propeller shaft brake

[superboots]

I want to make and fit a brake to my propeller shaft 35mm. There is not enough clearance between the shaft and the hull to fit a disc for a calliper - like automotive disc brake so I am thinking to fit an actuator with a curved shoe - 12 volt control from wheel is an advantage. Anyone made a similar addition? Or know where I can get information. Purpose made ones (Lancing Marine) are bulky and expensive

 

[Bobc]

Why not just fit a feathering prop. Far more efficient.

 

[RunAgroundHard]

I have have used a leather belt and mole grips to clamp the leather and react against the side of the hull; works fine but a faff. The leather allows the shaft to rotate while you pinch it and fit the mole grips and compress.

The other way I was figuring, but did not do it was to use two V blocks, mounted so they are a loose fit, then a device to clamp them in place around the shaft. I never progressed the idea as it is not an issue for me, despite drag.

Yes, a folding or feathering propeller will be the replacement one day.

Good luck with your shaft clamping.

 

[davidej]

Putting the engine in gear works for me.

 

[superboots]

Using the gearbox to stop rotation means selecting reverse gear - its then very difficult to disengage so want something easier that I can fit without a lift out and which is not expensive - unlike a feathering prop which also has other issues

 

[vyv_cox]

Using the gearbox to stop rotation means selecting reverse gear - its then very difficult to disengage so want something easier that I can fit without a lift out and which is not expensive - unlike a feathering prop which also has other issues

Start the engine with the gear in reverse. It is then easy to put it into neutral and forward. We have been doing this for 20 years without any negative effects.

A Bruntons feathering prop will continue to rotate in neutral but reverse on our Yanmar gearbox arrests it.

 

[Tranona]

Using the gearbox to stop rotation means selecting reverse gear - its then very difficult to disengage so want something easier that I can fit without a lift out and which is not expensive - unlike a feathering prop which also has other issuest research

Shaft brakes are things of the past and there is not an elegant way of designing one. In a previous life I investigated the market having designed what I thought was a possible solution, but my market clearly led to the conclusion that there was no viable market. As suggested the arrival of proper folding and feathering propellers killed it.

What "issues" do you see with feathering props? Apart from cost difficult to think of any downsides.

 

[Sneaky Pete]

Just a thought 35 mm is about the width of a bicycle wheel, could you rig something up using a block brake caliper and a cable to the handlebar lever a simple locking latch would hold the lever closed when clamped.

 

[rogerthebodger]

Have you considered using a bicycle disc brake and caliper

bicycle disc brakes - Google Suche

 

[onesea]

Putting the engine in gear works for me.

Until you have hydraulic gear box.
When we had this issue we tied to a strong point a short length of pushbike inner tube tube to a strong point.
Then we wrapped it round the shaft it self tightened if you forgot to remove it broke. No other damage done.

 

[Graham_Wright]

Whatever you fir, don't forget to release it before running under power. A friend of mine had a major fire due to forgetting.

 

[superboots]

Thanks I have given this more thought. Bicycle brake won't work because not enough space between shaft and hull.
I will use an automotive 12 volt actuator wired to ignition switch (to avoid accidental misuse) . Method of engagement with the shaft is still under consideration - coupling looks a possibility

 

[superboots]

But wondering about power/ strength of the actuator -

 

[Tranona]

If it helps my abandoned design had a disc flange in the coupling and a piston that was located in one of 2 holes to line the 2 bladed propeller in a vertical position. Disengaged and locked when not in use. The main market for shaft brakes on smaller yachts was to reduce drag when sailing. Of course a I suggested earlier redundant with the advent of folding and feathering propellers. If you just want to stop the shaft from turning with a mechanical box just put it in reverse. If you want to both do that and gain an average improvement is speed under sail of between 0.5 and 1knot, fit a feathering propeller.