Difference between saltwater and freshwater outboards?

[softdown]

Been told the only difference is the sacrificial anodes on the saltwater outboards?

I have some old outboards dating back top the 50's. Things could have been different then?

What happens when a freshwater outboard is used in saltwater for extended periods? Assuming that sacrificial anodes are used. That these may be old outboards as well.

 

[Scott Danforth]

Outboards from the 50's have steel shafts, not stainless.

If you use your 50's outnoard in salt, it will be destroyed in short order

 

[softdown]

When did they start using stainless shafts? I have ten old outboards to "play with". Though it has been misery to date.

 

[Scott Danforth]

Early to mid 80's. Depends on brand

 

[jimmbo]

Been told the only difference is the sacrificial anodes on the saltwater outboards?

I have some old outboards dating back top the 50's. Things could have been different then?

What happens when a freshwater outboard is used in saltwater for extended periods? Assuming that sacrificial anodes are used. That these may be old outboards as well.

Even newer ones succumb to salt and galvanic corrosion

 

[tpenfield]

Johnson and Evinrude were the preferred engines for salt water back in the day (1960's), because they tolerated salt water better than the Mercurys. Mercury got on board with stainless steel drive shafts in the late 1970's.

Outboards, in general are preferred for salt water, because they can be tilted up out of the water. The anodes, if used, would be different depending on if the engine was used in salt or un-salted water. Aluminum or zinc would be for salt and magnesium would be for fresh water.

The engines themselves are the same, of course. . .

 

[82rude]

Several mfg,s have had or do have salt water series motors.Marketing ploy or ?

 

[Roberthill]

Use a 1957 35 Johnson in salt water , had to replace upper shifting rod last week it corroded and collapsed , sixty years not bad , but I'm sure it was'nt used just in salt water . Shaft of course is steel but one thing we have to remember exhaust is in the same area and burned and unburned fuel and oil is deposited here and shaft shows no rust (use grease and o ring on spline) . I always rinse with fresh water

 

[softdown]

Even newer ones succumb to salt and galvanic corrosion

That appears to be a good illustration of the demise of aluminum without using sacrifical anodes made of zinc. Even freshwater will attack aluminum if the motor is not raised out of the water.

 

[Chris1956]

My 1958 Fat Fifty (Johnnyrude) was all stainless steel fasteners, drive and shiftshafts and brass or aluminum components. Saltwater had little effect on it. Also, 2 cycle fuel deposits a layer of oil on the exhaust portion of the motor, further decreasing corrosion. if you have Johnnyrude motors from that era, take a look at the casing screws and see if they are stainless. That will give clues to the corrosion resistance you can expect. Heck, OMC did not recommend fresh water flushing for many of their 50s and 60 motors.

Mercury switched from mild steel driveshafts to stainless driveshafts in the early 70s. More recently, Mercury started marketing a "Saltwater" version of it's larger motors. They claim greater use of stainless steel, than the non saltwater models. I have never analysed the difference.

Most outboards from the 70s have anodes, so that is not the difference between saltwater and non saltwater models..

 

[softdown]

My 1958 Fat Fifty (Johnnyrude) was all stainless steel fasteners, drive and shiftshafts and brass or aluminum components. Saltwater had little effect on it. Also, 2 cycle fuel deposits a layer of oil on the exhaust portion of the motor, further decreasing corrosion. if you have Johnnyrude motors from that era, take a look at the casing screws and see if they are stainless. That will give clues to the corrosion resistance you can expect. Heck, OMC did not recommend fresh water flushing for many of their 50s and 60 motors.

Mercury switched from mild steel driveshafts to stainless driveshafts in the early 70s. More recently, Mercury started marketing a "Saltwater" version of it's larger motors. They claim greater use of stainless steel, than the non saltwater models. I have never analysed the difference.

Most outboards from the 70s have anodes, so that is not the difference between saltwater and non saltwater models..

It is possible that the use of anodes is region specific. I own 10 outboards in Colorado. None of them have an anode...that I can see anyway. Anodes are often quite conspicuous.

 

[jimmbo]

Replacement trim tab anodes for mercury outboards are now Aluminium, the old ones were zinc