Are Saildrives becoming more popular?

dlochner · May 11, 2020

Bad Obsession said:
Am I right in seeing them as a potential issue? Why are the manufactures going to them now?

Yes. There is a big mother hole in the bottom of the boat with a sail drive. More aluminum underwater and an expensive bellows that needs to be frequently replaced.

Why? It is a lot cheaper to build a boat with a sail drive than with with a direct drive. No alignment issues, no strut, no stuffing box or shaft seal.

kloudie1 · May 11, 2020

For a manufacturer, it is much quicker to install and there are no worries about alignment ( skilled technician not needed). For the customers who do not pull the boat every year, the drive is a maintenance issue with corrosion being the biggest potential but also having a seal under water on the prop shaft is a problem that will happen and let water into the gearbox at the bottom of the leg.. As I have noted in the past, the legs could be made of an engineered plastic to stop corrosion, and a standpipe installed on the leg gearbox so that oil pressure in the box is greater than water pressure outside. That way, a drop in oil level in the standpipe would tell you that the seal is leaking but as long as you kept the level up by adding a little oil, you could schedule the seal change without worrying about ruining the gears and bearings.. The saildrive manufacturers do not have any incentive to improve the abominations (my humble opinion)..

Sandy Stone · May 11, 2020

Also on most boats you lose the effect of prop wash directly across the rudder, so low speed maneuvering becomes more problematic.

rgranger · May 11, 2020

I've been intrigued by the electrics...

Deep Blue Saildrive – Electric Saildrive – Torqeedo

The first and so far only sail drive of its type. Balanced, fully integrated complete system with 40 HP.

www.torqeedo.com

Sail drive - Oceanvolt

OCEANVOLT sail drive motors Oceanvolt offers a range of sail drive motors to provide propulsion and hydro generation for vessels ranging from 15 to 80 feet. Sail Drive (SD) Synchronous permanent magnet electric motor. Sail Drive with 1.93:1 reduction. Lightweight: weighs as little as 42.5kg...

oceanvolt.com

I like the idea of covering a sailboat with solar panels and truly being energy sufficient.... and if I ever own a boat like this.. I'll name it The Delta G.

capta · May 11, 2020

Anyone who has ever owned, used, had a neighbor or friend with an IO would probably never have one.
Cheap, unreliable junk and has no place on a cruising boat. Two 90 degree bends in the drive train and a pretty small, inefficient prop to boot.

dlochner · May 11, 2020

The benefits of a sail drive for electric production may be greater than the downside of having a big hole in the bottom of the boat and the smaller size and weight of the electric motor and transmission.

Sailing Uma just installed an OceanVolt electric drive.

and

BarryL · May 11, 2020

Hello,

My boat has a saildrive. My boat is a 2002 that I bought in 2013. I LOVE MY SAILDRIVE and my next boat will definitely have a saildrive.

I bought my boat from the original owner. He had not changed the seal between the leg and the bottom of the engine. The manufacturer recommends the seal be changed every 7 years. Since the boat was 11 years old when I bought it, I had it done the next year. The mechanic at my local yard did the work. It was not expensive, the original seal looked great (at 12 years old), and I will wait until another 10 years have gone by before having it changed again.

I have not had any problems with electrolysis, or leaking seals. I like that I can back up straight, that my prop and SD Leg are low drag, that I have no water dripping into the boat, packing gland to maintain, etc. My previous boat had the traditional shaft, shaft log, strut, cutless bearing, etc. I greatly prefer a saildrive.

Just my $.02

Barry

bawlmer · May 11, 2020

I think it is a design and manufacturing plus but there is just too big a hole and way too much metal in the water for my liking. My opinion of course.

rgranger · May 11, 2020

@capta
What does IO stand for?

JohnShannon · May 11, 2020

Inboard /Outboard it is used on some power boats you see machinery sticking out the back of the boat with the prop and stuff, but it isn't a complete outboard motor. The motor part is mounted inside the boat

capta · May 11, 2020

rgranger said:
@capta
What does IO stand for?

An I/O is a bastardization of an inboard and an outboard used on runabouts. Usually powered by a 6 or 8 cylinder gas engine coupled to an outboard like lower end. The idea was that the aluminum drive mechanism would tilt out of the water, but most only do so partially and the aluminum drive mechanism fouls and corrodes very quickly.

rgranger · May 11, 2020

capta said:
An I/O is a bastardization of an inboard and an outboard used on runabouts. Usually powered by a 6 or 8 cylinder gas engine coupled to an outboard like lower end. The idea was that the aluminum drive mechanism would tilt out of the water, but most only do so partially and the aluminum drive mechanism fouls and corrodes very quickly.

Oh right.... That confused me, I thought we were talking about saildrives... sort of a similar concept but not exactly a Merc either.

Barnacle Bill · May 11, 2020

Volvo Penta invented the sail drive and I have been dealing with them since I got into this game in the mid-70's. As mentioned above, there is no direct drive maintenance issues like stuffing boxes, cutlass bearings, shaft alignment, etc. Also, they take up less room when installed because there is no shaft, which often means there is more space to use for storage for other stuff. The other nice thing about sail drives is the prop is usually much bigger in comparison to direct drive props, so you have more torque and speed. The real downside of sail drives is galvanic corrosion and so zincs should be watched regularly and changed when needed. Early zinc maintenance required the prop to be removed, but later models have zincs that can be unbolted and replaced, even under water. I believe Volvo Penta makes sail drives for most other manufactures. In my opinion, they are not such a bad thing and that is why you see more and more of them. Also someone commented that manufactures were installing them because it is cheaper. Like that's a bad thing. Hopefully the customer enjoys the lower cost of this as it is passed down to them.

Mark Maulden · May 11, 2020

I don’t think Volvo makes SDs for other mfgrs. From my research, Volvo, Yanmar, others are actually a ZF.

odaydokay · May 15, 2020

I had an OMC (gas) sail drive in the 70's. I think 30 hp gear reduced to 15 if i recall right. I thought OMC was first but ion any case it had good power but was not reliable. I understand they were better in fresh water than in salt water as mine was.

jaysweet · May 15, 2020

This is mostly a question. I always assumed that manufacturers put in sail drives b/c it allows for more interior configurations (aft cabins, mainly), and interiors are mostly what sells boats these days. It hadn't occurred to me that it saves on labor as well. I believe Marlow-Hunter uses only sail drives these days(?).

I've always felt leery of them (in a very abstract way, since we've had the same boat since 2004) because of the corrosion issue. I've put 2 big egg zincs on our prop shaft every year, and most years they're around 80% intact when we pull the boat in November. One year, both were 100% missing. I assumed it was a stray current issue from another boat, but man: quite scary!