Prop shaft or Sail Drive

[Zindab]

It is my intention to install Yanmar sail drives, what are the Pitt falls with sail drives if any ??

[djmarchand]

Corrosion, corrosion, corrosion. You have a big chunk of aluminum hanging off the bottom of your boat. It is out of sight, out of mind, unlike outboard or I/O legs.

It is absolutely critical to keep the paint on the leg in top notch condition and renew the zincs religiously. Inspect carefully at haulout, preferrably yearly.

David

[westwinds]

The saildrive will cost about $2600 more for the 30 HP engine. I am also thinking the seals on the saildrive are going to give more problems than a cutless bearing; however, if your sailboat is not designed to take an engine with propeller shaft, then you have no choice. Also, if the propeller gets damaged (in some far off place?), I would rather pull and repair a sailboat with a propeller shaft.

[smj]

Originally Posted by djmarchand

Corrosion, corrosion, corrosion. You have a big chunk of aluminum hanging off the bottom of your boat. It is out of sight, out of mind, unlike outboard or I/O legs.

It is absolutely critical to keep the paint on the leg in top notch condition and renew the zincs religiously. Inspect carefully at haulout, preferrably yearly.

David

I couldn't have said it better. Also more drag with the saildrive compared with the io or outboards.

[delmarrey]

The only vessel I would install sail drives would be a Cat, if it had shoal keels to protect them. The reason is the access to Cat engine rooms are usually restricted back aft and shafts are usually too long to fit.

A shoal keeled Cats can be beached easily for inspections/maintenance.

Or, Race boats that come out of the water often.

[Zindab]

The more you look into it and people you ask about sail drives that own them it seems that old faith full prop shaft is the most reliable method of propulsion.
Look like engine bed adjustments coming up to fit shafts.

[downunder]

If you could fit shafts. Go shafts.

[Captain Bill]

The biggest problems I have with mine are the shaft seals, both the prop shaft and the front main seal. The yanmar shafts are terribly soft and the seals wear a groove in the shaft that eventually leak. My mechanics have put a chrome sleeve on my shafts to reduce the wear, but this was the second time I had them repaired. I called Yanmar Yanmar tech support and their response was "yea, that happens". I either have oil leaking out the top or water leaking into the bottom. I don't know how part availability is in OZ, but in the US I was once told there were no prop shaft seals anywhere in the US. This even though their considered a regular maintenance item. I was going to have to wait 3 weeks for them to be shipped from Japan. Fortunately I was smarter than the average mechanic and had the shipped overnight from the UK. Isn't the internet a wonderful thing.

A lot of people seem to have problems with the cone clutches, but I have been fortunate in that area. There have been a number of threads discussing Yanmar saildrive issues on the forum. You should do a search and judge for yourself.

[rabbi]

Originally Posted by Zindab

It is my intention to install Yanmar sail drives, what are the Pitt falls with sail drives if any ??

You have a large hole in the bottom that is sealed by some rubber. if it fails down she goes....

We had ours nearly ripped out when running into a huge pile of old fishing net under sail @9knots. Small leaks required a liftout, disassembly, some fibreglass work and reassembly.

These large rubber seals have a lifespan of 7years and cost around 1000 Euro just for parts for yanmar. Plus lots of work.
The lower seals should be replaced every other year. If they fail, your SD leg runs i salty oil and is ruined pretty fast.

[Therapy]

My choice would be shaft drives but almost no modern cats have them. Sail-drives are king. Cheaper? Provide for more jobs?

[ggray]

If you have saildrives, very important to install a galvanic isolator. Zincs last much longer.
Big hole in bottom is something to think about, but much more so in a keel boat. In cats, engine room is normally behind a bulkhead, so not so critical.
I'm at 12 years with original rubber gaskets; we'll see....
I installed an expansion tank well above the waterline for the saildrive oil. Helps keep water out.
Someone mentioned more drag with saildrives, but I've read that it's less. Guess it depends on shaft length, but i'm guessibg a shaft would need to be rather long on a cat hull.

[belizesailor]

Sail drives are fine most of the time, but when you do have trouble with them you need a mechanic with the right skills and training, and the proprietary tools, to fix them right. Also, the parts are proprietary and crazy expensive.

In contrast, I can fix a shaft drive anywhere in the world with basic machine shop services and basic hand tools.

I've had good luck with my sail drives, but my next boat will NOT have sail drives.

[delmarrey]

Originally Posted by ggray

If you have saildrives, very important to install a galvanic isolator. Zincs last much longer.
Big hole in bottom is something to think about, but much more so in a keel boat. In cats, engine room is normally behind a bulkhead, so not so critical.
I'm at 12 years with original rubber gaskets; we'll see....
I installed an expansion tank well above the waterline for the saildrive oil. Helps keep water out.
Someone mentioned more drag with saildrives, but I've read that it's less. Guess it depends on shaft length, but i'm guessibg a shaft would need to be rather long on a cat hull.

You would think these items should be part of the installation, especially these days with all the known faults!