Saildrives?

[geoleo]

It may sound silly but Im afraid of and irrationally opposed to saildrives. Bascally all I really know of them is: the larger Yamaha ones develope slipping "cones" and need special tools and big bucks to repair.what if you are in timbucktooo? The smaller Yamahas dont have this problem but are limited to 30hp. The Volvo saildrives are much more reliable but the volvo engines are not and parts cost a fortune. Why cant saildrives be converted to straight shat drives if there is room? What about those Beta saildrives and engines? Comments please--- Thank You

[belizesailor]

Some of your concerns are not silly and are quite valid -- especially in the context of a cruising boat which maybe in remote locations.

Saildrives, regardless of make, are mechanically complex, expensive to purchase initially, parts are expensive, any significant repairs not only require a long list of specialized tools -- but the experience to use them (which even pro's w/out sail drive training and experience do not have).

My Volvo sail drives have fortunately been quite reliable (as have the engines), but when I have needed to make repairs the parts have been absurdly expensive.

A good old fashioned shaft with a stuffing box I can fix, or completely replace, anywhere in the world with basic machine shop services.

For these reasons, my next boat will not have sail drives.

[JPA Cate]

Hi, George,

We have a number of friends with saildrives. Unless the boat it's on can be beached for servicing, they really add to costs. You either have to pay for lay days if the whole thing is removed, or install a plug that you trust; and it leaves a biiiiig hole. In the latter case, you pay for more in-and-outs. They are susceptible to galvanic corrosion, can lead to holing the leg; also prop falling off. Depends on the circumstances how serious that is. They are inefficient.

However, they're really easy for boat builders to install.

Only one friend has replaced his with shaft drive. Was quite pleased. It can be a huge job, though.

Ann Cate, s/v Insatiable II, Port Cygnet, Tasmania

[ggray]

Originally Posted by Ann T. Cate

Hi, George,

<snip>

They are inefficient.



Ann Cate, s/v Insatiable II, Port Cygnet, Tasmania

Yes, I agree there are several issues to be dealt with, but inefficiency? For some reason, I thought they were more efficient. Thrust is not angled down, and I thought there was less drag, but that would depend on the shaft length compared with.

Since they came with my boat, I have no option but to be aware of the concerns (primarily galvanic corrosion, so I installed an isolator) and be ready for them. Never had a shaft installation, but understand there are issues with them.

All that said, I'd have major additional concerns if I had one on a keel boat (I understand there are some of these). I think a little bit about that big hole in the bottom, but its behind a rather water tight bulkhead in a boat that wouldn't sink. A keelboat would be different story unless the engine were in some sort of cofferdam.

[44'cruisingcat]

Do Yamaha make saildrives?

[Jim Cate]

Originally Posted by ggray

Yes, I agree there are several issues to be dealt with, but inefficiency? For some reason, I thought they were more efficient. Thrust is not angled down, and I thought there was less drag, but that would depend on the shaft length compared with.

I believe that the efficiency loss is due to the two sets of bevel gears that turn the shaft downward and then aft again. These cause inherent mechanical losses that are not present in a shaft drive

But for me, the biggest drawback for distant cruising is that in order to do repairs, one must remove the saildrive from the boat, and this entails slipping the boat... not always easily done when in remote areas. And of course, that said repairs seem to be required fairly often!

Cheers,

Jim

[belizesailor]

Originally Posted by Jim Cate

....
But for me, the biggest drawback for distant cruising is that in order to do repairs, one must remove the saildrive from the boat, and this entails slipping the boat... not always easily done when in remote areas. And of course, that said repairs seem to be required fairly often!
...

Yes, hauling and removing the sail drive is certainly a negative. However, I would differentiate normal maintenance from "repairs". A couple of examples below.

Prop Shaft Seals. Replacing shaft seals is normal maintenance. The boat must be hauled to do this, but this is an easy job which can done on about the same schedule as a bottom job (every 1 to 3 seasons approx.). I usually replace mine when I haul for a bottom job whether they need it or not. They are nothing more than oil ring seals and be acquired inexpensively from any good bearing and seal shop (common even in "undeveloped" countries) as opposed to paying Volvo an exorbitant price for exactly the same thing. Really not much more of an issue than stuffing box maintenance is for a normal shaft installation.

Bellows Seal. Replacing the "bellows" (big rubber seal ring) also requires hauling, and physical removal of the sail drive, and typically replacement of few related parts also. It is a significant job. Fortunately, this is not something which needs to be done frequently. Volvo recommends every 5 years. It is quite common to run them much longer. This is normal maintenance, but has not equivalent to shaft installations. I've seen bellows in perfectly good condition after 10 years of service.

In my case, and many other charter boats in the fleet in Belize, these are the only two maintenance items I have ever had to contend with on my sail drives.

While they are reliable, if you do need to make more extensive repairs it is quite expensive. You need to haul, spend at least a few days in the yard, hire a specialist with appropriate skills and specialized tools, and the parts are absurdly expensive. And, each unit is in effect a one-off because they must be individually adjusted -- which requires lots of high-rate skilled labor. I agree with a Volvo technician friend of mine, that if a sail drive needs significant repairs then you are better off simply to replace the entire unit with a new one.

[Cotemar]

This whole thread is loaded with miss information.
The OP stated that Yamaha saildrives have problems.
Yamaha does not make sail drives.
Yanmar makes the saildrive with issues.

I have had Volvo and Yanmar engines and the parts are the same price.

If you do not want sail drives then buy a custom boat.
Most production cats are made with sail drives. They motor faster, because the prop is not on a downward angle.

[DotDun]

As with every design criteria on a boat, saildrives have pluses and minuses. For me, the pluses outweigh the minuses.

YMMV

[belizesailor]

Originally Posted by 44'cruisingcat

Do Yamaha make saildrives?

I'm assuming the OP made a typo and meant "Yanmar".

[amarinesurveyor]

Sail drives are more efficient motoring and less drag when sailing. I sailed with a well known naval architect once in the early 80's in Annapolis and I asked about the sail drive in the boat, thinking that it was much more drag when sailing (this was a race boat). He said that it was in fact less drag, which surprised me.
Sail drives are more vulnerable to corrosion because they are aluminum and they are prone to getting water in the oil because the shaft seals fail or are not changed regularly. I find salt in the sail drive oil very frequently when I take oil samples, which is very corrosive and can cause damage. Volvo drives seem to be less prone to salt water intrusion (maybe better seals), they are made by ZF in Italy, they make many gear boxes for boats. I'm not sure if Yanmar makes their own sail drives or if someone else makes them.
I like the valves on the Volvo drive water intake valve better than the Yanmar, the Volvo is a ball valve and the Yanmar is a gate valve, which seems to freeze up very easily if it's ignored for very long. And I also like the inner rubber seal design on the Volvo that you can see in the engine room, better than the Yanmar.
Sail drives are very common these days and they can last a long time. I recently surveyed a 25 year old 10 meter Catalac that had Volvo sail drives that had a very good maintenance program and they looked and performed great.
Brian

[Cotemar]

Originally Posted by amarinesurveyor

Sail drives are more efficient motoring and less drag when sailing. I sailed with a well known naval architect once in the early 80's in Annapolis and I asked about the sail drive in the boat, thinking that it was much more drag when sailing (this was a race boat). He said that it was in fact less drag, which surprised me.
Sail drives are more vulnerable to corrosion because they are aluminum and they are prone to getting water in the oil because the shaft seals fail or are not changed regularly. I find salt in the sail drive oil very frequently when I take oil samples, which is very corrosive and can cause damage. Volvo drives seem to be less prone to salt water intrusion (maybe better seals), they are made by ZF in Italy, they make many gear boxes for boats. I'm not sure if Yanmar makes their own sail drives or if someone else makes them.
I like the valves on the Volvo drive water intake valve better than the Yanmar, the Volvo is a ball valve and the Yanmar is a gate valve, which seems to freeze up very easily if it's ignored for very long. And I also like the inner rubber seal design on the Volvo that you can see in the engine room, better than the Yanmar.
Sail drives are very common these days and they can last a long time. I recently surveyed a 25 year old 10 meter Catalac that had Volvo sail drives that had a very good maintenance program and they looked and performed great.
Brian

Finally, someone who know what they are talking about. Very well said.
I have been trying to say this same thing for some time, but who am I.

Thanks amarinesurveyor,

People see a silver engine and say what a great engine, must be better than the green one.

Both engines are diesels and will last much longer than you will own the flippin boat.

[Jim Cate]

G'Day all,

I read the post by amarinesurveyor with interest, and it brought up some thoughts:

He says that they are more efficient while motoring (according to an un-named N.A.). I'm curious about this -- I wonder how they can be more efficient when they have at least two additional gear sets compared to a normal gearbox. This means LESS efficiency mechanically, not more! Perhaps he was referring to the different angle of the drive, being slightly more parallel to the surface of the water. Could result in sightly more thrust perhaps, but then the downward component of the shaft drive helps compensate for "squat" when motoring near hull speeds and may reduce drag. All pretty theoretical IMO, while the mechanical losses (easily calculated by an engineer) are unavoidable.

Now, he mentions that the oil/water seals often fail, and that such failure causes corrosion and eventual failure of the drive. The cure is frequent replacement of said seals... easy if you are near a boatyard or have annual slipping for bottom paint, etc. But, for long range cruisers, neither of these conditions are always present.

The issue of galvanic corrosion is mentioned in passing but without discussing what the consequences are. A close friend's saildrive was destroyed by stray currents in the marina in Kettering, Tasmania during a short stay. Bad marina wiring was the culprit, but cruisers often stop over in marinas with unknown electrical issues... a source of worry for our friends to this day. Further, one is advised to not use copper based anti-fouling on or even near the saildrive leg. As we all know, the non-copper based paints are less effective against most fouling organisms... another thing of concern for cruisers.

He doesn't mention the somewhat common mechanical problems (slipping cones for one) that keep appearing in posts here on CF... not that shaft drive trannies are immune to such faults... but it seems that I've seen a lot of whinging by saildrive owners!

The post ends by saying that saildrives are very common these days, and that they CAN last a long time. Somehow I'm lead to believe that this is due to the benefits for the builder, not for the cruising sailor.

So, for the OP, if you are considering long distance cruising, especially in remote areas, saildrives IMO are not the best choice.

Cheers,

Jim

[motion30]

There is a lot to be said for a straight inboard drive and a diesel engine

[downunder]

Originally Posted by Jim Cate

G'Day all,

I read the post by amarinesurveyor with interest, and it brought up some thoughts:

He says that they are more efficient while motoring (according to an un-named N.A.). I'm curious about this -- I wonder how they can be more efficient when they have at least two additional gear sets compared to a normal gearbox. This means LESS efficiency mechanically, not more! Perhaps he was referring to the different angle of the drive, being slightly more parallel to the surface of the water. Could result in sightly more thrust perhaps, but then the downward component of the shaft drive helps compensate for "squat" when motoring near hull speeds and may reduce drag. All pretty theoretical IMO, while the mechanical losses (easily calculated by an engineer) are unavoidable.

Now, he mentions that the oil/water seals often fail, and that such failure causes corrosion and eventual failure of the drive. The cure is frequent replacement of said seals... easy if you are near a boatyard or have annual slipping for bottom paint, etc. But, for long range cruisers, neither of these conditions are always present.

The issue of galvanic corrosion is mentioned in passing but without discussing what the consequences are. A close friend's saildrive was destroyed by stray currents in the marina in Kettering, Tasmania during a short stay. Bad marina wiring was the culprit, but cruisers often stop over in marinas with unknown electrical issues... a source of worry for our friends to this day. Further, one is advised to not use copper based anti-fouling on or even near the saildrive leg. As we all know, the non-copper based paints are less effective against most fouling organisms... another thing of concern for cruisers.

He doesn't mention the somewhat common mechanical problems (slipping cones for one) that keep appearing in posts here on CF... not that shaft drive trannies are immune to such faults... but it seems that I've seen a lot of whinging by saildrive owners!

The post ends by saying that saildrives are very common these days, and that they CAN last a long time. Somehow I'm lead to believe that this is due to the benefits for the builder, not for the cruising sailor.

So, for the OP, if you are considering long distance cruising, especially in remote areas, saildrives IMO are not the best choice.

Cheers,

Jim

Have to agree and support Jim's contention that shaft drives are best for long distance cruising such as in the Pacific vs Carribean which seems hardly out in the boondocks.

A lot of efficiency differences come back to design/shaft angle of the vessel. For instance a centrally located motor with a shaft angle of 4 degrees in a cat I suspect offers a lot of efficiencies. Such as fitted in Antares 44 and FF46 and other non production cats. It is very difficult to get an ideal shaft angle with motors mounted in aft compartments without using v drive which some consider less than ideal.

Sure there are plusses/minuses for both installations but for durability in out of way places shafts drives are hard to beat.

Reality is the French production cats don't offer this choice so that the argument is academic for someone wanting a FP cat.

But it is interesting FP and Lagoon fit shaftdrives rather than legs to their trawler catamaran range. I wonder why?

If I ended up with a newer FP, Lagoon or R&c cat I will end up with saildrive - no option. Doesn't necessarily make it the best option rather the only option available