I picked up a nice Prindle 16 in good shape a few weeks ago locally. It's in good shape so overall I am very happy but I noticed that the rudders keep kicking up quite a bit and helm seems very heavy. It appears adjustments to mast rake and helm on rudder lock mechanism may be needed. There's even a short guide in the P16 manual to adjusting helm on the rudder but before I started messing around with the tuning I wanted to see how folks usually do this on the dock before heading out.
Is this a trial and error tuning procedure between making adustments on land and then testing it out on the water or is there a more efficient way to do this?
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Marek
1992 Prindle 19
1981 Prindle 16
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Adjusting mast rake and helm on Prindle 16 rudders - trial and error?
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Posted: Aug 10, 2015 - 11:16 AM
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Posted: Aug 10, 2015 - 09:46 PM
I'm sure someone else can help more than I can but I do know that the prindle rudder system can be finicky. ]
The adjustment for a balanced helm is really guess and fixup and dependent upon individual boats. The more rake you have on the mast the more the center of effort moves back and the tendency for more weather helm. Tucking the rudders a little under the hulls can substantially help with this. Note that the rudder adjustment is a game of quarter inches. A little does a lot. Its a little less so with the mast but still a few inches of more or less rake can have a substantial effect. Once you get it dialed in, note everything so you can repeat it.
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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Posted: Aug 11, 2015 - 02:05 PM
thanks Dave. I will take a more careful look while setting the boat up on the dock before we go out next time. The helm was definitely way too heavy. I wonder also whether we really had the rudders locked in all the way since when I checked the rudder lock mechanism the day after on the trailer it seemed quite secure. Maybe we didn't tug really hard enough to lock it all the way in. Even if rudders were slightly up that would probably produce a much heavier helm..
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Marek
1992 Prindle 19
1981 Prindle 16
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Posted: Aug 11, 2015 - 02:44 PM
One thing that really helped me lock in the rudders on my P16 while underway was shims made from a plastic gallon milk carton. Cut 3" circles and drill a hole in the middle larger than the pivot bolt diameter. Put one of these on each side of the rudder at the pivot bolt inside of the casting. Tighten the pivot bolt only enough to take out all the wiggle.
A friend had enough room between rudder and casting that he used multiple shims to take up the space. The milk carton is thin enough that using multiples is easy.
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Sheet In!
Bob
_/)_____/)_/)____/)____/)_____/)/)__________/)__
Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Arizona, USA
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Posted: Aug 11, 2015 - 03:53 PM
thanks Bob, it's probably just a locking problem also looked over the pics of Prindle rudder lock mechanism in the technical section....it's somewhat described in the manual too but while I am at it I'd like to understand a bit more about how helm and rake can be tuned better. Browsing around I also found a few earlier posts about the rudder/helm and mast/rake topics. I'll be reading those too just not clear about the procedure how to optimize rake and helm efficiently..somewhere there's some mentioning about the enigmatic Smith procedure...
Then I found this article that talks about mast rake and helm...and making the boat faster..
http://www.catsail.com/archives/v3-i2/feature3.htm
Edited by marekli on Aug 11, 2015 - 03:57 PM.
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Marek
1992 Prindle 19
1981 Prindle 16
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Posted: Aug 11, 2015 - 04:15 PM
On the Prindle 16 and 18 classic you're going to want a little bit of weather helm... that is when you let go of the tiller the boat will softly head up... somewhat of a safety feature...
Also, you're going to want to carry some rake; about 10" is a good starting point. Unlike the 18-2 and the 19, if you set your stick streight up the boat will fall off the leeward in a rather violent way... actually it can be pretty cool if you're expectiing it to happen. and you are quick on the rudder.
I have usualy carried a 1/2" forward leading edge using the method outlined in the Prindle manual on the rudders and 10" to 12" of mast rake... Remember, the further back the mast, the more forward the rudder leading edge..
As for your rudders kicking up... this may be due to weak springs, bent rudder lock bolts, or a combination of the two... I replace these things every year.
Did you buy the one that was in Atascadero?
Edited by JohnES on Aug 11, 2015 - 04:23 PM.
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John Schwartz
Ventura, CA
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Posted: Aug 11, 2015 - 05:05 PM
thanks John. No, this boat came up locally in San Diego. Prindle's are fantastic buys for the prices they go locally in the San Diego area. You just gotta keep looking they don't come up as frequently as Hobies but they do once in a while. There was a 1998 Prindle19MX with 2 sets of sails (square top main, plus Mylar race sails) for $1500 available until a few days ago, that I was really tempted to buy. I might have had another problem at home so resisted the urge..
. I usually launch out of Oceanside or San Diego/Mission Bay...occasionally I drive up to Long Beach, Ventura or Santa Barbara like for the group sail to Catalina or the Tri Point coming up end of the week if I can crew or find another sailor interested in sailing on my Prindle..
Edited by marekli on Aug 11, 2015 - 05:07 PM.
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Marek
1992 Prindle 19
1981 Prindle 16
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