andyorr
Member
As a new boy to big boats - do I antifoul my prop and shaft etc? Other boats in my yard do but many only do the P bracket. Advice? I've got a new hull anode fitted.
Antifoul on shafts + props
- Thread starter andyorr
- Start date
seaesta
New member
look at previous postings . this subject has been talked to death repeatedly and with no consensus other than using lanolin is good
Twister_Ken
Well-known member
The other point of concensus is that using antifoul with copper as an ingredient on a bronze prop is bad, causing galvanic corrosion.
charles_reed
Active member
Without knowing the area, the prop type and frequency of usage I'd be loath to give any advice and I'd treat with reserve any specific advice offered.
I rely upon polishing my aluminium-bronze prop to prevent it from fouling.
After about six weeks of non-usage in water @ 14-18C (warmer than the UK) it gets sufficiently foul to cause the engine to labour when in gear. However I find about 12 minutes of running whilst tied up to the pontoon clears the prop off sufficiently to run and drive OK.
I'd suggest you try for one season without antifouling the prop - the P-bracket and shaft are another matter.
As has already been suggested Cu based antifoulings cause crevice-corrosion in 316 A2 stainless and can cause electrolysis of Admiralty bronze props (the most common prop material). Be very careful about what you use on Al alloy props - even some of the special antifoulings cause surface corrosion under certain galvanic conditions (shorepower and local minerals).
I rely upon polishing my aluminium-bronze prop to prevent it from fouling.
After about six weeks of non-usage in water @ 14-18C (warmer than the UK) it gets sufficiently foul to cause the engine to labour when in gear. However I find about 12 minutes of running whilst tied up to the pontoon clears the prop off sufficiently to run and drive OK.
I'd suggest you try for one season without antifouling the prop - the P-bracket and shaft are another matter.
As has already been suggested Cu based antifoulings cause crevice-corrosion in 316 A2 stainless and can cause electrolysis of Admiralty bronze props (the most common prop material). Be very careful about what you use on Al alloy props - even some of the special antifoulings cause surface corrosion under certain galvanic conditions (shorepower and local minerals).
charles_reed
Active member
Without knowing the area, the prop type and frequency of usage I'd be loath to give any advice and I'd treat with reserve any specific advice offered.
I rely upon polishing my aluminium-bronze prop to prevent it from fouling.
After about six weeks of non-usage in water @ 14-18C (warmer than the UK) it gets sufficiently foul to cause the engine to labour when in gear. However I find about 12 minutes of running whilst tied up to the pontoon clears the prop off sufficiently to run and drive OK.
I'd suggest you try for one season without antifouling the prop - the P-bracket and shaft are another matter.
As has already been suggested Cu based antifoulings cause crevice-corrosion in 316 A2 stainless and can cause electrolysis of Admiralty bronze props (the most common prop material). Be very careful about what you use on Al alloy props - even some of the special antifoulings cause surface corrosion under certain galvanic conditions (shorepower and local minerals).
I rely upon polishing my aluminium-bronze prop to prevent it from fouling.
After about six weeks of non-usage in water @ 14-18C (warmer than the UK) it gets sufficiently foul to cause the engine to labour when in gear. However I find about 12 minutes of running whilst tied up to the pontoon clears the prop off sufficiently to run and drive OK.
I'd suggest you try for one season without antifouling the prop - the P-bracket and shaft are another matter.
As has already been suggested Cu based antifoulings cause crevice-corrosion in 316 A2 stainless and can cause electrolysis of Admiralty bronze props (the most common prop material). Be very careful about what you use on Al alloy props - even some of the special antifoulings cause surface corrosion under certain galvanic conditions (shorepower and local minerals).
charles_reed
Active member
Without knowing the area, the prop type and frequency of usage I'd be loath to give any advice and I'd treat with reserve any specific advice offered.
I rely upon polishing my aluminium-bronze prop to prevent it from fouling.
After about six weeks of non-usage in water @ 14-18C (warmer than the UK) it gets sufficiently foul to cause the engine to labour when in gear. However I find about 12 minutes of running whilst tied up to the pontoon clears the prop off sufficiently to run and drive OK.
I'd suggest you try for one season without antifouling the prop - the P-bracket and shaft are another matter.
As has already been suggested Cu based antifoulings cause crevice-corrosion in 316 A2 stainless and can cause electrolysis of Admiralty bronze props (the most common prop material). Be very careful about what you use on Al alloy props - even some of the special antifoulings cause surface corrosion under certain galvanic conditions (shorepower and local minerals).
I rely upon polishing my aluminium-bronze prop to prevent it from fouling.
After about six weeks of non-usage in water @ 14-18C (warmer than the UK) it gets sufficiently foul to cause the engine to labour when in gear. However I find about 12 minutes of running whilst tied up to the pontoon clears the prop off sufficiently to run and drive OK.
I'd suggest you try for one season without antifouling the prop - the P-bracket and shaft are another matter.
As has already been suggested Cu based antifoulings cause crevice-corrosion in 316 A2 stainless and can cause electrolysis of Admiralty bronze props (the most common prop material). Be very careful about what you use on Al alloy props - even some of the special antifoulings cause surface corrosion under certain galvanic conditions (shorepower and local minerals).
Trevor_swfyc
New member
Polishing gets my vote but it requires repolishing during the season maybe twice.
I have never antifouled my prop in the twelve years I have owned the boat.
Trevor
I have never antifouled my prop in the twelve years I have owned the boat.
Trevor
ccscott49
Active member
How does copper antifouling on a bronze prop cause galvanic corrosion?
ccscott49
Active member
Re: Antifoul on shafts props
Charles, do you mean admiralty brass props? What is the percentage of zinc in admiralty bronze/brass? I'm getting a little confused here., as far as I knew, brinze is an alloy of copper, nickel and iron with sil/alu/phos etc. Also do you mean 316 A4 stainless? I thought 314 was A2 or am I completely screwed up yet again?
Charles, do you mean admiralty brass props? What is the percentage of zinc in admiralty bronze/brass? I'm getting a little confused here., as far as I knew, brinze is an alloy of copper, nickel and iron with sil/alu/phos etc. Also do you mean 316 A4 stainless? I thought 314 was A2 or am I completely screwed up yet again?
Twister_Ken
Well-known member
Dunno, but it gives it pink spots and it doesn't ring like a church bell when struck.
ccscott49
Active member
Re: Antifoul on shafts props
Then the prop is not real bronze, because what your describing is the early stages of de-zincification and in real bronze, theres no zinc. If you look at the classic marine.co.uk site, you can see in the reference data, the make up of all the bronzes (in general use) and ther galvanic table, with a lot of useful tips and hints, about the mixing of metals.
Then the prop is not real bronze, because what your describing is the early stages of de-zincification and in real bronze, theres no zinc. If you look at the classic marine.co.uk site, you can see in the reference data, the make up of all the bronzes (in general use) and ther galvanic table, with a lot of useful tips and hints, about the mixing of metals.
vyv_cox
Well-known member
Re: Antifoul on shafts props
Admiralty bronze is 70/30 brass with the addition of 1% tin. There is another version that also has about 0.5% arsenic, giving better corrosion resistance. Most small propellers are made from these alloys, unlike ship's propellers that are normally nickel-bronze or nickel-aluminium bronze.
There's a similar alloy that is a 60/40 brass with less than 1% tin but for some reason this is Naval brass, not Naval bronze, as might be expected. Perhaps even the Navy balked at calling something with only 0.75% tin a bronze!
What you call "real" bronze is used for decent skin fittigs and seacocks, and some other high quality components, but unfortunately not propellers.
Admiralty bronze is 70/30 brass with the addition of 1% tin. There is another version that also has about 0.5% arsenic, giving better corrosion resistance. Most small propellers are made from these alloys, unlike ship's propellers that are normally nickel-bronze or nickel-aluminium bronze.
There's a similar alloy that is a 60/40 brass with less than 1% tin but for some reason this is Naval brass, not Naval bronze, as might be expected. Perhaps even the Navy balked at calling something with only 0.75% tin a bronze!
What you call "real" bronze is used for decent skin fittigs and seacocks, and some other high quality components, but unfortunately not propellers.
PeterGibbs
New member
There is nothing to be gained by painting your prop shaft with anything - any drag from a barnacle or (even) ten has no practical bearing on performance.
Props are, of course a different matter. A bronze (or one that looks like bronze!) prop should not be painted for the reasons given elswhere in these replies. The best solution is to polish highly and lay on Vaseline. If you park in a heavily fouled area you will pick up some weed, and certainly barnacles. That's the way of it.
If you have an aluminium prop you can paint it with the systems availabel in the chandlery - essentially, a key, then primer, then several coats of special hard a/foul.
I have an ali prop and this is what works: but there are still lots of barnacles around.
Best not to think about it otherwise you will be banging the boat against walls every 4 weeks to scrape off a few barnacles - and all of a sudden summer has passed by!
PWG
Props are, of course a different matter. A bronze (or one that looks like bronze!) prop should not be painted for the reasons given elswhere in these replies. The best solution is to polish highly and lay on Vaseline. If you park in a heavily fouled area you will pick up some weed, and certainly barnacles. That's the way of it.
If you have an aluminium prop you can paint it with the systems availabel in the chandlery - essentially, a key, then primer, then several coats of special hard a/foul.
I have an ali prop and this is what works: but there are still lots of barnacles around.
Best not to think about it otherwise you will be banging the boat against walls every 4 weeks to scrape off a few barnacles - and all of a sudden summer has passed by!
PWG
ccscott49
Active member
Re: Antifoul on shafts props
I'm obviously a lucky man, because my props and shafts are bronze, don't know whether they are nickel, aluminium or silicon, but they are broinze. I used to use "black lead" (the real stuff) in the UK, but now in the meddy and in fact in Holland I antifoul my props, with hard racing antifoul same as the bootopping in fact. My Brother does the same, around the Ebro delta in Spain you had better! I have never seen any corrosion or any "copper spots" on my props or shafts. Everything under the water on my boat, including all fasteneings and keel bands etc, are bronze or copper, so I don't really expect any problems. Why the navy called anything with 37% zinc in it bronze is beyond me.
I'm obviously a lucky man, because my props and shafts are bronze, don't know whether they are nickel, aluminium or silicon, but they are broinze. I used to use "black lead" (the real stuff) in the UK, but now in the meddy and in fact in Holland I antifoul my props, with hard racing antifoul same as the bootopping in fact. My Brother does the same, around the Ebro delta in Spain you had better! I have never seen any corrosion or any "copper spots" on my props or shafts. Everything under the water on my boat, including all fasteneings and keel bands etc, are bronze or copper, so I don't really expect any problems. Why the navy called anything with 37% zinc in it bronze is beyond me.