European sterndrives / propulsion ahead of america?

This post got me thinking:
http://www.boatdesign.net/forums/bo...battery-technologies-21869-17.html#post282935

"If it comes to car comparison the US are 50 years behind the Germans."

The boats in the marine around here mostly have mercruiser sterndrives - lots and lots of bravo and old alpha drives that appear exactly the same as they did 20 years ago, a few volvopenta drives that look like silver versions of the above. About 10 years ago started seeing a few boats with duoprops which were new. Not much has changed in the last decade though, except more outboards and 4stroke outboards recently. About the same ratio of inboard to sterndrives. Haven't seen any surface drives in the slips.

What do you see in European marinas for stern drive or propulsion technology? Are they way ahead of us transmitting the power from the engine to the water?

 

Nobody in Europe does any development in sterndrives. You see as many here as in the US because once you own a boat with Merc's or Volvo's, you have to keep repairing and replacing. And if you sell the boat the next owner has to do the same if he wants to keep using the boat. BMW had the best sterndrive ever made, but pulled out because the production volume wasn't interesting.

But the market is rapidly shifting towards large 4-stroke outboards. More expensive but far better fuel economy compared to GM engines and much lower maintenance burden for the drive. No bellows, no underwater gearshift cable and no corrosion or marine growth. So probably, sterndrives (and with it Mercruiser) are a dying race.

 

Where in the world do you live? It must be a real backwater if you just saw duoprops ten years ago. VolvoPenta has been selling them for fourty years.

 

I'm not sure what type of sheltered marine existence you may have had Paul, but you clearly have a poorly informed view of marine engineering, both here and abroad. You should look up the figures and speak what you've learned, rather then spout off what you think you know.

 

Easy Par - was asking not spouting. Didn't mean to offend anyone with my ignorance I guess! Only posted what I saw walking the docks to ask what was elsewhere.

 

true Euro stern drives have been out front always
Also USA pleasure boats tended always to be gasoline
Down under we built(myself) many diesel sterndrives using Volvo They need maintenance and many got abused running them up out of the water coming onto beaches From time to time peoople would put the chev 5.9 and 6 l v8 in front of a 290 or 280 leg, the torque of these engines was low so the drives did handle it ok
However there were no USA sterndrives, apart from Sternpower, that would handle the torque of proper diesels, until Cummins teamed with mercruiser in order to use the b series cummins engines which have a lot of torque
Height is the prob with the b, you can get it under most soles in trailerable craft
this is a 360 shp I am putting in my last trailer boat Volvo
2 cycle outboards were hopeless in heavy seas, they just lost power all time, and one had to continually adjust throttle settings, a 130shp 4 cyl diesel volvo, had far more lo down torque than a 200 hp outboard, and used a fraction of the fuel
I have never used 4 cycle outboards, after my build days, but they make sense UNLESS one does say over 500 hrs a years, then diesel comes back as the favourite means of powering a boat
I thought your question was perfectly reasonable

 

Plus, anybody that could utter "If it comes to car comparison the US are 50 years behind the Germans" is dumber than a barrel of hair.

 

It's also a matter of preferences.. last autumn I took my car to maintenance (french small diesel) and got from them a BMW meanwhile they were working. Anyway the beamer had in the manual some 12 pages how to start the engine, and 17 how to close and open doors.. got a bit frustrated

 

CDK
You must be joking, the BMW had everything wrong with it as it was a wholey EU design.....do you want the list of where they f*cked up
Nice engines though...except for the raw water cooled exhaust manifold.
I was a service manager for a large BMW marine dealer in Melbourne (OZ)...10 minute drive from BMW headquarters.
Cheers

 

Ilmor just came out with a new drive for their V10 Chrysler?

Weismann also built a stern drive that was very good and pioneered multi speed gearboxes...
they used to make gearboxes for that European racing stuff ..whats it called..oh yer F1

 

Not sure about European marinas... but it's safe to say, I think, that we Canadians are a fair bit behind the times in marine propulsion.

Now, there's a good reason for this- if it's new, unique or rare, you are going to have one hell of a time getting parts for it in cottage country. On the other hand, every town of more than 1000 people has someone who can fix common 4-stroke GM blocks, which most small sterndrives- Merc or Volvo- use. Usually that same guy can fix a 20 year old 2-stoke outboard as well. And he'll probably have parts in stock for all the common sizes of Merc, Johnson/Evinrude and maybe Yamaha, Honda or Suzuki in his area.

But when you get into the big new direct-injected 2-strokes, computer controlled 4-stroke outboards, all these things that need proprietary parts (and, since there are only three such boats in the county, nobody bothers to stock said parts)- well, some people are a bit leery of such things. You do see them, but I think the mechanics sometimes have a hard time keeping up with so many technology changes from so many manufacturers.

Mainly for this reason, I still think that for a freshwater boat needing more than 150 hp or so, sterndrives have a lot going for them. Below that, of course, outboards are the only realistic option for many boats.

I have yet to see a single boat with IPS, Zeus, those giant supercharged outboards Merc's been pushing lately, or any other "cutting edge" drive system around here.

 

I have to say that surprises me a bit Mat. In Oz, we seem to latch onto the 'latest and greatest' as soon as it's released...more often than not it's so owners can say they've got it, but that's another story.
Back to Paul's original question....It's generally accepted that Volvo's duoprop is marginally better than the Bravo 3 in terms of overall efficiency. Beyond that, I think they're much of a muchness. Both drives, however, have undergone continuous refinement over the years. They may resemble their original forebears, but they're certainly not the same.
It's not just Europe and the US that have sterndrives all to themselves. Japan (in the form of Yanmar) is possibly about to pip them both, with a new drive of their own. And Yamaha have been building sterndrive's for years.
The jury is still very much out, IMHO, about both Zeus and IPS....
The US and Japan have the outboard market pretty much to themselves and development continues at an extraordinary pace everywhere you look.

 

Yours is the first negative opinion I saw, except for the obvious remarks that the BMW stern drive was too expensive to compete with OMC, Merc, Volvo and Yamaha, who all tried to get their share of the (then) booming market.

Although they stopped producing them many years ago, I see a few BMW stern drives each tourist season. What strikes me is that each one of them looks brand new: no corrosion, almost no marine growth on the shiny silver lacquer, the BMW badge proudly showing fresh colors.
Quite a difference when compared to the Alphas of the same era that nearly all rest in junkyards now.

 

I'll have to admit the paint was damn good on both the drives and the engines.
One issue I see with Sterndrive comments from the EU and US is that my experience in the US would tell me most stern drive boats are rack stored where as I dont see that to much in Europe so they moor them...not something I would recommend with a stern drive.
I'll make my list up over lunch today..might help you if you work on them.
cheers

 

The BMW story

Here we go the BMW story as I experienced as a dealer.
(10 minutes from the Australian headquarters of BMW)

Petrol engines, nice smooth and tough.
I remember having a B130 apart on the bench and next to it a 400TRS Merc.
I remember looking and the conrods looked the same!
All came heat exchanged as they had aluminium heads.
BUT they copied a Mercruiser inline ( not the 470) and forgot to put the exhaust manifold in the fresh circuit?
Saying that I never replaced a manifold.
Came out with points ignition….a bit behind the times I thought.
Sea water pump on he back of the cam..made it a bit hard to get to in most boats.
Copied the horrible Volvo wiring and used automotive plugs on the engine to dash harness so for sure it will fall out one day or corrode. ( never happen on a OMC or Merc.)
The cast iron is not the quality of the US so the exhaust elbows didn’t last as long.
A common problem to all except Merc has stainless now.

Solex 4A1 carb on the 6…hadn’t seen one of those since , since..Mercedes V8 years ago. Not bad but if you got water in it, over a AUD1000 ouch!

MK1 drive
Nice paint job and very good quality paint.
Had a lower unit hydrodynamics copied from Volvo 250, 270, 270 style.
Could use volvo props.
Bellows failure wont sink the boat or shift bellows.
Props got cavitation burns on them especially anything that did over 40mph.
The steering was also an abortion inside the boat similar to an old Volvo.
The steering pin inclined axis had the top inside the transom, hopeless.
OMC fixed this for Volvo after they got into bed together.
There was no power steering…a bit behind the game heh.

Hurth made the gear train.
The gears and shafts were very large diameter as were the bearings in a large volume of transmission fluid, (nice and pumped around once in gear ) due to the manual clutch pack shift which could take full power either direction, ( nice) and could also swap cogs at full power ( nice) ..I did this many times on BMW’s company boat which was stored at our marina.
The gears were not as hard as your typical stern drive so they were usually damaged ( the lower unit ones) if you hit something hard ( the top box was 1:1), I guess the same impact would twist or break a shaft in an Alpha 1 but have no effect on a II drive or Bravo.
Expensive job as BMW viewed that you could not remove the drive gear from the propshaft as it was also shrunk on, without damaging the shaft. So new shaft with gears each time and a complete ******* to rebuild.

The universal joint shaft was splined to the upper housing shaft, ok, but was part of the shaft that when through the gimbal bearing and into the engine.
BMW's view was the U joints are not serviceable item. Buy the whole shaft if you can get it out or pull the engine and dismantle the bell housing IF you can get the shaft out of the engine as it was a metal to metal spline?

The gimbal bearing was not sealed BUT not greasable DOH.
So on the Mk1 you had to get the shaft out of the housing as it was fastened to this shaft. Large slide hammer chained to the u joints, ugly or pull the engine.

The oil tube that connects the upper and lower housings was electrically isolated as it sat in o rings on each end. DOH!
Being made from tubing it was a different material than the cast housings so it would eat away, nasty!

The whole drive was electrically isolated from the engine, also causing electrolysis.
The reason you don’t see it is because the inside of the drive as in exhaust and water passages are not treated very well at all so they were slowly disappearing.
What were they thinking? Fresh water only, rack stored?

They contracted Sachs to make the trim cylinders and they looked like shock absorber tubes from a shocker…nice try for the uninitiated.
They were mounted such that the ram was inside the drive in the gear oil bath. Not bad as it eliminates one area for corrosion and looks quiet smart.
The tubes would expand (especially when you left it tilted up and it got hot) and allow the oil to get between the cylinder piston and the shock valve on the end of the rod.
Should just go down when under power you would think…NOT
( this was an assembly and not repairable).
The rods instead of being stainless were hard chromed steel, .which also pitted due to the electrical isolation.
BMW did admit they forgot to employ an application engineer…meaning they forgot to employ anyone who had ever seen a stern drive.

Mk11
New lower unit housing to help the hydrodynamics..missed by that much.
They increased the size of the pinion bearing so that the new housing had a pronounced bump in it and right behind this the props would cavitate burn so bad it would go right through the blades., The prop selection that came with these was absolute rubbish. We used to buy the prop bushes, machine them and fit them to Merc props.

Back to the universal joint saga…they changed the top box set up and splined the gimbal shaft on the engine side of the u joints so it came off with the drive.
It was shrunk fit on a taper as were several other items in the box but this had the fitting to pump it off which you needed to do if you needed to replace the joint assembly or the seal just behind it.

I remember at the first BMW service school run in OZ. We were all waiting to see them get it off….they had the SKF agent there and no mater what tool they used they could not remove it.
Then we had the clutch pack issue.
I don’t really know what happened but at the same time we also had problems with Borg Warner velvet drives.
( the BW’s would pump all the oil out the breather and blow up. Never found out why but replaced plenty under w/tee)
Oil?
Now that I see the trouble people have with Hurth HBW 360’s it is the same.
A perfectly good drive would suddenly have a large delay going into gear.
The clutch packs would show burnt plates?
BMW asked us to use Ford spec tranny fluid which is less viscosity then Gm Dexron II, didn’t fix it.
They then had plates with spirals in the fibre plates to spin the oil out. This helped.
Some drives kept going for years from new and some wouldn’t?

The Diesels, VM, nice.
The very sexy riser shaped Stainless exhaust on the mid mounted turbo ( where the turbo should be on a inline 6) was bolted to a fixed bracket at the top of the curve.
It didn’t like this so they all cracked spraying your engine with sea water.
They were out of stock for 3 months globally..ouch.
They never supplied a soft mount kit we just bolted it down with a piece of rubber underneath.
BMW always had there heads in the sand over everything.
All the parts were priced like Volvo parts. You could buy a new MerCruiser drive for the price of several parts..if you could get them.



I have saved the best bit to last..
Some clown designed the whole drive so that when you tilted it up the universal joints if aligned such that the center coupling long edge was at 3:00 and 9:00 and the drive and engine at 12:00 and 6:00, the yokes would bottom on the coupler as the joint could not bend as far as the drive!!!!
You can run everybody else’s drive at full tilt
This rapidly destroyed the universals and led to some large bills.
The assembly, although about the same diameter as a Mercruiser alpha 1, was built like the proverbial out house..why??? It weighed more than a MCM III drive assembly!


So there you go..
They were lucky they had the VM contract so Mercury was interested.to buy them.
BMW couldn’t wait to get out of the business.
My mate who was the National parts manager of BMW said 10% of my business and 90% of my problems
A shame really as the issues were all fixable and many people were interested as it was BMW.
They only needed to have an American on board from the start. ( or me!)