Seastoke
Well-Known Member
help
bronze props going pink ?
- Thread starter Seastoke
- Start date
VicS
Well-Known Member
bronze props going pink ? Dunno cant you tell by looking at them
Post some pictures if you are not sure,
They could be and if they are it suggests dezincification. (Manganese bronze is really a brass) Not serious if its only on the surface but if its deeper and the metal is losing its strength then it is more serious.
See the "Brass and bronze" section of Vyv Cox's website http://coxengineering.sharepoint.com/Pages/BrassandBronze.aspx
What other relevant facts are there. Anodes fitted ... and bonded properly... are they wasting away?
Are you on shorepower, if so is it normally plugged in, even if not in use .
Any recent electrical work which might be causing electrolysis?
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PCUK
Well-Known Member
Do the blades ring when you tap them with a small hammer, or just go thud? If it's the latter then they are passed saving due to dezincification.
Latestarter1
Well-Known Member
Are you berthed in a marina?
oldgit
Well-Known Member
Do not Panic !
As others have mentioned give the props a good thump with something metal .
If you hear a nice ring then probably OK. Really bad prop will give dull clonk.
One of my props has been on its way out for ages.Had it repitched a couple of years ago and prop man did comment that it looked a bit "pinky" but carried out work anyway......If it broke it broke !
It was repitched and and used for another 200 + odd hours.
On lift out this year a proper dull old thud was the result of me bashing it and edge of one blade looks definately a bit manky.
So its finally new prop time.
Old duff prop has gone back on until sensibly priced replacement propeller turns up at some point.
As others have mentioned give the props a good thump with something metal .
If you hear a nice ring then probably OK. Really bad prop will give dull clonk.
One of my props has been on its way out for ages.Had it repitched a couple of years ago and prop man did comment that it looked a bit "pinky" but carried out work anyway......If it broke it broke !
It was repitched and and used for another 200 + odd hours.
On lift out this year a proper dull old thud was the result of me bashing it and edge of one blade looks definately a bit manky.
So its finally new prop time.
Old duff prop has gone back on until sensibly priced replacement propeller turns up at some point.
tcm
...
A *bit* pink is not terminal, imho. But either your anodes aren't working, or were left too long, or too much HCl lashed around to clean the barnies and/or it wasn't washed off ... or there's too much electrolysis join on yer boat - possibly cos in a marina, plugged in, stray voltage, blah blah etc ... cure the problem with a galvanic isolator (£100 or so) (and replace anodes or assess anodes, make sure they are installed dry as poss etc, proper low-voltage electrical contact of course and with range of the props if not er actually on the props themselves...) and hope you don't need new props (much more than £100...)
GrahamHR
Well-Known Member
My problem with "bronze" props, and it seems I am not alone in the UK , mentioned on another thread.
DPH props going pink with some pitting
Nibral bronze , so no or little zinc content
Aluminium depletion ?
Inner hubs and prop nuts , connected to outdrive anodes are fine
This doesn't apparently happen in the Med !
tcm
...
I (massively) doubt that this is "only in the UK" or "never in the Med". The med is a bit warmer and a bit more salty, so any specific electrolytic action would happen a bit more all other things being equal.
An important inequality between marinas is the electric system to which most plug in with shorepower cable. You can isolate this with galvanic isolator mentioned above, quite cheap, buy them on the internet.
You say outdrive anodes are "fine" - they should get eaten up, like 50% a year plus or minus a fair bit, yes?
Nice article here https://www.proboat.com/beware-the-brass.html
Hope this helps
An important inequality between marinas is the electric system to which most plug in with shorepower cable. You can isolate this with galvanic isolator mentioned above, quite cheap, buy them on the internet.
You say outdrive anodes are "fine" - they should get eaten up, like 50% a year plus or minus a fair bit, yes?
Nice article here https://www.proboat.com/beware-the-brass.html
Hope this helps
burgundyben
Well-Known Member
Also, each time the boat is ashore I check the resistance with a meter between anode and major components, 0.3 ohm or less being my threshold.
If you think there is a boat or local problem, then a decent surveyor ought to be able to test with a silver chloride reference electrode to see what is going on.
If you think there is a boat or local problem, then a decent surveyor ought to be able to test with a silver chloride reference electrode to see what is going on.
GrahamHR
Well-Known Member
I also find it strange re the Med vs Irish Sea apparent difference in corrosion rate !
When I wrote the (zinc) anodes were fine, I meant they were working as they should do, eroding gradually; probably ca 1/3 or so gone in the total of 3 months or so immersion last season. Very similar erosion in fact to the zinc anodes on the trim tabs. The outdrive and transom shield anodes don't protect the outer prop hubs or blades though, as they are electrically insulated from the drive.
The boat was normally left with shorepower disconnected ( only connected a couple of nights to charge the batteries). It has a galvanic isolator. This season it has an electronic corrosion protection unit in place; I had one on my pevious boat and it really did cut down the anode erosion rate, with still no corrosion of the drive. ( that boat had stainless F series props, that suffered from crevice corrosion, as they all seem to).
tcm
...
More info here , with even more links at the bottom...
http://www.performancemetals.com/anodes/AnodeFAQs.shtml
again hope this helps (and we seem to have hijacked the OP's thread but still about same subject so hopefully all ok
)
http://www.performancemetals.com/anodes/AnodeFAQs.shtml
again hope this helps (and we seem to have hijacked the OP's thread but still about same subject so hopefully all ok
)GrahamHR
Well-Known Member
More info here , with even more links at the bottom...
http://www.performancemetals.com/anodes/AnodeFAQs.shtml
again hope this helps (and we seem to have hijacked the OP's thread but still about same subject so hopefully all ok
Thanks; funnilly enough, I have a set of aluminium anodes I'll be fitting later in the week. They will still leave the outer parts of the props unprotected though by anodes .
Bandit
Well-Known Member
Not much info to go on?
Bronze props on shaft or outdrive?
Seawater, fresh or brackish.
Where is the boat moored?
As Vic said photos would help.
as
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GrahamHR
Well-Known Member
Anyone tried nickel plating ? It should be easy on a copper based alloy. Very corrosion resistant, harder than silver or gold so erosion should be manageable.
