Just started working on the rudders for the Nacra 5.5 uni overhaul. Overall they seem in pretty good shape. I'd just like to strengthen any worn areas (rivets) and make them reliable, while taking out some slop where I can. I'll be adding all new down-lines and up-bungee. I'm aware that many get rid of the bungee and install pull-up lines, but I don't want to go there just yet, and will try to get the original system working well. I'll outline my basic questions directly below, then post pics after that with more detail. I've searched the internet for everything related to Nacra rudders, and have read countless pages on here and also Catsailor. I've found many good tips and tricks. Nonetheless, I'll share what I'm working with here, and I still have some unanswered questions.
So (onwards with the longest rudder post ever):
1. Pivot hole in blades worn and sloppy. Fill and re-drill? Use existing holes and pad insert with epoxy?
2. Castings are not the type with a delrin screw for blade rake adjustment. How major is this going to be in tuning the helm pressure?
3. bolt through end of tiller tube from cross-tie attachment is badly worn/oversized. Can I cut off an inch of tiller tube and drill new holes?
4. Add a sheave on the pin in the casting that the pull-down line runs over?
5. Proper hardware for each end of pintle?
The pivot hole through one of the rudder blades is badly worn (first photo). The metal insert, which the pivot bolt goes through, falls out of the blade easily. It is massively sloppy, and I'm concerned this will be felt through the helm. The other blade's pivot hole/insert seems pretty snug still (second photo). Of all the slop issues (many more below) this one seams the trickiest to fix. I've heard of people filling the hole and redrilling it. What filler product would be used? Any other options? Could I just pack some epoxy around the worn insert and make sure its centered in the hole as it dries? Should I not worry about it at all? It's not a race boat, but there's so many sources of slop in the steering right now, and I'd like to address as many as I can without getting to deep into it.
The second set of rudder blades are definitely in rougher shape. Not terrible though, so I could use them instead. The pivot holes don't seem worn to the point of needing fixing. They blades are a *slightly* different shape, with a little deeper curve on the upper leading edge. Somebody has taken a grinder to them and removed a little more from the curve, making it deeper still. It's a bit of a hack job, that makes them look pretty beat up in addition to having more wear and tear. I'm guessing the grinding was so they could be pulled down further and get more blade rake under the boat (given the castings don't have rake adjustment screws). Until I get the boat on the water I won't know if the helm is heavy or light and if I'll miss the rake adjustment or not. Otherwise I might have to balance it with mast rake only.
Castings look good. They must be a very old style, as they don't have the delrin screw (or hole for one) for rake adjustment (bummer). Oddly, of the 8 rivets in each casting holding the tiller arm, the 4 on the inside were stainless, and the 4 on the outside were aluminum. This was true for both port and starboard rudder assemblies. Can't imagine why. Like most aluminum rivets on this boat (shaking my head) they were loosey goosey and corroded. I replaced them with stainless and it locked down the tiller in the rudder casing nice and firmly, taking out a lot of play. Gudgeons look solid on the transom, and the only thing I will do is renew the silicon around them.
The port tiller appeared bent downwards (i'm assuming) as it barely cleared the hull. I inserted a piece of dowel into the tiller arm, and screwed the casting down to a heavy log round, and gently bent the tiller tube back up to match the starboard side. I held my breath during this operation, but I didn't hear any bad sounds or see any stress cracks. It didn't take much bending. Note all the extra holes in the tiller arms from previous setups (that is the general theme of this 35 year old boat). It looks as though the rudder pull down used to be internally routed and exited half way along the tiller tube (the large hole) and then through a side-mounted cleat (the small holes). The pivmatic system it currently uses was probably added later.
The tiller to tiller-crosstie attachment is the type with the welded bolt. I can see what people mean about your steering locking up if this piece pivots out of place. Obviously the welded bolt helps, but it doesn't eliminate the possibility. Any better ideas to absolutely avoid it happening? Again, the four aluminum rivets holding the stainless 'prongs' were were fatigued with heaps of play, so I replaced with stainless rivets and it firmed it up nicely.
Another view of the tiller to tiller-crosstie attachment. Note the deformed tiller tube from overtightened bolt. Also, the bolt hole through the tiller tube is *very* worn and oversized, creating a huge amount of slop. I'm wondering if I can drill a new hole, say, one inch down the tube toward the rudder casing. Would this create any problems. Could I cut of the inch or so with the old worn hole?
Very worn bolt hole through tiller tube, at the tie bar connection.
Shims around the pivot bolts were shot. I'll cut new disc out of milk bottle plastic or similar.
This is the pin inside the rudder casting, just under the tiller tube, that I've learned the rudder pull-down line must pass over the top of. I've also heard some assemblies have a small sheave on this pin. Is this a recommended/necessary upgrade?
The pivmatic looks kinda tired The composite part is quite perished and looks like it would crumble or crack pretty easily. I guess I'll go with it, assuming the cleat still grips ok. The starboard side looked like a newer composite piece was installed (it was more black than grey like this port side one).
I don't like this at all - pin holding the top of the pintle. Looks like it could get hung up with the rudders being turned hard, and even pop out. The bottom attachment was better - a small closed split ring. What is the preferred hardware? Small split ring (like in the second photo below) on both ends? I shouldn't need to take the rudders on and off very often, so quick removal isn't an issue.
Now, to try and remember all those tricks for proper/easy line/bungee replacement...
Edited by sierracat on Feb 23, 2015 - 12:44 AM.
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Tom
Hobie Getaway, Nacra 5.5, Hobie Tiger
Wish list: A-cat classic, F16 Viper!
Northern California
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