Hi Everyone,
There has been some debate about this 2:1 purchase modification for the Nacra rudder system that allows you to get the rudders tight to the transoms much easier than the stock setup. Some of us have been advocating this mod because with the stock downhaul it is tough to get the rudders all the way down:
http://173.205.126.48/index.php?module=pictures&g2_itemId=74162
The concern is that the extra force required to pop the pivmatic kick-up assembly would harm the rudders.
Well I certainly disproved that theory. I have brand new pivmatics on my boat, ran it into shore last weekend and caught a gust before I could pop the rudder up. They hit the sand shore and popped properly, no damage at all. Now that they have been broken in a bit they pop a little more easily but again no damage to the rudders (other than some scraping that would be expected when running them into 'rocky sand').
Fortunately I did get the daggers up or I would be asking about daggerboard well repairs right now...
edited by: Wolfman, Jun 28, 2010 - 11:31 PM
Are your rudders sticky Dave? During the winter rebuild I discovered one rudder had a crack along the leading edge. I dremeled it out, sort of like dentistry without the pain, & injected resin & glass mat. After setting up a jig to hold the rudders, they felt a bit stiff, & I considered that mod. However after taking them totally apart & cleaning the bushings & adding spacers made from a plastic juice jug they pull down quite easily. After replacing the pulldown lines with sta set, I can easily pull them tight against the stops, though they seem to move a millimetre or so at speed, probably due to line stretch.
Good to hear they popped, who needs the cost or downtime of finding new ones.
Good to hear Dave. I ran my rudders that way for over a year and they popped up atleast 10-15 times due to emergency beach landing or hitting something under the water and never had a single problem. Im glad you had the same outcome.
The trickiest part of this rudder mod is getting the knot tied in the right place! 😀
edited by: TurboCat, Jun 29, 2010 - 05:21 PM
What pray tell me are pivmatics? The Nacra rudder system on a Nacra 5.2 is wanting?
Oh Dave by the way your boat looks great. I really like the jib block set up.
EC, my undrestanding is that it has sort of been a historical problem especially with the early 5.2s. I probably should pull them apart and do the things you say I bet the bearings (nylon washers) are probably gone. Anyway it has always been difficult to get them those last couple of inches to the transom and the resulting weather helm sucks if you don't get them all the way down. And the line I use is VPC Vectran blend (LOVE IT!) so very low stretch.
Turbo, Yeah it took a few tries, but I got er.
Terry, the pivmatics are the automatic pop-up mechanism for a Nacra. It wasn't introduced until later on (1985?), but I HIGHLY recommend them if you don't already have them. A simple system that works well, really just a carbon fiber pipe that goes around the rudder 3/4 of the way and automatically tips up uncleating your downhaul if you hit something. At about $40 they are much cheaper than new rudder and transoms. Here's a link: http://www.murrays.com/mm5/merchant.mvc?Screen=PROD&Store_Code=MS&Product_Code=56-0266-1&Category_Code=
And thanks! I've finally got things pretty much the way I want them and all the kinks worked out! Took a few tries though. 🙂 You would think that using all that high tech line wouldn't make much of a difference but I think it does.
Are you sure they are carbon fiber? The ones I've seen look like glass.
I was in the middle of a downwind beach landing a few weeks ago and one of my rudders hit the sand before I could raise it, and jammed. It rounded me straight downwind, nose to nose into a hobie 16.
I've got some pivmatic brackets on order.
Well... they are black anyway. For $40 I pretend they are carbon fiber, that's my story and I'm sticking to it. 🙂 Actually they are more likely molded plastic of some kind, maybe glass fiber reinforced. They work, which is better than the other way, which you have figured out, lucky the gudgeons didn't pull out.
D.
Hey wolfman did u end up doing the barberhaulers?
The pivmatics are just cut up pieces of a hot stick. Ever look at a ariba stick and a pivmatic side by side? Im almost positive they are the same thing.
nevermind, went to your gallery and checked out the boat. Looks great! The only area for improvement may be some more purchase on that downhaul system. In a hard blow you would be glad you had it! Ill check and see if i still have the lower downhaul units from my 5.2 refit. If i have them still ill send them to you if you cover the shipping. Looking good Dave!
Turbo, thanks! This winter I'm getting a nicer jib made up by Chip Buck. I'm working on getting a swept back spreader also.
I would be more than willing to pay you a fair price for the extra downhaul parts!! I would love to have something stronger than the current 3:1 especially with that wicked sail!
D.
On my rudders the nylon shims, used to eliminate play were toast. There is also an SS bushing inside the rudder hinge point. That was full of crud as the cat hadn't been used in 2 years. Cleaning the bushings & making new shims really helped with the force required to pivot the rudders. Also make sure the pull down line is routed correctly, you lose what little mechanical advantage you have with an incorrect routing. Also try getting the rudders locked down while at idle speed, when the forces against you are small. As soon as i'm off the dock I head up into the wind, once boat speed is low they can easily be pulled down tight with one hand. I made little handles out of Canadian Red maple (you can just see one in the photo showing the traveler car & stopper knot)coated with spar varnish. They give a much better handhold than those little plastic balls.
edited by: Edchris177, Jun 30, 2010 - 11:32 AM