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PostPosted: Tue May 22, 2012 10:36 pm 
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Joined: Tue May 22, 2012 10:30 pm
Posts: 7
I would like to install a mast rotation arm in my Hobie 16. I have the kit, which consists of two compression plates, a compression sleeve, a bolt, a nut, and the arm. Would it be possible to get step-by-step instructions on how to do the installation?

Thank you very much.


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PostPosted: Wed May 23, 2012 6:51 pm 
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Joined: Mon Dec 31, 2007 6:06 pm
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Location: SE PA/ Chesapeak Bay
That's interesting .... but first you have a problem .... the H18 ia a "loose" footed mainsail ... the H16 has a mainsail that slides into the boom ....

So, you can't install a rotator on a H16 like it is on a H18 .... but you can install one .... UNDER the boom .... or at the mast base. Now if at the mast base do you want it installed on the trailing edge of the mast or on the leading edge ???? Rotators have been installed both ways on various Beach Cats over the years. I think "under" the boom would be best, then the mastbase/trailing edge would be next and could be made to work, (because of how the Jib sheeting system on the H16 is located/works) but would require some ... "eng-ga-neering" ...

It can be done ... and wouldn't be a difficult project/modification ....

Question: Why do you wish to do this??? Is your "Mast Base" on the front crossbar Ok ... or are the rotator stops rounded over and the mast over-rotates???

I've always believed the H16 should have been "upgraded" w/ a mast rotator, proper downhaul and outhaul w/ the mainsail being loosefooted ... it would make the boat more "tune-able" and widen the "performance envelope" (ie: the competitive crew wieght window would be wider) ... and all it takes is a H18 style boom ... but that's me ... and I gave up on trying to race a H16 at crew weights of +350lbs and being competitive ... ( does the term "DFL" mean anything ???) ... so I purchased a H18 ....

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HarryMurphey
H-18 mag/ #9458
Fleet 54 Div 11


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PostPosted: Thu May 24, 2012 4:39 am 
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Joined: Tue May 22, 2012 10:30 pm
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Thank you very much for your message. I have a loose-footed main, a modified Hobie 18 downhaul, and a 2:1 internal outhaul. The modifications have been introduced so that the boat can still be brought back to class legal by simply using the original hobie 16 main instead of the custom-made main (tri-radial premium pentex with square top).

The mast rotation arm is intended to go above the boom, very much like in the hobie 18. The mast rotation control kit consists of a hollow cylindrical strut, two compression plates (with rivets), a bolt, a nut, and the rotation arm. So, this is my plan unless otherwise warned against it:

Drill two holes on each side of the mast equidistant on the horizontal plane from the sail track. The diameter of these holes will be equal to the outer diameter of the cylindrical strut.

Insert the strut through the mast holes. The distance between the holes when looking at a cross section will be such that the strut will protude from the outer surface of the mast about 3 mm on each sides (which about the thickness of the compression plates).

Rivet the compression plates. The idea is that the two protuding ends of the strut will now be flush against the visible surface of the plates (the non-visible surface of the plates is the one against the mast).

Insert the bolt through the strut and attach the rotation arm with the nut.

Thank you very much for all your comments and feedback,
Jose


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PostPosted: Thu May 24, 2012 4:52 am 
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Joined: Mon Jul 14, 2003 7:11 pm
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Location: Detroit, MI
A mast rotation control on a Hobie 16 is not advisable for several reasons - that's why it was never approved for racing.

The real problem is that the rotator arm is right in the crew's face when they're on the trampoline (especially during a tack). It's downright dangerous.

I have a rotation control on my 14 and it's marginally useful. Problem there is that when you change the downhaul setting, the mast rotation setting changes (because the boom moves up and down).


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PostPosted: Thu May 24, 2012 6:05 am 
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Joined: Mon Dec 31, 2007 6:06 pm
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Location: SE PA/ Chesapeak Bay
That's a interesting point I hadn't thought of ....

... so ...

... if the H16 could use a H18 style boom w/ a loose footed sail it would be better since you could install the rotator arm ABOVE the boom ...

... or ...

you could install a rotator at the mast base level/trailing edge ... but that leaves you w/ how do you work the "adjustment" .... I know Tornados had mast base rotators, but their tramps were different (and mast rake ...) ... the adjustment line went down through the tramp in the center and went out to either hull, passing from under the tramp at the open space between the tramp and hull, and there was a Camcleat/Jr Jamcleat mounted on the hull to "cleat" the mast rotation adjustment line ...

Obviously the tramp on a H16 doesn't lend itself to a system configured this way ....

Now Nacra had mast rotators that were at the mast base/leading edge, ie: facing forward, but the jib sheeting system was totally different and not located on the front crossbar. I'm afraid that if a rotator was installed facing forward, the jib sheets would always be getting fouled around it. On the Nacra's the rotator was controlled using camcleats mounted on the front-crossbar (exactly were the H16 jib traveler is located ...).

This modification is not so simple and could take a little more "eng-ga-neering" then it appears at first glance ...

and again I ask ... Why do you wish/need to install a rotator on a H16??? What's wrong ???

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HarryMurphey
H-18 mag/ #9458
Fleet 54 Div 11


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