Hobie 20 mast rotation control

Stupid question time! I'm trying to figure out the stock rotation limit method for my H-20 mast. It would appear that my boat at one point had the Murrays one-line system installed on it (as evidenced by the screw holes on the underside of the boom), but it's now removed except for the relocated rotation arm and locating piece. I like the idea of the Murray's rotation set up, so I'm looking at rebuilding that. But.... I've been trying to figure out exactly how the stock set up works. Obviously the rotation limiting line goes from the end of the arm and into the grommet hole in the tramp. Then what? It would seem that a block on the end of the arm, and a continuous line from one side of the boat to the other would make it adjustable from both sides, but where does it cleat? How does it get back from under the tramp? Parts pics and stuff don't detail this, and no, I don't have the assembly manual...

Also, from the voices of experience, which way of rigging this actually is prefered? The Murrays way would be nice in that it will keep the rotation relative to the boom, but would only seem to be adjustable from the tramp. The stock way (if I understand it all) would permit control from each side, but the rotation is not maintained relative to the boom/sheeting angle. I figure for either of these, I'd use the shock cord to the bridles method of forcing over rotation. Any thoughts?

Keith,

On my previous boat, the rotation limiter was routed through the grommet to small blocks on the rear beam about in line with the hiking straps. Then turned out of the grommets at the back corners of the tramp. There were a pair of clam cleats mounted in the track to hold the line. It was adjustable from either side by the skipper. Some boats are set up to exit the tramp in the middle for the crew to make the settings.

I hope this helps.

Clayton

I use the "non stock" system. It uses a Nacra style bar for over rotation w/two cleats on main beam. For rotation limiting, there is a small block tied to the bar with a line run through it. The two ends of the line go into the center of the tramp pouch and through a gromet to the bottom of the tramp. From there, they split and go outboard (one starbord, one port) there they go through the tramp again (just inboard of the shrouds), through a cheek mounted to the deck, through a small cam cleat then they both tie together near the center of the boat. This way works great, I find it the easiest to work, most adjustable and reliable. Skipper or crew can work it from the boat or on the wire.

Will R

I'm not sure I understand this completely - is the NACRA bar in addition to the H-20 bar, or in place of it? Is it mounted in front of the mast or behind like stock? I'm not sure I understand why the limiting line would go through the tramp pocket to go under the tramp instead of going through the stock grommet.

Post deleted by Will_R

Here we go.....

Thats seems to be incredibly complicated for something as simple as mast rotation.

Great! That's kind of what I expected to see. Now, the big question - on my 18, the boom forced rotation in the majority of cases, the only time I needed to fuss with forced rotation was in lighter conditions, and then mostly downwind. I'm assuming this is the same with the 20? One thing that bothers me with the shock cord set up forcing rotation is that it'll always offer some resistance to the mast changing sides during tacks and jibes. Systems like this one need to be released before jibes (if it is needed at all for conditions), but should be unobtrusive when not needed?

Could someone come up with a similar diagram for the rotation system for the H17?

It involves a bungee, and a looped line around the mast and... I dunno what else.

It'd be nice to have something like the above diagram to figure it out

Bungie in light air is very unobtrusive IMO; is never as much trouble as getting battens to pop over (i.e., if the battens pop by themselves, the mast will rotate by itself). You'll never have a problem gybing. NEED forced rotation to get max rotation downwind, hold the mast still in chop, and usually to get best rotation angle upwind in light air. Don't think mast/boom/sail "work together" like an 18, and I'm not convinced that system is all that good. Let's put it this way: All the Olympic Tornados have forced rotation, and not via bungie, either... I like this rotation setup; same as mine but the slack is carried to the center; slick method for no hanging lines. No mechanical advantage, though.

Man, this is a 20, it ain't a crew-on-holiday, adjust it with a hammer 18 :-)

Chris Bolton

"Man, this is a 20, it ain't a crew-on-holiday, adjust it with a hammer 18 :-)"

Hell, it's just a boat with two hulls! And my crew's usually more on the ball than me - no vacations for them, matey. I also gave up adjusting with hammers and moved up to adjusting with NACRAs. That was not successful... ;-)

I used a system similar to the stock 20 design for forcing rotation on my 18, simple, not great, but again I only had to mess with it in light air (like other boomed boats I've crewed on). The only boats I've had to use forced rotation as a matter of course in all conditions have been boomless. Sounds like the 20 needs the forcing more routinely...

Only if you want to go as fast as possible...
"..20 needs to be forced..."
I guess that's the point I was trying to make. Small adjustments, small payoffs, but the point is you CAN make them, and the good sailors ARE making them.

Chris

I'm glad that someone found the drawings useful. It's not really complicated...and it works so well...

Will R

Hey Will. Do you normally have to tack the positive rotation when going to weather? We are currently using the bungie method but don't always get that 110 degree rotation we need going downwind whereas this set up would do it and we have plenty of Nacras at the yard to swipe one from. One thing I like (as crew) about the bungie is that I dont have an extra device to handle when tacking and gybing (did I spell that right?) You know how crew are, we can only remember to do a certain amount of things at each tack or gybe (does this thing have spell czech?)

The only time I use the positive rotation upwind is when it is light to help hold he mast in place. I really use it especilly if it's choppy. If it's windy enough to have the main sheet tight, the boom should force the mast into place.

The over rotation line is worked by the skipper. When you are going up or down wind and you would use it, the skipper is sitting in a perfect position to cleat and uncleat it. However I'm not 100% and am lucky enough to have a great crew that cleans up after me.

Will,
Do you know if this set up is class legal? I think this is much better than all that shockcord.
Thanks

Yes this is class legal. It was used on many boats at nationals for years.

Mike Hill
H20 #791

Hi, I've just posted 4 pix on various setups in the Files on the Hobie_17 Yahoo Groups http://groups.yahoo.com/group/hobie_17 for mast rotation for H17's with and without Booms. Any Q's please email me nigel@hobie17.com
Happy Sailing, Nige