Saildrive vs shaft & P Bracket

[Spacewaist]

I am having a new boat built. One early decision is whether to adopt the builders preference - a Volvo 150s saildrive - or revert to the conventional shaft and p-bracket.

Clearly with the drive further forward, the turning moment from propwalk will be less so I'd lose the opportunity to use propwalk to steer and park the boat. I am told that I will not lose the turning effect of the propwash over the rudder.

It's 45+ feet so I will use a bow thruster either way.

The sail drive is supposed to be less drag and more efficient. Can be maintained from inside the boat.

I have never used one nor knowingly been on a boat with one. Does anyone have any practical advice/experience either way?

 

[ashanta]

The sail drive was preffered by designers and builders as it it was cost effective and easier for them. The sail drive has a large gaiter that needs to be replaced (in Volvo's case) every 7 years. You cannot maintain the sail drive from inside. You need to dry out to change the drive oil.
They do perform well and turn very well. I recently changed to a Volvo folding prop and I find the handling and performance even better.

regards.

Peter.

 

[TigaWave]

I guess it really depends on the layout in the boat in many ways.
But a few points from my experience on sail drives, they take up less space in the boat, no rotating shafts, no stern gland issues.
Manouvering my last boat that had the saildrive nearly 5 ft from the rudder was very different from a shaft with prop close to rudder but you get used to it.
Things to watch for during use, keeping the cooling inlet holes in the leg clear of barnacles, planning for the renewal of the rubber gator, quite a big and expensive job. I thought you had to change the oil in the leg from outside we certainly did. But really they're pretty maintenance free. But get a folding prop as the volvo gear box on ours meant you had to leave the prop spinning which you could hear in the aft cabin. We had a folder but it threw a blade off and had to use the spare for a while.

 

[Sans Bateau]

I have had both types on different boats, given the choice I would always go for saildrive. Whilst I cannot think of any disadvantage of the saildrive, other than the fact you need to dry out to change the oil, (between tides?) you will also have to change anodes, which is a bit more complex than the spilt anode on a shaft.

With regard to use, you will get plenty of wash over the rudder, no prop walk, dead straight reverse, quieter running, more compact layout. There are probably others.

One problem that will not have. is lining up the gearbox/engine to shaft. One Myth (I understand) is the changing of the rubber gaiter. Volvo say 7 years, but then they sell them, they used to insist on every year! I was told buy a respected marine engineer, that in his 25 years in the business he had never heard of one failing; as he said if you inspect it regularly, you will get plenty of warning. My last boat was 13years old, my current boat 11years old, both on the original seal.

 

[Koeketiene]

Re: Saildrive vs shaft & P Bracket

Would always go for a saildrive.

If you can choose, tell your builder you want a Yanmar. Had Yanita re-engined last year with a Yanmar 3JH4 and an SD40 saildrive. You can change the oil in the drive whilst afloat and got a double ring keeping the water out.

 

[Joe_Cole]

Re: Saildrive vs shaft & P Bracket

Is it possible to fit a rope cutter on a saildrive setup? Just curious to know.

 

[Koeketiene]

Re: Saildrive vs shaft & P Bracket

Yes - ropecutter for saildrives are on the market (different ones for 2- or 3-bladed props).

 

[Guest]

I have a saildrive, currently removed due to a gearbox problem caused by an installation fault, (wrong single lever control).

The cost of the diaphragm is high, and changing it means removal of engine, so I checked out the recommended life and change time at this years LBS.

Result

Nanni---no recommendation for planned change time, never known one fail

Yanmar, has twin diaphragms--- indefinate, maybe twenty years, no recommended change time.

Beta--- as Nanni

And now the one which set the sevan years:-

Volvo--- 'at first we said five years, but that was then changed to seven, but we have only ever known of one needing changing, and that was due to damage when working on the boat' We now do not quote a life.

Dependent of the type, make sure the fitting is competent, mine, a Nanni, clamping rings cast aluminium, had both cracked, probably due to excessive and uneven tightening. The inner had been leaking slightly.
Both rings have an even number of studs (6 & 8) so tightening by the usual technique of doing every other stud a little in turn does not work.

 

[rwoofer]

Most of the answers seem very pro-saildrive. Personally I have never had one, but most people I know who have had both generally say that they would prefer the normal propshaft setup.

 

[malcp]

Re: Saildrive vs shaft & P Bracket

Do they say why?

 

[Will_M]

[ QUOTE ]
You cannot maintain the sail drive from inside. You need to dry out to change the drive oil.

[/ QUOTE ] Sorry your wrong on that count, the 150S as mentioned by Spacewaist has, as does the 130S, an inboard oil extraction tube, no need to lift to change the lube oil.

[ QUOTE ]
you will also have to change anodes, which is a bit more complex than the spilt anode on a shaft.

[/ QUOTE ] The 150S, same with the 130S, has a split anode, ie no need to remove propeller to change the saildrive anode, makes the job really easy!

Spacewaist, you say your saildrive package is the ‘150S’ so presumably the engine is the D2-75, nice smooth powerful engine btw.

If you wanted a rope cutter, the only sensible choice has to be the ‘Stripper’ from Ambassador Marine.

Would have to agree with the general consensus so far, opt for the saildrive instillation over the shat drive version.

Reasons, well as has already been said….. Smoother, loads of thrust/wash over the rudder, often far better steerage as distance between rudder & saildrive is often greater than rudder and shaft, straight reverse, compact instillation.

 

[Spacewaist]

Yes a Volvo D2 - 75 engine is in prospect. Is the ropecutter the only practical one? I need one, I havent researched it yet.

Many thanks for your helpful comments.

 

[Guest]

The oil on the Nanni (Selva leg) can only be changed from inside the boat.

There is only one screw on the outside and that is the pivot pin for the gearchange fork, best not disturbed.

On this leg, changing the anode means removing the prop, which with a folder means taking the blades out. As the pivot pins are s/s in bronze, annual removal and greasing is sensible anyway.
The pins can rust and convert the folder to fixed.