Saildrive VS Direct Shaft

[Get-away]

I view sail-drives as all the problems associated with stern drives with less accessibility to fix them.

Give me a conventional shaft and prop (Hundested if its going feather) any day.

An appropriately sized wooden tapered bung for every hole in the boat and a hammer IMHO is a much simpler solution to the potential problems of a saildrive.

[valhalla360]

Originally Posted by builder dan

the sail drives i have seen had dust in the bilges not water,still prefer the simplicity of a shaft though

That's one thing I won't miss about our old power boat.

[AD28]

It is always interesting to peruse threads populated by those who have no experience with that which they pontificate upon.

How do I know? Because I have a saildrive, I know that:
--I can change the oil in the water
--if maintained, there are NO leaks. Dry bilges.
--The saildrive is electrically isolated
--props are directed over the rudders
--I know how saildrive line-cutters work
--2-piece zincs are available

But you folks must know best, you read it all on the Internet.

[rabbi]

Originally Posted by stefano_ita

Interesting too...

Do you had mechanical or hydraulic gearbox? It must have lot of turque and do not slip the clucht to almost districate the saildrive...

Does it just moved from the bolts or the bolts cracked the fiberglass around them?

The story about the Lagoon 500 is here: Lagoon Litigation » The facts, the litigation, the arbitration and issues.
If I remember correctly the saildrive caught the dinghy painter and completly dislocated, opening a wide gap leading to a sinking boat.


As for our incident, that was a Lagoon 410. We were sailing @8-9kn with engine in neutral, so the props were free spinning. We ran into a huge pile (~size of a small house) of discarded fishing net floating just under the surface.

The net wrapped around the free spinning prop and brought the boat to a full stop (with all sails up). The forces were multiplied by the fact that the net was attached to the very bottom of the saildrive, giving a large lever.

The saildrive was moved aft maybe half a centimeter, the holes for the bolts were cracked and enlarged, and the fibreglass around the saildrive had several cracks.
The saildrive itself was still water tight, it was just leaking through the cracks in the fibreglass bed. The bilge pump would switch on every 30min or so.

[rabbi]

Originally Posted by AD28

It is always interesting to peruse threads populated by those who have no experience with that which they pontificate upon.

How do I know? Because I have a saildrive, I know that:
--I can change the oil in the water
--if maintained, there are NO leaks. Dry bilges.
--The saildrive is electrically isolated
--props are directed over the rudders
--I know how saildrive line-cutters work
--2-piece zincs are available

But you folks must know best, you read it all on the Internet.

Weee, I even have two of them

You can't get all oil out without draining, but pumping out is better than nothing. Saildrives require shaft seal replaceent, but I don't remember the frequency. I just did it last season, so should be good for some years.

[Scaramanga F25]

I love the idea od a saildrive.
I will never have one.

Corrosion corrosion corrosion.

Haulout November all AOK
January both need to be replaced 12K$.

Electrolysis. Bad marina electricals.

[bsurvey]

do you really want a hole that big in the bottom of your boat


you will need a galvanic isolator otherwise the drive becomes a very expensive sacrificel anode

[rabbi]

Or make your boat self sufficient. We have plenty of solar and never plug into shore power.

Our anodes are a couple of years old and won't need replacement for a few years. I replace the saildrive seals more often than anodes.

[Jim Krause]

After 2000+ motoring miles, I've had nothing but good experiences with the Volvo Penta / sail drive combinations in 2 different Bavarias I've owned and chartered. Very quiet too.

Originally Posted by AD28

It is always interesting to peruse threads populated by those who have no experience with that which they pontificate upon.

How do I know? Because I have a saildrive, I know that:
--I can change the oil in the water
--if maintained, there are NO leaks. Dry bilges.
--The saildrive is electrically isolated
--props are directed over the rudders
--I know how saildrive line-cutters work
--2-piece zincs are available

But you folks must know best, you read it all on the Internet.

[Terra Nova]

Originally Posted by SailAllDay

...Advantages are fuel and power efficiency...

Straight drive is more efficient.

[Cadence]

Originally Posted by stefano_ita

Thanks...

About engine placement what is the difference?

I saw boat of same dimension, same layout, some with saildrive and some with direct shaft (long about 6-7+ feet) with the aft part going up quite vertical, some with much inclined prop shaft but shorter...

For cost and time installation in a supply chain for sure saildrive win, until the owner get his new boat...

If it was a matter of engine placement a V-drive would probably solve most of those situations.

[Pete7]

Originally Posted by Cadence

If it was a matter of engine placement a V-drive would probably solve most of those situations.

But in larger installations they loose huge amounts of power, sadly because it would solve some of the problems.

[tdoster]

Originally Posted by StuM

With a saildrive, the prop is almost directly under the engine. With a shaft drive, it needs to be behind the engine - and if the engine is higher than the propellor, the further away it is, the better it is for the angle of the drive shaft. You really want your prop to be pushiing as close to horizontally as possible

In the case of my boat, saildrives mean that the engines can be in separate compartments in the sugar scoops behind the accomodation. If they were shaft drives, the engines would have to be further forward under the rear bunks - using up valuable storage space, increasing noise, heat vibration in the accommodation and making them harder to access and work one.

Plus I have a bulkhead between the engine compartments and the main hulls meaning that in the even of a catastrophe, flooding is limited to that compartment.

Stu, no disrespect, but all of the arguments I have heard on either side, this is the first on vertical shaft being an advantage. I have heard the argument that the straight vs the angle gearing on outboard/sail drive as a disadvantage, but not to argue for or against your point. Unless it is an old OMC gas saildrive, there is an output on the engine, to 90 down to 90 out on the typical saildrive on top of the traditional gearbox, correct? So, what did I miss on your argument?

I don't have a dog in this hunt other than after pulling many engines and gears from boats in the water with traditional shafts, have never had to pull the boat out of the water to remove it all.

Both have advantages, but both require different care and feeding. Failure to do so on either will equally sink the boat.

[stefano_ita]

Thanks all for the various point of view

[Cadence]

Originally Posted by Stu Jackson

I've always wondered about these stories. If you lose your prop shaft, could one not simply stuff a BIG rag in the 1 1/2" hole? I change my speed transducer and fully understand the amount of water that comes through that size hole, but it's not a whole lot of pressure. Surely a jury rigged plug of some sort would be high on a list of things to have "just in case" would it not?

Saildrive holes? Not so much.

The only way I could see anyone lose their shaft would be reverse pulling it out of the flange. Once it clears the flag and the keyway it stops turning the wheel.
I would think the packing gland would keep it in place. In most cases if not the rudder.
Now that's another story.