sternleg vs shaft drive

[jonathan 4]

Those who have owned sternleg boats...    are they as much trouble as some people like to make out?

 

how much maintenance do they require vs a cutlass etc

  

[Black Panther 1,584]

I loved my Volvo saildrive. Never any grief. Change the zinc and oil and paint.

[Rats 28]

I would not own a boat with a sternleg, simply too much trouble  with maintenance etc.

 

The question is: Why would you make a sternleg out of so many different metals and then immerse it in salt water,

 

This is borne of first hand experience with a multitude of vessels, I know of 2 vessels that have sunk and several that have come close to it due to poorly designed bits that cannot be easily seen that have corroded.

The most common damage is to lower ends because they  protrude down and are unprotected against any impact type damage -once impact damage occurs the seals often fail filling the lower end with saltwater.

Alloy props are less efficient however if they suffer an impact they typically absorb most of the impact and suffer the most damage conversely if you have stainless props they are less forgiving and often transfer the shock load of impact up the drivetrain which rapidly becomes an expensive proposition.

my ten cents worth

 

Give me a shaft /cutlass protected in large part by a keelson any day

 

What you sacrifice in boatspeed and yes there is a trade-off, is more than offset by downtime usually at holiday time related to sternleg maintenance.

Do not go near the variant IPS drives unless you love throwing serious coin away, coin I would prefer to spend while enjoying my holidays

[wheels 543]

Gone are the days of the unreliable outboard. Today, these things start easy, start with no hassles and need little in the way of maintenance. Speaking of the modern known named units that is.
 

 

 Why would you make a sternleg out of so many different metals and then immerse it in salt water,

 

 

Aluminium and a SST shaft. That is so many different metals? But anyway, to protect both, you have an Anode. I don't see a problem.
Shaft drive has Bronze and SST with the protection of an Anode. Whats the difference?
Outboard on a yacht can usually be lifted clear of the water when no in use. That's a big plus. Very much cheaper to replace than an inboard diesel.
And even protected behind a Keelson, don't go believing it if fully protected. Plus many Hulls these days can have a very exposed Prop and shaft. Also, you do not have the noise inside from a Diesel running. And outboard can be nearly silent from inside. There are some massive advantages to having an outboard.
The big downside is that you have no real platform from which you can run things like Fridge, Charging and watermaking if you so need.
I think there are pro's and con's for both and I don't see any one clearly benefiting over another. It really depends on needs.

[mattm 98]

Wheels, Jonathan asked about stern legs, which, unless you are assuming he has his terminology wrong and actually means an outboard, are used on bigger runabouts and launches. Common ones being Mercruiser or Bravo units. They are made of a cocktail of metals. It seems crazy. According to a local Volvo expert, 6 months is not bad for a set of anodes, 9 months is good, a set being 5 anodes! He also said they are likely designed with fresh water use in mind, hence the many differences deferent types of metals not being such an issue, then they change the anodes and say good to go for salt. You won’t find a boat part that will corrode away faster than a stern leg will if it’s unhappy with its anodes.

 

Add to that the seals and oil filled gearbox that live underwater, yeah I think they do deserve their reputation on a permanently moored boat. Not so bad on a trailer boat. Mored boats with legs seem to take longer to sell, and sell much cheaper.

[wheels 543]

Doh!!! I really need to stop posting so early in the morning till coffee has kicked in.
Sorry. Resume normal programing. Nothing to see here.

[1paulg 17]

I have Sternlegs that retract out of the water ( Cat) so they are only submersed when motoring - on the original anodes still - 6 years plus . Being in the water especially in a marina where there are likely to be electrical currents is the killer

[marinheiro 352]

Be mindful that the sterndrives sold and installed here were originally designed to power big fizz boats, not Kiwi launches weighing 6+ tonnes. Puts a lot of load on the legs. Apart from the corrosion problems mentioned previously the other major weakness for moored boat installations is the flexible boot protecting the CV or universal joint. If that fails you have a leg full of water.

You see very few commercial operators running srerndrives which is an indication of their reliability.