Rusty prop
Submitted by phatdog on Sun, 2007-09-09 17:37
I have just spent a heap of cash and put 2 new 4 blade stainless props on my sharkcat. The props sit on 1999 130hp Saltwater series Yammies. The motors are mounted on ali pods. On the last two occasions when I have been out fishing and pulled the boat out of the water, the starboard prop has rust on it. I have changed the annodes and checked the earth wires and they all appear to conected and clean. The port prop is no drama at all. Has anyone got an idea of what or why this is happening. Any feedback would be great.
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mangajack
Posts: 1
Date Joined: 29/08/07
It could be one of three
It could be one of three things causing this.
Most likely when the prop was manufactured they did not use a "Stainless Only" flap wheel, buffing wheel or polishing wheel. I suspect that possibly someone had cleaned up a bit of mild steel on this aparatus immediately prior to the prop being used on that same machinery. This embeds and basically welds in place minute fragments of iron into the grain of the stainless.
Secondly it could have been the wrong polishing compound used as they are abrazive and have some form of grit in them to perform the cutting required.
Thirdly and most unlikely the stainless was contaminated with ferritic stainless steel instead of Austenitic Stainless. Ferritic as the name suggests is ferrous (contains high levels of iron) and is magnetic and can rust quite quickly. Check this is easy with a small magnet, if it sticks its definitely ferritic stainless and i would return it immediately for replacement.
Jack.
phatdog
Posts: 4
Date Joined: 05/07/07
Rusty prop
Thanks for that Jack, Ithink however that is not the case, when I replaced the old painted stainless prop on the starboard side that also had rust on it,and I think the chances of that happening twice would be remote. Thanks for your idea though. This is driving me insane.
NOHA
Posts: 914
Date Joined: 24/06/07
Its electrolysis for sure.
Its electrolysis for sure. Metal is being deposited on your prop from another source. You need to get your boat checked out by a good marine sparky.
I can have a free look for you but I live down in Rockingham, dont know how far that is from you.
If you know how to drive a multimeter or have someone who does I can talk you thru some of of the things to check for.
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phatdog
Posts: 4
Date Joined: 05/07/07
Rusty prop
NOHA thanks for the offer but I live in Port Hedland may be a bit far for one of us to travell. But I certainly agree with your thoughts
scottnofish
Posts: 1617
Date Joined: 28/08/07
you still know how to use that ?
its been a while since you done any real work hey
NOHA
Posts: 914
Date Joined: 24/06/07
Hey I did think of you but
Hey I did think of you but then I did say a good electrician.
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Feral
Posts: 1508
Date Joined: 01/11/06
not sure as im no outboard
not sure as im no outboard mech.... but couldnt it be caused be prop ventilation ??
as the water boils behind the prop it might heat it up enough to blister the old props paint off and discolour the new prop to look like rust ??
just a thought as it sounds strange to just be happening to only one prop.
and electrolisis should affect the annodes and alli pod well before it attacks the s/s
NOHA
Posts: 914
Date Joined: 24/06/07
and electrolisis should
and electrolisis should affect the annodes and alli pod well before it attacks the s/s
That would be true if the system is in perfect working order. If not thats when strange things happen. Like rusty looking props for example.
I spent 15 years as a specialist marine sparky and I have seen this many,many times before.
With out seeing the guys boat of course I cant be sure but it sounds to similar to not warrant checking out.
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