Maxprop - Issues with Feathering

[OceanSeaSpray]

Originally Posted by Ex-Calif

I have a MaxProp Duo. Has never failed to feather. I pack it "full" of grease. I shut the engine off in gear (saildrive) then go to neutral.

Late in a hull cleaning cycle I did hear the tranny turning - so I know what it sounds like if it doesn't feather. There was enough buildup on the prop that feathering was not an option.

This is certainly a possible way of doing it as well and it avoids going into reverse.

Barnacles do mess them up, mine never refused to feather, but it won't pull. This seems even worse than with fixed props. Last time I was out, I had a go at doing my Max-Prop with a silicone-based antifouling coating (Prop-Speed), see picture attached. After considering my options, I ended up coating it in its fully assembled state. The trick was not moving it after cleaning it to prevent any grease from seeping out.
I expect zinc consumption to be well down too now.

[carstenb]

Originally Posted by OceanSeaSpray

This is certainly a possible way of doing it as well and it avoids going into reverse.

Barnacles do mess them up, mine never refused to feather, but it won't pull. This seems even worse than with fixed props. Last time I was out, I had a go at doing my Max-Prop with a silicone-based antifouling coating (Prop-Speed), see picture attached. After considering my options, I ended up coating it in its fully assembled state. The trick was not moving it after cleaning it to prevent any grease from seeping out.
I expect zinc consumption to be well down too now.

Do you have what may seem excessive zinc consumption? how often do ou change? When I had the volvo prop, I changed every year on haulout (regardless of what it looked like - just to be on the safe side) This haulout, however, the zinc on the maxprop was gone - as was the one on the drive shaft. I'll be diving on it over the summer to see what happens.

carsten

[Ex-Calif]

Originally Posted by OceanSeaSpray

This is certainly a possible way of doing it as well and it avoids going into reverse.

Barnacles do mess them up, mine never refused to feather, but it won't pull. This seems even worse than with fixed props. Last time I was out, I had a go at doing my Max-Prop with a silicone-based antifouling coating (Prop-Speed), see picture attached. After considering my options, I ended up coating it in its fully assembled state. The trick was not moving it after cleaning it to prevent any grease from seeping out.
I expect zinc consumption to be well down too now.

IIRC that Prop Speed stuff is pretty expensive. I have painted mine with urethane paint before. It wore off in no time and barnacle build up recurred.

Our waters are pretty fertile and the only hope is diving and wiping it monthly or so.

Let us know how you fare with the prop-speed.

[OceanSeaSpray]

My boat has had a Max-Prop on since the beginning, so can't comment about any differences there with zinc consumption with another prop.

It was very low initially, but it went up when I got rid of the flexible coupling that was just causing shaft stability problems. It also electrically insulated the shaft from the engine, now they are connected together.
Still, consumption is not tremendous. I still have some left after 18 months. Make sure you fully seal the water out around the stainless bolts holding the anode together. Put urethane sealant, epoxy paint, epoxy filler, tallow, lanolin, anything that will prevent water from getting between the stainless and the zinc, otherwise your anode eats away there at an accelerated rate and you end up losing it. It will last a lot longer if you do that.

Max-Props are known to be quite sensitive to lack of anodic protection, so careful there.

[OceanSeaSpray]

Originally Posted by Ex-Calif

IIRC that Prop Speed stuff is pretty expensive. I have painted mine with urethane paint before. It wore off in no time and barnacle build up recurred.

Our waters are pretty fertile and the only hope is diving and wiping it monthly or so.

Prop-Speed is generally quite successful around here and it is reasonably warm, especially in summer. Failures originate from application problems or mechanical damage to the coating.

If you can buy a 1L kit and do the job yourself, it should last you for ages because it only takes a couple of tablespoons of product or so to do a prop, so actual cost might be around $10 each time if the product keeps (I reckon it should). It is a combination of a 2-part etch primer followed by a clear coat that feels like runny silicone. When you get into it, you have to work really fast.

I had ordered the product before fully researching the matter... there are at least two other ways I know of going about it:

1. Sand the prop bright with a fine paper, clean it and spray a few good coats of zinc-rich paint (cold galvanising type stuff). Not only it will keep it clean (maybe just "cleaner" in warm waters?), but it drops down the zinc consumption too.
2. Make your own Prop-Speed. Sand the prop bright, clean it, paint it with a 2-part epoxy primer and coat it in silicone while the primer is still tacky. You get silicone sealant out of a tube and "melt" it in a bowl by adding epoxy thinners to it until obtaining the right viscosity for brush painting it.

Both have been done successfully. Method 2 would be a bit more work when it comes to redoing it, because you will be sanding off the high-build epoxy.
If the Prop-Speed doesn't keep, I will be looking into either of those options.

[fstbttms]

Originally Posted by OceanSeaSpray

Make sure you fully seal the water out around the stainless bolts holding the anode together. Put urethane sealant, epoxy paint, epoxy filler, tallow, lanolin, anything that will prevent water from getting between the stainless and the zinc, otherwise your anode eats away there at an accelerated rate and you end up losing it. It will last a lot longer if you do that.

What you are really doing is coating a portion of the anode's surface, thereby preventing that area of the anode from giving up its atoms in protection of the prop. It has nothing to do with keeping water out of the screw holes.

Originally Posted by OceanSeaSpray

Max-Props are known to be quite sensitive to lack of anodic protection, so careful there.

They are no more prone to corrosion than any other prop made of a similar material.

[OceanSeaSpray]

Originally Posted by fstbttms

What you are really doing is coating a portion of the anode's surface, thereby preventing that area of the anode from giving up its atoms in protection of the prop. It has nothing to do with keeping water out of the screw holes.

They are no more prone to corrosion than any other prop made of a similar material.

What you are doing is keeping the water away from the screw holes and immediate surrounding area. The closer the dissimilar metals are, the stronger and faster the reaction depleting the zinc. By doing this, you are displacing the electrolyte away and without electrolyte there is no galvanic reaction possible in these areas.

Props are made out of a wide range of cuprous alloys, with varying quantities of zinc in them, i.e. brasses. Old props were made out of bronze and didn't care. A few people have pointed out to me that Max-Props are not made of an alloy that is particularly tolerant when it comes to lack of galvanic protection, following experience. I am not intending to verify it myself.

[fstbttms]

Originally Posted by OceanSeaSpray

What you are doing is keeping the water away from the screw holes and immediate surrounding area. The closer the dissimilar metals are, the stronger and faster the reaction depleting the zinc. By doing this, you are displacing the electrolyte away and without electrolyte there is no galvanic reaction possible in these areas.

Unless you are creating a waterproof seal between the entire base of the anode and the end cap of the Max Prop, there is no possible way you are keeping water out of the screw holes.

Originally Posted by OceanSeaSpray

...Max-Props are not made of an alloy that is particularly tolerant when it comes to lack of galvanic protection.

As a PYI-recommeded Max Prop installer and hull cleaner with twenty years experience, I can tell you with absolute certainty that Max Props are not more prone to corrosion damage than other props.

[OceanSeaSpray]

I create a waterproof seal between the fasteners and the zinc as much as I can by applying a compound that adheres to both the stainless and the zinc. As such, it "coats" the zinc, but I find it easier and more practical to fill the gap and displace the water out than carefully coat the metal and leave the water around it. All of the products I mentioned seem to work reasonably well.
Since I have never managed so far to mix together sea water and cured Sikaflex, I must assume that if I fill the hole with the latter, the water doesn't get into the same space afterwards.

When I replace the anode, the area around the head of the screw/nut is normally the last one to remain relatively undamaged of the entire anode, the metal eats away from outside and around. I find that I get more useful life out of the anode because it doesn't fall off or work loose prematurely.

Thank you for flagging your commercial interests associated with Max-Props. I am just an end-user, I have machined my propeller shaft, installed my own Max-Prop and I service it myself.

[fstbttms]

Originally Posted by OceanSeaSpray

Thank you for flagging your commercial interests associated with Max-Props. I am just an end-user, I have machined my propeller shaft, installed my own Max-Prop and I service it myself.

Not "flagging my commercial interests." Merely letting you know that my decades of professional experience with the product do not coincide with what your friends tell you (and what you feel compelled to repeat as if it were Gospel.)

[botanybay]

Originally Posted by donradcliffe

Once the shaft is stopped, the Maxprop will feather and stay feathered. However, if the shaft is allowed to freewheel, the prop will remain engaged.

If you have a transmission like a Hurth or Twin Disc, the simplest way to stop the shaft is to stop the engine and THEN put the transmission in reverse. Putting the trannie neutral obviously does not work, and leaving the trannie in forward does not work, as these transmissions have a one-way ratchet effect that allows the prop to spin faster than the transmission.

If you have a hydraulic transmission, its a bit trickier, as there may not be enough friction in the transmission to stop the propshaft. A friend told me what works on his boat, but I forget what it was.

With my Borg warner v-drive I would leave the transmission in forward, shut the engine down.

There was enough hydraulic pressure to stop the prop from spinning for a couple of seconds and the blades always feathered.

Is it possible the prop was assembled for right hand rotation vs left hand rotation?

If you were accidentally using the props "reverse" as your forward then the blades would not feather by design.

Prop would power the boat correctly either way and the blades would face the right way either way.

People use the reverse does not feather to power shaft generators and the like.

From memory the only difference between right handed prop and left handed prop setup is the alignment of the internal cone with the outer hub.

If it is a "VP" version it can be adjusted with an external ring.

[Amnesia II]

I'm surprised this seems to be an ongoing issue. When I bought my boat in California, on the sea trial the Catalina broker demonstrated how to feather the prop. On stopping the motor in neutral he flicked the gear lever into forward momentarily and back to neutral...prop was duly feathered! Still works for me to this day.


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