Prop anode help on Catalina 350

Jul 1, 2010
962
Catalina 350 Lake Huron
I noticed the Catalina 350 we bought last year didn't have a prop anode on it so I bought one this spring to install. No room for a shaft anode, so I got one of the prop nut anode assemblies that replaces the nut.

The first thing I noticed was that the boat has only a single castellated nut on it instead of a double. The location of the cotter pin makes it impossible for a double, and as far as I can tell, Catalina designed it that way.

The anode assembly that I bought also will have a fit issue due to the very short space (see pics attached). I can cut it down on a mill to fit, but wonder if that's the right thing to do. I'll have to take a bit off as you can see from the pic with the ruler on it. The small nut area and a bit of the large nut area would have to be removed, but the # of threads left would be the same as the original nut. The threaded cage on the anode kit might actually provide more thread contact than the original.

Is there a better method for attaching an anode to the prop on this boat that I should look for?
Suggestions? Figured I should ask before, than find my prop missing later.
 

Attachments

May 24, 2004
7,129
CC 30 South Florida
Contact a Catalina dealer and see what they recommend for the boat. I suspect that with a bronze prop and so very little of the shaft exposed that most do not use an anode at all. A seasonal check to detect any early signs of corrosion might set your mind at ease.
 
Oct 22, 2014
20,992
CAL 35 Cruiser #21 moored EVERETT WA
@sesmith from the image of your prop it is clear there is a limited area for a traditional anode.
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But they make an anode for limited space configurations. My diver calls the donuts.
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This one is advertised in the Fisheries Supply catalogue. https://www.fisheriessupply.com/sea...au-micro-limited-clearance-collar-anodes-zinc

This one shows made out of zinc. I did not search for Mg. But suspect they are available somewhere. Manufacturer is Sea Shield Marine.
I wonder if it might fit your need.
 
May 10, 2008
392
Catalina 355 Boston
Sesmith,
I’m not sure if I’m misinterpreting your post, but the prop nut anode goes on in place of the castellated nut. The cage allows for a cotter pin. This is the setup for Catalina’s with a partial keg (350 and 5 Series like mine).
Before I replaced my standard prop with a Gori, I used this setup with no problems for 7 seasons. Gerry Douglas has recommended not using a shaft collar zinc to avoid water flow issues into the cutless bearing.
 
Jan 30, 2012
1,123
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
No need for a double, but if you insisted the inner nut (called a jam-nut) would be about 2/3 the thickness of the outer. The inner gets about 2/3 the torque of the thicker outer. This is old school lock-nut technology by the way - unreliable because the final assembly depends on distorting the threads of the inner nut - just not too much.

As it is now - just mill off a bit of the new nut forward shoulder. That way the flats of the new nut will move forward. Bore a new cotter pin hole by drilling through the flats - thus to duplicate the old pin position on the new nut when it is tightened up. Use the new hole for the cotter - ignore the slots. The anode is set with an allen head screw. If it interferes with the prop shoulder just mill a bit off the forward end of the anode so it clears the prop shoulder.

Charles
 
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May 24, 2004
7,129
CC 30 South Florida
His picture shows how his setup will not allow for the insertion of the cotter pin. Would not use a donut in the restricted space so close to the cutlass bearing. A new hole could be drilled for the cotter pin on the replacement nut assembly if it is deemed strong enough to secure the prop.
 
May 10, 2008
392
Catalina 355 Boston
His picture shows how his setup will not allow for the insertion of the cotter pin. Would not use a donut in the restricted space so close to the cutlass bearing. A new hole could be drilled for the cotter pin on the replacement nut assembly if it is deemed strong enough to secure the prop.
Actually the cotter pin fits nicely through the slits in the nut. Unfortunately I don’t have a close up of the pin.
 
May 10, 2008
392
Catalina 355 Boston
Actually the cotter pin fits nicely through the slits in the nut. Unfortunately I don’t have a close up of the pin.
You can barely see the head and tails of the cotter pin if you look closely
 
Jul 1, 2010
962
Catalina 350 Lake Huron
Thanks Charles. That sounds like the fix. I may not even need to mill anything off if I just drill the cotter hole in the flats. That would avoid having to mill off the end of the anode every time I replace one.
 
Jul 1, 2010
962
Catalina 350 Lake Huron
Solstice, thanks for the pics. Yours looks exactly how I expected mine to look, but the cotter pin hole in my shaft is too close to the prop for the anode assembly to work as it should. Take a look at my pics and you'll see what I mean.
 
May 10, 2008
392
Catalina 355 Boston
Solstice, thanks for the pics. Yours looks exactly how I expected mine to look, but the cotter pin hole in my shaft is too close to the prop for the anode assembly to work as it should. Take a look at my pics and you'll see what I mean.
I see now, sorry about that! Do you know if your shaft is original from Catalina? My shaft had a ‘tail’ at the end that had the hole. There were no threads at that point. I ended up cutting this off to fit my Gori...
 
Jul 1, 2010
962
Catalina 350 Lake Huron
Sorry, didn't measure, and I'm currently 3 1/2 hours away from the boat. Not much, though. Less than the length of a standard anode. Maybe a couple of inches at the most.
 
Jul 1, 2010
962
Catalina 350 Lake Huron
[QUOTE="Solstice, post: 1532357, member: 39170"Do you lyknow if your shaft is original from Catalina?
[/QUOTE]
No reason to believe that it's not. I've seen pics of other 350s with the same setup. I do know that one of the previous owners changed out the original 2 blade prop for a 3 blade prop. Other than that, I believe it's original

Prop looks like there have been no issues so far with any damage from electrolysis. I noticed lots of boats on the hard in our marina with no anodes and no obvious issues, so it's not likely a big deal where we are on Lake Erie. I do want to get one on eventually, especially before we head to any salt water areas. The boat does have a galvanic isolator, for whatever protection that may provide in the marina.
 
Jul 1, 2010
962
Catalina 350 Lake Huron
Thanks. How much free space do you need to have behind the cutless for water flow?
 
May 10, 2008
392
Catalina 355 Boston
Thanks. How much free space do you need to have behind the cutless for water flow?
You should have 1.5” clearance. The reason Catalina recommends not using a limited clearance collar is because the Cutlass Bearing protrudes from the stern tube and is not a press fit. The Stern tube is FG and you can do some damage if a collar zinc were to spin loose.