Saildrive Reliability

[longjonsilver]

How reliable are saildrives? Are they more prone to failure than shaft drives? How often do the seals need to be replaced?
thanks
jon

[Jim Cate]

You will find this to be a contentious subject, Jon. One the one hand, many defend t hem as being perfectly reliable, but requiring more maintenance than typical shaft drives. Others report lots of problems, either from personal experience or vicarious adventures from acquaintances or media sources.

My observations have been that in boats that go cruising to distant places, places that don't have slipways or travel lifts available, a shaft drive is less likely to cause strife because one can service more parts of the drive with the boat in the water. Others disagree...

One thing for sure: the aluminium housings of saildrives are subject to stray current corrosion events. A short visit into a marina with defective wiring caused the total destruction of a close friends saildrive... a very inconvenient and expensive happening, and not all that uncommon.

But every time this subject comes up on CF there are passionate arguments, so you will have to decide which side rings true to you.

Jim

[Vasco]

Jim sums it up really well. Personally I would never have one.

[Cotemar]

Most new boats come standard with saildrives today.

If you think you will not like a saildrive, then you just limit your boat selection to the very limited shaft drive boats out their.

I have had both types and have never had an issue with either system.

[DotDun]

Yanmar SD20

2600 hours, 14 years old, now replacing lower leg bearings, prop shaft, seals, and hull diaphragm. FWIW, the hull diaphragm that was removed looked in perfect condition. I will not worry about the diaphragms again until it's time to pull the saildrives at some point in the future (take it off the better service by x date list).

The lip seals wore the prop shaft enough to that seals were leaking within a year or so after replacement. Hence, the impetus to pull the drives was to replace the prop shafts. The rest of the work was the 'it's open, might as well replace'.

I'm of the opinion the upsides of saildrives out weigh the downsides.

[robert sailor]

I'm totally bias in the not in love with sail drive camp. When I first got into sailing several boats were built with either or and the sail drives were cheaper of course. I was told by my sailing instructor that they were ok on lakes but not in salt water, lol. On resale it was harder to sell a sail drive back then. A friend down the dock had his sail drive lower unit eaten up from stray current and of course we all discussed that at the time reinforcing my bias. Having said that life moves on and while I shied away from iron keels for a bunch of obvious reasons they are now used on most of the mono hulls so are sail drives. So as Cotemar points out its pretty hard to find new boats with shaft drives unless you can write some larger cheques, slim pickens for sure.

[Jim Cate]

While it does seem that many new boats do come with saildrives, the OP was asking about their reliability, not about whether he would be able to buy a new boat with a shaft drive.

IMO, saildrives are just one more cost saving "feature" that manufacturers are touting as advantages. Again, these are contentious ideas, and I do not expect that all will agree.

Jim

[DotDun]

To answer your direct question, replace the seals whenever the boat is hauled out for another reason (i.e. bottom paint). Replacing the lip seals is no harder than changing the prop. It's 2 lip seals and 2 o'rings.

[Captain Bill]

My first set lasted a little more than 3200 hours and could have been rebuilt, but the difference in price was only a thousand each for new ones. Also the new ones went in in about 4 hours, and the old ones would have been in the shop 3-4 weeks depending on what they found when the got them apart. Even in a cheap yard that price difference would have been eaten up in yard fees and housing costs pretty quickly. I do know of one guy who lost his drives to stray current, but the Marina's insurance paid for new ones. Still inconvenient though. IMHO no sail boat transmission is designed with cruisers in mind. I personally know 4 people who have destroyed conventional transmissions and 3 that have destroyed sail drives. In my personal small sample size it is probably not statistically different. Sailboat transmissions of any design, conventional or saildrive are designed to get you in and out of the marina/harbor where you begin sailing, not motoring. They simply are not designed for motoring long distances as cruisers are prone to do. One of my saildrives was partially overhauled at 1700 hours. It had developed a small leak in the prop shaft seal and a small amount of water was in the oil. I needed to make a bridge opening so I was running at 100% for about 20 minutes and the oil got so hot that the water boiled. It blew out every seal in the drive and blew 90w oil all over my engine room. Of course with no seal and no oil it proceeded to fill with seawater. Water seals on the prop shafts are notorious for wearing a groove in the shaft and causing leaks. They make chrome sleeves to go on the shafts to help with this problem. I know one guy who had his cat like mine converted to shaft drives to the tune of nearly $50K. Last time I talked to him he said it was a big mistake. I paid about 14K for two new Yanmar SD60's installation and yard fees included. The new ones seem much better built than the SD40s I replaced. I have about 500 hours on them now and they are coming up on their 3rd oil change in about 50 hours. When my old ones had this much time on them the oil was quite dirty when I had about 100 hours on it. With these new ones I have trouble reading the dipstick the oil is still so clear at 200 hours on it. I'm hoping that this means that they are built to higher tolerances and are not wearing like the old ones.

You can look through any number of threads here in CF and find lots of people having trouble with sail drives and shaft drive, so it's pick your poison. It's a boat, something breaks every day.
.

[SV DestinyAscen]

I'm not aware of any smaller shaft drive boats being made new other than the Sun Oddessy 349, which is sort of an oddity.

Both can go wrong and both can be reliable. Listen to Jim.

[Dulcesuenos]

We've had more problems with shaft drives and engine alignment and seal leakage and cutlass wear on last two cats than saildrive issues with current cat, SD 20s 22 years old 5100 hours. Original cases, not sure but probably on internals.

[belizesailor]

Originally Posted by Cotemar

...

I have had both types and have never had an issue with either system.

Have owned both too, few issues with with either.

I do agree with Jim on serviceability though...a shaft is very simple and serviceable anywhere with basic yard/machine shop services. A sail drive internals problem requires special tools, skills, and parts. Even basic maintenance like changing the shaft seals requires a lift or at least careening.

My preference on a cat would be mid ships mounted engines with a shaft, but very few are built that way.

[Rapanui]

We replaced our engines and saildrives at about 6500 hours and 12 years in charter, not because had any problems but so that we had new drive trains for when we left charter and started private use. It made sense as the cost was offset against profit from chartering. Replaced Yanmar 2GM20/SD20 with 3YM30/SD20s. Seals were replaced annually during winter antifoul. The original engines/saildrives were sold on.

[boatbod]

SD60 has some known issues with linkage adjustment causing burned up clutch packs. Its predecessor the SD50 had known issues with glazed cone clutches. Volvo drives have had issues with corrosion and also clutches - Volvo seemingly changed their recommendation on which oil to use several times!

If you look after them, sail drives are fine, but like anything they go to hell quite quickly if you take your eyes off them.

[longjonsilver]

Thanks, guys and ladies, for helping me to decide which boat to look for.
Much appreciated
jon