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Repairing pitting on rudder

R

rmm

Regular Contributor
One of my rudders has a small

One of my rudders has a small area about 1.5" x 1.5" of pitting. I think it is from an electrolysis problem originating from the dock.

Is there a good way to patch this? Could I use like JB Weld or some other product to just fill the pitted area and then sand and fair it?

Any other ideas? Thanks
 
"You can try but if you don&#3

"You can try but if you don't stop the electrolysis, the patch is just going to pop off. Check to see that your rudders are properly bonded and that they have adequate zincs installed."
 
you can ground your rudders fr

you can ground your rudders from inside the boat as well as some that have zincs attched to them under the water. I have some old anodized ones on my boat with the zincs attached. I have new ones that I will install in spring that I will attach to bonding system just above the packing nut. I can clamp them with the same awg ground/bonding wire that I have running thru the boat.
 
Scott do you have a pic of the

Scott do you have a pic of the zinc attached above the packing nut? Looks like from your pic we have the same or (or close) boat a 1988 Tiara 31'.

Thanks
 
"I just re-read my post and do

"I just re-read my post and don't know how clear I was...

Instead of attaching zincs to the rudders, attach the rudder inside the boat to the bonding system above the packing nut.

Because I currently have zincs on rudders and shafts and will be removing the zincs from the rudders, I will need to add more zinc. I had a great ideal that a zinc on the transom would be ideal. I more inspect it and change it more easily.

There is a formula of needed zinc surface area underwater and its based on the surface area of you underwater bronze and stainless steal (take a look at http://boatzincs.com/faqs.html).

You can always estimate and measure with a multi-meter and reference electrode.

I bounced my "brain storm" of an ideal of ditching the rudder zincs and adding a large transom zinc by Scott Bytweck at Tiara and he sent a picture of that same implementation and politely told me that the newer Tiaras all come with transom mounted zincs now (and for many years).

Well the best ideas are found over and over again.

So before you get wet again, drill zinc mount holes for studs (get the typical transom zinc first http://www.boatzincs.com/zc-406.html). Get threaded bronze studs. Fill with 5200 and attach the transom zinc. Inside boat wire a ground wire from bonding system to the stud.

(Actually someone verify I should use bronze studs or is stainless steal fine.)


the pictures are 4 alltogether and too large to post send me your email and I'll send to you..."
 
""(Actually someone ve

""(Actually someone verify I should use bronze studs or is stainless steal fine.)"

I replaced a couple of 1/2" stainless rods going to my transom zinc, a divers dream. Why? Stainless has about 42x the resistance of electrical copper! A 1/2" SS rod = about a #8 copper screw! Moving to Silicon Bronze gets you about a 4X improvement. This matters more for lightning mitigation than for galvanic protection."
 
"Scott thanks, I had been thin

"Scott thanks, I had been thinking about that as I see them on many boats and was not sure why Tiara didnt install originally. I just HATE drilling holes below the waterline. I think would definetly help to prevent electolysis.

New question, if remove zincs from rudders are just planning on leaving holes open? I have round single hole zincs now. Why not use both?


Email is [email protected]"
 
"You can bring rudder to the s

"You can bring rudder to the same place you bring your prop. They can fit it unless too much have been lost. Mine are damaged and are being replaced. They don't have a hole to begin.

You really need to measure the current at boat. Based on your observation you are under protected.

You could overprotect and screw up your bottom paint, but that is less a problem for fiberglass boats.

Dave,
I see rods in range of 33 a foot for 1/2 dia. - don't see that they are threaded so I need to have that don't as I haven't tap/die anymore.

Did you replace yours in the water? Just wondering how? 5200 okay wet? 2 man job?

Ps what washers and nuts are used?"
 
"JD has 1/2"x13 threaded i

"JD has 1/2"x13 threaded in 3' lengths. I also used a total of 6 nuts and 4 flat washers. I used 3m101 on this job, during a scheduled hauling."
 
"Thanks Al and Dave.
I have

"Thanks Al and Dave.
I have an overnight on sling sometime in march to install new rudders. I will do it then.

Dave or others, how well can you protect from a lightening strike. I hear of "frying electronics" but will any setup protect you? I guess each hit has its distinct intensty."
 
"Frankly, I don't think yo

"Frankly, I don't think you can eliminate the possibility. You MAY be able to bleed off the " electrical potential" between the positive and negative charges but MY OWN OPINION is IF it is a direct strike...You are screwed ( to put it nicely )This opinion comes from my experience as a ham operator with a 70' metal tower calling out to any charged atmsopheric masses every time a thunder storm passes thru..it scares the heck out of me every time..Check out Gauss's Law"
 
"More "Fried" than &#3

"More "Fried" than "Screwed" with a direct strike. I 'rebuilt' a few instrument pods that experienced the lightning strike - remove and replace with new. The current in a lightning bolt can easily exceed 10000 amps and solid state electronics just don't tolerate it.

there are a few 'new' guys in the lightning protection business - do a google on the topic, if interested.

I've opted for the 'bond all the metal together' school on this topic. the premise is that given enough opportunities, the strike will occur. When it does, you want to provide a 'controlled' escape path for the electrons once they arrive en mass."
 
"Dave,
Just checking if you h

"Dave,
Just checking if you have a 1 foot of the 1/2 inch silicon bronze you used last year? I would pay any resonable price.

I'm going to use the 1/2 as well. I dont know what to do with the extra lenght from the 3 foot section that I can get. Its about 90-100 for that now a days..."
 
"do you guys have your swim pl

"do you guys have your swim platforms connected into the bonding system? My Trojan doesn't and I have corrosion on almost all of the mounting points/hardware.

I was going to add the platform while I'm cleaning up the wiring unless there's a reason not to...

What about the propshafts?

My boat has an extra hose clamp on each stuffing box packing nut with a wire tucked underneath. It doesn't look like a factory setup (it looks pretty bad actually) and I wonder if I need it?

Off of the clamp are a couple of short wires which connect to some of the thru hulls nearby.

If I eliminated the propshaft/hose clamp setup, I can easily run seperate wires to each of the through hulls which would look a lot better.

The engine block is bonded which is connected the transmission and ultimately connected to the transom plate.

I have a zinc on each shaft, none on the trim tabs or rudders but they are bonded already.

Bob"
 
The swim platform is bonded by

The swim platform is bonded by builder (Tiara).
Stuffing box is grounded the same way all the thru hulls are... drilled hole and screwed in with wire ends (screws are ss in bronze fitting!).

I dont have a wire connection from engine to transmission but they are bolted together. The engine ground is the main source for all the ground wires (the studs are packed).

I have two large shaft zincs one "hand" in front of the cutlass bearings. I am adding transom plate and removing the rudder zincs when i replace the damaged and oxidized rudders.

I dont know if the tabs have a connection and are not "zinced" (but look pretty good). How are your tabs bonded?
 
"Bennett tabs are not easy to

"Bennett tabs are not easy to bond. Typically, use one half of a rudder zinc on the top side of the SS plate. On the swim platform SS supports, i've used a shaft zinc on the submerged upright. They last years. I'll check to see how much 1/2 SB i have left."
 
"My tabs had shown some eviden

"My tabs had shown some evidence of a previous problem and I found these zincs that mount to the ss plate where the piston mounts to the plate. As a 1 x 3" rectangle, they seem to have done a reasonable job. I also use one of the halves of a rudder zinc on top of the plate and small shaft zincs on the 3 SS brackets that hold up my teak wood swim platform.

Seems like the most abuse to the zincs are at the shafts and those trim tab rectangles. The others usually seem to last 2 seasons or more. I change them routinely anyway"
 
"I missed saying that the plat

"I missed saying that the platform mounts are bonded from inside the transom. I understand that as long as all the metals exposed to the sea water are bonded together, then you could just rely in the large enough transom zinc. The exception would be the drive shafts because they are only bonded by the transmission and that was gears and ATF invloved. Thats way you want the shaft zincs on them. also the voltage spikes from electrical system grounded to engine would hit them."
 
"Bob:

No platform here so c

"Bob:

No platform here so can't say on that item.

I'd be inclined to clean up your 'hose clamp' cluster just like you are thinking.

I use the whole rudder zinc on the tabs...been like that since day 1 and never had a need to change it...don't use much of the tabs.

My stuffing boxes are NOT in the bond system; again factory issue. Hull is '86 and not problems to date.

Rudders have zincs and are in the bonded loop.

Shafts are in the bonded loop, via the coupler-gear-engine block, and have zincs (camp X type). They came doubled from factory but a single one has sufficed for as long as I remember.

Some have dedicated grounding brushes for the shafts. I wouldn't think they are needed unless you have a "drivesaver" or something similar.

I change all the zincs, underwater, annually."
 
"Couple quick questions:

I

"Couple quick questions:

I will be installing transom zinc with SB studs next weekend. I will use 1/2 inch and the divers dream plate.

1. Does the placement on transom matter too much. I'm in salt water now and most likely will stay, but in fresh water I would think deeper in water is closer to the metals.

2. Bolts and washers are going to be set up as following... starting from inside the transom two nuts, one to attach ground/bonding wires and other next to the large washer to secure the stud on transom. Will sealed hole with 3M 101 or 5200. I will not have anything between outside transom and the zinc plate (or should I put a washer between?)
After the zinc I will use a washer and two nuts to lock to each other to avoid losing it as zinc melts.

Does that sound right?"
 
"On the diver's dream. Zi

"On the diver's dream. Zinc "melt" won't cause looseness, since the threaded rod/nuts don't touch zinc. There is some other stable, flat metallic surface in there. So, you do want a single nut over a flat washer on the outside, followed by the DD, and then the final nut. So, it looks like a total of eight 1/2" SB hex nuts and four flat washers. There will be no zinc touching either the hull or the rods."
 
Project completed. I have extra 1/2 inch 20 silicon bronze for sale at no net loss. I can send some pics for those that might want to do same upgrade.

Thanks for the help folks (DD).
 
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