electrical grounds

Bill Roosa · Mar 1, 2011

Grounding or bonding

I think you mean you need to bond some things not ground them. A technical difference.
You should bond (non current carrying conductors for corrosion prevention) to the keel or your "common ground point" You should ground (current return to the battery) to the battery negative buss or engine block in some cases.
You want to avoid "ground loops" which happen when the bond wire ends up carrying current and that leaks directly into the water and rust (very quickly BTW) other metal parts in contact with the water and also bonded
If you bond to the battery negative and one of those current carrying connections corrodes and drives current into the bond circuit you will get some bad things going on under water.

rpwillia · Mar 1, 2011

Can comment on 1 part

redhead78 said:
Fiirst the coupler,the thing is plastic, do I need to jump over the coupler to flange?.

If this is the flex coupling, the one I have I paid $30.00 for the Earthing Connection that looked like a piece of bubble gum that rolled up inside and was shoved between the sections to make the electrical connection. After opening the package and seeing it, I really thought a piece of copper wire wrapped around both sides would have worked.

Was it this one? http://www.randdmarine.com/downloads/RandD_Shaft.pdf

You would want an Earthing Connection, but as I said a piece of copper wire wrapped tight around both sides would seem to work to me. Of course that leaves me thinking "What would Main Sail do?" :dance:

Witzend · Mar 3, 2011

I do not have my flex coupling jumper-ed over. I noticed that this year there was somewhat less galvanic action on my zinc than in previous years.

Maine Sail · Mar 3, 2011

rpwillia said:
You would want an Earthing Connection, but as I said a piece of copper wire wrapped tight around both sides would seem to work to me. Of course that leaves me thinking "What would Main Sail do?" :dance:

I wire to ABYC standards:

"6.5.5.2 If a non-conductive flexible coupling is used, an
alternative means of grounding the shaft must be provided."

Beyond that I do not use flexible couplings.. They are band-aids, at best, that often times make vibration issues worse, by inducing more shaft whip, and I have yet to see one "fail" and save a shaft or prop on small diesels as they claim to do. I remove more of them then I'll ever install. Just last Satuday I was commiserating with Larry K. the owner of Accutech Prop and he was ranting on and on about the misuse of flexible couplings and the fact that they are pretty much unnecessary devices on properly installed systems.. Felt good to vent...!

That being said the PYI is a slightly better piece of equipment IMHO then the red hockey puck but either of them are really unnecessary if your prop, shafting, mounts and alignment are done correctly. Folks most often install them because the previous mentioned items are not done correctly and wind up using them as a band-aid... It's kind of like adding potions and additives to a dirty fuel tank, your better to just address the real problem and the additives/hockey puck can both actually exacerbate the problem...

rpwillia · Mar 3, 2011

MS, I hear you but ...

In the Universal Manual they recommend you have one.

Maine Sail · Mar 3, 2011

rpwillia said:
In the Universal Manual they recommend you have one.

Yes they do. They actually recommend a specific brand "Drivesaver". That brand specific suggestion has always struck me as odd. Why don't they also recommend the PYI version?

I have not seen Yanmar recommend one and their mounts are even more flexible and I have lots of Yanmar manuals on my hard drive.

These devices can actually induce shaft whip and cause vibrations especially with folding or feathering props where the blades are already quite a distance from the p-strut bearing. An extra turn on one coupling bolt and the rubber gives under the added torque compared to the others and you're off a few thou in alignment. I had one on my own boat and actually removed it.

My neighbors hit a lobster pot hard enough to stall the motor from cruise RPM, bent the shaft took a ding out of the prop and fried the damper plate but the Drivesaver never budged and never blew apart as it claimed it would. It never protected against all the things it claimed to. They were in their 70's at the time and installed it to specifically avoid those issues. They were great sailors but as they aged, they actually sailed into their 80's, they hit more pots...

You can use one I am just sharing my experiences & thoughts with them. I would also say if it voids your warranty then you should install one at least during the warranty period but I doubt it does because Catalina ships out boats with no Drivesaver's and those engines are covered by a warranty. I have yet to see a Universal engine installer/boat builder like Catalina install a Drivesaver with a new engine though I am sure some do.

Universal also says to change the gear box fluid annually. Don't know to many folks who do that and those HBW's will die faster from dirty fluid than not having a Drivesaver IME. Our Hurth gear has over 3200 hours on it with no Drivesaver but has had fluid changes yearly. She is also smooth as glass without a Drivesaver.

It's a personal choice and unfortunately I have seen them exacerbate more issues than solve. Wish I could say better things about them but my experiences have been less than stellar...

Roger Long · Mar 4, 2011

Maine Sail said:
Wish I could say better things about them ..

You've said almost exactly what the top propulsion specialist who did the detail drivetrain design on three of my research vessels did.

I have one on my boat but only because the PO buggered up the bolt heads so badly it isn't coming off until I take the engine out of the boat. It doesn't seem to be causing any problems though. The boat runs quite smoothly.

Bill Roosa · Mar 4, 2011

There are five types of grounds, DC current returns (to the negative ground bus going to the batts), AC green wire chassis grounds (to the common ground point via the AC ground buss), Radio Frequency (RF) grounds ( to the common ground point via a ribbon strip) and electrolytic grounds (bonding)(to the common ground point), and lightning grounds (to the common ground point)
WM advisor has a great article on how to do them all and avoid "ground loops"
Your prop shaft should ground to the engine which should have a wire to the common ground point most which is commonly a keel bolt.

Maine Sail · Mar 4, 2011

redhead78 said:
Where should I bond thru hull and shaft tube???? Red

Red,

If you want to bond your underwater & engine metals they should all be electrically connected to remain at the same potential. It basically takes two simultaneous events to create a stray current cell.

1- You have a break somewhere in the bonding system. In the case of a shaft saver this could be it or you could just have a corroded terminal on a seacock no longer able to electrically pass current, or you have left an item not bonded, such as the engine, rudder, strut etc. etc...

2- You have a ground fault.

BUT if you had all the items in #1 electrically connected at the same potential with no breaks in the armor then even with a ground fault you can't create a stray current cell becuase all the bonded items are at the same potential electrically..

Seacocks, rudder box, rudder, strut, engine, thru-hulls/seacocks are allmost always bonded back to the engine or DC negative buss as well as the boats AC (green wire).

It is important that the green "bonding" wires are NOT used to carry DC current or used as a DC path. Unfortunately most engines do not use isolated ground alternators and starters. If you want to properly bond an engien then the block should never be use as a DC negative return conductor. Most any alternator/starter repair shop can convert an alt and starter to isolated ground meaning that it does not use the engine block to pass DC current back to the battery.

Grounding your macerator to the seacock in the head for example, seen it done, would work electrically but now you've introduced a second electrical path. All DC negative loads run to the DC buss & battery neg post. The DC buss is then jumped to the engine block with one non-current carrying system grounding wire (not a negative wire) wire from the buss to the engine block.

Keep in mind that stray DC current is far more damaging than and stray AC current....

Bill Roosa · Mar 4, 2011

running ground wires

Totally agree MS but the routes the wires take have to be pretty specific. You can't mix and match the circuits or you can actually cause a wores problem.
an example is when you run a bonding loop to both the DC ground buss at the batteries and an additional wire from the bonding loop to the common ground point. If you get an DC appliance that has a corroded ground (current carrying) connection or wire (almost 100% certian that is going to happen eventually) at the battery negative buss. The current is then forced into the bonding circuit which puts all the items on it at various low voltages (voltage potential). this is an example of a "ground loop" and is to be avoided at all costs. Basicly never connect the different ground systems together at anywhere but the common ground point. And never connect the different ground circuits to the common ground point from more than one place on the circuit.
So in Red's instance he would want to ground the prop to the engine and the engine to the common ground point. He would also want to connect all his thru-hulls ect with a bonding circuit and then run one wire from the bonding circuit to the common ground point. He would not want to run the bonding circuit to an engine ground unless that is the common ground point and there is one and only one wire going from the engine ground to the keel or no wires going to the keel at all. The keel would only have one (none)wire going to it in that case which would drive you to connecting your lightinig ground to the engine. IMHO that is not a good idea for veriety of reasons, safety being the chief of them.
The WM advisor artical explains this pretty well
http://www.westmarine.com/webapp/wc...catalogId=10001&page=Marine-Grounding-Systems

Maine Sail · Mar 4, 2011

redhead78 said:
huuuuuuh, should I bring the seacock and the shaft tube to the keel ground??? Red

Most boats are grounded through the engine not the keel. Once you get a waterproof epoxy barrier coating on one, even an exposed lead keel looses most of its ability to act as a ground and it is greatly diminished in the ability to be a good earth ground. Lightning systems & bonding systems are most often bonded to or pick up a keel bolt, and lightning will literally blow the barrier coat right off ad I have seen this. The engine is the main ground point on almost all sailboats.

Some boats even have encapsulated keels so there are no keel bolts and no option of grounding through the keel.. Nothing wrong with bonding to keel bolts but your main ground point should be the engine or an added grounding plate but not a sintered bronze plate, they can actually blow up if hit by lightning. With an SSB though you'd want on or some serious sq feet of copper or sintered bronze.

You asked about bonding and there are two camps. I am not a bonder but some are. Either method needs to be done well. There is no way I am using my keel as a ground point after it was 100% stripped and wrapped in 1708 with West epoxy and then received 7 coats of Interprotect 2000E and this is why my engine is my main ground point just as it is on most boats.

As a vendor at the New England Boat Show I was just on a number of brand new boats and got to really dig into them BEFORE the crowds showed up. I was on boats from Hunter, Catalina, Island Packet, C&C, Tartan & Sabre, Hanse & Jenneau & and about two dozen power boats. While some of their practices are rather questionable all used the engine as the main ground point. Incidentally all the manufacturers using metallic thru-hulls had also bonded their boats Hunter, Beneteau, Jenneau, Island Packet & Hanse all had bonded thru-hulls and all the bonding systems wound up back at the engines......

Bill Roosa · Mar 4, 2011

To bond or not

For the record there are two schools of thought, bond all underwater parts together to creat a situation where there is no voltage potential between them or unbond everything so there is no way current can flow between them. A third solution is to use plastic everywhere you can to remove those items from the mix.
I personally like the unbonded scheme as it gets rid of the "hot marina" issue.

electrical grounds

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