Burnt out starter motor

[NigelFortune]

On a recent passage to Greystones from Holyhead in my Sigma 33c we had an exciting time F6 gusting F7 and 2.5- 3.0m seas. During the passage we took several "green uns" over the bow and into the cockpit. To speed things up we decided to motor sail as the furled Genoa was not being too efficient. One of these waves dumped several gallons of saltwater that ran down the port gunnal and onto the instrument panel located on the inside of the transom. There is a Perspex cover that I manufactured that covers the panel mainly meant to keep the rain off whilst in dock which we did fit when we saw the sea state.
After 20 or 30 mins we had and electrical problem. All the instruments died for my sailing companion who was down below said that the engine sounded differnt for a few seconds then returned to normal noise.
We motored into Grey stones tied up all ok. Two days later decided to go up to Dunloghaire when tried to start engine nothing happened. After an hour a fault finding found starter motor to be shot. Removed motor and stripped to find commutator completely stripped from shaft and brush gear totally mangled. Order new motor through Bryco in Daventry turned up 2 days later fitted all ok.
Was only after our return did we realise how lucky we had been. I believe that the water had got into ignition switch and shorted out the start contact, engaging the starter motor while the engine was running. The motor showed signed of getting very hot the insulation on the solenoid had melted and the paint was blistered. We could have had a problem if we had switched engine off while it was blowing as we were both nackered and had to negotiate the marina and also a strong possibility of fire.
I have now ordered a new ignition switch and looking at making a more waterproof cover.

Nigel

 

[William_H]

Yes starter motors do not like to be engaged when the engine is running. The power to the solenoid would have thrown the pinion into the ring gear.
This causes the stater motor armature to be rotated very fast causing parts to depart under cenripital force. The current ot the starter motor itself has little effect, it is that mechanical engagement with engine doing say 2000RPM and a gear ration of perhaps 20 to one makes starter turn at 40 000 RPM a bit cruel.
It would have made a strange noise for a short while. Although in some starter designs the pinion might have been throw out by the drive. If it has a twisted spline. Not so for a straight spline. So yes another thing to watch out for in rough weather. Perhaps you might want to fit a further isolation switch to the starter circuit. good luck olewill

 

[NigelFortune]

Yes I actually fitted a gash on/off switch in the starter wire to the solenoid to make sure I didn't repeat the process with the new motor. The Bosch starter motor did not have a "bendix" type starter gear. It had an electromagnetic clutch that was actually still working after I removed it.

 

[30boat]

I never liked the engine panel to be exposed so when I got my boat I installed it under the companionway. It's still accessible from the cockpit but stays dry all the time.