Brass Shaft Brush Connected to Metal Hull Does this Really Work?

We received a good query from reader Gerry this week that is worth sharing a bit of discussion on. The photo he sent in is on his aluminum hulled sailboat. What you see in the photo is a flat brass bar that someone applied some solder to (the grey stuff at the end and rubbing against the prop shaft). The other end of the brass bar is simply screwed to the aluminum cross piece you see running under the shaft. The brass bar gets bent up and is rubbing against the propeller shaft. You can see where it has been rubbing against the shaft as it spins.

So, what is this all about anyhow? The concept here centers around bonding of the shaft to the hull for the purpose of mitigating corrosion. The idea is that propeller shafts really don't make a very good electrical connection to the rest of a boat's bonding / cathodic protection system since the propeller shaft is connected directly to the transmission (reverse gear) at the back of the engine. Electrical continuity through the transmission is always a bit dicey, especially when underway. So, how do these shaft brushes do in this situation? Usually not too well frankly. Most of us that deal with matters of marine corrosion don't actually recommend them. The failure rate for these brushes, and especially something as jury rigged as the one in the photo above is just too high. I've checked many of these over the years for electrical continuity and found an open circuit between the shaft and the brush.

So, what's the answer here? Simply provide adequate shaft anodes to protect the shaft and propeller for a reasonable amount of service time and treat any other underwater metal you wish to protect separately with additional anodes as needed. Most of these shaft brushes are just going for a ride on the boat they're installed on and really not contributing much to help in the corrosion protection area.

Typical Use of European RCD Devices on US Boat

Blue Sea ELCI Set Up, Easily Retrofitted

North Shore Safety Unit Available through Marinco, 30 and 50 AMP Service

Our recent entry discussing ELCI devices got a new query on the topic from Jim. Here it is:

"Ed,
I'm trying to make sense out of the ELCI/RCD stuff. Very difficult. n the marine marketplace, what's actually available? Blue Sea Systems seems to have units available now. The Hubbell/North Shore/Airpax-Sensata/Techsol solution does not seem ready to go yet. Blue Seas is physically large. Hubbell/NS/Sensata is better. Legarnd and the EU solutions appear to be a current transformer and breaker in a single unit. Based on your experience and your industry knowledge, can you provide a list of manufacturer's and products that are actually available and meet ABYC, E-11, 2012 for retrofits - *not* new construction - retrofits to existing boats, as of 1Q2013?"

The bottom line here is that the newest version of ABYC E-11 standard that addresses this whole ELCI device issue is very open at this point to allow a variety of products that are indeed available to be used. To quote E-11 directly it now states:

An Equipment Leakage Circuit Interrupter (ELCI) or Type A Residual Current Device (RCD) shall be installed with or in addition to the main shore power disconnect circuit breaker(s) or at the additional overcurrent protection as required by E-11.10.2.8.3 whichever is closer to the shore power connection.

EXCEPTION: Installations where an isolation transformer is installed within 10 feet (3 meters) of the shore power inlet or the electrical attachment point of a permanently installed shore power cord and supported according to 11.14.6.3

"11.11.1.1 The trip level shall be a maximum of 30mA. The trip time shall be a maximum of 100ms.

11.11.1.2 This device shall meet the requirements of UL 1053 Standard for Safety for Ground-Fault Sensing and Relaying Equipment and the requirements of UL 943 Ground Fault Circuit Interrupters with the exception of trip level and trip time, or

11.11.1.3 IEC 61008 Residual current operated circuit-breakers without integral overcurrent protection for household and similar uses or IEC 61009 Amendment 1 - Residual current operated circuit-breakers with integral overcurrent protection for household and similar uses and IEC 61543 Residual current-operated protective devices (RCDs) for household and similar use - Electromagnetic compatibility

NOTE:

1. Trip levels of less than 30ma and times of less than 100ms may result in nuisance trips in certain environments.

2. If included, the circuit breaker must also meet the requirements of E-11.10.2 Overcurrent Protection.

3. IEC compliant RCD’s must be rated for 125, 250 V 60Hz applications

11.11.1.4 The ELCI or RCD shall be readily accessible."

All of the above parameters allow fairly broad latitude at this point. To my mind the only glaring issue is with 100 amp shore power systems, but I do firmly believe at that point the boat is large enough so that not installing an isolation transformer in the shore power is absolute foolishness. The exception above eliminates the ELCI requirement if said transformer is installed.

So, we are now narrowed down to 30 and 50 amp service considerations. Between Blue Sea and Marinco (Northshore) I think we are covered at both the 30 and 50 amp levels. As for the European gear, I believe a call to Ward's Marine Electric in Ft. Lauderdale will get you what you need.  www.wardsmarine.com

Susan wrote in over this past weekend with some questions about this little beauty that she's building currently:

Basically Susan wants this to be an all electric boat, totally traditional look with better than space shuttle technology utilized. Its going to be a cold-molded design and is actually a bit heavy for its size @4660 lbs. Just under 20 ft. LOD plus the bowsprit. Just over 9" beam. The intended use parameters are critical for a concept like this. So, all near shore, basically to get the boat in and out of the harbor and to act as an auxiliary if the wind dies altogether but never intending to be more than about 5 miles away.

OK, will first of all I would advise that those parameters are subject to change as time marches on, so building in a bit of reserve capacity is prudent in my view.

Our friends at Mastervolt do a good job of helping out here. For a boat like this, The DriveMaster 5.0 kW matched up 14 kWh of battery capacity will meet Susan's required electrical needs for 3-4 hours of sailing (Mastervolt recommendation). She can always add capacity by installing an additional battery if needed.

Another option that I personally think is a bit undesirable for this boat is the Sailmaster set-up, which basically is an electric motor with a saildrive. Trouble is, this will create the need for a motor box in the cockpit. This might not be a problem depending upon exact measurements and personal taste.

Susan came at us with an array of questions which are all good examples of things people need to ask as they contemplate an e-power set-up for a boat.

The list looks like this:

• AGM or lithium ION batteries? It depends on the specific AGM and LION. Calculate predicted cycle life and cost per cycle to see what might work.
• Ability to fast charge the batteries. Both AGM and LION have outrageous charge acceptance rates, so much thought need to be applied here to come up with a high output charging system that can meet the use / need environment i.e. charge time plugged in or on the mooring.
• The above plays heavily into decisions that will need to be made about wind generators, solar panels, perhaps running a portable generator to charge the batteries. To do this right, you really need to honestly look at "a day in the life" for the boat before you just start throwing thousands of dollars at it.

One final question Susan asked that few think to ask is an important one, plays into the day in the life issue. Do batteries need to be charged to full capacity each time they are discharged? Is it better to top them off if they are not depleted?

To answer that I'll refer back to a very comprehensive article I wrote for Practical Sailor Magazine a few years back looking at LION batteries. One of the things I learned in my research for that piece was that a LION that is continually left at 100% stat or charge will actually loose cycle life quicker than on left a 80% state of charge for extended periods. So, the answer to that one I think is that if your are using the boat everyday, leaving it at full charge overnight is no big deal. For longer periods like a week away, the 80% value is a better bet.

Susan, sorry it took me a few days on this one, been a busy month!  Ed

I've been getting a lot of queries lately about nuisance tripping of the new ELCI devices and whether or not some of the European systems that we see on a lot of the Beneteau and Jeanneau boats are OK and comply with US Standards and so forth. Well, we talked about the ELCI thing in my January 3 rd post (scroll down the home page for that). Today, let's compare and contrast the European units used and the common US units. Below you see one of the commonly used 30 amp Blue Sea Systems ELCI units installed in a new shore power system.

OK, but the problem we have is that some folks have complained that getting the 50 AMP service units is still tough and that on some installations nuisance tripping is still occurring. This is especially likely if the boat is equipped with an inverter. Seems the ELCI will trip when the switching goes from shore power to invert mode. We've had some go off when keying the VHF mic to transmit. The designers are supposedly working on this, but my boat builder friends are not necessarily seeing good results.

So, the question becomes, can we get European product that will work? I'll go back full circle on all of this to the fact that Our French friends and other have been using shore power RCD (residual current device) 30 mA devices for 15 or 20 years and I have not heard of these nuisance trip problems. So now the question is, will these devices work on a US built boat with US wiring? Will that boat be compliant with ABYC standards? The answer: Yes, ut it depends on the specifications for the RCD device. The ABYC E-11 standard (2013 version) allows for it as long as the voltage and frequency specs for the device match up properly. Basically that means 12 Volts and 60 Hz. The photo below (sorry, not such a good photo) proves the units are available and used.

Both of the units above are dual rated. You need to check with companies like, Eaton and Schneider Electric to find product. The units above are labeled "legrand". It is a French boat, I can't remember whose.  Although I'm not familiar with the particular brand in this case, they are indeed labeled as meeting the specifications needed.

Last week's dirty battery post raised a good comment from reader Mike. Basically he was questioning whether the blue case visible at the top of the photo was a battery charger and if so, he was commenting that it is not a good thing. Good eye Mike! You are right, at least based on ABYC Standard A-31 which is pretty clear about mounting battery chargers and other equipment directly over a battery. To quote directly from the standard:

"To avoid corrosive fumes, battery chargers, inverters and inverter/charger shall not be installed directly over batteries." So besides the photo from last week's post, here is yet another from my collection:

So, in the above installation, we not only have the battery charger (grey and orange) installed directly over the battery, we have a battery isolator (blue fins) and on the left, a high amp main fuse for the boat's electrical system. So what's up you ask?

The truth is the ABYC standard could probably use a little tweaking in the way its worded to better deal with today's realities in this area.

Historically this was a major no no. But, I contend that it is much less of a concern in today's world. Why you ask? Its simple, modern batteries are far less prone to "gassing" than their older cousins. There is a long list of technical reasons for this which I'll probably discuss in a different post, but suffice to say that gassing is really not such a big deal anymore. In the old days, battery gassing while re-charging was more the norm than the exception and this corrosive gas had a way of migrating upward into the innards of any nearby battery charger. The corrosive gasses would gradually destroy the charger from the inside out, often with a default failure mode in the full over-charge mode. This would further contribute to even more gassing as the battery was then being subjected to a severe over-charge situation. All bad stuff.

Well, the good news today is that not only are the batteries themselves less prone to gassing, most are also sealed except for an over pressure relief valve which is often vented outside of the boat and away from the battery compartment altogether. Combine that fact with the fact that many of the chargers available today are actually "potted" and essentially sealed hermetically and we have a situation where the problems of old are virtually gone.

So, from where I sit, I look at this sort of thing on a case by case basis. It depends on the batteries being employed and the type of battery charger in use. Thanks for noticing Mike, it gave me a chance to discuss this matter.

So, Mike responded to my thoughts here right away. His view is quoted right here:

"I do not think the standard needs tweaking in the above case the builder needs to re think its design. While a clean and neat installation, I see lead acid/wet batteries here which do have vents. I see no protective covers on the battery terminals on the isolator or batteries. The strap over the top of the batteries works as a hold-down but is the material able to with stand electrolyte attack?? How about thinking of the 12" dielectric shielding.
All being said careful planning/design are important here most potential boat buyers have no clue and rely on the builder to properly install systems."

Well Mike, I agree that several things in the photo above fit right into your response. But, what is not totally clear when looking at the photo is that the battery and the components shown are actually inside an enclosed dedicated compartment. None of the components are installed directly over the battery either. So, the exposed battery terminals are not too worrisome. But your point about not knowing what a boat owner will replace sealed batteries with in the future is valid. So, perhaps the whole thing could be remedied with a warning label that simply states that a compartment is designed for use with sealed batteries only? Or perhaps, compartment and surrounding are not intended for use with unsealed battery technology....or something to that affect. As for the 12" dielectric shielding,  that applies to metallic fuel lines in ABYC Standard E-10.