Variprop won’t go astern

[Rigger]

Final day of a weeks cruise. Engine performed perfectly until entering berth tonight when engaging astern led to surge forward. Further investigation showed shaft rotating correctly forward and astern so presumed must be a problem with the prop. Prop is a Bruntons Variprop.
Dive overboard revealed large amount of fouling on prop definitely preventing blades rotating. All fouling removed. There appeared to be some play between the prop and the shaft, and unfortunately I still get forward drive in reverse gear. Any ideas as to what’s wrong ?
Thanks in advance

 

[penfold]

Play needs to be defined; feathering props like this rotate relative to the shaft, with the angle of the blades controlled and synchronised by what amounts to a differential with a sun wheel typically fixed to the shaft and planet gears on each blade. Depending on the make wear elsewhere may be repairable through replacement of parts or machining. Regardless of make the boat needs slipped and the prop dismantled, cleaned and inspected.

 

[Tranona]

A VariFOLD is a folding prop and an AUTOprop is a variable pitch prop. Assume it is the latter and the blades are not rotating into the reverse position. should not be any play between shaft and prop as the prop is keyed to the shaft as well as being on a taper. should not affect the rotation of the blades though.

 

[penfold]

A VariFOLD is a folding prop and an AUTOprop is a variable pitch prop. Assume it is the latter and the blades are not rotating into the reverse position. should not be any play between shaft and prop as the prop is keyed to the shaft as well as being on a taper. should not affect the rotation of the blades though.

Bruntons seem to have held a franchise for the SPW Variprop feathering propellor at some point, it maybe this is what the OP has.

 

[Rigger]

A VariFOLD is a folding prop and an AUTOprop is a variable pitch prop. Assume it is the latter and the blades are not rotating into the reverse position. should not be any play between shaft and prop as the prop is keyed to the shaft as well as being on a taper. should not affect the rotation of the blades though.

It is a Variprop. I don’t think they make them anymore. The blades rotate and don’t fold. The play is about 10 degree on the shaft but I was assessing underwater so not the easiest to measure

 

[Tranona]

It is now called the Autoprop - same design. There should be no play and sounds like the prop has come loose and will move forward on the taper for forward drive.

 

[penfold]

I don't think telling the OP they're wrong about what's on the end of their propshaft is productive; until it's slipped, dismantled, cleaned and looked at it's all academic anyway.

 

[Arcady]

Hmmm. Not wishing to be unduly pessimistic, but I experienced exactly those symptoms with my Variprop on our last boat. It turned out to be some fractured gear teeth in the hub that ultimately required a new prop. Not a cheap solution. Here’s hoping that’s not the case for you.

 

[Arcady]

Additional thought for the OP: after you cleaned off the fouling and dived on the prop, did you check that you could rotate the blades through the full 180 deg + ? If you were unable to, that might suggest a problem internal to the hub.

 

[Rigger]

Additional thought for the OP: after you cleaned off the fouling and dived on the prop, did you check that you could rotate the blades through the full 180 deg + ? If you were unable to, that might suggest a problem internal to the hub.

Yes I could rotate fully. I’ve spoken to Bruntons and the only thing they can suggest is the blades are over rotating ie to a forward thrust pitch. Possibly due to a sheared stop pin internally. I’m arranging for a lift and to take the prop off. Unfortunately that’s not easy as I also need to remove the rudder due to lack of space. Luckily I have the old fixed prop which I may well end up re fitting. ( Anyone want to buy an old Variprop which works fine goimg forward!!!)