We sail a C-22 in fresh water, and keep it in a slip. The boat did not have any zinc on the swing keel when we bought her. Do you think that zincs are needed? I know that in salt water they are a must, but what about fresh? Thanks Dale
Do you need zincs in fresh water
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Conductance of fresh water
I am also a fresh water sailor, but I agree that zincs are a good idea. They will last much longer than in salt water, however. Here is an interesting note on conductivity in fresh water, salt water and copper. VERY PURE water is a poor conductor of electricity. However, very small amounts of impurities, especially salts, greatly increase the electrical conductivity of water. The main carriers of electrical current are dissolved ions. Different ions can help carry the electric current, some more / some less, depending upon their electrical charge and their size. More highly charged, smaller ions are more efficient carriers of the electrical current. The higher the concentration of ions, the greater is the conductance of the solution. None of the ion electrical current carriers of salts dissolved in water are as mobile as "free" electrons in a metal are. And the differences are very large. For example, if the conductivity of VERY PURE WATER is 0.000004 conductivity units, the conductivity of a saturated solution of common table salt NaCl is 23 conductivity units, and the conductivity of a typical metal such as copper wire is 60, 000, 000 conductivity units. So while the ions in a dissolved salt behave something like "free" electrons, they are very slow and sluggish moving.
I am also a fresh water sailor, but I agree that zincs are a good idea. They will last much longer than in salt water, however. Here is an interesting note on conductivity in fresh water, salt water and copper. VERY PURE water is a poor conductor of electricity. However, very small amounts of impurities, especially salts, greatly increase the electrical conductivity of water. The main carriers of electrical current are dissolved ions. Different ions can help carry the electric current, some more / some less, depending upon their electrical charge and their size. More highly charged, smaller ions are more efficient carriers of the electrical current. The higher the concentration of ions, the greater is the conductance of the solution. None of the ion electrical current carriers of salts dissolved in water are as mobile as "free" electrons in a metal are. And the differences are very large. For example, if the conductivity of VERY PURE WATER is 0.000004 conductivity units, the conductivity of a saturated solution of common table salt NaCl is 23 conductivity units, and the conductivity of a typical metal such as copper wire is 60, 000, 000 conductivity units. So while the ions in a dissolved salt behave something like "free" electrons, they are very slow and sluggish moving.
Assuming shore power?
If your marina does not provide shore power, there may be no stray current to worry about. We have our boat in fresh water where there is no shore power. No zincs, no problem.
If your marina does not provide shore power, there may be no stray current to worry about. We have our boat in fresh water where there is no shore power. No zincs, no problem.
Zinc is needed in fresh water.
Mostly for internal electrical flaws. Fresh water is not nearly the killer that salt water is. However, the only metalic contact I have on my 25 O'Day is the lower unit of the outboard motor. It consumes a zinc anode to the point of major pits every year. Part of the problem is all battery functions are connected to the negative terminal which is connected directly to the battery and the outboard. I also have an onboard charger. When plugged in and charging it is connected to the negative terminal and thus the outboard. One thing I am going to do is to install a seperate switch for the outboard electrics, so that they are not online when charging. If you have and electric start outboard and there are white metalic zits on the lower unit, or if you are grounded to your metalic keel of rudder, and you have small white zits, electrolisis is occuring. You need 1 or more zincs in volnerable places. I think it is manganese that is more sensitive than zinc that is recommended for fresh water. Good luck finding it. The aluminum on your lower unit will act as the zinc if you do not have one/or more. r.w.landau
Mostly for internal electrical flaws. Fresh water is not nearly the killer that salt water is. However, the only metalic contact I have on my 25 O'Day is the lower unit of the outboard motor. It consumes a zinc anode to the point of major pits every year. Part of the problem is all battery functions are connected to the negative terminal which is connected directly to the battery and the outboard. I also have an onboard charger. When plugged in and charging it is connected to the negative terminal and thus the outboard. One thing I am going to do is to install a seperate switch for the outboard electrics, so that they are not online when charging. If you have and electric start outboard and there are white metalic zits on the lower unit, or if you are grounded to your metalic keel of rudder, and you have small white zits, electrolisis is occuring. You need 1 or more zincs in volnerable places. I think it is manganese that is more sensitive than zinc that is recommended for fresh water. Good luck finding it. The aluminum on your lower unit will act as the zinc if you do not have one/or more. r.w.landau
Ross
Aluminum is preferable to zinc in fresh water since it acts as a more effecitve anode. A zinc anodes work by generating a small galvanic current which makes the boat's underwater stuff cathodic compared with the zinc. In fresh water, to obtain the equivalent effect, aluminum is more effective. If you are asking why, check out any chemistry book.
Aluminum is preferable to zinc in fresh water since it acts as a more effecitve anode. A zinc anodes work by generating a small galvanic current which makes the boat's underwater stuff cathodic compared with the zinc. In fresh water, to obtain the equivalent effect, aluminum is more effective. If you are asking why, check out any chemistry book.
Don the galvanic series of metals
Link attached. Now try again to explain how aluminum is more effective than zinc. Active (Anodic) Magnesium Mg alloy AZ-31B Mg alloy HK-31A Zinc (hot-dip, die cast, or plated) Beryllium (hot pressed) Al 7072 clad on 7075 Al 2014-T3 Al 1160-H14 Al 7079-T6 Cadmium (plated) Uranium Al 218 (die cast) Al 5052-0 Al 5052-H12 Al 5456-0, H353 Al 5052-H32 Al 1100-0 Al 3003-H25 Al 6061-T6 Al A360 (die cast) Al 7075-T6 Al 6061-0 Indium Al 2014-0 Al 2024-T4 Al 5052-H16 Tin (plated) Stainless steel 430 (active) Lead Steel 1010 Iron (cast) Stainless steel 410 (active) Copper (plated, cast, or wrought) Nickel (plated) Chromium (Plated) Tantalum AM350 (active) Stainless steel 310 (active) Stainless steel 301 (active) Stainless steel 304 (active) Stainless steel 430 (active) Stainless steel 410 (active) Stainless steel 17-7PH (active) Tungsten Niobium (columbium) 1% Zr Brass, Yellow, 268 Uranium 8% Mo Brass, Naval, 464 Yellow Brass Muntz Metal 280 Brass (plated) Nickel-silver (18% Ni) Stainless steel 316L (active) Bronze 220 Copper 110 Red Brass Stainless steel 347 (active) Molybdenum, Commercial pure Copper-nickel 715 Admiralty brass Stainless steel 202 (active) Bronze, Phosphor 534 (B-1) Monel 400 Stainless steel 201 (active) Carpenter 20 (active) Stainless steel 321 (active) Stainless steel 316 (active) Stainless steel 309 (active) Stainless steel 17-7PH (passive) Silicone Bronze 655 Stainless steel 304 (passive) Stainless steel 301 (passive) Stainless steel 321 (passive) Stainless steel 201 (passive) Stainless steel 286 (passive) Stainless steel 316L (passive) AM355 (active) Stainless steel 202 (passive) Carpenter 20 (passive) AM355 (passive) A286 (passive) Titanium 5A1, 2.5 Sn Titanium 13V, 11Cr, 3Al (annealed) Titanium 6Al, 4V (solution treated and aged) Titanium 6Al, 4V (anneal) Titanium 8Mn Titanium 13V, 11Cr 3Al (solution heat treated and aged) Titanium 75A AM350 (passive) Silver Gold Graphite http://www.corrosion-doctors.org/Definitions/galvanic-series.htm
Link attached. Now try again to explain how aluminum is more effective than zinc. Active (Anodic) Magnesium Mg alloy AZ-31B Mg alloy HK-31A Zinc (hot-dip, die cast, or plated) Beryllium (hot pressed) Al 7072 clad on 7075 Al 2014-T3 Al 1160-H14 Al 7079-T6 Cadmium (plated) Uranium Al 218 (die cast) Al 5052-0 Al 5052-H12 Al 5456-0, H353 Al 5052-H32 Al 1100-0 Al 3003-H25 Al 6061-T6 Al A360 (die cast) Al 7075-T6 Al 6061-0 Indium Al 2014-0 Al 2024-T4 Al 5052-H16 Tin (plated) Stainless steel 430 (active) Lead Steel 1010 Iron (cast) Stainless steel 410 (active) Copper (plated, cast, or wrought) Nickel (plated) Chromium (Plated) Tantalum AM350 (active) Stainless steel 310 (active) Stainless steel 301 (active) Stainless steel 304 (active) Stainless steel 430 (active) Stainless steel 410 (active) Stainless steel 17-7PH (active) Tungsten Niobium (columbium) 1% Zr Brass, Yellow, 268 Uranium 8% Mo Brass, Naval, 464 Yellow Brass Muntz Metal 280 Brass (plated) Nickel-silver (18% Ni) Stainless steel 316L (active) Bronze 220 Copper 110 Red Brass Stainless steel 347 (active) Molybdenum, Commercial pure Copper-nickel 715 Admiralty brass Stainless steel 202 (active) Bronze, Phosphor 534 (B-1) Monel 400 Stainless steel 201 (active) Carpenter 20 (active) Stainless steel 321 (active) Stainless steel 316 (active) Stainless steel 309 (active) Stainless steel 17-7PH (passive) Silicone Bronze 655 Stainless steel 304 (passive) Stainless steel 301 (passive) Stainless steel 321 (passive) Stainless steel 201 (passive) Stainless steel 286 (passive) Stainless steel 316L (passive) AM355 (active) Stainless steel 202 (passive) Carpenter 20 (passive) AM355 (passive) A286 (passive) Titanium 5A1, 2.5 Sn Titanium 13V, 11Cr, 3Al (annealed) Titanium 6Al, 4V (solution treated and aged) Titanium 6Al, 4V (anneal) Titanium 8Mn Titanium 13V, 11Cr 3Al (solution heat treated and aged) Titanium 75A AM350 (passive) Silver Gold Graphite http://www.corrosion-doctors.org/Definitions/galvanic-series.htm
galvanic table
Ross Often things are not as simple as they would appear. The chart you copied well but failed to consider the distinction when it comes to salt vs fresh water which changes the efficacy of the more cathodic metals. I wasn't being sarcastic when I suggested you check out a chemistry book which may help you understand the principles involved.
Ross Often things are not as simple as they would appear. The chart you copied well but failed to consider the distinction when it comes to salt vs fresh water which changes the efficacy of the more cathodic metals. I wasn't being sarcastic when I suggested you check out a chemistry book which may help you understand the principles involved.
Don, you are saying that the lower unit
of an outboard is better to be less noble than zinc? Don you have it wrong, Ross is right on this one. If you like giving bad advice, continue your arguement. If you wish that good advice is given acknowledge and back out. My brother lost the end of his lower unit to electrolysis. It does not matter if the marina has power. If you have a motor with a charging or an electric start system, it is endanger of electrolysis occuring and the associated metals being degraded. The chart Ross has posted showed the nobility of the metals involved. I want something less noble than the aluminum on my engine protecting the metals on my boat. Don, you use aluminum and then give us the results of your two year study. Until then I wish that serious boat owners would listen to Ross. r.w.landau
of an outboard is better to be less noble than zinc? Don you have it wrong, Ross is right on this one. If you like giving bad advice, continue your arguement. If you wish that good advice is given acknowledge and back out. My brother lost the end of his lower unit to electrolysis. It does not matter if the marina has power. If you have a motor with a charging or an electric start system, it is endanger of electrolysis occuring and the associated metals being degraded. The chart Ross has posted showed the nobility of the metals involved. I want something less noble than the aluminum on my engine protecting the metals on my boat. Don, you use aluminum and then give us the results of your two year study. Until then I wish that serious boat owners would listen to Ross. r.w.landau
Don, if we start with distilled water and immerse
A zinc electrode and an aluminum electrode into it and measure the potential between them and measure the current flow we should get zero in both cases. as soon as we deviate from the distilled water we are moving towards very dilute sea water. If you will provide reference to a text I will check my library and see what I can find. My engineering texts and the handbook of chemistry and physics do not seem to support your thesis. I shall be interested in learning the details that support your position here.
A zinc electrode and an aluminum electrode into it and measure the potential between them and measure the current flow we should get zero in both cases. as soon as we deviate from the distilled water we are moving towards very dilute sea water. If you will provide reference to a text I will check my library and see what I can find. My engineering texts and the handbook of chemistry and physics do not seem to support your thesis. I shall be interested in learning the details that support your position here.
Don't take a chance.........
....they are much cheaper than an oil change. Better to be safe than sorry. When in doubt put one on.
....they are much cheaper than an oil change. Better to be safe than sorry. When in doubt put one on.
Example
I have had my H333 in fresh water (Lake MI) for 8 years and have gone through 2 zincs. So I think they sacrifice much slower but still there is galvanic action at work. They ar cheap, easy to install, and will keep your shaft from falling out should it ever disconnect from the trans.
I have had my H333 in fresh water (Lake MI) for 8 years and have gone through 2 zincs. So I think they sacrifice much slower but still there is galvanic action at work. They ar cheap, easy to install, and will keep your shaft from falling out should it ever disconnect from the trans.
Thanks everyone
I would like to thank everyone for all the input. I will be putting them on in the spring. Thanks again. Dale
I would like to thank everyone for all the input. I will be putting them on in the spring. Thanks again. Dale
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