Centerflex uncoupling

Centerflex uncoupling

3rd December 2010

Regular readers will know that Wand'ring Bark threw a coupling stud in the summer, or it may have broken years ago but only coming to my attention whilst we were on the Thames.

Coupling in place minus the offending stud

Having successfully crossed the Thames tideway, and then made it 150 miles back to Calf Heath, and then down to Gloucester and back up an in flood Seven, and then the Four Counties Ring plus the Caldon Canal it really was time to get the problem sorted out.

Coming loose

With a centimetre of stud jammed in the bottom of a threaded hole in the body of the coupling there was nothing to do but to get the unit out of the boat and onto the workbench at home and see if it is save able. I could get and engineer in to do the job but I get a real sense of achievement by doing these jobs myself, so I determined to give it a go. How hard can it be?

Stubbornly stuck on the propshaft

Answer - much harder than expected.

First I unbolted the three remaining nuts, two of which undid the studs from the housing which wasn't what I had planned. The gearbox didn't offer enough clearance to get them out so I ended up cutting them off. With the coupling detached from the gearbox the prop shaft slipped back and it was time to get the coupling off the shaft.

Popping of with the aid of a trade secret

I undid the  eight bronze bolts expecting the compression joint to pop free, but no such luck. I tried levering it off with an axe handle and the boathook, but all to no avail. In the end I despaired and called Phil Jones, my local boat engineer and sought expert support. He quizzed my enthusiasm for the ask and then let me in on a secret. Take two of the bronze bolts and insert them into two opposite threaded holed and crank them in gently. When they touch, grump them - which I took to mean give them some welly. I tried the technique and off it popped. Oh for a bit of know how!

The offending Centreflex coupling out on the deck - no going back!

Now the coupling is out of the boat I will see if I can get the offending stud out - who knows. A replacement unit will cost £200 so its worth a try.

More of the task another time.