Saildrive VS Direct Shaft

[stefano_ita]

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.

Interesting point of view, i did not calculated the aft bulkhead....with engine, all the seacock and rudder'sbearing all in one bulkhead would be great

[Dennis.G]

When I was shopping for a boat, the presence of a saildrive system counted as negative points. Not that shaft drive is without its own issues, but the stories I have heard from saildrive owners supports my basis of scoring. Not a complete deal breaker, but a negative in my opinion.

[stefano_ita]

Originally Posted by Dennis.G

When I was shopping for a boat, the presence of a saildrive system counted as negative points. Not that shaft drive is without its own issues, but the stories I have heard from saildrive owners supports my basis of scoring. Not a complete deal breaker, but a negative in my opinion.

Quote 100%

[Stu Jackson]

Originally Posted by stefano_ita

Thanks,

The photos has been taken by opening an acced from the aft cabin alright? for extra mainteniance do you hang up the compantionway's ladder?

That photo was taken from the saloon looking aft. The companionway ladder (steps & enclosure) lift up on gas struts, so it's up and out of the picture.

Does that clarify it for you?

[stefano_ita]

Originally Posted by StuM

My saildrive propellors are so close to the rudders that I can't fit folding props

That's really bad

Just to know, is it possible to install a rope cutter on ALL the saildrive or do they have the outpout prop shaft always very short?

[stefano_ita]

Originally Posted by Stu Jackson

That photo was taken from the saloon looking aft. The companionway ladder (steps & enclosure) lift up on gas struts, so it's up and out of the picture.

Does that clarify it for you?

Yes thanks! (more an english understandment issue)

Let's say the prop is on the same side of the engine, as viewing the saildrive's leg as center of reference

[Cheechako]

I like the simplicity of the direct drive type. Especially if there is any aluminum in the saildrive.

[stefano_ita]

Originally Posted by Cheechako

I like the simplicity of the direct drive type. Especially if there is any aluminum in the saildrive.

Yep, with bronze prop, stainless screw and shaft, zinc, add bit of salt and pepper and the soup is done (italian's says "soups is done" meaning the worst is happened as previously planned...)

[valhalla360]

All else being equal, I would prefer an outboard first (with boat designed for it), shaft drive second, sail drive last. That said, we just bought a boat with them.

The main driver for them is flexibility and ease of installation.

I will question the threat of sinking. I've heard a number of stories of lost prop shafts that lead to sinking or near sinking, so I suspect it's about a wash.

Assuming no maintenance, issues, saildrive will be better than shaft but probably not enough to make a difference.

Maintenance is only an issue in terms of using the proper zincs and keeping them in good shape. Don't do that and it's bad news.

[Kokanee]

Saildrives do have their advantages, especially for boat manufacturers. There is more flexibility in engine placement and boat layout. Weight placement is more central. They are quieter. No alignment issues.


Shaft drives are simple and I can do my own repairs. They suit my needs better.

[Stu Jackson]

Originally Posted by valhalla360

I will question the threat of sinking. I've heard a number of stories of lost prop shafts that lead to sinking or near sinking, so I suspect it's about a wash.

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.

[Terra Nova]

Originally Posted by stefano_ita

...What do you think about a...saildrive...

I would not own one.

[valhalla360]

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.

If you are in a quiet anchorage working on the stuffing box...sure. Of course, it's pretty unlikely, you will removing the sail drive in that situation.

If you are bouncing around in a seaway and there is already a foot or more of water and it's a V-drive setup with the stuffing box under the motor...it could be a bit more challenging.

Again, it gets back to flexibility of installation. You can make the shaft easy to service but that will eat up a lot of space on a small boat.

As with most things, there are always trade offs.

[builder dan]

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

[SailAllDay]

The newer sail drive model 130 are great, they have a 2 piece zinc, and you can change the gear oil from inside the boat. The older ones suck, you have to take the prop off to swap the zinc and haul out to change the oil. The diaphragm failure is very rare and there's two of them stacked on each other so It's a non issue.

Advantages are fuel and power efficiency, less vibrations, ease of installation/removal, and less space in the engine compartment.


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