My prop just fell off

[markleuty]

We had a new prop fitted on our 40 ocean in May 2017 (we also had one fitted in May 2012) because the rubber thing in the middle had worn and apparently you can't replace just that part... (it's a sail drive).

Today as we arrived at the marina, I suddenly lost the ability to go backwards or forwards, so I assume it is the prop that is missing. I checked the cables and they seem to be engaging the gears correctly.

Anyone have any ideas why I'm getting through so many props?

It is fixed prop and I put her in reverse gear when sailing.

Mark

[Symphony]

If your prop has actually fallen off then it is likely because the locking screw has undone, either because it was not done up properly or more likely the screw was re-used without any thread lock. Ideally the locking screw should be replaced with a new one each time, although correctly applied loctite is satisfactory.

[Boatname]

Don’t understand why you think the prop is missing.

Turn on engine.

Select forward gear.

Are you getting prop wash?

[tckearney]

I Had exactly the same problem leaving a marina once.  I also checked the cables were engaging the gears.  I managed to get back in to port and lift out.  Could not find anything wrong.  While in the sling I put it in gear both forward and revers with no engine running and could not turn, as you would expect.  Changed the prop for my spare and away again.  I then took the prop to the workshop expecting to find the rubber bush between prop and hub had given way but could not find anything wrong with the prop at all.   I never did get to the bottom of it and its never happened since.     As mentioned in the last comment, if you’ve lost the prop then it wasn’t fitted properly last time. 

[Odysseus]

It's common occurrence for fixed Volvo props to fall off.

Did you put Loctite 243 on All of the bolts  

It's critical.

Odysseus
Bag 38

[Yngmar]

We also have a 40 Ocean with a Saildrive 120S-E and a 3-bladed fixed Volvo aluminium prop. It's never fallen off yet. Whenever I reinstall it, I put some blue Loctite (medium strength threadlocker) on the bolt and torque it and the cone up correctly.

I do this myself of course, like all maintenance work. Maybe your problem arises from "having things done" instead of "doing things"? I've found in any industry, and certainly the marine industry, work is done poorly much of the time, unless closely supervised.

[MarkTheBike]

...It is fixed prop and I put her in reverse gear when sailing...

As an aside, Volvo recommends letting the prop spin in neutral when sailing ( MD2030D handbook). Something about lessening wear on bearings or keeping oil moving. I wouldn't be surprised if other VP manuals say the same (e.g.  www.catamaransite.com/files/Volvo_Penta_MD22P_Instruction_Book.pdf Pg-21). I was further convinced in YM that a locked 3-blade prop creates lots more drag than a spinning prop ( https://www.yachtingmonthly.com/gear/lock-prop-let-spin-29526 ). I guess my 2-blader will act the same but with less drag overall. I note it says it's OK if you can lock a two-blader in line with a keel - we can't do that so I leave my spinning but the noise drives me up the wall and makes the rope-cutter mandatory...

Hope this helps

[JEN-et-ROSS]

Fixed blade props all create more drag if locked, so logically they should be left to spin in neutral.
On the other hand folding props like the 3-blade VP we have will start to spin in neutral just like the fixed bladed ones and so create similar drag, so they should be popped into gear to stop them spinning and the water flow will closed the blades.
As for feathering props...?...I've no idea...

[Symphony]

Same with feathering props, the recommendation is put in reverse and the blades align with the waterflow.

Although the recommendation for fixed props is to allow them to spin many people (including me) leave in reverse with no ill effects. Trade off between noise and drag.

[Ricd]

Pretty sure D1-30 manual states put gear into reverse when sailing. Checked this specifically last year when installed new engine/ saildrive.  It’s also something I have done for 25 years without issue. Can’t bear the noise from a prop turning under sail

[Ricd]

Pretty sure D1-30 manual states put gear into reverse when sailing. Checked this specifically last year when installed new engine/ saildrive.  It’s also something I have done for 25 years without issue. Can’t bear the noise from a prop turning under sail

Just read manual and I got it wrong...states reverse for folding prop and neutral for fixed blade. I hVe a fixed blade but will continue to knock into reverse when sailing...nothing worse than the noise of a whining prop while under sail. As Insaid, 25 years without an issue. On the drag issue, watching others sailing I am convinced there drag from the prop is the least of their worries 🤫

[markleuty]

Thanks for all you replies, we're having her lifted out in the next couple of days so I'll see exactly what has happened. And yes, Yngmar, I ought to be doing more of this myself..

Where do you find out information about torque settings?

Mark

[Symphony]

Don't think there is a specific torque setting for the locking screw. Just do it up as tight as you can with the normal allen key - and either use a new screw which has an insert of locking compound or use loctite. You can use the general torque settings for the size (google for tables) if you wish.

[Yngmar]

Here are my notes for the saildrive bottom from last time. Torque values are mostly from the workshop manuals, or generic tables for stainless bolts:

Prop shaft housing: Loctite on bolts (allen), then 30 Nm

Drain plug, soak fibre washer in oil for 15 minutes before installing. 10 Nm

Anode bolts (flat blade) 12 Nm

Propeller cone 70 Nm - grease splines first
Cone lock bolt 20 Nm - with Loctite on threads

[markleuty]

had her lifted out, it's not the prop. It's internals... :-(