Ideas please for clamp to use as a shaft brake

[pcatterall]

I posted recently about the advisability of stopping the shaft while sailing. The consensus was that I should try to stop the rotation of the prop as I have a hydraulic TMP gear box. I want to make a simple brake ( I can stop it with my hand so not a lot of friction would be required)

I had thought that something like a laboratory retort holder might be adaptable ( these have a cork lining on the arms and a simple wing nut is used to tighten the clamp. I like something along these lines as a mistake in starting up would probably not do any damage. A simple cantilever bike brake might work with a lever to hold and release the cable. Possibly there are other similar devices which some of you may have seen which could also be adapted and I will value information on these. I know that some of you have adapted a bike disc brake but I would prefer not to fit anything to the shaft (Its 30mm by the way).
The best place to fit such a device in my boat is under a simple small sole board where there is a substantial wooden beam around 180mm above and across the shaft.
Its just some ideas for the main 'gripping/clamping’ part that I am after rather than a debate about folding props or the efficiency of the prop being locked or free.

Thanks guys.
( PS I am still having to paste my posts as there are still problems with missing key strokes )

 

[jerrytug]

How about an oil filter strap wrench?
How about a simple hardwood wedge?

In fact, how about a length of old jackstay webbing. one end screwed to a suitable beam. The other end wrapped around the shaft? The turning force from the prop would hold it tight. Job jobbed, one guinea please.

 

[Robin B]

Land Rover handbrake? Brakes the prop-shaft

 

[paul-essex]

how about fix one end of a bit of rope pass it around the shaft a few times and tension it of if it dose not grab enough add another turn. When released the shaft should spin inside the coil (we hope )��

 

[Lakesailor]

here is a Rolls Royce solution.

However a similar clamp is available from photographic manufacturer Manfrotto. I have one myself.

 

[Spyro]

Mole grips?

 

[TimBennet]

Try a bicycle disk rotor mounted on the shaft coupling and then an Avid cable disk brake operated from the cockpit.

 

[longjohnsilver]

I posted recently about the advisability of stopping the shaft while sailing. The consensus was that I should try to stop the rotation of the prop as I have a hydraulic TMP gear box. I want to make a simple brake ( I can stop it with my hand so not a lot of friction would be required)

I had thought that something like a laboratory retort holder might be adaptable ( these have a cork lining on the arms and a simple wing nut is used to tighten the clamp. I like something along these lines as a mistake in starting up would probably not do any damage. A simple cantilever bike brake might work with a lever to hold and release the cable. Possibly there are other similar devices which some of you may have seen which could also be adapted and I will value information on these. I know that some of you have adapted a bike disc brake but I would prefer not to fit anything to the shaft (Its 30mm by the way).
The best place to fit such a device in my boat is under a simple small sole board where there is a substantial wooden beam around 180mm above and across the shaft.
Its just some ideas for the main 'gripping/clamping’ part that I am after rather than a debate about folding props or the efficiency of the prop being locked or free.

Thanks guys.
( PS I am still having to paste my posts as there are still problems with missing key strokes )

I had the same problem stopping my prop spinning on a swinging mooring with very fast currents. Tried all sorts but the most effective was fishing line. Worked well, and even better, if I ever forgot to remove it, it simply snapped so caused no damage and was simple to replace.

 

[TQA]

I have used a piece of string with a loop placed on a coupling bolt. Sized to break if someone puts the engine into gear.

A pair of mole grips.

Both do the job.

 

[TQA]

I have used a piece of string with a loop placed on a coupling bolt. Sized to break if someone puts the engine into gear.

A pair of mole grips.

Both do the job.

 

[Piers]

Hi pcatterall. Haven't seen your previous post re the advisability of stopping the shaft. Is your prop a fixed prop? If so, I believe you'll find that the drag of a stopped prop is more than a prop that's free-wheeling.

 

[MrCramp]

You can get very big plastic clamps, rather like very big clothes pegs, which should be OK to hold the shaft stationery but would not cause damage if you forgot to remove it. Aldi an Lidl sell them sometimes but I think you will get them at any DIY store.

 

[pcatterall]

Thanks guys. Some good practical ideas there. I have considered mole grips but was worried that forgetting them could cause damage or at best they would have to be fished out of the bilges!
Piers... we will have to put p with extra ( small) drag.
I will look for those 'extra large clothes pegs' and that camera type clamp looks possible but not sure of its 'robustness'
I like the string on a coupling nut idea though access to the coupling is less easy underway.
Wedge type solutions and friction straps would work but I don't like the idea of putting unopposed forces on the centre of the shaft.
Thanks again

 

[rjp]

Your 30mm shaft is not far off the width of a standard bike rim, so I wonder if a bike brake caliper could be arranged to grip the shaft. There is then the possibility to mount a brake lever remotely via a standard cable. If you could arrange a simple latch to hold the lever on, that would lock the shaft, unlatch and the shaft is free. All off the top of my head, but I don't like the idea of having to dive under the cockpit sole or engine cover to release some device if I need to use the engine in a hurry.

 

[Lakesailor]

that camera type clamp looks possible but not sure of its 'robustness'

You won't break one. They are made from a cast alloy.

 

[Greenheart]

I was thinking mole grips, just as I read it in an earlier post. I'm assuming you'd park the grips in a place where there isn't room for them to rotate without contacting the hull?

Given that the shaft can be prevented from turning with a hand's grip, wouldn't it be smart to glass a ribbon of grp around the shaft to provide better roughness for the grips to hold on to, without necessitating excessive tightness?

A few feet of burgee halyard between the grips and a secure spot within reach, and there'd be no danger of the grips dropping irretrievably into the bilge.

 

[pcatterall]

Your 30mm shaft is not far off the width of a standard bike rim, so I wonder if a bike brake caliper could be arranged to grip the shaft. There is then the possibility to mount a brake lever remotely via a standard cable. If you could arrange a simple latch to hold the lever on, that would lock the shaft, unlatch and the shaft is free. All off the top of my head, but I don't like the idea of having to dive under the cockpit sole or engine cover to release some device if I need to use the engine in a hurry.

Yes, thanks rjp that is one of my possibilities . I thought to modify the 'shoe' to increase friction.

 

[ghostlymoron]

I presume it's to reduce the annoying noise in your aft cabin rather than to reduce drag (which it won't). My mothers walking aid has got a lock on handbrake (cable operated) which could be modified to act as a shaft brake. Get down to Able World.

 

[theoldsalt]

As has been hinted at in previous posts, I think it is important to consider the consequential effects of forgetting to remove the device before starting the engine and putting it in gear - whichever solution you choose.

 

[Greenheart]

My mother's walking aid has a lock-on handbrake (cable operated) which could be modified to act as a shaft brake.

Or, you could cut a 9" stone-cutting disk in half, after drilling out the centre-hole to 30mm...then weld it around the shaft and align a bicycle disc-brake to stop it, as & when...

...and if ever you want to cut some patio slabs to size for really artistic aft-deck crazy paving, just fire up the diesel.