Does an inboard engine need a path to earth?

[LifesBetterWhenYoureBeating]

My inboard engine is connected to my DC negative, but between the engine and the prop shaft I have a non metallic flexible coupling (drive saver) so my engine is not connected to any underwater metals. Does it need to? I can't seem to find a definitive answer

[Uncle Bob]

Originally Posted by LifesBetterWhenYoureBeating

My inboard engine is connected to my DC negative, but between the engine and the prop shaft I have a non metallic flexible coupling (drive saver) so my engine is not connected to any underwater metals. Does it need to? I can't seem to find a definitive answer

Mine has no path to prop/shaft, cutless and drivesaver isolate them completely. You will need adequate zinc's on the shaft to protect prop/shaft.

[Bowdrie]

Originally Posted by LifesBetterWhenYoureBeating

My inboard engine is connected to my DC negative, but between the engine and the prop shaft I have a non metallic flexible coupling (drive saver) so my engine is not connected to any underwater metals. Does it need to? I can't seem to find a definitive answer

Is this just a continuation of your other thread about bonded thru hulls and paint?

I too use a "Drivesaver", but (you may already know this,) that Drivesavers come with a metal jumper to provide electrical conductivity across them.
If one wishes to electrically isolate the shaft from the engine that jumper needs to be removed or not installed, (it's just a little stamped piece of metal).
Does the engine need, or not need conductivity to the shaft?
That question is not a yay or nay, it depends upon other criteria that have to do with DC bonding and AC protection of people both in the boat and/or swimming in the water near the boat, (look up articles on ESD, "Electro Shock Drowning").

[LifesBetterWhenYoureBeating]

Originally Posted by Bowdrie

Is this just a continuation of your other thread about bonded thru hulls and paint?

I too use a "Drivesaver", but (you may already know this,) that Drivesavers come with a metal jumper to provide electrical conductivity across them.
If one wishes to electrically isolate the shaft from the engine that jumper needs to be removed or not installed, (it's just a little stamped piece of metal).
Does the engine need, or not need conductivity to the shaft?
That question is not a yay or nay, it depends upon other criteria that have to do with DC bonding and AC protection of people both in the boat and/or swimming in the water near the boat, (look up articles on ESD, "Electro Shock Drowning").

So assuming my AC Grounding is not connected to my DC negative and I have a whole boat RCD, the engine doesn't need a path to earth (via the shaft or some other way), then?

I didn't know the Drivesaver (that's the actual name of mine) comes with a jumper. The manual I found for mine didn't mention it

[Bowdrie]

Originally Posted by LifesBetterWhenYoureBeating

So assuming my AC Grounding is not connected to my DC negative and I have a whole boat RCD, the engine doesn't need a path to earth (via the shaft or some other way), then?

There are 2 main issues, (actually 3, the 3rd being protection from a lightning strike, but we can forgo that for right now).
1, Bonding as a means of minimizing metal deterioration, primarily dealing with low voltage DC.
2, Protecting people against electrocution from AC power.
The concept of connecting the AC ground to the DC ground was a way to provide a low resistance path to the water to keep people safe, (you're leaning on a water heater that's leaking AC and you reach down to a seacock).
That premise, (connecting AC and DC grounds together,) only works if EVERY piece of metal touching the water or has a potential path to the water is bonded together, (what if you touched the only piece that wasn't bonded, = shock).
That scheme does protect people in the boat, but it does not protect anyone in the water, (a swimmer who passes thru the AC leaking into the water from your bonding system that has the water heater that's leaking AC.
For that we need the various GFCI devices, they use different acronyms, but they do the same job.
In the US boats tend to be bonded and AC/DC grounds tied together.
In Europe boats tend to not be bonded and GFCI devices are used to protect people in and out of the boat.
The European system has much to recommend, however, you never put all your eggs in one basket.
A rigger goes up the mast with a safety line, a skydiver carries a reserve parachute.
If you have only one GFCI device, you have no backup should that unit fail in the "on" position.
I cannot tell you what your surveyor wants to see, or what your insurance requires, nor can I tell you to disregard what ABYC says.
I can only tell you what I use for my boat, (others may object, that's ok).
1, I don't bond anything, there is absolutely no/zero/nada electrical path to the water from anything in the boat, both AC and DC, engine included.
2, The dock power has a GFCI breaker.
3, An RCD is within 12" of the AC shore power inlet.
4, Every AC outlet is GFCI protected.
5, Every installed AC device, (chargers/water heater/refrigeration,) uses a GFCI as a "feed thru" device, (line in/load out) installed in a weatherproof box.
I feel safe without the AC ground having any path to the water, (or the DC system).
As for the DC ground(s) not having a path to water, for me that's good.
Everything that's underwater is bronze except for the lead keel, (bronze bolts,) and the prop shaft, (Monel).
And no electricity can come into my boat from another source.
It works for me.

[DefinitelyMe]

What about the raw water used for cooling? Doesn't that ground the engine?

[boatpoker]

Originally Posted by Bowdrie

There are 2 main issues, (actually 3, the 3rd being protection from a lightning strike, but we can forgo that for right now).
1, Bonding as a means of minimizing metal deterioration, primarily dealing with low voltage DC.
2, Protecting people against electrocution from AC power.
The concept of connecting the AC ground to the DC ground was a way to provide a low resistance path to the water to keep people safe, (you're leaning on a water heater that's leaking AC and you reach down to a seacock).
That premise, (connecting AC and DC grounds together,) only works if EVERY piece of metal touching the water or has a potential path to the water is bonded together, (what if you touched the only piece that wasn't bonded, = shock).
That scheme does protect people in the boat, but it does not protect anyone in the water, (a swimmer who passes thru the AC leaking into the water from your bonding system that has the water heater that's leaking AC.
For that we need the various GFCI devices, they use different acronyms, but they do the same job.
In the US boats tend to be bonded and AC/DC grounds tied together.
In Europe boats tend to not be bonded and GFCI devices are used to protect people in and out of the boat.
The European system has much to recommend, however, you never put all your eggs in one basket.
A rigger goes up the mast with a safety line, a skydiver carries a reserve parachute.
If you have only one GFCI device, you have no backup should that unit fail in the "on" position.
I cannot tell you what your surveyor wants to see, or what your insurance requires, nor can I tell you to disregard what ABYC says.
I can only tell you what I use for my boat, (others may object, that's ok).
1, I don't bond anything, there is absolutely no/zero/nada electrical path to the water from anything in the boat, both AC and DC, engine included.
2, The dock power has a GFCI breaker.
3, An RCD is within 12" of the AC shore power inlet.
4, Every AC outlet is GFCI protected.
5, Every installed AC device, (chargers/water heater/refrigeration,) uses a GFCI as a "feed thru" device, (line in/load out) installed in a weatherproof box.
I feel safe without the AC ground having any path to the water, (or the DC system).
As for the DC ground(s) not having a path to water, for me that's good.
Everything that's underwater is bronze except for the lead keel, (bronze bolts,) and the prop shaft, (Monel).
And no electricity can come into my boat from another source.
It works for me.

No galvanic isolator or isolation transformer ?

[Bowdrie]

Originally Posted by DefinitelyMe

What about the raw water used for cooling? Doesn't that ground the engine?

There probably is some measurable conductivity with the engine running.
With the engine off the water level is below the pump in a rubber hose, so the only part in contact with the water is the bronze strainer.
In any case, the engine and its starting batteries have zero to do with anything else on the boat, (except the hoses filled with Prestone that go to the water heater,) admittedly I don't know, (or really care,) how much conductivity a 50/50 mix of Prestone and distilled water has.

Originally Posted by boatpoker

No galvanic isolator or isolation transformer ?

Without an AC ground to DC ground connection, and the engine isolated, and all the underwater metal isolated what would a galvanic isolator do?
I'll have to clear something up.
The entire boats DC system together with the house batteries and the big alternator that charges them are isolated from the engine, it's an off-engine alternator mounting with isolated ground.
The engine lives in its "own little world" with only its starter batts and the little engine mounted alternator to charge them, there are no electrical connections between the engine and "ships service".
Yes, I would like an isolation transformer, no doubt they offer "the next step" in protection.
Edit, there are 2 batt chargers, so the house and engine batts are not in any way sharing any connections at all.

[goboatingnow]

Originally Posted by Bowdrie

There are 2 main issues, (actually 3, the 3rd being protection from a lightning strike, but we can forgo that for right now).

1, Bonding as a means of minimizing metal deterioration, primarily dealing with low voltage DC.

2, Protecting people against electrocution from AC power.

The concept of connecting the AC ground to the DC ground was a way to provide a low resistance path to the water to keep people safe, (you're leaning on a water heater that's leaking AC and you reach down to a seacock).

That premise, (connecting AC and DC grounds together,) only works if EVERY piece of metal touching the water or has a potential path to the water is bonded together, (what if you touched the only piece that wasn't bonded, = shock).

That scheme does protect people in the boat, but it does not protect anyone in the water, (a swimmer who passes thru the AC leaking into the water from your bonding system that has the water heater that's leaking AC.

For that we need the various GFCI devices, they use different acronyms, but they do the same job.

In the US boats tend to be bonded and AC/DC grounds tied together.

In Europe boats tend to not be bonded and GFCI devices are used to protect people in and out of the boat.

The European system has much to recommend, however, you never put all your eggs in one basket.

A rigger goes up the mast with a safety line, a skydiver carries a reserve parachute.

If you have only one GFCI device, you have no backup should that unit fail in the "on" position.

I cannot tell you what your surveyor wants to see, or what your insurance requires, nor can I tell you to disregard what ABYC says.

I can only tell you what I use for my boat, (others may object, that's ok).

1, I don't bond anything, there is absolutely no/zero/nada electrical path to the water from anything in the boat, both AC and DC, engine included.

2, The dock power has a GFCI breaker.

3, An RCD is within 12" of the AC shore power inlet.

4, Every AC outlet is GFCI protected.

5, Every installed AC device, (chargers/water heater/refrigeration,) uses a GFCI as a "feed thru" device, (line in/load out) installed in a weatherproof box.

I feel safe without the AC ground having any path to the water, (or the DC system).

As for the DC ground(s) not having a path to water, for me that's good.

Everything that's underwater is bronze except for the lead keel, (bronze bolts,) and the prop shaft, (Monel).

And no electricity can come into my boat from another source.

It works for me.

Yes it’s the best way no onboard sea water connection. In Europe there will be multiple RCBOs between the mains supply and the boat.

One could argue the shore connected earth wire is redundant. Install a isolating transformer and make it so

[Rumrace]

I think you are in the wrong spot to figure out electrical. Simple isolated protected circuits. I have a relatively new French boat. As to meeting CSA CUL ULC or ETL they fail brand new out of the box. The primarily area CE and CSA UL have always disagreed switches sockets and wire burial. That and using cheesy Chinese LED lighting kinda a facade of the lovely tech lighting is. All the code violations were 120v. 12 & 24V no worries. IKEA was the first company to get a half plastic socket UL approved. There is not another domestic lighting company which agrees. I can assure you bargain led systems don’t save a cent.

[goboatingnow]

CSA CUL ULC or ETL

Who cares none are relevant on a boat anyway

All my bargain 12v Chinese leds are great and all survived my recent lightening strike which killed all the “ branded “ electronics

[boatpoker]

Originally Posted by goboatingnow

Who cares none are relevant on a boat anyway

All my bargain 12v Chinese leds are great and all survived my recent lightening strike which killed all the “ branded “ electronics

I cut the 120V transformer off cheap Ikea (made in China)LED lights and installed them in 2006. I've since sold the boat but know that they are still running fine. I've since sold the boat but know that they are still running fine. Even did a little post on my website about it. Cheap LEDs For Your Boat


I was so pleased with them that I installed the exact same units on my current boat 7 years ago (photo) while refitting and still no issue.
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