Lost propeller – a tale of slippery hubs

[Steve S]

I let my lad use Tigerfish and whats my reward. Phone rings, "hi Dad the port side propeller has gone!!"  "What did you do?" "Nothing, honest." "What did you hit?" "Nothing." "Have you been ragging the engine?" "No." Further questions ensued but if I believed him it must have come off in the Solent during normal motoring.

 

Tigerfish has 2 Volvo D4 260s with DPH drives with duoprops.

 

The rear port propeller, cone and nut had gone. It is not supposed to ever happen on DPH drives. I searched the Internet and found nothing to indicate loosing props from DPH drives was a problem.

 

I bought a new rear prop from Keypart, lower cost than direct from Volvo. On fitting it rubbed against the front prop, tried on the starboard side it rubbed on that side as well. On checking against the old rear prop the hub was in a different place, see the photo’s. I assumed the new hub must be made incorrectly, but on checking against a drawing it was the old one that didn’t comply. Basically the hub was 3mm further forward on the old prop, or put another way the props had moved backwards. I was starting to think something had happened to all the old props, this was confirmed by a chat to Propeller Solution who told it like this.

 

Over time the props move back on their hubs and after about 600 engine hours or more the rear hubs moves back so far that the prop starts to press against the cone, which presses against the nut. Result the nut comes undone and the prop is lost. All my hubs had moved by the same amount, around 3mm. I’ve now had them all rehubbed by Streamlined Propellers and with everything fitted Tigerfish is running fine again.

 

 

 

The new hubs have apparently some sort of lip which should stop this happening. The service schedule does not so far as I’m aware recommend checking for movement of the hub. I think it should. Volvo typically won’t admit the problem so I’m told.

 

So DPH drive owners I recommend checking yourself, the main thing to look for is that there is a gap between the hub and the cone. If not a lost prop is a possibility. Rehubbing is the lowest cost way to correct the issue, both front and rear props need to be done at the same time.

 

Adam very kindly lent me the cone off his boat, it's not going anywhere for a while...., they are out of stock at present.

[Mike Fox]

Astonishing!

 

Glad you found a root cause.

 

Will you lend him your boat again?

 

Mike

[great white]

Thanks Steve

 

Will check that carefully when the boat comes ashore

 

Charlie

[Steve S]

I think so, I don't think he did anything wrong. He told me he took it easy once he felt the engines were having trouble syncing.

 

Without trust the world's a poorer place.