularity and Interesting Designs

Originally Posted by Arcb View Post
Just noticed this. Not sure when the last time you took a big broach in big weather on a big boat was, its not a guaranteed game ender, but stuff can get real fast. Stuff can break, rig can break, breakers might trip, people might fall. The boat might actually exceed a 90 degree course correction. If you have no one near the over ride, the auto pilot will do what auto pilots do, turn you back on course, back down wind, you will pick up speed again, maybe broach again, maybe stuff again, then you have more stuff breaking, more people falling.

Helmsman sitting at a control station or with a portable over ride on his person may decide the best escape from the broach is to temporarily turn up wind, slow the boat down, even if its just for 30 seconds so people can get back on their feet, he may decide to turn beam to the sea, or sail diagonally down the wave to scrub some speed. Your auto pilot that you insist on setting and forgetting can not do this.

You may convince the readers that surfing big boats in big seas that setting and forgetting the auto pilot is a good move, but you will not convince me it is, no need to even try.
I don't know why you keep saying that I insist on setting and forgetting the AP while doing 27kts in those conditions. I have stated repeatedly that our boat will never find itself in that state. You seem to be creating the argument.

Once the boat has turned far off course, or steering control is lost, our AP sounds a loud alarm and tries to hold course - it does not try to go back to the original course. Our AP also tries to not steer down waves in a reactive mode such that the boat is yawing. It steers like a helmsman by feeling the point before the bow yaws and applying early rudder to compensate. In the trough, it does the same to bring it back before it yaws.

I don't know of many people who can recover a boat from a broach. Generally the physics overwhelms the steering foils and the best anyone can do is let the boat get on its feet and proceed from there. On a mono, the rudder and most of the keel isn't even in the water. This is not the case for a catamaran.

I don't understand why you are wound up on this AP thing? The video does not represent catamarans in general or any catamaran owner I know. The use of the AP is inconsequential to the situation they are in. My feeling is that a helmsman could not do a single thing differently than their AP to avoid, or get them out of, trouble. The video, IMO, only represents someone operating their boat unsafely - and the AP has nothing to do with that. Why aren't you picking on the full sail set instead?

BTW, broaching is rare on a catamaran because they tend to slide in those conditions. It is more a monohull thing. Pitchpoling from burying a bow is more likely in a catamaran.


Dolphin 460 Catamaran "Reach"

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