Keith-i
Well-Known Member
I’m working through some annual maintenance and usually antifoul my rudder. However, I see some rudders (and props) are left uncoated. Any experience out there of pitfalls?
Bronze rudder - antifoul or polish?
- Thread starter Keith-i
- Start date
penfold
Well-Known Member
Is it really bronze? I'd antifoul it otherwise it will just get things growing on it; crusty old salts smear their props with lanolin which looks like a coat of nothing from a distance, or there is clear aerosol antifoul sold for outdrives and outboards.
Rappey
Well-Known Member
I would also carry on antifouling it. Weed grows on any surface and I'm not convinced a shiny prop or rudder is going to last that long unprotected against growth.
johnalison
Well-Known Member
On the advice of another owner I tried just polishing my prop. It was useless.
[70521]
Well-Known Member
Boat was lifted for a jet wash last week after 24 months in the water and very little movement due to COVID. Zero weed on a naked prop. She went straight back in the water.
Tranona
Well-Known Member
If it really is bronze then coat it with Velox. Widely used on propellers and works if you follow the instructions
antifoulingpaint.net available from most chandlers in UK.
antifoulingpaint.net available from most chandlers in UK.
pandos
Well-Known Member
I never coated my prop...but a few years ago it got covered in barnicles And became useless in a few weeks..so bad I though the gearbox was shot...
This year I'll use some spray on stuff recommended by a guy in yard...
[70521]
Well-Known Member
I kept my last boat on the Exe, where Exmouth Mussels - Home Page grow their product! You could feast off the amount of mussels that would attach themselves to the prop if the boat was not used frequently.
Keith-i
Well-Known Member
Thanks for the input. I’m on a drying mooring so not particularly high foul but certainly some. The prop stays reasonably clean even with little use hence why I am pondering the rudder. I think I will antifoul it though as it’s not clear cut.
Neeves
Well-Known Member
The previous answers were possibly made on the basis of 24/365 immersion, not a drying mooring. If your prop stays clean enough for you - then maybe the rudder will be the same.
If its really a drying mooring why not polish it and see what happens. Your investment is the time to polish but with some battery powered hand tools a 'flat' rudder might not be so difficult nor time consuming. If you get it wrong, or it does not work, its hardly difficult on a drying mooring to paint a rudder. You mention you have seen other gear, apparently, left naked - PropSpeed, a silicone based coating to replace AF is yellow and looks like polished metal when the PropSpeed is underwater and when view from above. It actually looks, with a quick glance, like polished metal when applied new and is still on the hard. I'd say PropSpeed is more common on MoBos than sailboats - but I see more sailboats than MoBos.
Be warned Velox is expensive and is commonly used on props which are considerably smaller than a rudder. Be also warned coating 'bare' metal with AF or Velox needs careful preparation, keying, or the coating will all fall off (and you would have been as well to polish it!). PropSpeed is another coating to consider - but it is not cheap either. Applying Velox, PropSpeed and a primer coat on bare metal need to fully understood and follow the instructions - if it says rub with 50 mesh paper - that's what it means
. If it says don't touch it - it means don't touch it! I know - because I thought a slight difference would not matter - when I got back to my own mooring and had a look half the AF had been stripped off. PropSpeed used to be professional applicator only, may or may not be the same now. There is another similar system, it was called PropGold b ut might called PropOne?? and could be sold to private individuals.You can source AF for vessels that are left stationary or move slowly but most AF is designed to work as a result of movement of the vessel (see Sandy's post No 8). The same AF works some years but not others and the same AF works on some yachts but not, as well, on others. It still seems too much of an art
Our experience has been the more copper in the formulation, check the weight per litre or the Specific Gravity, the better it works (and the more expensive the paint). We tend to find that the more expensive the paint the better the resin system - so we tend to buy from the upper cost layers - and get a 2 year life. Jotun, Hempel and International make good paints (so might others - we have not tried them). Re-emphasising following the instructions - AF has recommended c overage and I'd say too many try to eke out the paint and don't develop the recommended coating thickness - and then wonder why the AF does not work. Be generous.
The best paints are commercial and/or professional applicators only - if you can gain access.
I ran a trial for Practical Sailor in which we divided our hulls up into 1m wide vertical strips and then painted each hull each side with about 10 different AF altering the position of each paint on each hull and on each side. It was the result of that test that convinced me that Specific Gravity and price were the best indicators of effectiveness and why, or how, I know about professional application paints. I also went through a PropGold professional applicator training course (and am a certified applicator
) but prefer Velox. Given the variability of conditions (think climate) I'm quite happy using top of the range from Hempel, International or Jotun - it really depends on availability. It does not matter what colour you use - except white (or what has been said to be white, tends to have less copper in it). Finally - if you need to slip your yacht every 18 months for anode replacement then you are wasting your money with an AF that would last 2 years. Try to balance AF life with other demands - which unfortunately might take a few years to work out.Jonathan
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tross
Well-Known Member
If it is easy to remove, get it copper plated. I di my prop last year and it came out clean this year - I reckon the ROI is about 3 years
Neeves
Well-Known Member
Vyv Cox did the same thing - copper coated his prop - but I forget the result. He was going to write it up for PBO - but I don't know if this eventuated.
How do you calculate the ROI - what was your normal practice, AF, Velox, PropSpeed
Jonathan
How do you calculate the ROI - what was your normal practice, AF, Velox, PropSpeed
Jonathan
Keith-i
Well-Known Member
Thanks for the detailed reply Neeves. My rudder has got a somewhat copper complexion to it already which might be the subject of another thread soon!
vyv_cox
Well-Known Member
I wrote it up some time ago, published in PBO. Here is the part relating to the plating.
I was in the situation that I needed to buy a replacement propeller. I contacted propeller specialists Castle Marine at Caernarfon who, rather surprisingly, advised that my cheapest option was to buy a replacement from USA, made in Michigan. The prop is three-bladed with dimensions 18 x 14 inch, DAR 42% and having a brand new one in pristine condition required some research into the best antifouling I could buy. Since I use the boat as a test-bed for various projects I decided that this might be the ideal opportunity to investigate copper plating it.
Copper sheathing of ships’ hulls for antifouling was first suggested by Charles Perry in 1708, although the first experiments were not made until 1761. It was soon found that copper performed very well in preventing the growth of weed by the formation of a poisonous compound copper oxychloride that deterred the marine organisms forming the fouling. Over time the film washed away, taking away any growth that did attach itself. It seemed to me that copper plating a propeller should provide similar benefits, which led me to consider any problems or disadvantages. The only other example of a propeller plated in this way known to me is in Australia, where according to a poster on the ybw.com forums it has been totally fouling free for more than a year.
The first question was whether the copper plate would be hard enough to resist the erosive nature of flowing seawater. Pure metals are generally soft by comparison with alloys made from them and erosion is perhaps the greatest concern. My research found that plating by the acid copper method would result in the hardest and thickest coating that was also capable of being polished, a further aid to anti-fouling.
The next question was whether corrosion of the propeller might be induced by the application of copper plate. Copper is more anodic than any of the common propeller materials: manganese bronze, which is a brass with small additions of other metals, tin bronzes such as LG1 that are used for more expensive propellers and the aluminium bronzes or nickel-aluminium bronzes used for high performance propellers. Fortunately the galvanic voltages between these alloys and copper is low, so the corrosion rate of the copper should be negligible. If any galvanic action does take place it will be the copper plate, rather than the propeller, that is consumed.
I contacted a number of companies via Google but the only one who showed much interest was Lathco in Sheffield, who offered to apply a 90 micron thick coating of hard copper for a total sum of £108. Sheffield is not too far away for me to deliver the prop to them and I collected it in less than a week. I was delighted with the result.
As my primary sailing location is Greece during the summer time, Cecilia is launched late in the year and used in winter: for the first season with the new propeller she lay in a drying mud berth at Port Dinorwic. We managed to use her several times before Christmas 2015, mostly under engine, but the poor weather after New Year meant she was used less than we hoped until mid-April, when we motored and sailed her. She was lifted out at Dinas Marine in May 2016 after six months afloat. I was delighted to see that the propeller was discoloured, as expected, but spotlessly clean, whereas the hull and rudder were moderately fouled. Clearly one winter in a mud berth was not much of a test but looking around the dock at boats in similar circumstances showed that most other propellers were fouled quite badly.
At this point in my life fate took a hand. I was diagnosed with an aggressive form of prostate cancer towards the end of 2016. The radiotherapy treatment that I would undergo would prevent us from sailing in Greece for the whole of the 2017 season, so we decided to base Cecilia in Pwllheli marina, where she would be convenient to use if I was not feeling entirely 100%. We relaunched in April 2017 and motored round the Lleyn peninsula to our new base at Pwllheli. At this stage my treatment had not begun, although I was undergoing various scans, tests and injections. Up until the start of my treatment the weather was good and we managed a few local trips along the coast and out to St.Patrick’s Causeway, particularly impressive at LW springs.
Unfortunately, my treatment was not as comfortable as we had hoped and other lifestyle changes intervened, with the result that Cecilia lay almost unused for the next two years, other than as a floating caravan in the marina. It was not until August 2019, two years and four months since launching, that we were able to lift out for a check on the progress of the propeller antifouling. As expected the hull was heavily fouled with black slime, shell and copious numbers of mussels, all of which was scraped off using garden hoes by the yard gang prior to pressure washing. Most pleasing though was the condition of the propeller, with only relatively few barnacles to show for the long exposure to the marine environment.
My only action for the propeller was to scrape off the barnacles, easily done, and lightly abrade with 240 grit paper. The plating appears to be in good condition, no pitting or any other form of corrosion. One blade has a slightly rough edge, which may be mild plating loss or corrosion, not enough to worry about. Cecilia goes back in the water early in September 2019, hopefully with many years of fouling-free service ahead.
vyv_cox
Well-Known Member
Is Velox still available in UK? Last I saw it had been withdrawn because the cost of undertaking the hazardous materials testing required for import to UK was unjustifiable against the sales figures.
Keith-i
Well-Known Member
Thanks Vyv. Very interesting and something I would consider if I end up with new underwater stern gear.
