Trying to put rudders together based on my knowledge of Prindles. There's a pdf manual online for assembling Nacras, but the pictures are very grainy and descriptions leave alot out.
I probably don't have all the pieces (recently bought from a non-sailor). Anyone have a picture of their rudder assy or better manual? I can see where one line goes thru the edge at the top of the rudder, and when pulled tight and cleated on the rudder arm, it would hold the rudder down. There must be something that latches the rudder down (pivomatic?), otherwise the water would always be pulling at the rudder line and stretching.
There's also a set of jib travelers in a box, apparently never assembled to the boat as there are no holes in the hulls. I imagine the location of these travelers would be pretty important, and specialty fasteners into hulls? I think my Prindle had a set of jib travelers on the mast-crossbeam.
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Pairajacks
1985 Nacra 5.2
Corvallis Oregon
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Nacra 5.2; What the hell is a "pivomatic system?"
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Posted: Jul 10, 2011 - 04:33 PM
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Posted: Jul 10, 2011 - 05:03 PM
I just have a couple of minutes or I would explain further. The pivmatics are just a 3/4 round piece of plastic (maybe carbon) pipe with a cleat on it. It is pinned to the rudder bars and when your rudders hit something in the water (rock, beack, deadhead, small child etc) it pivots up and releases the rudder downhaul line. Simple ingenious system, if you don't have them, get them, they are relatively cheap and will save you a large repair.
As far as the rudder system, take a look at my album here: http://www.thebeachcats.c…ictures/?g2_itemId=74162
I have a couple of photos. Basically shock cord goes throught eh rudder bar and is attached via the cross bar boalt and to the back of the rudder. The downhaul fits into the hole into the rudder and comes up through the cast ing up the bar to the cleat. I have mine rigged with 2:1 purchase to make sure they go down all the way, you don't need that.
Also check out Airborne's album: http://www.thebeachcats.c…ictures/?g2_itemId=35563
for a few more pics.
My jib blocks are mounted to wires that go from the front to the rear beam so I can't help much with placement. They probably should be mounted to allow travel from about 24" from the rear beam to just in front of the daggerbaords.
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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 10, 2011 - 05:51 PM
If you don't have the pivmatics, get them. Get the ones with the aluminum cleat, and use a good no streach 3/16 inch line. The pic above shows the rudder pull down rigged 2:1.
1:1 will do fine and take half the preasure to kick up.
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Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
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Posted: Jul 10, 2011 - 07:19 PM
As Ron says, use 3/16" line. I used 1/4" Sta Set, & it is a little big to fit the pivmatics, it doesn't go fully down into the cleat, but it does hold OK, & kicks up when needed.
Here is a photo of my rudder tie bar assembly. You can see the 1/4" line does not fit into the pivmatic as well as 3/16" would. When the rudder strikes an object, the cleated line takes the pull. See the pin at the end of the Piv? The 1/2 tube(that fits over the tiller bar) will be pulled back, & pivot up & rearwards on that pin. As it rotates, the line will no longer be held in the cleat, the pull will now be in a direction that releases the line, allowing the rudder to flip up. Slick eh?
It is possible to have the U joint between tiller & tie bar move into a position where it can lock your rudder travel. Just wrap some wire around the base of the U on one side, so that it cannot turn. The pivmatic is at the end of the tiller bar, where the rudder pull down line goes through. If you go to my album "1984 Nacra 5.7" under members, I have fairly high res photos. If you click on the little tab to blow them up to full size, you can often pick out more detail.
Here is a rigged rudder.
Place a knot at one end of pulldown line, feed the other end into the hole, & pull all the way through. The line then goes up & OVER a roller that is held by that little ring ding, then along the tiller bar to the pivmatic.
The shock cord is fed through the hole at top edge of rudder, then through the inside of the tiller tube. In order to work, the bungee will not be long enough to extend through the tiller tube. Tie a line to both ends so you can stretch it out while you hog ring or tie the ends where needed. You can hold the stretch using the line you tied on, or vice grips while you work the tie bar bolt between the two lines. Nacra manual explains.
In this photo the rudder pivot bolt has been removed, & the rudder slightly displaced. Just above the white circle you can see one of the shims, used to remove slop between rudder & casting. Cut your own shims out of plastic juice jugs.
Finally, see the little white nub, behind the long pin that attaches the rudder? That is screwed in/out to make final adjustments of where the rudder bottoms against the casting when pulled down. It will allow some adjustment of lee/weather helm, & tiller tug. I have tons of them, PM me I'll send you a few for cheap if yours are missing.
Edited by Edchris177 on Jul 11, 2011 - 05:58 AM.
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Hobie 18 Magnum
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Posted: Jul 10, 2011 - 07:23 PM
1984 Nacra 5.7 dude. ;) http://www.thebeachcats.c…ictures/?g2_itemId=71715
Edited by Wolfman on Jul 10, 2011 - 07:24 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 10, 2011 - 09:06 PM
Pivmatics are things that save you a weekends worth of fiberglassing, sanding and painting. Been there Done that. Spend the money and get them.
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Nacra 5.2
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Posted: Jul 11, 2011 - 05:15 AM
jib travellers have no place on a 5.2, which is why there were no holes on the hull or beam, as above the only place for the jib blocks to be and work well with the 5.2's large old-school, overlapping, reaching jib is just over the tramp about a foot in from the daggers -
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Posted: Jul 11, 2011 - 06:18 AM
Regarding Airborne's album: http://www.thebeachcats.c…ictures/?g2_itemId=35563
The fourth photo is a good depiction of line placement.
Note that he used line (red) for the uphaul instead of shock cord. Consider your own sailing area first. The bungee does tend to wear, as it rubs on the sides of the rudder. This is easily controlled by a short piece of tubing, or even taping the affected area. Bungee makes lifting rudders automatic.
Bungee stretched enough will hold the rudders clear of the water. If you solo, or have inexperienced people on your boat, & launch/retrieve in congested or rocky areas, it is simpler to just pull the line out of the pivmatic & let the bungee take care of your rudders.
The line can "catch" in the cleat, not allowing them to come all the way up. I pull it up, then keep my finger over the cleat for a half second so it cannot re engage. Tossing the line to the back also seems to work fairly well, & my 1/4" line is less prone to re engage.
If you elect to substitute line for bungee, you have to uncleat the downhaul, then physically pull the up line & cleat it to keep the rudders even horizontal. In areas where you have to jump off the boat & carefully back it into a spot it is very easy to snag a rudder that is hanging down.
The standard system works very well when correctly rigged.
In my above post I incorrectly stated that those little adjustment screws allowed for some latitude in lee/weather helm. It is more correct to say that your helm is established by the sail plan, & adjusting rudder rake helps with the resulting tiller forces. Many posts have complained about large weather helm, & the need to bottom the rudders against the casting, & keep them there, ie no stretch line. Your mileage may vary, depending on mast rake etc. I need to turn those adjusters in, & keep the rudders 1/4" off the edge of the casting.
Here is a good writeup on balancing the helm;
http://www.thebeachcats.c…s/15/about-weather-helm/
Edited by Edchris177 on Jul 11, 2011 - 06:39 AM.
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Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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Posted: Jul 11, 2011 - 07:40 AM
dang floating deadheads...they need a miracle every day.
Edited by coastrat on Jul 11, 2011 - 07:41 AM.
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bill harris
hattiesburg, mississippi
prindle 16- "BLUE RIBBON"
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Posted: Jul 11, 2011 - 09:19 AM
Heh heh, insert your own Mel Brooks History of the World joke here.
Deadhead = Old Semi-waterlogged Tree that floats just below the surface and will knock the lower unit off your outboard or daggerboard into your well. Also sometimes seen following Jerry Garcia around when he was alive.
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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 13, 2011 - 12:04 AM
Thanks to all of you who took the time to reply. It will help quite a bit! I'm eager to try some of this rigging out on the lake. I'm sure it'll take several times out to get the rigging right
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Pairajacks
1985 Nacra 5.2
Corvallis Oregon
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Posted: Jul 13, 2011 - 12:18 AM
I guess one question I still have is where the jib pulleys go... I read that they should be just forward of the dagger board; how is the jib block anchored? To the hull? Off of the shroud?
The rope holes at the top of the dagger board are a bit confusing. I see where the dagger boards are kept in position with side pressure from shock cords and a roller. Maybe it's shock corded several feet above the deck to the shroud to keep the dagger boards more secure.
Thanks again for all the help, you folks are awesome!
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Pairajacks
1985 Nacra 5.2
Corvallis Oregon
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Posted: Jul 13, 2011 - 01:20 AM
watch these videos and hit pause whenever you see the jib blocks
http://vimeo.com/5075989
http://www.youtube.com/watch?v=j55lMDEBmP8
