Stainless prop and Galvonic Corrosion?

[BAYLINER185]

I just came into some $$ so I decided for the hell of it I will buy a SS prop for my New BAYLINER. They look cool and they have less flex and will get you closer to full pitch. I have a 23" Pitch aluminum tht came stock and Im easily able to do 52 MPH so I just bought a STILLETO in the same exact size and pitch in SS. My bayliner dealer says the SS will make very little differance on this boat. Im happy with performance as it is so any more is great to.

I thought I read that adding SS props can increase Galvonic corrosion now that you are introducing another metal and a hell of a lot of it. I see small pits on all my trim anodes but they are still all intact and not less then 50% yet.

On the plane plate on the sterndrive above the prop is the flat circular trim tab without the small fin and Im thinking I should replace that with the trim tap that has the fin ( above the prop ) so that it adds more of the anode metal to the drive.

I had a SS prop a really long time ago on my 1st boat and had the trim tab in place but that was back when I didnt even know why it was there. I dont want my brand new stern drive to be subject to more then normal galvonic corrosion so of course I will keep a watchfull eye on all my drives anodes but is this somehtign I should be concerned with and is there any truth to creating more of the galvonic reaction by added a SS prop to my drive?

 

[Frank Acampora]

Re: Stainless prop and Galvonic Corrosion?

Back a while ago, I acquired a salt water used stainless prop. I don't remember the condition of the lower unit but the prop was pitted on the blades and hub. Some of them more than 1/8 inch across. So, even with anodes on your lower unit, if left in salt water, there is a good bet that corrosion will happen. If moored in the water, just be sure that none of the prop touches the water when the boat is not in use or remove the prop during non use times.

 

[BAYLINER185]

Re: Stainless prop and Galvonic Corrosion?

I guess I should have mentioned that I only run in fresh water and I trailer my boat to and from the lake. The most it would ever stay in the water would be over night if were out fishing really late or if I ever go camping for two or three days but that s about it. I always wipe dry and rince off the boat if it gets dirty and I plan on doing a fresh water engine flush and blow dry and wash any water marks before I stop using the boat for the 'winter' Like we have on here in Arizona lol.....

I take it I need not worry then about glavonic corrosion any more then I would with an alunimum prop.

thanks for the reply.

 

[rndn]

Re: Stainless prop and Galvonic Corrosion?

I had an SS prop on a boat I used to own for 10 years. Never left it in the water but never had any corrosion on the outdrive. If you're using it in fresh water and usually don't leave it in the water for days on end, you should be fine.

 

[Texasmark]

Re: Stainless prop and Galvonic Corrosion?

Rest easy Bayliner. There are tables which show compatibility of metals when in contact with each other. Materials in the same group are considered to be identical in nature and minimize galvanic corrosion (compatible).

Group II Chart lists the following: Alum, Alum Alloys, Zinc, Cadmium, Tim, SS, Tin-Lead (solder).

Zinc is used as the sacrificial element as it seems to be best adapted to molecular movement; hence sacrifice by oxidation long before the other metals in the group are affected.

Mark

 

[BAYLINER185]

Re: Stainless prop and Galvonic Corrosion?

Sounds like this is all good!

Thanks again for the responces!

 

[wire2]

Re: Stainless prop and Galvanic Corrosion?

Re: Stainless prop and Galvanic Corrosion?

OMC's SST line of ss props were coated with black teflon to reduce galvanic action. It worked fine until you get into a bit of sandy bottom and polish it off.
Powder coat works well too.

But 1-2 days at a time in fresh water, no issues.

 

[Texasmark]

Re: Stainless prop and Galvonic Corrosion?

Hear you on the teflon as I had one of the first that came out on a 125 John. I got tired of having alum's repaired. I noticed in the early days that there was not as much nickel in the mix as their is today. I had a Merc prop back in the '80's and it had little rust specs in it even though it was a fresh water boat. I never wore the teflon off my OMC so I don't know what it did.

One of my current props is an '02 model and there is no corrosion on it...fresh water also, nor any on later editions I bought. They seem to be polished out better nowadays also.

Mark

 

[Texasmark]

Re: Stainless prop and Galvonic Corrosion?

Some FYI that may be of interest:

Beins we were on the subject, yesterday I got to thinking about the early days when the only option to alum, or maybe before the advent of alum even (dunno) was bronze......remember seeing bronze props on the old OMC opposed 2's and 4's.....ran bronze props in the '50's and 60's.

Well my compatibility table ( which by the way comes from MIL-STD-454) lists bronze over in Group IV. That says that "copper and it's alloys" are not compatible with alum but are with SS. So the bronze spline in the hub is ok with SS props but unprotected (they say), can readily corrode alum and the bronze splined hub on the splined SS shaft is also ok.

Don't remember having noticeable corrosion on any alum prop I removed from an engine........even back in the days when OMC had the shear pin which was always breaking (requiring frequent prop removal) at the most un-opportune times....like on the windward side of riprap with a gale blowing. Course back then the engine wasn't in the water more than half a day or so and when it got home it got a thorough cleaning.

Mark

 

[Cricket Too]

Re: Stainless prop and Galvonic Corrosion?

I don't think your gonna have much of a problem with galvanic corrosion, with any prop no matter what the metal or situation, or with any metal on your boat for that matter, in fresh water, especially if you trailer it.

I have only run in saltwater my whole life, and the boats sit in the water from March until December, both with aluminum and stainless props. The only major corrosion I ever notice is on the anodes(zincs) where it's supposed to be.

Also one major contributor to galvanic corrosion, other than the natural process, is when the boat is sitting in a marina, with many other boats, and dock power running around the docks and into other boats. Any of that electricity that leaks from either the dock or from another boat, adds to the processes happening throughout the immediate area in the marina.

Even with that, I have never experience a problem as long as the zincs were kept up with.

I have noticed some slight surface rust/oxidation on the stainless props over the aluminum, but nothing major.

 

[BAYLINER185]

Re: Stainless prop and Galvonic Corrosion?

I totally agree with that as it seems reasonable

I have seen my anodes gettign eaten up each time I go out and back I see them blistered and slowly getting smaller and smaller. I wipe off the blisters and then have white powder on my fingers.

I'll keep an eye on them and when they get really worn down to 1/2 they will be replaced!

 

[Texasmark]

Re: Stainless prop and Galvonic Corrosion?

They are doing their job. I noticed that OEM's especially Merc (beins I've had them for the last many years) uses a whole lot more Zinc than they used to. Obviously it's paying off.

Mark