As an aside from all of this railway modelling, I’ve managed to do a bit of work on a boat.
“Little Miss Minty”’s biggest problem was the coupling between the motor and propshaft. I had used molybdenum tube but this kept failing. It looked like that I’d need to do major surgery to get a conventional coupling to fit – they were all too long for the space available.
At the boat show when I wasn’t buying new kits (yes more projects, but I only go to one big boat show a year so I have to stock up OK !?) I took a look at the Deans Marine stand where they had several couplings. These look like they are modular and the smallest version looked promising. At seven quid it wasn’t a cheap bet but I though I could always use it on something else if needed.
An initial check showed things looked promising. All I had to do was release the motor from its mount with a bit of screwdriver fiddling. The access wasn’t easy but I managed by using a combination of tools. If I had planned better perhaps I’d get a straight run at the screw heads but then I don’t intend taking the motor out much.
The couplings input & output shafts were 2.6mm. This is fine for the motor but my enlarged propshaft was too big. A few minutes with drill and reamer cured this giving me a nice snug fit. Happy I reassembled everything.
Once I’d done this I rotated the prop and noticed it caught on the hull. A quick look showed it had moved backward by about 4mm. The problem was that the propshaft was as far into the coupling as possible and it wasn’t enough. I did ponder living with it but gave in and took everything to bits again.
A big fat pair of wire cutters dealt with the excess shaft with a bit of a struggle but they did it. I then put it all back together. Result a nice free running propeller which under power is quiet and therefore efficient. I haven’t had a chance to try the boat on the water but hopefully (fingers crossed) this won’t result in another drive failure in the middle of the pond.
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