Sunday, 14 June 2015

Sorting out the gremlins...

My previous work had left us with a new new control unit but also a couple of troublesome issues which took a while to sort out and, for a while, baffled a variety of canal engineers...

The first problem was that the engine would mysteriously cut out for no apparent reason when put into gear. It would start OK but then when the throttle lever was returned to upright position would quietly die... 

This made it pretty difficult to carry out most manoeuvres such as setting off from a mooring or winding. Pretty much anything really... Once restarted it would run fine.

At one point I even had to abandon the boat by the side of the canal at Wrenbury Mill and yomp back to the marina in order to go down to Worcestershire for (irony of ironies) a boat maintenance course! I picked the instructor's brain about possible causes, all of which sounded potentially expensive.

Alison and I returned to the boat the following weekend ready, if necessary to bow-haul the boat 4 miles back to the marina. We had the engineer from Wrenbury Marine on the boat for about two hours trying to locate the problem. He could replicate but not identify the issue.

This was eventually solved by a guy walking his whippet along the tow-path. He asked whether we had checked the stop cable... Turned out that the throttle cable was just touching the stop cable and would pull it enough to stop the engine whenever it was put into gear! The engineer, who had returned (100 yards) to base to consult with colleagues, was amazed when I wandered along to tell him that I had fixed it!

The second problem was an annoying problem with the alternator which would randomly decide not to charge the batteries. Would be fine when starting off from the marina but after spending a night moored somewhere else would fail to generate.

After removing the alternator, getting it refurbished, checked and tested didn't solve the problem, I eventually tracked this down (thanks Google!) to lack of excitation!

Apparently alternators need some current up front so they can remember what electricity is... This is normally provided through the warning lamp on the control panel.

Now... I had replaced the old style warning lamp with a nice purpose built job with nice neat symbols on it. Turns out that this does not draw enough power to excite the alternator... It was presumably OK when starting from the marina because the batteries were fully charged from the shoreline.

However after mooring overnight, the batteries were still plenty charged to turn and start the engine but not enough to excite the alternator.

I fixed this while moored in Middlewich at the Folk and Boat Festival by putting an old style bulb in parallel inside the control box. Now works fine. Go figure!

Since then things have been fairly trouble-free. (Did I really say that.... Touch wood!)

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