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

[a64pilot]

My only anode in the water is on my Brunton Autoprop.
Needless to say, I went through them quickly. For me painting the prop made no difference.
Islers diving used to make an adapter for an Autoprop that allowed the use of a standard prop anode, which increased the anode size by at least 300% and did away with the annoying screw holes. It’s worth it’s weight in gold, but I think is no longer made?
However what has made the most difference is hanging a large “guppy” zinc, which is just about 5 lbs or more zinc is all, just make sure you have a good direct connection to the engine, don’t clip it to the SS rigging. It may be grounded, but SS is such a poor electrical connector you can’t get a good connection to the underwater metal.
Since the guppy zinc, my prop zinc consumption is greatly reduced, and the guppy is so large I haven’t noticed much consumption there either. I think one guppy is good for years.

My theory is you have to have zinc to be consumed, best to shift it from the expensive tiny, hard to replace prop anode to a big, cheap easy to replace one.

[charliehows]

I used to use antifoul on the prop, last time i hauled out i just used enamel house paint - no difference. Fortunately I can scrape my prop in the water, and thats what works - every few months it gets a cleanup. I myself wouldnt bother with expensive high tech prop coatings. Bottom line with antifouling - regular haulouts. I'm glad I dont have a feathering or variable speed prop - can see how these might be quite a problem if they are not in constant use.

[Pete7]

Originally Posted by bigman1

I would consider painting the prop with several coats of epoxy resin,the plastic in the epoxy should shield the prop from galvanic current.Anyway some of the more technical forumites should keep us on course.

I tried and failed to get epoxy tar to stick to my bronze prop even when I was applying it by scratching it onto the surface with 80 grid sandpaper. The epoxy went in the bin and at that point changed to Velox.

[RobertoD]

Don't paint your props - wax them. Made in Canada - Natural Marine Easy On Bottom Wax. Non-toxic barrier system. AlexMilne.com. Works well, easy to use!! And my boat docks in a weedy, zebra mussel area.
AlexMilne.com

[Pete7]

Originally Posted by RobertoD

Don't paint your props - wax them. Made in Canada - Natural Marine Easy On Bottom Wax. Non-toxic barrier system. AlexMilne.com. Works well, easy to use!! And my boat docks in a weedy, zebra mussel area.
AlexMilne.com

Roberto, we have problems with fouling using the strongest paint legally available, are you saying wax will be more efficient at keeping slime, weed and barnacles off objects underwater. Will this wax be a cost effective solution given the price of a lift to fix it if it fails?

On you tube there are a series of videos showing Fast Bottoms of this parish wiping clean yachts hulls which he does for a living. It astonishes me that with a single swipe of a sponge or something the weed just falls off. In 3 hours time I will have to use a commercial hot pressure wash for an hour to clean my 31ft yacht.

Pictures are from last year and not great due to the low light and dark hull colour. I will try again this year, but what ever that green weed is a hobby pressure washer isn't up to the task, hence use the boatyard one.

If there was a better product we would use it like a flash, but currently the options are polish it and use lanolin or similar with lots of lifts during the season or paint it and perhaps get away with one lift mid season scrub.

Pete

[Uncle G]

We have an aluminium hull with a big fixed bronze prop on a stainless shaft. There are no anodes on the prop or shaft. I used to leave the prop bare, but it got covered in barnacles fairly quickly. 5 or 6 years ago I painted the prop with Jotun Vinygard (one-pack primer) and antifouled it with Seajet Emperor (non-copper antifoul) - along with the rest of the hull. Now the prop stays completely clean for two years in between haul outs.

Our shaft and prop are isolated from the engine and hull with a phenolic cutless bearing and an R&D plastic disc between the gearbox flange and the shaft coupling. There is never any corrosion on the shaft or prop. The two small anodes on the hull last about 6 years.

Seems to me that isolating your shaft and prop may be worth looking into - rather than electrically tying everything together and causing the zincs to disappear.

[Neptune's Gear]

OK, 1st, I am a marine electronics specialist.
Too much zinc will cause excess marine growth.
If you are connected to shore power, ever, you should have a galvanic isolator, or an isolating transformer. Not to do so is foolish, can destroy your vessel surprisingly quickly, and you can provide zinc to the whole pier!
Antifouling, especially soft/ablative, is not water proof, so its not an insulator. It wont make any difference.
Get a marine electrician with corrosion experience to measure your boat with a silver/silver chloride reference electrode. They can tell you if you have the correct amount of zincs on your boat, and check for any stray current corrosion which will consume you zincs (Then your saildrive/prop/exposed lead etc) at an alarming rate.
If you consume zincs quickly without a shore power connection (or with it and a galvanic isolator) then the issue is on YOUR BOAT. Commonly this might be a wire in the bilge water - like a bilge pump...
Get it checked!

[Siberian Sea]

If your zinks are being used up at an abnormally high rate it is not because your prop is not painted rather you or vessels near you have some stray current flowing into the water. Look how many boaters just use the cheap automotive battery chargers with no understanding of the great difference between these chargers and real marine chargers. Often these chargers are a a major part of marina problems. Matter fact in some areas it’s illegal to use these automotive chargers because the risk of electrical shock.
Check to make sure all underwater through hulls are bonded with good quality copper straps, when charging from shore power use a real marine battery charger and check all your vessels grounds.
We can do little about our neighbors vessels but we can clean up ours and this will make a vast improvement

[Cheechako]

It seems to me painting does help growth a bit anyway. The blade edges will slough off the paint fairly quickly, but the growth is often more away from the edges anyway. If you sit at anchor 4 weeks in some places your prop will not work and will look like a coral reef.

[IdoraKeeper]

I am sure you know this but don't confine your stray current search to your own boat. Check the neighbors as well. Who knows what they may have done.

[chris95040]

Man I can't go 2 months with a bare prop without it getting seriously covered in growth. I used to just go clean it up once a month, but now I use some cheap rattle can, it's grey, I'm thinking maybe Pettit zinc for outdrives? It gets me through my 6 month season without any growth.

[Pete7]

The boatyard lifted my yacht out of the water a couple of hours ago. Took some photos which might be interesting to this thread. So the history, yacht antifouled with Hempel Tiger Extra and the prop with Velox in May 2017. Hull and prop pressure washed at the end of October 2017 just before I popped over to meet Dockhead for a weekend. The fouling has all grown over the winter with a water temperature varying from 9c to 6c and back to the current 10.c

I am pleased that despite a lengthy motor down to the English West Country last summer the paint has remained stuck to the prop. Interestingly the front of the blades are cleaner than the rear of the blades, haven't quite worked that one out yet.

So for a prop that has spent 6 months static in a very heavily fouling area, Velox seems to have worked quite well even towards the end of the 12 months. The antifouling perhaps not so good judging by the picture of the hull and bilge keel taken half way through the pressure wash.

I am just preparing the spare prop with Velox to replace this one now.

The anodes look very good and I am tempted to leave them for another year, this despite the fact we were on shorepower for a month whilst living on board in February.

Does painting the prop and shaft reduce anode losses? I don't know because I don't have a definite reference point, but I think so based on the wear rate during our early ownership when both shaft and hull nearly disappeared each year

Pete

[CascadeThumper]

Prop speed is often used around the PNW. Works good for me. Incidentally, the galvanic isolator I recently installed seems to be making a substantial difference too.

[sand6000]

I do not believe antifouling a prop will have a link to anode consumption but if you are only getting 4 months from an anode system then something is wrong. A simple and inexpensive check is to have a 1/2 cell meter over the side which will tell you instantly if you have enough anode material or not enough. A marine electrical engineer should have a 1/2 cell and it only takes 10 minutes.

[PEACEMAKER 455]

Copper plating the prop means copper chloride will be formed on surface continually under way or at dock killing any growth same reason they sheathed sailing vessels in copper to prevent growth. No loss of performance from prop coated in copper. I own electroplating company so have done many