Thanks JB, look forward to an update in due course.
Rowen

Hi Rowen, unfortunately, still waiting for it to arrive. I'll be trying to make some stepped bolt on adaptors for either end, (motor and d-shaft) now I have the lathe, to make them easier to fit. They will probably end up like the one pictured, but with the silicone between the two rather than a plastic universal.

JB

Hi JB,
Did you ever try out that tubing?
Best
Rowen

Hi Rowen, have just ordered some thick walled silicone tube to try - 3mm ID x 7mm OD, for fitting straight on the shafts-(3 and 4mm) and some 6mm ID x 11mm OD for trying with the adapter idea. Might be here in a month or so if I'm lucky (or if at all)

JB

Thanks JB, our winters can be long. If you come up with a better installation please drop me a note.
Unlikely to make much progress until the beginning of the year as have two other projects would like to finish first
Rowen

Hi Rowen, I'll be interested to see how you get on. I might have managed an improved system by then.

JB

Thanks Dave and Jbkiwi.
Much food for thought, but am now confident enought to continue.
The sailing season is all but over in Canada. Will upgrade a couple of models over the winter to silicone tubing.
Will report back next Spring with results.
Rowen

Hi Rowen
Small low powered models work fine with silicon fuel tubing as the power and revs involved are normally low.
As jbkiwi says he intends to use his lathe to make a more substantial fitting for small spaces.
On a more powerful planing type craft the revs and power will be much greater and more substantial silicon exhaust type tubing works better. Space will not normally be a problem. This does have a larger internal diameter so you do need a bush on both the prop and motor.

If you have access to a lathe then these can be turned from brass and grub screws fitted to lock. You may need to put a pin thro the silicon and bush if friction does not prove sufficient. Huco coupling brass inserts may also be used and as they are splined work well to grip the tube.

I have used both types with success, but would not personally use silicon with any brushless motor as they produce a great deal of power and need good a good solid mounting and drive train. Any problem with either and you are likely to see magic smoke or worse and there will be little or no warning, as I well know.
regards
dave

Hi Rowen, I've used silicone tubing for years on all my models as it's flexible, quiet and cheap. 4mm is a good size to fit the rc aircraft fuel tubing on, and as long as both shafts are cleaned of any oil, they will stick really well. They also have the advantage of breaking loose under too big a load, (such as a weed pick-up and stall situation) if your motor is strong enough.

For anything reasonably powerful, you can fit a firm plastic tube which just fits over the silicone, and force the silicone onto the shafts. My Hartley jet boat can pull 30A with a 3000kv 45D brushless inrunner on 3s, and it seems to handle it ok. On brushed motors or brushless inrunners, you will need to make a 'stopper' at the motor end to stop the tube migrating up to the front bearing, (see my vintage runabout post on this).

Now that I have the lathe, I will be working on a better system for utilising silicone tube, especially in confined spaces, as most of the couplings of this nature (I think CMB sell a few of this style with a captive silicone or rubber insert) are too long for a lot of tight spaces (not to mention expensive.

JB