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Old 01-01-2016, 07:22 PM   #41
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CeeBee, thanks for the thread, I have 2015 Jenneau Velasco 43, I imagine all the fittings are the same, I checked everything after reading the thread, and see no evidence of anything like this, we love the boat and although everything is not up to mega yacht perfection, for the money, room and s
peed it is hard to beat. Will keep an eye on this, but I agree with many of the posters it would appear to be something local to the slip, and not a boat issue.
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Old 01-01-2016, 08:45 PM   #42
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Originally Posted by fletch View Post
CeeBee, thanks for the thread, I have 2015 Jenneau Velasco 43, I imagine all the fittings are the same, I checked everything after reading the thread, and see no evidence of anything like this, we love the boat and although everything is not up to mega yacht perfection, for the money, room and s
peed it is hard to beat. Will keep an eye on this, but I agree with many of the posters it would appear to be something local to the slip, and not a boat issue.
Although I've never seen a Velasco, the 37 and the 43 definitely fill that same area of the market Swift Trawlers do. Also, the Jeanneau NC's fit the market well, just don't have the flybridge.
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Old 01-01-2016, 09:25 PM   #43
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This has been an interesting thread. Several posters identified stray current corrosion as a possible cause (probable in my view). I didn't see any discussion of causes and remedies. There are two:


One is internal. The most typical is a bilge pump wired backwards or a bare terminal lying in bilge water. That will supply DC voltage to the underwater metals and eat them away quickly whether they are really bronze or just crappy brass. Note the picture of the folding prop above.


The other is external. An adjacent boat has a similar DC to ground problem and that DC voltage comes over to your boat on the shore power ground. It will do the same thing to your boat. A good galvanic isolator will stop most ground leakage. An isolation transformer is even better. Or just keep your shore power unplugged.


David

So I'm thinking of wiring a sump pump in my bilge for my AC to drain into. Do I need to do something special with the wiring so I don't cause a DC voltage "leak"?

There are some terminals available high in the bilge that supply the bilge pump that I was thinking of tying into. Will that be OK?
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Old 01-01-2016, 09:43 PM   #44
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If you are using a packaged sump, pump and float switch for the A/C drain, wire the pos DC to the switch and the negative to the motor. I suspect that the wire to it will be color coded red and black, so just follow that. Crimp the connections with heat shrink connectors and by all means keep them up high out of any bilge water.


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Old 01-02-2016, 09:25 AM   #45
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Wiring a bilge pump "backward" i.e. reverse polarity, will not necessarily cause stray current corrosion per se (interestingly, the pump, if of the submersible variety, will often still work if running in reverse, just not very efficiently).

Wiring a bilge pump so the negative lead is wired to the float switch, on the other hand, can allow current leakage, as carbon trails within the pump motor create a path to the motor's shaft and into bilge water. This practice gained some popularity in an effort to mitigate the possibility of stray current corrosion, in the belief that the float switch and its wiring were more likely to be a source of current leakage. While that may be true, the scenario sets up the pump to become an almost certain source of leakage, making this wiring approach the greater of two evils. If positive power is supplied to the pump at all times, with the negative lead switched, it does so even when the pump isn't running, offering up this leakage path 24-7, vs. only when the pump runs, which is why the positive lead must be wired to the float switch.

Bilge pump, and more specifically float switch, wiring is among the most common source of stray current. Every effort should be made to ensure connections remain above normal bilge water levels. My recommendation is to make connections 18" above the base of the pump (good quality pumps and switches are made with leads much longer than this). If this isn't possible, ensure butt splices are waterproof/submersible by using heat shrink butt splices (take note, it is very easy to pierce these with overly aggressive crimping dies, the pierce expands when the terminal is heated, so inspect yours carefully after heating, pierces can be "fixed" with silicone sealant) or by adding resin style heat shrink tubing over a conventional butt splice. Avoid having two wires travel into one end of a heat shrink connection as it's difficult to make a good watertight seal when doing so, if you must, knead the heat shrink around these wires while it's still warm to work the resin into the gap, or again, seal with silicone. Corrosion aside, bilge pump connections should be robust and watertight so that pumps will continue to work in the event of a flooding scenario, if the pump quits as soon as the connections are submerged, it does little good in an emergency such as this.
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Old 01-02-2016, 09:30 AM   #46
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Electrolysis check for Swift Trawler Owners

Ok. Thanks David and Steve. I figured I could screw this up somehow. I would have not thought through the possible electrolysis effects of wiring the positive to the motor.

I really need a boat electronics class.
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Old 01-02-2016, 09:54 AM   #47
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Electrolysis check for Swift Trawler Owners

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Good grief. Confused again. Instructions in the package are vague.

Opened up the package and found three wires. Black, solid brown and brown/white. The brown/white is the switch wire and solid brown is the positive pump wire, from what I can tell?
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Old 01-02-2016, 09:58 AM   #48
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Steve should write a book, clean, concise easy to understand and spot on.

Thanks for your contributions!
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Old 01-02-2016, 10:01 AM   #49
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While it is true ESD is essentially a fresh water issue, it must still be taken seriously (especially for marine industry professionals) even in typically saltwater regions. In certain parts of the country, where boats are kept in estuaries such as the the Seattle Area, portions of SF Bay, Chesapeake Bay, and in any harbors or bays into which rivers flow, the salinity can change dramatically seasonally and after heavy rainfall, and even with tidal fluctuations. Where I live on the Chesapeake Bay, into which several large rivers flow, this is very noticeable.

Additionally, any electrical fault aboard a vessel that can cause ESD, can potentially cause an onboard electrocution or electrical fire.

I've seen stray current corrosion consume AQ22 (the most corrosion resistant shaft alloy) shafts, stainless steel swim platform supports, silicon bronze through hulls and struts and manganese bronze (this is actually brass since it contains zinc) propellers with astonishing rapidity. I know of no metal that is immune to this phenomenon.

While shore power connections, specifically the AC safety ground, or inadvertent onboard neutral to ground connections, can complete a galvanic cell and lead to galvanic or even stray current corrosion, except in very rare cases, those with very high current density and with aluminum hulls or outdrives, Shore/AC power is not a common corrosion source; which is why the "hot marina" theory holds little water. Boats can be "hot" leaking stray DC current into the water, but that rarely lasts for long as they typically consume their own underwater metals pretty quickly, however, and again with rare exceptions, a marina's own AC power typically isn't the cause of the problem.

Galvanic isolators, a corrosion prevention tool, and a veritable requirement for any vessel with shore power, blocks only DC voltage for this very reason, it's the source of the most common type of corrosion, galvanic, while permitting AC voltage to flow in the event of a fault. Galvanic isolators typically cannot block stray current corrosion caused by a nearby vessel that shares the same shore power source, as they are limited to blocking about 1.4 volts. Galvanic corrosion is slow and is typically less than a volt, while stray current corrosion is battery derived and therefore is much greater, up to 24 volts.
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Old 01-02-2016, 10:12 AM   #50
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Dude, black wire connects to ground.
Brown wire connects to the Manual side of the three way switch.
Brown /White wire connects to the Automatic side of the three way switch.
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Old 01-02-2016, 10:30 AM   #51
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Electrolysis check for Swift Trawler Owners

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Dude, black wire connects to ground.
Brown wire connects to the Manual side of the three way switch.
Brown /White wire connects to the Automatic side of the three way switch.

Light bulb! I savvy now. Forgot about the bilge pump switch with the manual activation side. I think I killed one too many brain cells New Years Eve. 😢

So If wire this into my existing bilge pump switch, if/when I hit the manual switch for the bilge pump then this little sump will also get energized. What if there's no water in this sump tank? Will that ruin this little pump. It's a very cheap sump pump.
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Old 01-02-2016, 11:25 AM   #52
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Originally Posted by Steve DAntonio View Post
While it is true ESD is essentially a fresh water issue, it must still be taken seriously (especially for marine industry professionals) even in typically saltwater regions. In certain parts of the country, where boats are kept in estuaries such as the the Seattle Area, portions of SF Bay, Chesapeake Bay, and in any harbors or bays into which rivers flow, the salinity can change dramatically seasonally and after heavy rainfall, and even with tidal fluctuations. Where I live on the Chesapeake Bay, into which several large rivers flow, this is very noticeable.

Additionally, any electrical fault aboard a vessel that can cause ESD, can potentially cause an onboard electrocution or electrical fire.

I've seen stray current corrosion consume AQ22 (the most corrosion resistant shaft alloy) shafts, stainless steel swim platform supports, silicon bronze through hulls and struts and manganese bronze (this is actually brass since it contains zinc) propellers with astonishing rapidity. I know of no metal that is immune to this phenomenon.

While shore power connections, specifically the AC safety ground, or inadvertent onboard neutral to ground connections, can complete a galvanic cell and lead to galvanic or even stray current corrosion, except in very rare cases, those with very high current density and with aluminum hulls or outdrives, Shore/AC power is not a common corrosion source; which is why the "hot marina" theory holds little water. Boats can be "hot" leaking stray DC current into the water, but that rarely lasts for long as they typically consume their own underwater metals pretty quickly, however, and again with rare exceptions, a marina's own AC power typically isn't the cause of the problem.

Galvanic isolators, a corrosion prevention tool, and a veritable requirement for any vessel with shore power, blocks only DC voltage for this very reason, it's the source of the most common type of corrosion, galvanic, while permitting AC voltage to flow in the event of a fault. Galvanic isolators typically cannot block stray current corrosion caused by a nearby vessel that shares the same shore power source, as they are limited to blocking about 1.4 volts. Galvanic corrosion is slow and is typically less than a volt, while stray current corrosion is battery derived and therefore is much greater, up to 24 volts.
Great that you're posting here, Steve. Saw you present at Trawlerfest in Baltimore a couple years ago and learned a lot. Thanks for sharing your considerable expertise.
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Old 01-02-2016, 11:34 AM   #53
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Howdy all! - I'm simply posting to stay up on this thread. Planning to haul our Tolly and do as needed; hopefully can find time in not too distant future.

Carry on... Great info here!
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Old 01-02-2016, 01:27 PM   #54
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Dude, Yes both pumps would run if you switch it to manual. You can probably get away with it. These type of pumps can run dry for a surprisingly long time. Fuse size might be an issue.

I would install a separate switch for the sump. It's not hard or expensive.

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Old 01-02-2016, 01:42 PM   #55
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Shore/AC power is not a common corrosion source; which is why the "hot marina" theory holds little water.
So very true.

Literally every one of the many dozens of marinas I have worked in over the years has been described to me as "hot" by someone or other. My response invariably is that rapid anode depletion or corrosion issues are almost always due to a problem aboard the boat in question. The "hot marina" is simply the excuse boat owners use to deflect responsibility.

Example- the pic I posted of the badly corroded folding prop earlier in the thread? The owner refused to take my advice and have an electrician track down the problem. He was convinced it was the powerboat in the neighboring slip that was the cause. It wasn't until his bilge pump failed and he had one of his maintenance guys replace it that the broken 12-volt wire was discovered. And again, it ultimately cost him the prop.
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Old 01-02-2016, 02:41 PM   #56
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So very true.

Literally every one of the many dozens of marinas I have worked in over the years has been described to me as "hot" by someone or other. My response invariably is that rapid anode depletion or corrosion issues are almost always due to a problem aboard the boat in question. The "hot marina" is simply the excuse boat owners use to deflect responsibility.

Example- the pic I posted of the badly corroded folding prop earlier in the thread? The owner refused to take my advice and have an electrician track down the problem. He was convinced it was the powerboat in the neighboring slip that was the cause. It wasn't until his bilge pump failed and he had one of his maintenance guys replace it that the broken 12-volt wire was discovered. And again, it ultimately cost him the prop.
This is also why I'm so in favor of GCFI at marinas. All the boat owners whining when they can't connect. They are being warned and if they respond they may be avoiding major problems with their own boat. I have known people to have problems from the neighboring boat (remember in FL we have all the double slips), but most often it's themselves. Essentially it serves as a test on the boats. Then owners are forced to find their problems.
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Old 01-02-2016, 03:36 PM   #57
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Question:


If a boat is not hooked up to shore power at all and it is tied by lines-only in mid slip... can stray electric current from other boats or the dock or nearby land harm that boat's submerged metal items?


Please have the answer include what if in salt water or if in fresh water.


Thanks!
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Old 01-02-2016, 04:02 PM   #58
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Originally Posted by Art View Post
Question:


If a boat is not hooked up to shore power at all and it is tied by lines-only in mid slip... can stray electric current from other boats or the dock or nearby land harm that boat's submerged metal items?


Please have the answer include what if in salt water or if in fresh water.


Thanks!
No. It is the common ground connection between the various boats at the marina that causes problems.

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Old 01-02-2016, 08:51 PM   #59
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No. It is the common ground connection between the various boats at the marina that causes problems.

Ken
Thank you, Ken!

Therefore (and, please correct me per chance I’m incorrect)... if the boat is fully isolated from the dock (as I mentioned in post #57 ) i.e. it touches the water only, and then, as well, all batteries on boat have been fully isolated via tall amp switch (Perko or otherwise) turned off .... then the boat's metal parts will experience no galvanization, current corrosion/electrolysis or other metal destructive electric current effects.

That is how I keep our Tolly when berthed. She has had no metal problems. I learned to do this from boating in NY / LI salt waters during mid 1900’s. I also keep plenty of anodes in the proper locations.

Happy Marine-Metal-Saving Daze - Art
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Old 01-02-2016, 10:57 PM   #60
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On the boat in question, all those sea cocks were un-bonded, so electrically isolated from everything in the boat. Given that, it's hard to blame the degradation on stray current since there was nowhere for current to flow to or from the sea cocks. It seems more likely that it's just really crappy metal and finally met it's maker. Or am I not understanding this, which is entirely possible......
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