One arm of folding prop missing - do I need to take out the boat to fix it?

[thunderhoof]

I see in the manual that the blades are numbered 1-4. see picture b:4. The blades may be balanced a set. You should query Volvo about whether you need an entire set of blades, or that you need to respect the numbering, i.e.; if blade 3 is missing you need one with number 3.
This is another reason to have a diver remove the prop.
My major concern is that the blade went missing for a reason. For example, if the set screw was overtightened, stripping the threads. That would mean any replacement set screw would probable work loose.

Another issue is that Loctite will not set properly under water. It should be applied with the prop out of the water.
BTW, buy replacement zincs and install them.

[DougR]

Without knowing the brand of propeller it is difficult to say too much, but most of what applies to Volvo 4 blade will also apply to FlexOFold....

I’ll make a few comments about the Volvo folder, as that is what I have experience with....
- you don’t have to worry about the “key” as mentioned by another poster because if it’s a saildrive application, there is no key, and if it’s a regular inboard the original key is still in place because you didn’t loose the hub, only a blade.
- thanks to Dsanduril you now have an installation manual and can see how they go together.
- the attached photos show the general configuration, where the head of the Allen screw keeps the blade mounting pin in position. This means that you should not run the prop because if one screw is missing then two pins can escape and you might loose another blade.
- If you want to try and run the engine with only two blades, you still need all four screws in place to avoid loosing the pins. If you run only two blades, then the blades won’t be geared together and opening in reverse might be marginal, but still better than nothing..
- the blade numbering system ( number 3 which you see in the foto)is used to make sure the blade teeth mesh correctly and all blades open and close the same amount.
- you can buy a blade set separately from a whole prop, but I am not so sure that you can buy just one blade....
- there should be a number cast or stamped onto/into the outside of the blade near the pin end which identifies the Pitch/diameter of the set. This is not the part number of the set , but can be used to identify the part number.

Any other questions about a Volvo prop, feel free to ask.

[MathiasW]

Thanks for all these very helpful comments and suggestions. Really much appreciated.

I will stay put here at anchor and not move, if I can help it, until I have all parts and have at least a temporary fix.

[JPA Cate]

@ Mathias W:

Not too nice being stuck at anchor without knowing how to move the boat. Have you considered hip tying your dinghy to one of the hull's quarters, and using it to propel the boat around to the shipyard? If your weather is going to be stable long enough for your to get all the parts, delivered, that's one thing, but if not, you'll need a plan to get somewhere safe.

I am not aware of loctite that can be used under water. If it is required for your prop, then the prop repair should be done out of the water. My concern here is that you may lose other blades, if they weren't properly fixed from the beginning, and so you will want to re-do all the set screws, for peace of mind.

Imo, you will do far less collateral damage, using the dinghy to move the boat than by running the ship's engine while everything is so out of balance.

Ann

[MathiasW]

Originally Posted by JPA Cate

@ Mathias W:

Not too nice being stuck at anchor without knowing how to move the boat. Have you considered hip tying your dinghy to one of the hull's quarters, and using it to propel the boat around to the shipyard? If your weather is going to be stable long enough for your to get all the parts, delivered, that's one thing, but if not, you'll need a plan to get somewhere safe.

I am not aware of loctite that can be used under water. If it is required for your prop, then the prop repair should be done out of the water. My concern here is that you may lose other blades, if they weren't properly fixed from the beginning, and so you will want to re-do all the set screws, for peace of mind.

Imo, you will do far less collateral damage, using the dinghy to move the boat than by running the ship's engine while everything is so out of balance.

Ann

Yes, indeed, I am very much aware of being a lame duck right now and the option of using the dinghy to get me into the marina had come to me. I will make use of it should I see the forecast for the weather deteriorating. For now the weather forecast is ok, and we have been doing fine for 6 months at this anchorage already, but who knows how long it will take to get the parts.

The marinas charge the hell out of you here, and so I have to choose between pest and cholera, really.

[billgewater]

New blades are not cheap. Have you considered diving at the spot where the blade came off to see if it can be retrieved? It might show up on a good bottom scanning sounder.
What ever happens it seems as though it needs the usual balancing check and eliminating any bent shaft or damaged bearings issues. It may have been one of these issues that caused the prop blade to come adrift in the first place.
If the boat is never used for racing it may pay to consider replacing the entire folding prop. with a conventional fixed blade prop. It is not unusual for fixed props. to have no problems over many decades. Folding props. can get jammed from barnacles,rubbish etc., leading to all sorts of problems and damage. They need more TLC.

[MathiasW]

Originally Posted by billgewater

New blades are not cheap. Have you considered diving at the spot where the blade came off to see if it can be retrieved? It might show up on a good bottom scanning sounder.
What ever happens it seems as though it needs the usual balancing check and eliminating any bent shaft or damaged bearings issues. It may have been one of these issues that caused the prop blade to come adrift in the first place.
If the boat is never used for racing it may pay to consider replacing the entire folding prop. with a conventional fixed blade prop. It is not unusual for fixed props. to have no problems over many decades. Folding props. can get jammed from barnacles,rubbish etc., leading to all sorts of problems and damage. They need more TLC.

Deep mud in 5 metres or so - I do not think I have a chance. Plus, by now my position is likely 50 m away from the original position.

[mlydon]

For underwater repairs, there are threadlockers where you put a drop on the screw, then let it dry before installation. They use them on the screws that hold maxprop zincs on, among other things.

That being said, fully removing the prop from the shaft should be fairly easy, particularly compared to rebuilding the prop under water. I strongly recommend doing so, then rebuilding the prop on dry land(or cabin), then having it re-installed.

Matt

[DougR]

Originally Posted by mlydon

For underwater repairs, there are threadlockers where you put a drop on the screw, then let it dry before installation. They use them on the screws that hold maxprop zincs on, among other things.

That being said, fully removing the prop from the shaft should be fairly easy, particularly compared to rebuilding the prop under water. I strongly recommend doing so, then rebuilding the prop on dry land(or cabin), then having it re-installed.

Matt

An underwater thread locking compound might work to install the blades...

But, most folding prop hubs have to be installed and secured on the shaft before the rest of the prop can be installed, so the prop cant be assembled except after the hub is on the shaft.

[David B]

For an idea on how these props go together, have a look at this vid:

https://www.youtube.com/watch?v=fConQRkPfMM&t=74s

[MathiasW]

Thanks so much for all the detailed responses and suggestions received!

The shipyard has now come back with details:

Propeller VOLVO PENTA 4 folding blades:
REF MOYEU 3583927
REF KIT PALE HELICE 3583919

So, I will see to get the set of blades, also a new anode, excellent suggestion, and then take it from there...

[tdh1849]

I had a diver do mine at my dock, was not a big deal.

[GrowleyMonster]

Been there, done that. Working on a folding prop in the water is a big PITA. If you are just going to pin a new blade in, meh. Maybe do it in the water. The thing is, if you lost one blade out of four, with one new blade you will have three out of four suspect blades that you can't trust. I would pull it and give it a good inspection and replace anything that needs replacing. And since with most folding props you have to remove the blades separately before you can remove the hub, IYAM you should haul the boat out.



If you want to do it in the water, I suggest anchoring bow and stern in shallow water with sandy bottom. Cut a 8' x 8' piece out of an old sail, weight it down on the bottom. That's your parts catcher. They show up fairly well on the white sail material, should you happen to drop anything.



What is your draft? Can you anchor in water shallow enough to stand in? That makes doing this with snorkel (or without even a snorkel!) much more do-able, if you do not have scuba or hookah gear. A good diver with proper tools can have your prop off in an hour or less. So hiring a diver is still WAY cheaper than a haulout, if you are not comfortable with doing this yourself.



Getting the prop off is much harder than putting it back on. You might have a diver pull it and stick a fixed 3-blade on there if you have a standard taper shaft. Then when all is right with your folder, swap it back on yourself. If you lose something, stick the fixed prop back on temporarily again.


If you are ready for a bottom job anyway, or want a new through-hull or have some other reason to take advantage of a haul-out, haul her out for this. But I would buy a spare prop first. Then you can take your time repairing the old one, and have it for a spare while the new one is on the shaft. Don't use Loctite Red! Use the blue. And sparingly.

[fstbttms]

Having done this many times underwater, I can tell you that the most likely part that will trip you up is this little washer:



Once you realize that it is there and what has to be done with it, the rest of the R&R is fairly straightforward. But it sounds like you are only going to replace the blades which is much easier.

[Wayne Bostow]

Forgive my ignorance, but might it be possible to temporarily restore balance by removing the opposing ear? If you could pull the pin mentioned earlier, you could use the orphaned blade to order new, then perhaps pilot to a marina with the two ears? --WB