mikejames
Well-Known Member
Before changing to non-yanmar , the only good thing I can think about the Yanmar alternators is that in my experience, leaving the battery switch OFF while the engine running doesnt fry all of the electrics.
Marine alternator
- Thread starter Cobra25
- Start date
Ships_Cat
Well-Known Member
Every boat I have seen has a standard frame earth alternator
Then you have not seen many good modern boats. Many engines come standard with isolated ground alternators (even our 1996 Volvo did). They are good practice in any boat and especially so in a steel or aluminium one.
Apart from removing the risk of corrosion due to earth leakage currents, there is also improved safety from arcing fires if the boats DC systems are such that they are completely isolated from the engine (alternators, starter and instruments all isolated) such that there is no low resistance path (if there is a path from block back it is usually fused with low amperage fuse) back to high energy souces via the block or starter/alternator chassis's.
It is a fact of life that many, including myself, do not like to go backwards when maintaining (sic) their boats by putting inferior equipment in them or recovering stuff from the dump for replacements.
John
Then you have not seen many good modern boats. Many engines come standard with isolated ground alternators (even our 1996 Volvo did). They are good practice in any boat and especially so in a steel or aluminium one.
Apart from removing the risk of corrosion due to earth leakage currents, there is also improved safety from arcing fires if the boats DC systems are such that they are completely isolated from the engine (alternators, starter and instruments all isolated) such that there is no low resistance path (if there is a path from block back it is usually fused with low amperage fuse) back to high energy souces via the block or starter/alternator chassis's.
It is a fact of life that many, including myself, do not like to go backwards when maintaining (sic) their boats by putting inferior equipment in them or recovering stuff from the dump for replacements.
John
William_H
Well-Known Member
"The alternator is unecconomical to repair." Try for another opinion. Unless it is obviously corroded to pieces I can't see it being possible. If it has an insulated negative then you may be able to retain the body and rectifier plates while replacing the rotor. The most common fault in alternators is a worn slip rings. These can be turned down but if they are too far gone then a new rotor is indicated. I think you will find the rotor is common to many vehicle alternators of the same manufacturer. So it is likely an alternator of similar manufacture from a wreckers yard (we call them) will provide a suitable rotor for your old alternator. In any case pull the old one apart and see for yourself. "don't let the [--word removed--] get your money"
olewill
olewill
G
Guest
Guest
galvanic corrossion ... pah !!!
To have an effect that he is trying to suggest means an electrical path that would be a disaster .... it would mean one of two things :
a) Completely wrong set-up and water available to complete the link,
or
b) boat is able to have engine and alternator running under water ............
Sort of twaddle as far as I'm concerned .....
Maybe he can answer this then .... So why are so many boats fitted with bog standard alternators ?? Why are they not falling apart from G. corrsossion ???
The magic word is there ladies and gents ..... MARINE
/forums/images/graemlins/tongue.gif
To have an effect that he is trying to suggest means an electrical path that would be a disaster .... it would mean one of two things :
a) Completely wrong set-up and water available to complete the link,
or
b) boat is able to have engine and alternator running under water ............
Sort of twaddle as far as I'm concerned .....
Maybe he can answer this then .... So why are so many boats fitted with bog standard alternators ?? Why are they not falling apart from G. corrsossion ???
The magic word is there ladies and gents ..... MARINE
/forums/images/graemlins/tongue.gif
Cobra25
Well-Known Member
Yes, this was the advice I received - replace it with like. Have gone for 70 amp replacement. Don't feel i can take the bull by the horns and hope it will be all right even though others have had no probs though the marine bit always hikes the price I know. Adverc say insulated earths are less common in grp boats but essential in metal. Waiting on answer from Yanmar
charles_reed
Well-Known Member
The Hitachi alternator
fitted to the 2GM20 is either a 35 or 55 amp output one. Not a really adequate output for 400 ah of batteries.
It had (on my engine) a standard uninsulated earth return.
It did have ss bearings, unlike a car alternator and far better insulated rotor.
I replaced that when it finally blew its diode bridge with a 70 amp Lucas marine alternator (from Adverc).
As this had an insulated earth return, to get it to charge I had to earth it to the engine.
It cost me £46, but that was a long time ago.
As the smart regulator makes the alternator work really hard, there's always a tendency for the diode bridge to overheat, and as the Adverc requires a feed from the field, I now carry a spare, a Magnetti Marelli 100 amp one. That cost £110.
When I've had to have the diode bridge replaced it's only been about £25 and it's easily done by any auto-electrician.
PS Lucas and Magnetti Marelli are the same company now.
fitted to the 2GM20 is either a 35 or 55 amp output one. Not a really adequate output for 400 ah of batteries.
It had (on my engine) a standard uninsulated earth return.
It did have ss bearings, unlike a car alternator and far better insulated rotor.
I replaced that when it finally blew its diode bridge with a 70 amp Lucas marine alternator (from Adverc).
As this had an insulated earth return, to get it to charge I had to earth it to the engine.
It cost me £46, but that was a long time ago.
As the smart regulator makes the alternator work really hard, there's always a tendency for the diode bridge to overheat, and as the Adverc requires a feed from the field, I now carry a spare, a Magnetti Marelli 100 amp one. That cost £110.
When I've had to have the diode bridge replaced it's only been about £25 and it's easily done by any auto-electrician.
PS Lucas and Magnetti Marelli are the same company now.
Ships_Cat
Well-Known Member
Re: galvanic corrossion ... pah !!!
Nigel
You are leading people astray quite badly and your advice could lead to the unnecessary loss of someones boat should they follow it. I did not want to reply before I had made some measurements on my own boat to demonstrate what I mean and to forestall any trivial rebuttal.
I have mentioned in my last post the risk from arcing. If one has a engine with the alternator and its other mounts (cranking motor, instrument senders, etc which I will refer to as "mounts" from now on) isolated from the engine block, etc then one is greatly protected from arcing fires in many boats. Normally an engine with an isolated alternator can be expected to have the other mounts isolated as well.
Some may say that the risk is small, but I know, just from casual contact (remember I am 10,000 miles away from most forumites), two UK forumites who have had arcing fires on board at the engine - one of those I know to have been a new installation with a non isolated engine as that forumite kindly described his setup to me.
So, on to the tests I did this weekend on my own engine which has all mounts isolated and the service battery (and of course, the cranking battery) negative not bonded to the engine. First I measured the voltage between both my alternators' positive terminals and also the cranking motor/solenoid positive to the engine block and alternator chassis's. For the sake of completeness I did this with all isolating switches closed and the engine key switch also in both the "On" and "Off" positions. I obtained, as I expected, a voltage approximating that of the respective batteries. This voltage appears because although everything is isolated the insulation is not perfect so a high non infinite resistance exists over which one will measure a voltage. Lets call this high resistance X.
Next I wired a 15 watt 12 volt bulb between each of the points mentioned above where I measured the voltage and, as I expected, the bulb DID NOT light up. This is because in series with the bulb is the very high resistance X referred to above, so only a miniscule current can flow and that was not enough to get a glimmer from the bulb.
So, I think most will see from that, that in the case of a positive cable coming loose from any of the alternators or the cranking motor/solenoid it cannot arc against any part of the engine. Parting of these cables is always possible as they are subject to the vibration and torque of the engine at their terminations. They are also connected to high energy sources so arcing can be serious (and often not always protected from by a simple fuse at the battery as some expect).
It is common on the service battery side to bond the negative to the engine. In my view this should not be how a boat should be wired, especially if one has gone to the expense of an isolated engine. Of course, if the service battery negative is bonded to the engine then the arcing protection on the service side is compromised. However, even if that is so, it would be most unusual in a boat with an engine with isolated mounts to bond the cranking battery negative to the engine, so protection from arcing should always exist on that side.
So, if people have an engine with isolated alternator, etc, before they rush off and replace it with a non isolated alternator, or add an unisolated one (for service battery charging, for example) they should be either very sure that they are not compromising the protection from arcing that they might have, or if they do that they are happy for that compromise to occur (which would seem a rather silly thing to do after paying extra for an engine with isolated mounts)
Some may say this only applies to new fangled engines. That is not so, my own engine (a Volvo) is 9 years old and was delivered with isolated mounts. A high capacity isolated alternator was also added. Also, our boat is metal (but all of the above applies regardless of the material the boat is constructed from) and was specified to have all DC systems isolated from the hull ie the negatives are not grounded to the hull, and this is common with metal boats (and should be with any, in my opinion). The result of this is, in the same way as I explained for the protection against arcing to the engine, there is the same protection against arcing against the hull throughout the boat.
So, if one has a metal boat there is this further consideration. If one replaces an alternator with an unisolated one, one may be compromising the protection against arcing that may exist (if the boat has been wired so) elsewhere in the boat as well (and also compromising its protection against corrosion).
I do not know how Cobra25's boat is wired, but he made a safe and sensible decision in my opinion. I hope others have not been misled into thinking isolation is trivial and does not matter.
John
Nigel
You are leading people astray quite badly and your advice could lead to the unnecessary loss of someones boat should they follow it. I did not want to reply before I had made some measurements on my own boat to demonstrate what I mean and to forestall any trivial rebuttal.
I have mentioned in my last post the risk from arcing. If one has a engine with the alternator and its other mounts (cranking motor, instrument senders, etc which I will refer to as "mounts" from now on) isolated from the engine block, etc then one is greatly protected from arcing fires in many boats. Normally an engine with an isolated alternator can be expected to have the other mounts isolated as well.
Some may say that the risk is small, but I know, just from casual contact (remember I am 10,000 miles away from most forumites), two UK forumites who have had arcing fires on board at the engine - one of those I know to have been a new installation with a non isolated engine as that forumite kindly described his setup to me.
So, on to the tests I did this weekend on my own engine which has all mounts isolated and the service battery (and of course, the cranking battery) negative not bonded to the engine. First I measured the voltage between both my alternators' positive terminals and also the cranking motor/solenoid positive to the engine block and alternator chassis's. For the sake of completeness I did this with all isolating switches closed and the engine key switch also in both the "On" and "Off" positions. I obtained, as I expected, a voltage approximating that of the respective batteries. This voltage appears because although everything is isolated the insulation is not perfect so a high non infinite resistance exists over which one will measure a voltage. Lets call this high resistance X.
Next I wired a 15 watt 12 volt bulb between each of the points mentioned above where I measured the voltage and, as I expected, the bulb DID NOT light up. This is because in series with the bulb is the very high resistance X referred to above, so only a miniscule current can flow and that was not enough to get a glimmer from the bulb.
So, I think most will see from that, that in the case of a positive cable coming loose from any of the alternators or the cranking motor/solenoid it cannot arc against any part of the engine. Parting of these cables is always possible as they are subject to the vibration and torque of the engine at their terminations. They are also connected to high energy sources so arcing can be serious (and often not always protected from by a simple fuse at the battery as some expect).
It is common on the service battery side to bond the negative to the engine. In my view this should not be how a boat should be wired, especially if one has gone to the expense of an isolated engine. Of course, if the service battery negative is bonded to the engine then the arcing protection on the service side is compromised. However, even if that is so, it would be most unusual in a boat with an engine with isolated mounts to bond the cranking battery negative to the engine, so protection from arcing should always exist on that side.
So, if people have an engine with isolated alternator, etc, before they rush off and replace it with a non isolated alternator, or add an unisolated one (for service battery charging, for example) they should be either very sure that they are not compromising the protection from arcing that they might have, or if they do that they are happy for that compromise to occur (which would seem a rather silly thing to do after paying extra for an engine with isolated mounts)
Some may say this only applies to new fangled engines. That is not so, my own engine (a Volvo) is 9 years old and was delivered with isolated mounts. A high capacity isolated alternator was also added. Also, our boat is metal (but all of the above applies regardless of the material the boat is constructed from) and was specified to have all DC systems isolated from the hull ie the negatives are not grounded to the hull, and this is common with metal boats (and should be with any, in my opinion). The result of this is, in the same way as I explained for the protection against arcing to the engine, there is the same protection against arcing against the hull throughout the boat.
So, if one has a metal boat there is this further consideration. If one replaces an alternator with an unisolated one, one may be compromising the protection against arcing that may exist (if the boat has been wired so) elsewhere in the boat as well (and also compromising its protection against corrosion).
I do not know how Cobra25's boat is wired, but he made a safe and sensible decision in my opinion. I hope others have not been misled into thinking isolation is trivial and does not matter.
John
G
Guest
Guest
Oh dear ....
Ships cat ......... I will not argue with your post - just comment this :
Charles Reed post shows that he had to bond the alternator to the engine to get it to charge - so that immediately has removed a large part of your "protection".
Second ........ to be honest I read through your post ... long one isn't it .... and wasn't any clearer about the actual mechanism you are illustrating ....
Thirdly ......... if any supply cable gets compromised you wil always have possibility of arcing / electrical violence ....... insulated or not ... you only have to look at the electrical paths used on engines ........... starters negative bonded to engine ... any other gauges etc. - so batterys / electricla systems are NOT separate and truly isolated ... as we all know elctricity is like water - it will always find a path.
Finally - if a company produces a Marine item in a certain fashion - they must believe that there is a need for it. I do not say never use it or do not buy .... I just question it based on multitudes of engines fitted to boats over many years that have survived ... operated without. Having not experienced problems or incidents as you promulgate - I am yet to be 'educated' to this .... My perkins has a bog standard alternator as most other perkins etc. have. I do not see any documents or reccomendations from BWA / Insurnance Co's etc. to fit anything different ... a good indicator as they would insist to lessen their risk etc. You may consider I lead them badly astray ....... I do not agree as the final decision is up to them ... and I am actually only one of many who has said WHY ?? One of the real pains in boating is the Cheque book Marinised item ... something we can well do without .... Cobra25 will check his engine I hope and see which alteranator is actually the 'drop-in' replacement without altering connections etc. That is the sensible way to go ....
Ships cat ......... I will not argue with your post - just comment this :
Charles Reed post shows that he had to bond the alternator to the engine to get it to charge - so that immediately has removed a large part of your "protection".
Second ........ to be honest I read through your post ... long one isn't it .... and wasn't any clearer about the actual mechanism you are illustrating ....
Thirdly ......... if any supply cable gets compromised you wil always have possibility of arcing / electrical violence ....... insulated or not ... you only have to look at the electrical paths used on engines ........... starters negative bonded to engine ... any other gauges etc. - so batterys / electricla systems are NOT separate and truly isolated ... as we all know elctricity is like water - it will always find a path.
Finally - if a company produces a Marine item in a certain fashion - they must believe that there is a need for it. I do not say never use it or do not buy .... I just question it based on multitudes of engines fitted to boats over many years that have survived ... operated without. Having not experienced problems or incidents as you promulgate - I am yet to be 'educated' to this .... My perkins has a bog standard alternator as most other perkins etc. have. I do not see any documents or reccomendations from BWA / Insurnance Co's etc. to fit anything different ... a good indicator as they would insist to lessen their risk etc. You may consider I lead them badly astray ....... I do not agree as the final decision is up to them ... and I am actually only one of many who has said WHY ?? One of the real pains in boating is the Cheque book Marinised item ... something we can well do without .... Cobra25 will check his engine I hope and see which alteranator is actually the 'drop-in' replacement without altering connections etc. That is the sensible way to go ....
Ships_Cat
Well-Known Member
Re: Oh dear ....
you only have to look at the electrical paths used on engines ........... starters negative bonded to engine ... any other gauges etc
That is where you have gone astray Nigel.
On many marine engines those things are not negative bonded to the engine. You will find on such engines (and they are not uncommon engines, for example mine, as I said, is a plain vanilla 9 year old 2 litre Volvo) that all the instrument senders are two wired back to the panel and the negative is not common with the engine - similarly with the starter/solenoid and the alternator. If you measure the resistance between the negatives on those items and the engine block or the items own chassis you will measure a very high resistance ('cos they are isolated).
The tone of your response is dismissive of what I say, apparantly because you cannot understand it. I can only suggest that you read my post again, especially the bit about the tests I did on my own engine with respect to the protection against arcing. Anyone not understanding my post should not be offering cavalier advice to others about "how it should be done".
I suspect many others will see that it is worth taking what I say seriously - if not, that is their and your own choice. I have had my say.
John
you only have to look at the electrical paths used on engines ........... starters negative bonded to engine ... any other gauges etc
That is where you have gone astray Nigel.
On many marine engines those things are not negative bonded to the engine. You will find on such engines (and they are not uncommon engines, for example mine, as I said, is a plain vanilla 9 year old 2 litre Volvo) that all the instrument senders are two wired back to the panel and the negative is not common with the engine - similarly with the starter/solenoid and the alternator. If you measure the resistance between the negatives on those items and the engine block or the items own chassis you will measure a very high resistance ('cos they are isolated).
The tone of your response is dismissive of what I say, apparantly because you cannot understand it. I can only suggest that you read my post again, especially the bit about the tests I did on my own engine with respect to the protection against arcing. Anyone not understanding my post should not be offering cavalier advice to others about "how it should be done".
I suspect many others will see that it is worth taking what I say seriously - if not, that is their and your own choice. I have had my say.
John
G
Guest
Guest
Re: Oh dear ....
To apply your situation to all others is wrong ............ I do not do it and I expect you and others to do similar.
There are thousands of engines out there that are negative bonded via engine ... and we are not only talking marinised car / van engines etc.
I am not dismissive of your post ... just cannot really undserstand why you want to write a long post about a phenonemum that any school-boy can recite ... of course their will be a high restitance found when you have isolated items ....
What I am saying is that isolated is NOT the be all and end all ... that it is common for many boats to have non-isolated items .... same as my BOG STANDARD PERKINS 4-107, the 4-99 before it, the Vire 6 in previous boat, the Stuart in my fathers ......
Let's go one step further ........let's put up a poll shall we .... see if we can find out .....
Ships cat ---- get back to being a pussy and stop being the tiger .... you have a point ... and so have I .... both based on observation ....
To apply your situation to all others is wrong ............ I do not do it and I expect you and others to do similar.
There are thousands of engines out there that are negative bonded via engine ... and we are not only talking marinised car / van engines etc.
I am not dismissive of your post ... just cannot really undserstand why you want to write a long post about a phenonemum that any school-boy can recite ... of course their will be a high restitance found when you have isolated items ....
What I am saying is that isolated is NOT the be all and end all ... that it is common for many boats to have non-isolated items .... same as my BOG STANDARD PERKINS 4-107, the 4-99 before it, the Vire 6 in previous boat, the Stuart in my fathers ......
Let's go one step further ........let's put up a poll shall we .... see if we can find out .....
Ships cat ---- get back to being a pussy and stop being the tiger .... you have a point ... and so have I .... both based on observation ....
Avocet
Well-Known Member
Re: Oh dear ....
I can see both sides of the argument and if I was infinitely rich, I'd probably go for the isolated one. As it is, I'm not infinitely rich and I need to prioritise. If I can save £250 by getting a car alternator from a scrapyard (as indeed I did!) I'm half way to a cheap life raft. My PERSONAL view, therefore, is that I'd rather check my wiring frequently and put the money towards a liferaft which I could use if I had an arcing fire - or any one of a large variety of other disasters!
I can see both sides of the argument and if I was infinitely rich, I'd probably go for the isolated one. As it is, I'm not infinitely rich and I need to prioritise. If I can save £250 by getting a car alternator from a scrapyard (as indeed I did!) I'm half way to a cheap life raft. My PERSONAL view, therefore, is that I'd rather check my wiring frequently and put the money towards a liferaft which I could use if I had an arcing fire - or any one of a large variety of other disasters!
Ships_Cat
Well-Known Member
Re: Oh dear ....
Reread my post Nigel. I am not applying it to all. I make it very clear that what I am saying applies to engines that have isolated alternators, starter/solenoid, instrument senders, etc.
I think as has been said, for your poll you need a "Haven't got a clue" option, 'cos that will be the situation for many.
Take it from me, there are many engines that are isolated in the way I say, from the sailboat auxiliary/low powered MoBo engines to the large (I buy the larger ones - V8's/V12's etc - to go in client's power boats). My own sailboat engine, a 2 litre Volvo MD22L is one such engine and that engine model alone was fitted in many, many production boats in Europe, so such engines are not uncommon.
For Avocet's benefit I am not claiming that all installations should be isolated, that is personal choice. I am just saying that if they are, the benefits are lost if an unisolated alternator is fitted and people should therefore not just give blanket recommendations to replace isolated alternators with non isolated ones without making the consequences clear.
John
Reread my post Nigel. I am not applying it to all. I make it very clear that what I am saying applies to engines that have isolated alternators, starter/solenoid, instrument senders, etc.
I think as has been said, for your poll you need a "Haven't got a clue" option, 'cos that will be the situation for many.
Take it from me, there are many engines that are isolated in the way I say, from the sailboat auxiliary/low powered MoBo engines to the large (I buy the larger ones - V8's/V12's etc - to go in client's power boats). My own sailboat engine, a 2 litre Volvo MD22L is one such engine and that engine model alone was fitted in many, many production boats in Europe, so such engines are not uncommon.
For Avocet's benefit I am not claiming that all installations should be isolated, that is personal choice. I am just saying that if they are, the benefits are lost if an unisolated alternator is fitted and people should therefore not just give blanket recommendations to replace isolated alternators with non isolated ones without making the consequences clear.
John
Joe_Cole
Well-Known Member
Re: Oh dear ....
I've got an outboard so I havn't got a clue what you are both talking about, but I think you'll have to agree to disagree.
I've got an outboard so I havn't got a clue what you are both talking about, but I think you'll have to agree to disagree.
G
Guest
Guest
It is obvious that over-statement is being added here ....
I am not advocating losing any benefit if the engine is an isolated type ... sorry - but as a surveyor rare to see on boats I get into contact with .... can't actually remember the last one !!
What I was saying and maybe didn't make it clear enough ... if the engine installation is not dedicated isolated system - why do it .... replace like with like.
My other point was that I do not automatically agree to 'marine' items and also do not automatically agree to a single persons advise ....
Generally most boats have 'marinised' auto engines or as Yanmar .... generator based engines .... often the only bits that are seriouslyt altered are cooling and speed governing etc. The charging systems are often left as is. You may be lucky and have anti-corrosion parts fitted .... but as likely not.
How common are Perkins on a boat ? Pretty widespread I'd say and are a good example of exactly this ... you quote Volvo .......... now please do not tell me all volvo's are isolated as that is not true. I will likewise not tell you all Perkins are not isolated ....... someone somewhere would have done it .... maybe the new ones supplied to Volvo are ??
A car / van / truck has a harder life I believe than a boat engine - so why the emphasis ........ genuine question not a safety issue .... Would have thought that average van / truck puts a heavy strain on all components of an engine .... average marine engine has a holiday compared to that ....
So both of us have a point ....... no problem there ... but let's take it in context ....
Oh and the "Have'nt a clue" box ......... I wouldn't put it as I didn't want to unbalance the result so that others could argue against the poll !!!!
Now got to go - Formual 1 !!!! Hope its more interesting this week !!
I am not advocating losing any benefit if the engine is an isolated type ... sorry - but as a surveyor rare to see on boats I get into contact with .... can't actually remember the last one !!
What I was saying and maybe didn't make it clear enough ... if the engine installation is not dedicated isolated system - why do it .... replace like with like.
My other point was that I do not automatically agree to 'marine' items and also do not automatically agree to a single persons advise ....
Generally most boats have 'marinised' auto engines or as Yanmar .... generator based engines .... often the only bits that are seriouslyt altered are cooling and speed governing etc. The charging systems are often left as is. You may be lucky and have anti-corrosion parts fitted .... but as likely not.
How common are Perkins on a boat ? Pretty widespread I'd say and are a good example of exactly this ... you quote Volvo .......... now please do not tell me all volvo's are isolated as that is not true. I will likewise not tell you all Perkins are not isolated ....... someone somewhere would have done it .... maybe the new ones supplied to Volvo are ??
A car / van / truck has a harder life I believe than a boat engine - so why the emphasis ........ genuine question not a safety issue .... Would have thought that average van / truck puts a heavy strain on all components of an engine .... average marine engine has a holiday compared to that ....
So both of us have a point ....... no problem there ... but let's take it in context ....
Oh and the "Have'nt a clue" box ......... I wouldn't put it as I didn't want to unbalance the result so that others could argue against the poll !!!!
Now got to go - Formual 1 !!!! Hope its more interesting this week !!
Ships_Cat
Well-Known Member
Re: It is obvious that over-statement is being added here ....
maybe the new ones supplied to Volvo are ??
And indeed some of the old Perkins used by Volvo are too eg the MD22's which I gave as an example have been around since the 1980's and are Perkins engines.
With your claimed surveying experience you must have come across many of them - there are many, many thousands of MD22's in boats. For years were the common fit to HR's, Beneteaus, etc, etc.
John
maybe the new ones supplied to Volvo are ??
And indeed some of the old Perkins used by Volvo are too eg the MD22's which I gave as an example have been around since the 1980's and are Perkins engines.
With your claimed surveying experience you must have come across many of them - there are many, many thousands of MD22's in boats. For years were the common fit to HR's, Beneteaus, etc, etc.
John
jerryat
Well-Known Member
Re: Oh dear ....
There is nothing to stop you doing as I was advised and taking a heavy duty cable directly from the alternator neg. back to the battery neg.
It is far better practice to do this than relying on the 'contact' between alt. and engine for the return.
Like you (and I suspect thousands of others) I've happily sailed for 33 years with 'standard' alts fitted, so whilst the dreaded arcing may happen the next time I go out, I think I'll live with the risk!! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
Cheers Jerry
There is nothing to stop you doing as I was advised and taking a heavy duty cable directly from the alternator neg. back to the battery neg.
It is far better practice to do this than relying on the 'contact' between alt. and engine for the return.
Like you (and I suspect thousands of others) I've happily sailed for 33 years with 'standard' alts fitted, so whilst the dreaded arcing may happen the next time I go out, I think I'll live with the risk!! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
Cheers Jerry
Ships_Cat
Well-Known Member
Re: Oh dear ....
And I would also live with the risk if I had a boat with a non isolated alternator/engine (although I would pay an extra lot of attention to the cabling) - after all we do most days when we drive our cars /forums/images/graemlins/smile.gif. And, as sure as hell, I don't go worrying about it if I go for a ride on someone elses boat.
But, of course, the only point I am making (although some seem to be keen on extrapolating that into my saying that everyone should have isolated engines /forums/images/graemlins/crazy.gif) is that if one has an isolated alternator and other auxiliaries then it would be silly to compromise the protection that can give by then installing an alternator that is not isolated.
I think it is, however, good practice though to have an isolated DC system in the boat. But I am the first to agree that often these things are driven by budget or by you get what you get, whatever that happens to be, when you buy the boat
John
And I would also live with the risk if I had a boat with a non isolated alternator/engine (although I would pay an extra lot of attention to the cabling) - after all we do most days when we drive our cars /forums/images/graemlins/smile.gif. And, as sure as hell, I don't go worrying about it if I go for a ride on someone elses boat.
But, of course, the only point I am making (although some seem to be keen on extrapolating that into my saying that everyone should have isolated engines /forums/images/graemlins/crazy.gif) is that if one has an isolated alternator and other auxiliaries then it would be silly to compromise the protection that can give by then installing an alternator that is not isolated.
I think it is, however, good practice though to have an isolated DC system in the boat. But I am the first to agree that often these things are driven by budget or by you get what you get, whatever that happens to be, when you buy the boat
John
Avocet
Well-Known Member
Re: Oh dear ....
Hey wow! Thanks, a post just for my benefit - I'm honoured!
I know what you were saying - heaven knows, you've said it enough times in this thread! I do, however, think you're unfair suggesting that others are making dangerous "blanket recommendations". I even went to the trouble of putting the word "personal" in block capitals! I do, however, think that most people on here should have enough common sense to take their own decisions as to the level of risk they are prepared to take. Sailing is, after all, inherently risky anyway and I doubt that electrical fires as a result of not having isolated alternators is right up there near the top of the list of causes of death among boaters! Furthermore, as Nigel's poll seems to be suggesting, you are, perhaps wrong in suggesting that people go to the expense of paying extra for an isolated setup in the first place. In fact, I suspect many (most?) people tend to pay for a boat without ever knowing if the engine is isolated or not! You were right to point out the dangers of compromising the electrical isolation of the engine but I also think (as many of us on here sail on a tight budget) that Nigel was also right to point out that there were cheaper alternatives available.
Hey wow! Thanks, a post just for my benefit - I'm honoured!
I know what you were saying - heaven knows, you've said it enough times in this thread! I do, however, think you're unfair suggesting that others are making dangerous "blanket recommendations". I even went to the trouble of putting the word "personal" in block capitals! I do, however, think that most people on here should have enough common sense to take their own decisions as to the level of risk they are prepared to take. Sailing is, after all, inherently risky anyway and I doubt that electrical fires as a result of not having isolated alternators is right up there near the top of the list of causes of death among boaters! Furthermore, as Nigel's poll seems to be suggesting, you are, perhaps wrong in suggesting that people go to the expense of paying extra for an isolated setup in the first place. In fact, I suspect many (most?) people tend to pay for a boat without ever knowing if the engine is isolated or not! You were right to point out the dangers of compromising the electrical isolation of the engine but I also think (as many of us on here sail on a tight budget) that Nigel was also right to point out that there were cheaper alternatives available.
Ships_Cat
Well-Known Member
Re: Oh dear ....
I think if you look at Nigel's poll and consider that the isolated components are likely to be fitted only to diesel engines, you will find that quite a high percentage are isolated.
Currently, assuming the probable case those with isolated components are all diesel (eg petrol engines have spark plugs, the ignition return being back through the engine so not isolated), 16 out of 66 respondents ie a quarter, state that they have instruments isolated from the engine which is probably the best indicator of whether the engine was originally built isolated or not (the percentages reported in the poll against each choice appear to be against the total number of all engines whether petrol, diesel or outboard so are low for all choices). It is likely that the total number so fitted is higher than this as many would not know if this was so or not on their own engines. Even if only a quarter, I would not regard that as a small number.
You use words to the effect that the danger from arcing is small. I suspect that it is no smaller than some of the other things people take care to protect themselves against on board. As I said earlier, I know of 2 forumites (active forumites so out of quite a small population) who have had such fires on board. I am in NZ and the majority of forumites are in the UK, so it has only been by chance that I know of those two, so quite probably more.
At least we all seem to agree it is a personal choice.
There, you have been "honoured" with another post /forums/images/graemlins/smile.gif.
John
I think if you look at Nigel's poll and consider that the isolated components are likely to be fitted only to diesel engines, you will find that quite a high percentage are isolated.
Currently, assuming the probable case those with isolated components are all diesel (eg petrol engines have spark plugs, the ignition return being back through the engine so not isolated), 16 out of 66 respondents ie a quarter, state that they have instruments isolated from the engine which is probably the best indicator of whether the engine was originally built isolated or not (the percentages reported in the poll against each choice appear to be against the total number of all engines whether petrol, diesel or outboard so are low for all choices). It is likely that the total number so fitted is higher than this as many would not know if this was so or not on their own engines. Even if only a quarter, I would not regard that as a small number.
You use words to the effect that the danger from arcing is small. I suspect that it is no smaller than some of the other things people take care to protect themselves against on board. As I said earlier, I know of 2 forumites (active forumites so out of quite a small population) who have had such fires on board. I am in NZ and the majority of forumites are in the UK, so it has only been by chance that I know of those two, so quite probably more.
At least we all seem to agree it is a personal choice.
There, you have been "honoured" with another post /forums/images/graemlins/smile.gif.
John
sailorpop
New Member
Where is the best place to get an "Isolated Lucas Marine Alternator" rebuilt or purchase a rebuilt one?
Do they still sell these new? If so where can I get one?
Do they still sell these new? If so where can I get one?