Electrical Faults

[oceandawn]

Hi Would anybody know what would cause a major power surge which short circuited  the starter system resulting in a burnt out motor,  frizzled cables and a melted isolater switch. The boat was not in used at the time but in a boatyard.We are at a loss. We managed to obtain a starter motor from a company in Plymouth. Excellent service next day free delivery. Worth knowing in the future for motors and alternators.Thank you in advance .

 

[Turnoar]

Struck by lightning?

[Turnoar]

I almost set a yacht on fire once trying to start the engine. I gave up after a while and with a bit of smoke having been generated, which I’d wrongly assumed but an exhaust leak or drawn back in to the engine bay, an emerging electrical smell gave a clue and the smoke built so having taken the gas bottle off the vessel and someone letting an extinguisher off all was safe again. Investigation found a nail in lieu of a fuse but could a wrongly rated fuse cause this much damage in your case?

[grendel]

Now I could see a burned out starter motor shorting the system and frazzling the wiring, but not the other way around

[oceandawn]

Hi The key apparently got stuck and wouldn't turn but worked ok when the other wiring bits were sorted so don't think it was the switch.Wrong key perhaps.Really bemused.

 

[MargeandParge]

I've known them to stick engaged and they are then turned by the engine once started creating a dynamo, alternator effect.  That fries wires big time. 

Kindest Regards Marge and Parge 

[BrundallNavy]

7 minutes ago, MargeandParge said:

I've known them to stick engaged and they are then turned by the engine once started creating a dynamo, alternator effect.  That fries wires big time. 

Kindest Regards Marge and Parge 

I believe this is what happened to the boat at Loddon. 

[oceandawn]

That is our concern not knowing.Our feeling was that the key had jammed or the wrong key used.Either way worrying to leave it. The whole boat was professionally rewired four years ago so the wiring is good. Happy Days.Many Thanks for the replies

[Smoggy]

2 hours ago, grendel said:

Now I could see a burned out starter motor shorting the system and frazzling the wiring, but not the other way around

Like wot he said, a short anywhere other than the starter motor would just cook the wiring, why would the key be in use if the boat was not in use? I know on my volvo's if the key is in the engine stop position instead off the fully off position the fuel solenoid is powered up but not linked to starter circuit and only likely to flatten battery or burn out fuel solenoid.

Always good to turn battery isolators off when leaving boat for any length of time, I always do between visits as well as seacocks and gas.

[oceandawn]

The boat was having work done in a yard so presumably moved around.It wasn't until it was being returned that one engine wouldn't work and the key wouldn't engage.We assumed that is was just the motor until further investigation revealed the extent.We were not  with it so it is difficult ascertain how  it all happened.

[annv]

Hi Ocean Dawn What can happen with inert a starters is pinion jams on flywheel ring gear then if key turned to start will fry the starter which then overheats solenoid causing it to stick/weld its contacts closed creating a dead short. If a prengage starter its either the solenoid or the key that gets stuck turning it into a motor which if left running will burn out the starter motor as they are only designed to run for short time ie engine starting,They can also stick on the armature shaft then when engine starts will be powered by the ring gear which then burns/shorts the windings in the motor turning it into to a dynamo  if this happens you only get a humming sound from the motor spinning, easy to hear on a car but sound proofed on a boat, Hard to start engines also cause overheating of starters. John