True but I have seen this mod about 4 more times in different places. The rudders on the 5.2 require a LOT of force to get them up tight and this looks like a good way to overcome that. I'm don't think that doubling the required kick up force is going to do much more damage to the rudders than the normal kickup. If you quadrupled it you might be in trouble. If you hit sand (like where I am) you will probably won't do much to them. If you hit rock your are going to nick them regardless.
Truthfully I consider the PivMatics to be just a fail safe in case something goes wrong. With daggerboards on the boat I think thier usefullness is seriously reduced while sailing (you will definitely kill your daggers before the kickups work). I am not planning on counting on them to kick up the rudders under normal beachings (I don't have them installed yet and haven't had a problem with the manual rudders). They are just a measure of insurance in case I can't get back to the rudders after I lift the daggers.
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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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The annoying questions begin - (Nacra 5.2)
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Posted: Jul 27, 2009 - 09:51 PM
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Posted: Jul 27, 2009 - 10:06 PM
I think the pivmatics protect the transom more than the rudders. My rudders on the 5.8 were hard to pull down till I replaced the plastic shims and adjusted the pivot bolt. Here is a HOBIE with the transom ripped out. http://www.thebeachcats.c…pictures&g2_itemId=10836
edited by: skarr1, Jul 27, 2009 - 09:13 PM -
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Posted: Jul 27, 2009 - 10:29 PM
Ah, that actually makes more sense now that I think about it. Yikes, what a mess! I will test out how much force is required to pop them with and without the block when I get around to installing the pivmatics.
On another note I have been looking at Airborne's and Erice's boats. It appears that theire jib blocks are attached to both the front and rear beams with wires. Mine are just attached with 1/4" line to the rear beam. Is this a standard or modified setup? What advantage is there to attaching them to the front beam? Is it just to keep the blocks in place?
Regards,
Dave
edited by: Wolfman, Jul 27, 2009 - 09:34 PM
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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Posted: Jul 28, 2009 - 01:01 AM
The line on their boats allows the jib block to be adjusted fore-aft.
I would imagine that since yours is attached only to the rear beam, its essentially in the rear most position allowed by your setup. If you have the line coming out of a pocket on the tramp, even if the length of your 1/4" line is allowing the jib block to be forward of the line's exit point in the tramp it is still functioning as though its cleated at the exit point from the tramp. If it's all above the tramp, its functioning as though you have it cleated from the rear beam. Their wire holds the block down to tramp level so that as they adjust the position forward or backward the direction of force pulling on the clew of the jib is changed.
The farther back that your angle of sheeting is, the more wind you're spilling from the top of your jib.
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Rob
OKC
Pile of Nacra parts..
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Posted: Jul 28, 2009 - 05:00 AM
the stainless line between the beams stops the jib blocks from being pulled up by a big wind in the jib
the line from the rear beam allows adjustment along that line
the 5.2 has a big overlapping jib and getting the jib down on the tramp probably is important for maximum efficency
early model 5.2's had this line completely above the tramp
later models ran it below the tramp near the beams but brought it up through reinforced slits in the tramp near the aft of the daggerboard wells -
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Posted: Jul 28, 2009 - 12:06 PM
Dont worry about the pivmatics popping as they still work fine on my boat. I have popped them a few times and the rudder doesnt get damaged and the pivmatic still works. -
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Posted: Jul 28, 2009 - 01:31 PM
Good to know Turbocat, I was pretty sure that there couldn't be enough force to damage the transome 2 times load considering the sideways loads they experience. That being said it's always good to have confirmation.
As far as the jib wire is concerned. Do you think that it is reasonable to substitute 1/4" low stretch/prestretchd line instead of wire in the short term? I have some vinyl coated wire but I am waiting for my swaging kit to get here (hopefully by the end of the month).
I will likely put grommets in my tramp at the correct locations and run the wires underneath (that should clean things up a bit too). What do you use to prevent the wire from wearing against the the tramp (or rather the tramp wearing against the wire)?
Regards,
Dave
--
Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Posted: Jul 29, 2009 - 03:19 AM
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Posted: Jul 30, 2009 - 09:53 AM
I run low stretch line under the tramp that is connected to an eye strap on the front and rear beam (under tramp). I will post some pics later tongiht for you to see. I will be working on my boat tonight so when im done i will post them. -
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Posted: Jul 30, 2009 - 10:21 AM
I use vectran line instead of the wire cable for my 4way jib adjuster. vectran has no creep issues like dyneema does (creep is elongation over time... not stretch)
High Modulus line (dynema, vectran, etc) is stronger (and cheaper) than steel cable.. and much more comfortable when you sit on it.
The draw back of this line is you lose about 1/2 its strength with knots.. but since 5mm can lift a car (4500 lbs) its not really an issue.
but 12 braid (without a core) is VERY easy to splice, and is a great way to get into splicing. you can buy a 4mm selma fid from Murray's for under $10....
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