Giu-

This guy wants to know about SAILDRIVES.

 

Giu-

This guy wants to know about SAILDRIVES.

Ruh rho

 

My opinion only. The saildrive you need to avoid is the OMC Zypher saildrive. Although I do have an OMC Zypher myself, I can say this from experience. "This thing works great without any prop washing of any kind and it is always in the water as aposed to an outboard. As far as shaft drives I can't say. I think the single unit of a saildrive has many advantages and the technoligy of saildrives is getting better all the time. Be compfortable with it, and get to know as much about them as you can, many have an internal anode plug that must be monitered. Just do your homework, saildrives aren't going away anytime soon.

 

Take a ook at this thread regarding saildrives: LINK.

 

I would also avoid the Volvo saildrives. New stuff is fine...but the older stuff is a PITA.

 

Take a ook at this thread regarding saildrives: LINK.

Ah hah! So a "Saildrive" is a drive unit, not a particular make & model of engine. Thanks, SD.

The issues with anodes and the like "go away" in freshwater, no?

 

Ah hah! So a "Saildrive" is a drive unit, not a particular make & model of engine. Thanks, SD.

The issues with anodes and the like "go away" in freshwater, no?

No, I think just a little less critical in fresh water. There are two types of anodes, one type for salt water and the other for fresh water. Either way anodes also protect the metals from stray current a marina might omit, they are always necissary.

 

Ah hah! So a "Saildrive" is a drive unit, not a particular make & model of engine. Thanks, SD.

The issues with anodes and the like "go away" in freshwater, no?

Anodes are usually magnesium in fresh water, zinc or aluminum in salt water.

 

Is having zinc anodes in fresh water an issue? What's the reason for using different anodes? We just moved our P40 from salt to fresh but didn't change out any anodes...

 

Labatt-

The difference has to do with how galvanic corrosion works in fresh water versus saltwater. Saltwater requires a less reactive zinc, or it will degrade too rapidly, and leave the boat unprotected from galvanic corrosion when the zinc disappears. Magnesium is more reactive on the galvanic scale than zinc, and will do a better job of protecting your boat's underwater metal portions than a zinc "zinc" would in fresh water.

 

We'll be leaving her in freshwater for about 5 months or so. Do you think it's important enough that I should haul her to replace the zincs with magnesium?

 

We'll be leaving her in freshwater for about 5 months or so. Do you think it's important enough that I should haul her to replace the zincs with magnesium?

Leave it as is. It is more of a danger the other way around as Magnesium will simply corrode away in salt water even without any galvanic current.

 

If you split your time between fresh water and salt water or dock the boat in brackish waters, you can get aluminum "zincs" that are halfway between the magnesium and the zinc "zincs" in terms of their reactivity.

Granted, Magnesium will just corrode away quickly in salt water... but using zinc "zincs" in fresh water can leave your boat effectively unprotected. YMMV.

 

Many years ago we sailed a Laser 28 with a Bukh DV8 fitted with a saildrive. The beauty of the Bukh saildrive is that the raw water intake is through a separate thru-hull/seacock and not through fins in the saildrive casting itself (like some saildrives).

All this leads to simpler construction, enhanced reliability and fewer worries regarding sealing water from oil.

Noteworthy also is that saildrives are usually installed such that the propeller output shaft is c. parallel to the streamline, and so, is essentially prop walk free.

Regards,

 

No its not prop walk free...that I can guarantee you...

 

You don't need zincs on a boat. Changing them out all the time is a real pain and can get expensive. Better yet, get a LOOOOONG pair of jumper cables and find a Sea Ray near by. Much cheaper and it works as lightning protection too.

- CD

oohh, I am giving away all my secrets.

 

You don't need zincs on a boat.

Good to know! Then you won't mind if I take yours?

 

Labatt, You must understand.....CD is a good ole Country boy...a Cowboy..If I may....

He has it all figured out....tired of having to replace those half round pieces of metal that corroded away in 6 months....he had custom ones made out of Satinless steel...they last a life time now......just like a good ole boy would do!!! ehehehehehe

 

I hook them on to my BBQ grill. Please dont take my BBQ grill. My boat will sink. (smile).

- CD

 

Labatt, this thread started about saildrives. I don't know about saildrives in general, but Volvo saildrives have aluminium housings, and my understanding is that it's the aluminium housing that needs to be protected in fresh water. We're in fresh water, and we have a magnesium annode on the saildrive drive shaft and a zinc annode on the maxprop (maxprop doesn't seem to make a magnesium annode). After one-year in the water, there was noticeable erosion of the magnesium annode and no noticeable erosion of the zinc annode. There was also no noticeable erosion elsewhere.

Anyway, I'm convinced that a magnesium annode is necessary for saildrives with aluminium housings in fresh water.

 

Just to add,... since the S-drive housing is aluminium, copper based anti-fouling paints should not be used on the Bukh saildrive, less the entire unit is well encased with a 2-part epoxy paint or similar. The folks that built the Laser 28 did a nice job in the factory.

The Bukh manual in fact recommends not using copper-based antifouling paint period. If you suffer damage to the S-drive paint while working on your underbody, make sure to repair the finish.

 

Aluminum and copper-based anti-fouling paints should never be mixed.