Question about hanging a zinc over the side

[Juanona]

I don't need to paint the bottom this year, but I should change the zincs on the prop shaft and on the strut. I would rather not have to haul the boat just to change the zincs. The club I wintered at here in Holland say they can lift my stern a couple feet with their crane, placing a strap just forward of the rudder skeg. Lying on their low profile raft, I could then change the zincs.

I feel pretty comfortable going this route, but if for some reason it looks dodgy, I wondered about the option of simply hanging a zinc over the side this summer, connected by 8 AWG wire to the same internal terminals. Other than when on passage the zinc would be in the water over the side.

Is there any risk in this alternative? My prop shaft zincs typically look like they are near new, though the strut teardrop ones look pretty worn by the end of a season.

I'm in fresh water this winter, soon heading to Norway/Sweden and salt water, so will be interesting to see how the minor growth on the bottom reacts.

Thanks,
Max

 

[dlochner]

For the zincs to work, they need to be attached to the thing they are protecting or at least pretty close. Hanging the zinc off the side will offer some protection, but it is better to have it on the strut and shaft.

Can you hire a diver to install them?

 

[Juanona]

Hi Dave, I've asked about divers both here and in the U.K., even asked at a 'scuba club' and no one seems to be interested or able for one reason or the other. Sometimes I think I'll just do it myself with a snorkel once the water warms up, but that's probably a pipe dream. It seems there ought to be an easier way to do a job 18" under the waterline.

 

[Gunni]

Is going for a swim to change the zincs more painful than shelling out $350 USD for a short haul? Throw in a bottom pressure wash and inspection to make the haul more valuable. Forget the zinc fish.

 

[jssailem]

Juanona
It is a 5 minute task for a diver. Need a small bag for the new zincs and a tool to screw the zincs tight. My diver uses a T driver with the proper hex drive. It is a simple task.
Holding your breath you could probably do it.

Or there is the ancient mariner route and keelhaul a young virgin to accomplish the task... opps that is wrong.

Move your boat to shallows. Anchor and let tide go out. Step out on to sand beach change the zinc. Wait till tide comes back in. All done. Be sure you have enough beer. It's going to be a 12 hour project.

 

[Bill19233]

If you really, really can't get new zincs on the shaft, and you feel you have to do something. You need to hang multiple zinc fish (3 or 4) as close to the prop shaft as possible, The lead wires from the zincs need to be connected inside the boat directly to the prop shaft and a jumper wire to the strut bolts. The circuit current path from the anodes to the intended protected metal component needs to be as low resistance as possible to get anything out of the zincs. You always hear current takes the path of least resistance. No, current takes all paths, just more where the resistance is lower. Sitting in water, metal components are in a corrosion circuit that has so many paths for the current to take, you need to make sure you have the lowest resistance path for your anode current to take to the component you want to protect. The dissimilar metals of the strut, shaft, and prop in contact with each other cause more corrosion than immersion of the single metal components in an electrolyte (water). The galvanic potential of the zinc is "greater" or more negative than the bronze or stainless and the anode will corrode instead of the other metals as long as there is a lower resistance current path. Water movement will keep the circuit from polarizing, but they protect North Sea oil rigs and moving ship hulls with anodes, not guppy anodes, but you have to work with what you got.

 

[dlochner]

Mantus (the anchor people) make a perfect SCUBA set up for us sailors. It is relatively inexpensive and only has a 20 minute capacity, but for replacing anodes and quick bottom cleanings it is perfect. However, it is necessary to get he full SCUBA certifications. Alternatively, a floating hookah system would enable a skipper to stay underwater long enough to do the same.

 

[justsomeguy]

$2,600 bucks for a compressor and regulator?

 

[Jeremy McGeary]

Max -- you hail from tidal waters. I don't know what kind of tides you have where you are now or where you are going, but you must be able to find a wall to tie up to and dry out for a tide. Used to be common practice over there. I've seen sailors from over there dry out against a wall in Newport, RI, to perform essential maintenance under the puzzled gaze of tourists. (Or is that the gaze of puzzled tourists?)

 

[justsomeguy]

(Or is that the gaze of puzzled tourists?)

Either way is fine.

 

[Michael Davis]

Gotta love tidal grids!

 

[dlochner]

$2,600 bucks for a compressor and regulator?

Didn't say it was cheap. But considering the cost of SCUBA certification and equipment, maybe it is. Then you can rent yourself out and make some money back.

 

[JamesG161]

I'm in fresh water this winter,

Fresh water only slows down the zinc loss rate. It is not a cure or piece of mind.

Sounds like a drop zinc would work for shaft, not sure about the strut electrical connection.
You might call this guy and see if he knows someone to help you. Try a local marina too!
http://diverlou.com
He is in Portland, Maine.
Jim...

 

[JamesG161]

Oppps... I thought Holland, Me.... oh well , not sure how a web search works in the country of Holland.
Jim...

 

[RBG]

A snorkel with a hose attached, tied up a bit up above the water line at 18" you should be able to breath though it forever..

 

[colemj]

Didn't say it was cheap. But considering the cost of SCUBA certification and equipment, maybe it is. Then you can rent yourself out and make some money back.

There is nothing about that setup that allows one to forgo certification, and Mantus states that directly. You will have to show certification to get the tank refilled in most places.

BTW, it costs $600, not $2,500, but that is still relatively expensive. One can easily put together a pony bottle and regulator on a backpack for $400. Less, if one shops around hard.

Mark

 

[colemj]

A snorkel with a hose attached, tied up a bit up above the water line at 18" you should be able to breath though it forever..

18" is about the maximum a person with very strong diaphragm can use. Most people will struggle with it, and anything greater will be either impossible or very dangerous. Most boats require one to be deeper than that to reach the prop shaft and strut.

Mark

 

[dlochner]

Fresh water only slows down the zinc loss rate. It is not a cure or piece of mind.

Zincs last longer in freshwater because they don't work in freshwater. A more reactive metal is necessary. In freshwater use magnesium or aluminum anodes. Aluminum works in fresh and salt water.

 

[All U Get]

Zincs last longer in freshwater because they don't work in freshwater. A more reactive metal is necessary. In freshwater use magnesium or aluminum anodes. Aluminum works in fresh and salt water.

Zincs last longer in freshwater because they don't work in freshwater. A more reactive metal is necessary. In freshwater use magnesium or aluminum anodes. Aluminum works in fresh and salt water.

Which is why you shouldn't forget about the beer you hung over the side to cool.

All U Get

 

[dirt rd]

I have used a J Zink compressor with air line for a long time. Nothing better than seeing for yourself what's going on. Doesn't hurt to have a wetsuit either.