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PostPosted: Thu Jun 04, 2015 3:55 pm 
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Joined: Mon Feb 04, 2008 1:31 pm
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Location: New Jersey


Well here is some sick video of my son and I at the bottom of 8 foot wave. I would certainly do some things differently next time, but I am glad everything worked out. When I lost steering going down the wave the kayak did the correct thing turning back into the wave as the main sheet was released.

The TAI is ready to be pushed to its limits

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PostPosted: Thu Jun 04, 2015 7:17 pm 
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Joined: Sat Apr 28, 2007 11:59 pm
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Location: Coffs Harbour, NSW, Australia
Glad you and you're Son got home OK.

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PostPosted: Fri Jun 05, 2015 6:11 am 
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Location: South Florida
yakman wrote:
When I lost steering going down the wave the kayak did the correct thing turning back into the wave as the main sheet was released.

The TAI is ready to be pushed to its limits

Your TI did what all boats do in that situation (lose steering going down a wave), it broached. That is a very dangerous situation and frequently leads to boats capsizing. My guess is that it is very hard on equipment also. Releasing the main sail was critical to avoiding capsize, but not avoiding the broach. I'm glad you and your son got through it ok, but it is something to be avoided in general. Running across waves at an angle, rather than straight down, might avoid the problem. The boys in Hawaii ought to know.

Keith

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"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein

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PostPosted: Fri Jun 05, 2015 7:18 am 
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Location: Forster, NSW, Australia
Actually Keith, the reverse is true, running straight down the wave is safer. If you have any angle at all, the broach is caused by the bow reaching the slower-moving water at the bottom of the wave while the back of the boat is pushed along in the faster water in the wave. So sailing straight is the nerve-wracking, nail-biting, butt-clenching safest way. Centreboard or dagger board should be completely up, minimal sail out, and crew weight as far back as is practical (not so easy in an Island but)

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2012 Tandem Island "SIC EM" with Hobie spinnaker


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PostPosted: Fri Jun 05, 2015 7:38 am 
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Tony, once you lose rudder control, going straight down the wave your bow slows but your stern has lots of momentum. If your boat can somehow, continue straight down the wave, fine. But, at that point, most boats will not be going perfectly straight down the wave. Any little angle will result in a broach. You have no control over the boat. Yakman's boat broaches. Not a safe practice.

I'm talking about sailing across a wave (at a significant angle) in order to keep you rudder in the water and in use controlling your boat.

Keith

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"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein

"Less is more" Anon


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PostPosted: Fri Jun 05, 2015 3:27 pm 
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Location: Kailua 96734
Keith &Tony, I think you both have it half right. :mrgreen:

Our rudders work fine as long as you stay ahead of the wave on a "clean" shoulder and point it just right (Keith's suggestion). For me that's about 20-30º max. You can't stay there forever though. Beyond that angle, I am ready to exit the wave before it crashes.

Once the wave breaks, or catches up to you, you typically lose some rudder control due to reduced (or even reversed) water flow over the rudder. It's a temporary situation and does not mean an automatic broach. You you still have momentum, a planing surface with some keel, 2 Amas and a sail to help steer the boat. Using your mirage drive can help too.

There are several dangers that would tend to cause a Huli while surfing.

The first is "perling" the bow at the bottom of the wave, which rapidly slows the front of the boat and causes a train wreck to begin behind you. We experience this "porpoising" all the time while surfing open water wind swells less than 6 ft. Keith is well aware of it. If you can stay pointed basically straight ahead (as Tony suggests), you will slow down, dig in and the wave and whitewater will usually pass over you. It might even bury you. If you choose to twist the rudder at the last moment, or are already too parallel to the wave, it WILL jackknife the boat. At that point, if your sail is still sheeted, and you use tramps like yakman, your sail will suddenly fill with air (on a reach) and your windward tramps will fill with water pressure. You now have a great recipe for a Huli.

The next danger is a plain old broach, usually at the top of a steep wave, where you lose rudder control because the blade actually leaves the water, or is neutralized by waves catching up and passing you. Even if you are doing 10 mph with the blade submerged, the 20+ mph flow of water from behind causes the rudder to momentarily lose grip. You go from having a super-sensitive rudder to having little or no control at all. Sensing this, you start to overcorrect. :shock: The stern wants to come around and is gladly obliged by the wind and whitewater. Monohulls with big daggers/keels tend to experience this more, (Tonys point).

Lastly, whenever you exceed your hull speed, or "brake" suddenly, you could easily break a rudder pin or Aka brace. My old twist and stow rudder used to stretch and "pop" loose when I hit speeds over 15mph and would screw up an otherwise decent ride.

All waves are different. Reef breaks and shore break waves are different from channel sandbar waves - and very different from mixed open ocean swells.

Our Hobies surf like pigs on all of them, so be selective, steer with your sail as much as possible - and expect surprises.

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PostPosted: Fri Jun 05, 2015 4:18 pm 
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Glad I had it half right! It is a complex situation and to be avoided if possible.

Keith

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2015 AI 2, 2014 Tandem

"Any intelligent fool can make things bigger and more complex ... It takes a touch of genius and a lot of courage to move in the opposite direction." A. Einstein

"Less is more" Anon


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PostPosted: Fri Jun 05, 2015 5:44 pm 
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Location: Central Coast NSW Australia
Yakman,
Loved the "nervous" looking behind clips, waiting for the wave.
Great video that demonstrates well that Island versatility does NOT cover surfing! :wink:

NOHUHU wrote:
Our Hobies surf like pigs on all of them, so be selective, steer with your sail as much as possible - and expect surprises.

Sound advice Nohuhu and great explanation of just what goes on when surfing. 8)


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PostPosted: Fri Jun 05, 2015 6:46 pm 
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Location: Forster, NSW, Australia
Half the secret is just thinking about the possibilities, and trying to avoid being in surfing conditions if possible. Islands don't handle surf like SUPs!.

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2012 Tandem Island "SIC EM" with Hobie spinnaker


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PostPosted: Fri Jun 05, 2015 7:04 pm 
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Location: Maui, Hawaii
+1 As NOHUHU said :)

And "perling" an ama at the bottom of a wave is one of the easier ways to break a aka shear-pin and will easily "elbow" the rear aka if using a stronger than stock pin.

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