Marine Starter Motors???

[PaulRainbow]

In 1999 there was a gas explosion onboard the MoD vessel "Lord Trenchard", a Nicholson 52. The gas system was badly installed, the boat was poorly operated and a combination of these facts and a series of errors led to the incident. If the gas system was correctly installed, maintained and used, it would not have happened.

https://assets.publishing.service.gov.uk/media/547c717be5274a429000013b/lord_trenchard.pdf

 

[dragoon]

You most certainly do.



In post #22 you said "Marine engine electrical accessories technically should all be of the insulated earth type and not have a negative feed via the case or chassis. "

In post #27 "My Volvos have isolated earth senders, starters and I dare say the original alternators were. "

You now say it's bonded to Earth and has sensors that are not isolated return, therefore you engines are NOT isolated return.

I don't suggest you go into contract law. I stand by all of the above statements;

1) TECHNICALLY they should if you want to eliminate as much as possible the possibility for galvanic action caused through stray current.
2) Yes, this is correct.
3) I didn't say anywhere the whole engine was isolated return - you've implied this. I made a point of also pointing out that the alternators are likely no longer isolated earth.

Also, back to my other point. I didn't design or make these engines and their components - Volvo Penta did, and Storebro installed them.

 

[PaulRainbow]

I don't suggest you go into contract law. I stand by all of the above statements;

1) TECHNICALLY they should if you want to eliminate as much as possible the possibility for galvanic action caused through stray current.
2) Yes, this is correct.
3) I didn't say anywhere the whole engine was isolated return - you've implied this. I made a point of also pointing out that the alternators are likely no longer isolated earth.

Also, back to my other point. I didn't design or make these engines and their components - Volvo Penta did, and Storebro installed them.

You really need to stop digging.

In post #31 you said "You can tell me it’s nonsense all you like. I have a boat with an insulated earth setup from the maunfacturer. It’s not a sail drive setup. I also have a boat that has a conventional bonding from the manufacturer. I can see both types exist. I would be careful mixing components between so types, especially where it started as insulated earth."

Either you have an isolated return or you don't. If you have single wire sensors, you simply DO NOT. If the engine is bonded to anodes, you DO NOT.

 

[179580]

It isn't nonsense...It's a fact...the starter motors are different. It may not cause an explosion, but LPG is heavier than air and sinks to the bottom of the bilge. A spark in the engine bay, even on a diesel boat has the potential to cause an explosion. I had nothing to do with the design, but it makes sense to me...Now MY boat has a diesel engine and no gas on board (other than a couple of small canisters for a camping stove). Still, I'm happy someone at Perkins (and presumably Fairey) as well as the MoD (where the boat was originally, when new) specified minimizing any potential risk.

I served an apprenticeship with MOD(N), let me comment on that. It was not someone at Perkins or Fairey that specified that system. It would have been built to a specification issued at the time of tender. Given the nature of business of the MOD they covered all eventualities and indeed incorporated many big ship systems in their launches and small boats. If you further look into the commercial shipping, many ships lifeboats have keel cooling and dry exhausts which minimize the risk of a blocked raw water cooling system from flotsam and jetsam not to mention contamination from fuel oil. Life boats in the oil and gas industry are totally enclosed and contain cylinders of high pressure compressed air to sustain the crew and propulsion in a possibly flammable atmosphere. The risk of an incident from a diesel engine is negligible.

 

[dragoon]

You really need to stop digging.

In post #31 you said "You can tell me it’s nonsense all you like. I have a boat with an insulated earth setup from the maunfacturer. It’s not a sail drive setup. I also have a boat that has a conventional bonding from the manufacturer. I can see both types exist. I would be careful mixing components between so types, especially where it started as insulated earth."

Either you have an isolated return or you don't. If you have single wire sensors, you simply DO NOT. If the engine is bonded to anodes, you DO NOT.

This is very boring, honestly. I never knew anyone cared so deeply about an old 40 series engine.

I can provide you links to the parts that are insulated earth if you're really interested. They exist. I've replaced some of them, and the modern replacements are insulated earth.
Here's one, the low oil pressure switch - Keypart Note, it doesn't look like a car oil switch, but I know one of those fits, as I temporarily installed one when it broke.

So, why do you think they are insulated earth? I doubt as its to save costs. I suspect it's more to do with diverting current away from metal to metal circuits - last time I looked a cooler case was around £4000, and the tube bundle a similar cost.

I realize you have these sweeping views that everything is nonsense. It isn't, things are engineered for a reason. Sometimes they get it right, sometimes they don't, sometimes corners are cut to save cost, and things don't last for ever.

 

[38mess]

Can I just get back to the op. I fitted an alternator from a motor factor to my Perkins. It cost £45, it keeps my batteries charged, it's been working fine for over 5 years on my commercial passenger boat, if I bought a marine alternator it was over 300 quid

Edit
Just checked and I can get a marine alternator from parts4engines for £103, which is over double what I paid.

 

[179580]

This is very boring, honestly. I never knew anyone cared so deeply about an old 40 series engine.

I can provide you links to the parts that are insulated earth if you're really interested. They exist. I've replaced some of them, and the modern replacements are insulated earth.
Here's one, the low oil pressure switch - Keypart Note, it doesn't look like a car oil switch, but I know one of those fits, as I temporarily installed one when it broke.

So, why do you think they are insulated earth? I doubt as its to save costs. I suspect it's more to do with diverting current away from metal to metal circuits - last time I looked a cooler case was around £4000, and the tube bundle a similar cost.

I realize you have these sweeping views that everything is nonsense. It isn't, things are engineered for a reason. Sometimes they get it right, sometimes they don't, sometimes corners are cut to save cost, and things don't last for ever

 

[179580]

Can I just get back to the op. I fitted an alternator from a motor factor to my Perkins. It cost £45, it keeps my batteries charged, it's been working fine for over 5 years on my commercial passenger boat, if I bought a marine alternator it was over 300 quid

And probably will for the next 5 or 50. No prob.

 

[geem]

Still nonsense to suggest that diesel powered boats need ignition protected starters. You cannot ignite diesel with a spark from a starter motor. If a boat has LPG onboard it's far better (and more usual) to fit gas alarms, rather than rely on an ignition protected starter, what happens if you don't use the engine for a few days when you're onboard and LPG is leaking into the bilges ?

Ignition protected starters are normally fitted to petrol boats, not diesels. Yours is an exception, not the norm. It was not fitted as standard by Perkins, or Fairey, it was fitted as part of the MoD spec (a fact you omitted to reveal in your original post. It was fitted because the MoD were paranoid about gas explosions, they managed to blow a Nic' 52 up with LPG after a catalogue of errors and a badly designed system, leading to the generator igniting LPG in the bilges.

My 86hp Perkins M92b is isolated earth. These engines are often fitted for commercial use on fishing boats. Its a standard feature

 

[PaulRainbow]

My 86hp Perkins M92b is isolated earth. These engines are often fitted for commercial use on fishing boats. Its a standard feature

I'm aware that some engines are isolated return. I disputed the claim that all marine engines should be.

 

[38mess]

I'm aware that some engines are isolated return. I disputed the claim that all marine engines should be.

As stated above, I fitted a car alternator to my Perkins, I just checked the parts4engines website online and it says I need an insulated return which I guess the car alternator is not, it's been working fine for 5 years.

 

[john_q]

Particularly on trucks, allows use to the ADR regs. Carriage of inflammable liquids etc.

I bought a new AC/DELCO starter motor for about £100 and had it converted to Insulated return for about £10 by the AC/DELCO dealer
US Marine supplier quoted me between $750 and $1,440 for new CAV or converted AC/Delco

 

[PaulRainbow]

This is very boring, honestly. I never knew anyone cared so deeply about an old 40 series engine.

I can provide you links to the parts that are insulated earth if you're really interested. They exist. I've replaced some of them, and the modern replacements are insulated earth.
Here's one, the low oil pressure switch - Keypart Note, it doesn't look like a car oil switch, but I know one of those fits, as I temporarily installed one when it broke.

So, why do you think they are insulated earth? I doubt as its to save costs. I suspect it's more to do with diverting current away from metal to metal circuits - last time I looked a cooler case was around £4000, and the tube bundle a similar cost.

I realize you have these sweeping views that everything is nonsense. It isn't, things are engineered for a reason. Sometimes they get it right, sometimes they don't, sometimes corners are cut to save cost, and things don't last for ever.

You're right it's boring, but that's because you have dug yourself a hole and won't stop digging.

I'm perfectly aware that sensors, starters, alternators etc are available in isolated return, i didn't say they were not.

I'm perfectly aware that engines are available as isolated return, i didn't say they were not.

You stated that all marine engines should be isolated return, but most are not. You stated you had one that was and one that wasn't, then you claim you didn't say that and both are not isolated return. You clearly don't understand the subject matter.

Bye the way, it's isolated return, not Earth, there is no Earth in 12V DC marine circuits, just positive and negative.

 

[PaulRainbow]

As stated above, I fitted a car alternator to my Perkins, I just checked the parts4engines website online and it says I need an insulated return which I guess the car alternator is not, it's been working fine for 5 years.

Depends on the engine and who marinised it, as well as which side of the bed they got out out of when they designed the wiring. Some of the Volvo marinised Perkins are all over the place. One day they are isolated return, the next they are not, then another day they fit isolated return alternators, starters and or sensors (or any combination of) but connect a fat negative cable straight from the engine battery to the block and connect cables from the alternator/starter to the same bolt.

 

[dragoon]

You're right it's boring, but that's because you have dug yourself a hole and won't stop digging.

I'm perfectly aware that sensors, starters, alternators etc are available in isolated return, i didn't say they were not.

I'm perfectly aware that engines are available as isolated return, i didn't say they were not.

You stated that all marine engines should be isolated return, but most are not. You stated you had one that was and one that wasn't, then you claim you didn't say that and both are not isolated return. You clearly don't understand the subject matter.

Bye the way, it's isolated return, not Earth, there is no Earth in 12V DC marine circuits, just positive and negative.

I have no idea what your point is.

Electricity and salt water are a poor mix around a metal boat engine. Corrosion is common, parts are expensive. Manufacturers fit isolated return parts to minimise the issue. Technically, if you want to eliminate as much as possible, they should use this strategy everywhere on every engine, but it's expensive and not always practical.

If you're changing parts for non manufacturer fitted parts, you should be aware of the changes you're making and the possible implications of doing so. The law of unintended consequences applies.

Oh, and boats do explode - it's not nonsense.

 

[PaulRainbow]

I have no idea what your point is.

Electricity and salt water are a poor mix around a metal boat engine. Corrosion is common, parts are expensive. Manufacturers fit isolated return parts to minimise the issue. Technically, if you want to eliminate as much as possible, they should use this strategy everywhere on every engine, but it's expensive and not always practical.

If you're changing parts for non manufacturer fitted parts, you should be aware of the changes you're making and the possible implications of doing so. The law of unintended consequences applies.

Oh, and boats do explode - it's not nonsense.

My point is, you type nonsense. Then you type some ore nonsense to cover up the previous batch of nonsense.

I'm perfectly aware of what changes i might make, i fit the correct parts for the installation. I understand how the parts work and how the different installations work. I can tell the difference between an isolated return system and one that just has some random isolated return parts in it, just because that's what Volvo decided to fit on the day. I can spot that an isolated return alternator, fitted to a non isolated return engine, can be replaced with a standard alternator and save my customer a load of money. I do this all day, every day, never had a problem yet. But thanks for the advice.

Out.

 

[dragoon]

My point is, you type nonsense. Then you type some ore nonsense to cover up the previous batch of nonsense.

I'm perfectly aware of what changes i might make, i fit the correct parts for the installation. I understand how the parts work and how the different installations work. I can tell the difference between an isolated return system and one that just has some random isolated return parts in it, just because that's what Volvo decided to fit on the day. I can spot that an isolated return alternator, fitted to a non isolated return engine, can be replaced with a standard alternator and save my customer a load of money. I do this all day, every day, never had a problem yet. But thanks for the advice.

Out.

I'm deleting my last comment as I wish to leave this conversation as a gentleman.....

 

[Gary Fox]

You don’t believe there is a risk of accidental ignition on boats?

Almost every single electrical item on both my boats, and all previous ones, has been capable of causing a spark when operating normally or switching on. Spark proofing and insulated returns aren't needed.

 

[179580]

Almost every single electrical item on both my boats, and all previous ones, has been capable of causing a spark when operating normally or switching on. Spark proofing and insulated returns aren't needed.

Perzactly,

 

[Spirit (of Glenans)]

In 1999 there was a gas explosion onboard the MoD vessel "Lord Trenchard", a Nicholson 52. The gas system was badly installed, the boat was poorly operated and a combination of these facts and a series of errors led to the incident. If the gas system was correctly installed, maintained and used, it would not have happened.

https://assets.publishing.service.gov.uk/media/547c717be5274a429000013b/lord_trenchard.pdf

The connection between the name of that boat and this discussion has just reminded me that I once read somewhere that when aircraft were imported from the US during WW2 they all arrived with an earth return electrical system but had to be rewired to comply with the RAF's standard two wire standard.