Sail Drive versus shaft drive

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raro3

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Thanks to the guys who responded to my post yesterday on the Warrior 40, very helpful. As I mentioned, it is fitted with a sail drive, with which I'm totally unfamiliar. I hear mixed reports about them, mostly negative because of the need to haul-out just to change the oil and potential problems with (and cost of) the seal. I would appreciate opinions from those in the know. The one I'm looking at is Volvo and is about 10 years old (but apparently has a recent seal). Thanks.
 
We've got a Yanmar one about 15 years old, never had a problem.

Pluses:
Easier to install
No vulnerable P brackets
No alignment issues
More compact installation
Quieter drive with less vibration
No stern gland issues

Minuses
Seals need to be replaced periodically (but nowhere near as often as recommended)
Having to have a huge hole in the hull
Possible limitation on drive HP and propeller sizes
 
Likewise, I've had no problems with mine - twin Yanmars, now 8 yrs old, 16000 miles on the clock and 1200 hours on each.

The biggest bonus with them is the ease of installation but of course that won't affect you.
 
No problem. I have a Volvo 120S saildrive.

Shaft seals fail, P brackets fail and shafts can rip out of boats. I've heard of shaft couplings failing and the shaft falling out. OK, these are all relatively rare but I've never heard of a failure with a saildrive seal and they fit them to round the world racers.

But it is a big hole!
 
My saildrive has been fine in the two years I have had the boat (Volvo 10 hp). I did have the seal replaced last year as they recommend every 7 years and that was 8 - a big job and expensive involving taking engine off the mounts and decoupling the engine and saildrive.

Since then the gaiter, which is the rubber bit you see from the outside, has flopped down a few times which is not optimum and Volvo now recommend a stronger adhesive which seems to have done the trick.

As my boat is dry sailed mostly I can look at the bottom regularly but it would have gone unnoticed on a mooring and of course the front end flopping down is not great for speed through the water.
 
For blue water work I'd be wary of the saildrive for the following reasons:

Aluminum casting and very small and expensive anodes means very regular haul outs if it isn't going fizz away.

Most saildrives incorporate the engine raw water intake. Perfect place for the little wrigglers and their calciferous cousins to live and thrive.

As the saildrive/engine combo is very compact, the boat builder has shoehorned the thing in so access to the engine is unnecessarily difficult. On one boat I owned even getting to the dipstick was a struggle. To change the lift pump would have entailed removal of the engine....
 
wouldnt touch saildrives with a barge pole, Only reason they exist is that builders can install them faster with cheap labour. They offer nothing for the user, in some boats changing the gator requires complete removal , try getting the engine out without demolishing the boat!
 
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It depends a little on hull / keel layout but shaft drives may be better protected by the keel, avoiding wraps around the prop

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I dont agree, with a fin keel the sail drive is far closer to the keel making prop wraps unlikely, in fact when I first got mine I spoke to one of the rope cutter people and he talked me out of fitting one, saying they were unneccessary - so we didnt.
He was right after 15 years and nearly 28,000 miles I never had anything round the prop.
With shaft driven craft I had three wraps in 10 years
 
I can't speak for the Volvo but on a Yanmar you can split off the leg, unbolt the flange around the gasket and lift the leg out. It's a half hour job for one man. It should be possible to drop the gearbox through the hole if unable to get it out from above. Replacing the gasket means splitting the leg, probably a job for the pros.

Having a saildrive doesn't necessarily mean restricted access, I can walk round mine!

A shaft drive means the prop is a long way aft of the engine. That tends to mean the engine is nearer the CG and the prop is nearer the rudder. A saildrive will conversely tend to have the weight further aft (not a problem in a modern broad-sterned hull) and/or the prop a long way forward of the rudder which means the helm will be slower to respond from stationary.
 
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It depends a little on hull / keel layout but shaft drives may be better protected by the keel, avoiding wraps around the prop

[/ QUOTE ]

I dont agree, with a fin keel the sail drive is far closer to the keel making prop wraps unlikely, in fact when I first got mine I spoke to one of the rope cutter people and he talked me out of fitting one, saying they were unneccessary - so we didnt.
He was right after 15 years and nearly 28,000 miles I never had anything round the prop.
With shaft driven craft I had three wraps in 10 years

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which is why I said it depends on the hull / keel layout.... I have a Rival with a long fin keel which to date has done an excellent job of protecting the shaft driven prop.... repeat..... it depends on the hull / keel layout
 
Just to balance the replies.

My old boat had the saildrive leg shear off completely and sea water shoot out of the dip stick hole.

IMHO the bottom bearing seized (the leg had continuous problem of water in the oil).

For the new owners Insurance claim it hit a sunk container.

New owner was a fed up as me with Volvo so replaced it with a Yanmar saildrive. No probs for last 4 years heavy charter use.

Ignore the 100hrs oil change (boat lift necessary) as charter boats get it done once per year whatever the engine hours.

I now have shaft drive and cuttless bearing needs doing at 1200hrs. Personally I would have no concern about either saildrive/shaft providing neither were Volvo!
 
Yup, it's another world. All those pags given over in the mags to offsetting prop walk in reverse - none of that mallarky with a S drive. Whiz round marinas and tight spots with confidence.

Oil change - normally every 2 years is fine. Most boats are out for AF at least once during that time!

Gaiter change -every 7 years or so - it's critical that the seal is in good nick but it's very tough and not going to rupture dramatically under anything like normal usage and maintenance. Changing it can be arranged when out for AF.
Change takes once day and is within scope of competent DIY owner.

Drive train should not decide the choice of boat, but S leg is not a major neg - far from it.

PWG
 
I've got Volvo 110S, it was fitted when I bought the boat (although why the previous owner removed a Perkins 4108 and 2.5 box & shaft I'll never know!!!!). I'd want a shaft drive preferably as its a simpler fitting and a little hole, as oppposed to hole I dive through.

I didn't need to change the anode behind the prop this year as there little corosion to it, although the previous year when I was marina based in the uk it went in about 12 months.

I manage to change the oil in the leg by using a syphon through the filler hole, you can remove about 400-500 ml this way so over short period of time you can renew the lot (so to speak).

If they get a knock or pick a rope small enough to 'weld' itself around the stub shaft, you will blow the seal alowing water in and also damage the top and bottom bearings.

Given the choice I would never have one of these things, expensive to maintain and causes loads of drag. Bloody horrible things, they are!
 
Also unless you have the length to fit a CV style coupling in the shaft, to let the engine waggle about in a shaft drive installation, it is difficult to decouple the vibrations of the engine.The three point suspension on the saildrive works really well in damping down NVH (noise vibration and harshness) Glad to hear there is a better glue for the fairing rubber piece as mine has disappeared completely despite using the best one part Italian evo-stik substitute!Hi Racecruiser, could you let us have the spec for the goo!
No copper based antifouling is used on these drives, not even recommended anywhere near them. Leave shorepower connected at your peril, alu props fizz away really quick, but leave the anode and the leg pristine!Possibly consider isolating diode block in incoming earth, or more expensively an isolating transformer fitted by a suitably intelligent person!Problem is not unique to saildrives and mooring near those massive piles holding the marina in place, coupled with warm water and perhaps a current leak from another nearby vessel and the removal of material from the underbody of your vessel begins its inexorable process.Let's go sailing instead before it all withers away! Good boating and sailing to all!
 
Do not be concerned about having a Saildrive. Some people have very fixed views about them, but there are thousands in use all over the world and have been for over 20 years. so this is not new, untried technology. The worlds two largest suppliers of engines for yachts use them and approx 50% of new boats built in Europe fit them. Some like Bavaria use them exclusively, but most builders use both shaft and sail drives depending on model of boat.

Ignoring the benefits for builders - and even then they are not clear cut as Benetteau use shafts, Bavarias saildrives and Jenneau a mixture, the benefits for users are. Generally quieter and smoother, less prop walk: no potential for drips in th boat from stuffing boxes; no vulnerable P bracket and exposed shaft.

Possible negatives - and most of these are exaggerated are the hull seal - but the one on the boat you have been looking at has been replaced and short anode life. The latter however is not universal and is usually connected to the location of the boat. In marinas and where shore power is used usually equals short anode life. Bluewater sailing away from marinas, or swinging moorings longer life. Fitting big chunky bronze folders or feathering propellers also can affect anode life.

Saildrives are no more or less vulnerable to fouling. Close proximity to keels may offer some protection from lines and nets, but they are still vulnerable to floating debris - particularly plastic bags. If it is not fitted with a cutter then I suggest you look at boats out of the water in south coast marinas You are likely to find a majority of saildrives fitted with cutters!

Some have said that the water intakes could be blocked, but this is true of ordinary thruhulls - just that they may be easier to clear. You can always put in a conventional thruhull and a Y valve in the raw water circuit if this worries you.

In my experience there is less chance of a saildrive being badly installed as there no choice open to the installer. Cramped installations are just as common on shaft drives.

Hope this presents a more balanced picture. Concentrate on the characteristics of the boat. You stand just as good chance of getting good service out of either types of drive.
 
Just to add to the sense that Tranona has written, the oil in some drives is not engine oil but a fully synthetic gear oil. This costs about €66 for 3 litres in Italy from a Volvo dealer.If regular inspection of the oil reveals no trace of milkiness or contamination, that the service interval is probably quite long, maybe several seasons (comment?).the noticeable advantage of the oil described is that the S drive (120E in my case) does not overflow and make a mess. This occurred initially on 12 hour use patterns on warm French canals.Since changing to the fully synthetic Volvo oil, the problem has disappeared.The plate on the saildrive says what to put into it!I like Guinness put into me!
 
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