Shaft or Saildrive ?

[Hurleyburly]

Whenever I see a saildrive unit on a boat I'm always a bit wary.

It seems they require far more maintenance and cause many more problems than a conventional shaft.

Is this true and what are the benefits of a saildrive ?

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[Twister_Ken]

>Is this true and what are the benefits of a saildrive<

Reduces build costs.
No need to fiddle around with alignment (although modern shaft couplings obviate this to a degree)

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[goupil]

True, that's certainly the main reason.
My boat had one, I think it's smoother and quieter than a shaft. Maintenance is once a year, I never heard of particular problem as long as you use a specific antifoul for aluminium on it.

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[nicho]

A lot of builders are going saildrive now including the likes of Hallberg Rassey. Whilst my experience is only over the last 6 months (Bav 36), it is certainly smooth and quiet in operation, no vibrations etc, as can be found in some shaft operations. There is some lag in the wash reaching the rudder for close quarter manoeuvres, but not a problem (it's minimal, around 1 second).

I believe these units are more than capabl;e of lasting the life of the engine at least, so would not anticipate too many problems longer term, but no doubt there will be some horror stories generated here(!), however most owners of saildrives seem satisfied.

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[Rich_F]

I understand that another "advantage" of a saildrive is that the prop tends to be closer to the CLR of the hull, reducing the perceived propwalk compared to a stern-mounted prop.

Of course, you may not see this as an advantage...

Rich

PS. Of course, being pedantic, the amout of lateral thrust from the prop is no different. The difference is that most of that thrust will be generating a small amount of "leeway", rather than a large amount of angular movement.

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[nicho]

That's true, on my Bavaria, there's virtually no prop walk - even when you want it most!!

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[Oldhand]

I tend ot agree with you. Boat builders love Saildrives as they are cheap to install and they don't have to worry about the removal to change the hull seal, which was recommeded at 7 year intervals when I had one.

I now have a shaft installation which icludes an Aquadrive coupling and the vibration is just as low as a Saildrive.

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[goupil]

To complete my first answer : IMO, to reduce build costs doesn't mean cheap boat-building, (mine was a Gladiateur from Wauquiez and cost 40 % more than others same size/year).
It's used in production boats because it proved to be reliable and it's easier to do a good job than with a shaft.
Manufacturer says that you must change the rubber seal each 5 years, I checked some 15 years old, as good as new in appearance. But I don't say that's the right way to do...

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[coco]

I am interested in hearing from your experiences with the Gladiateur. May I PM you?


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[goupil]

Of course, go ahead :
Specific questions would be answered by PM those of general interest by thread.
Both would be a pleasure...

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[tom52]

Saildrive advantages= quieter, no P bracket, no stuffing box, no leaks, no vibration, no alignment problems, no prop walk*, reduced prop wash effect*, incorporates raw water intake ( one less hole in hull), less underwater moving parts to attract rope.

* May be disadvantages for manouevering

Saildrive disadvantages= Very big hole in hull that requires expensive seal replacement every seven years ( Volvo )

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[dulcibella]

Not easy to instal on a long keeler.

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