Anyone got a shaft brake on propeller shaft?

[Anonymous]

Before you fit the shaft brake, I suggest you jury-rig some kind of brake to allow you to assess the reduction in speed you will experience when you stop the shaft turning. I lose between half and three-quarters of a knot at around 6.5kts. In my case I am saving up for a folding prop and will then stop the shaft but you said that a folding prop is not suitable for you....you will lose speed, I think, but do try it out first as some people claim that their speed increases /forums/images/graemlins/confused.gif

 

[BrickSailor]

Two things here -
I also have a 20ish ton long keel boat, and fitted a Bruntons Autoprop (at vast expense!) which does a wonderful job of improving motoring speed, reducing propwalk and reducing sailing drag. It doesn't, however, stop the shaft turning completely when sailing.
Since I also have a hydraulic gearbox this was a problem. I understood that the reason the shaft musn't be turning is that the gearbox relies on engine oil pressure for lubrication of the operating mechanism. This is not to be confused with the gearbox oil which lubricates the gears themselves, hence the fact that they say up to six hours at a time is OK.
I looked at shaft brakes, but thought that having already given one arm and one leg for the prop, sailing could be a bit tricky if I now gave away the others. I have found though that a line looped round one of the coupling bolts tied to one of the cabin sole beams works a treat!