The previous owner of my N20 moved the mast rotation control bar to the bottom of the mast and the only control is a rotation prevention line that simply runs like this...
port hull cleat ---- tramp grommet ---- rotation bar ----- tramp grommet ---- starboard hull cleat
I'm guessing that you guys know a better (yet simple) way to improve this system.
Suggestions with ascii art (or real pictures) appreciated.
TIA
The system you describe is not a bad one, as long as there is a block attached to the end of the rotation arm to reduce friction. This set up gives you a 2:1 mechanical advantage. You can increase this to 4:1 by shortening the line so that the ends are under the tramp. Tie a small block to each end of the line. Now tie a line to a convenient point close to the cleat on the hull (tramp lacing might work) and run it through the block on the end of the first line and back to the cleat. Do the same on the other side. You now have a 4:1 mechanical purchase (a 2:1 cascade on a 2:1 system). This is used by quite a few F18 sailors. To control slack you can rig some blocks on the line that runs to your attachment close to the cleat and run the bungee from these blocks in a big loop to the corners of the rear cross bar under the tramp (using a couple of small turning blocks). Use thin bungee or else it will tend to pull the rotator back when tacking or in light air conditions.
Chris.
Thats a good system - nice and simple. Stitch some markers on the tramp so that you can tell when it is pointing at the end of the rear beam and the shroud on each tack.
OK.. I'll put a block on the rotation control arm for now, mark the tramp. I'll leave positive rotation and 4:1 for later.
Thanks!
That's the same system as the stock Hobie 20 system. As other's have said, it's not a bad system, but I eventually went away from it.
First, several posters have suggested adding a block to the rotation bar to reduce friction. In my experience, I have found that adding a block usually does more harm than good. The reason is that when the rotator switches from side to side, the block has a tendency to twist which causes more friction than just going straight through the bar.
There were a few reasons that I eventually went away from the double sided system. The first is that every double sided system has a problem in that the line can get pulled all to one side. This means that there may be situations where the crew would have to crawl down to the leeward side to make an adjustment - not always possible.
The second reason is similar to the first, and it is that I generally found that I didn't like having to make the adjustment from out on the hull. I guess if you think you will be fine tuning the rotation upwind from out on the trapeze, you would want this system, but I never found that to be the case, too many other things to do. I prefered that either myself or the crew could come to the center of the boat to make all the adjustments quickly (rotator, downhaul, outhaul, jib luff) and then move to another position if necessary.
I eventually ended up modifying the system so that it cleated on the boom rather than out on the hull. One last advantage to cleating on the boom is that if there is a lot of load on the rotator (from a positive mast rotation system for example) the crew can put one hand on the rotator and the other on the rotator line and pull both in to easily bring in the rotation.
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