Propeller -- To Paint or Not to Paint? That is the Question.

[Dockhead]

I've had two Bruntons on two different boats over more than 20 years. I've always kept them in bare bronze and scraped and polished them on every haul out.

But one problem I have is voracious anode consumption -- I can barely get 4 months out of one of the standard anodes (even when I protect the screw bosses with Prop Speed so that they don't fall off). Surely the large amount of exposed bronze has something to do with this. Maybe it makes sense to paint the prop with hard antifoul, or wax with Prop Speed, as many do?

What are the pros and cons?

[Pete7]

I am just painting my spare prop with Velox for the third season. Not perfect but pretty good stuff. However, its all in the preparation so having two props helps. You also need to scuff up the blades by sanding with 80 grade sandpaper which does take a layer of bronze off. Worth having a read of the guide before choosing this option:

PYI Inc. | How-To Apply Velox Plus Antifouling Paint

Previously I just roughed up the prop, slapped a thin layer of primocon on and then the same antifoul paint as the hull. This also worked quite well.

To clean the prop I use this, which gives a really nice clean finish.

https://www.toolstation.com/shop/p17...yABEgK0oPD_BwE

[Dockhead]

Originally Posted by Pete7

I am just painting my spare prop with Velox for the third season. Not perfect but pretty good stuff. However, its all in the preparation so having two props helps. You also need to scuff up the blades by sanding with 80 grade sandpaper which does take a layer of bronze off. Worth having a read of the guide before choosing this option:

PYI Inc. | How-To Apply Velox Plus Antifouling Paint

Previously I just roughed up the prop, slapped a thin layer of primocon on and then the same antifoul paint as the hull. This also worked quite well.

To clean the prop I use this, which gives a really nice clean finish.

https://www.toolstation.com/shop/p17...yABEgK0oPD_BwE

Thanks for the excellent answer to the "how" part of my question. What about the "why" part? WHY do you paint your prop?

Looking around at all the boats on the hard at Cowes Yacht Haven, it seems that few of the props are painted.

[Pete7]

I don't do the miles you do, so without lots of miles a year or a good coat of antifoul the weed and barnacles will have a frenzy on the prop. The one thing I learnt from the years of owning a rib is keeping the prop clean is so important as even a slight imperfection has an effect on performance be it a ding or barnacle.

BTW the biggest change to our anodes came about when we fitted solar and stopped using shore power. What was an annual change of the hull and prop shaft anodes has now been extended so the hull anode lasts 2 years and the shaft 18 months. Can't quite stretch the shaft anode to 2 years unfortunately.

I don't have any data for clean polished props versus antifouled props. The previous owner kept her in Swanwick and used Lanolin, but at the price of having Moodys lift and pressure wash the hull and presumably clean the prop several times a year.

[Dockhead]

Originally Posted by Pete7

I don't do the miles you do, so without lots of miles a year or a good coat of antifoul the weed and barnacles will have a frenzy on the prop. The one thing I learnt from the years of owning a rib is keeping the prop clean is so important as even a slight imperfection has an effect on performance be it a ding or barnacle.

BTW the biggest change to our anodes came about when we fitted solar and stopped using shore power. What was an annual change of the hull and prop shaft anodes has now been extended so the hull anode lasts 2 years and the shaft 18 months. Can't quite stretch the shaft anode to 2 years unfortunately.

I don't have any data for clean polished props versus antifouled props. The previous owner kept her in Swanwick and used Lanolin, but at the price of having Moodys lift and pressure wash the hull and presumably clean the prop several times a year.

I wonder if your anode use is influenced by having a painted prop?

As you know I was on a Hamble River mooring for years without shore power. My anodes still only lasted 4 months. The new antifouling (Micron 77) would allow me to go a good 6 months between scrubbing the hull, but my anodes don't last that long. Hull and shaft anodes are wasted as well as the prop one. For some reason, the fridge and thruster anodes last longer

[Pete7]

Originally Posted by Dockhead

Looking around at all the boats on the hard at Cowes Yacht Haven, it seems that few of the props are painted.

How often are those boats being lifted out for a clean?

If you're thinking of using hard antifouling, before Velox I used the same ablative paint like Seaget 33 and Cruiser Uno that went on the hull with reasonable results. Likewise I also painted the stainless steel shaft and put a blob of silicone sealant on the shaft anode like you to keep the bolts in place.

Hammerite do a special metals primer but I couldn't get it to stick to even a roughed up prop so went back to using a thin layer of Primocon as the primer.

[Pete7]

Originally Posted by Dockhead

Hull and shaft anodes are wasted as well as the prop one. For some reason, the fridge and thruster anodes last longer

Whilst she is out of the water it would be worth checking over the electrical circuits to see if you have a leak somewhere that is taking out the hull anode early. Also worth checking if the GI is still working properly or that current from the genny or ssb aren't leaking to the anode. The Bruntons anode I can understand, but the hull one is more worrying.

How about bringing in a marine electrician for half a day?

Originally Posted by Dockhead

I wonder if your anode use is influenced by having a painted prop?

Possibly but also painting the shaft too so that both dissimilar metals are covered.

[Paul Kelly]

I have a Brunton on my Westerly Storm which I moor in Poole Harbour. At the end of last season when the boat was hauled out, the prop and shaft were covered in weed. I don't think that helped the engine's performance. I've recently coated the prop and shaft with Prop Shield. I hope that will make a difference, but I'm afraid you'll have to wait until November before I can reveal the results.

Also, Prop Shield is a waxy type substance that you paint/smear on. It dries hard extremely quickly. They say melt the tub in hot water to make the contents soft. I found it much easier to use a hot air gun on it.

[SCarns]

I don’t know if painting it will reduce galvanic action. But I concur with the above atatement about the maine electrician. It ounds reasonable that you may be putting some current into the water somewhere.

[Boatyarddog]

Why waste money on paint at all.
Boost your local economy, and keep pollutants out of the water as well by using your local dive services.
Small local divers need the business, and the Waterways need less pollution.
DONT PAINT.

[billknny]

Originally Posted by Dockhead

Thanks for the excellent answer to the "how" part of my question. What about the "why" part? WHY do you paint your prop?

Looking around at all the boats on the hard at Cowes Yacht Haven, it seems that few of the props are painted.

WHY-to is anti-fouling.

All props have their efficiency suffer greatly with even a little bit of bio growth. Most sailors don't really notice.

But Autoprops are REALLY sensitive to growth. If one blade has even just a barnacle or two it no longer takes the same pitch as the others and the whole caboodle gets out of balance. It can vibrate to beat the band, or just overload the engine like it was seriously over-proped.

[fstbttms]

Originally Posted by Boatyarddog

Why waste money on paint at all.
Boost your local economy, and keep pollutants out of the water as well by using your local dive services.
Small local divers need the business, and the Waterways need less pollution.
DONT PAINT.

These guys are all in the UK, where in-water hull cleaning just ain't done, apparently.

[CAR54]

The first four years my folding prop was not painted. The last two years speed prop was applied. There was no difference on the rate of deterioration of the prop shaft anode. The boat stays at the dock with shore tie while not underway.

The Solent is such great sailing! I have chartered Sunsail there four times now.

[Locquatious]

Over the past few years we have used PropPurr™ which goes on very easily. It just requires a light sanding to form a very smooth metal surface. Do a quick solvent cleaning to remove sanding residue and any oils. Then just wipe it on. It dries in an hour. Since PropPurr™ chemically bonds to bronze and forms a thin silicone coating on the surface, you don't need a rough surface. Rough surfaces give marine life a better chance of forming a mechanical bond. Besides rough sanding just wears away the metal.

Never use acid to clean the prop. Acid reacts with some of the bronze alloy components, making the metal more porous. The porosity significantly increases the surface area and speeds electrolysis. Even acidic primers are best avoided.

We find that a just running the prop hard or light sponge wipes on the surface cleans the prop, if growth settles on.

We have noticed that the zinc anodes last longer when we use PropPurr™. The silicone coating is an electrical insulator and the smooth surface has low surface area.

[Greg Mason]

I have always painted the prop with anti-fouling, just for marine growth. Never moored in a place where the water flow was good either. Now that I am running twin 4 blades, I still paint them, but this year had a soda blast to remove all previous anti-foul, including the props, so, I put on 2 coats of Interprotect 2000E on everything first, before 2 coats of Micron CSC. If you are using/losing zincs quickly, almost a given that shore ground and 12 volt ground will touch each other somewhere. A good place to start.