New HI-PRO TRACTOR DRIVES FROM VOLVO

[Backfire]

Volvo Penta's new drive breaks cover

By IBI Magazine

The Swedish manufacturer's Inboard Performance System, due for worldwide launch at the London boat show in January, has been praised by Motor Boat & Yachting in an Internet pre-release story.

The IPS, with its unique forward facing twin propellers on a bottom-mounted leg, had been subject to embargo. However news was already publicly filtering out of Scandinavia via at least one magazine article in Sweden and an Internet story released by vibatagare.com, prompting the decision to publish by London, UK-based Motor Boat & Yachting to similarly break cover on its findings from the press launch.

"Volvo have just rewritten the rules with regard motorboat propulsion systems," authors Tony Jones and David Marsh declare. "In a stroke they may have consigned stern-drives and shaft drives to history, and in the process revolutionised the way motorboats are designed and built."

Motor Boat & Yachting believes that IPS has sweeping ramifications for boats in the 350hp-500hp sector and predicts that it could cover a much broader power band of between 260hp-715hp if it settles down well in service over the course of the next 18 months. There are two launch models, rated at 310hp and 370hp, approved only for twin installations.

For the full Motor Boat & Yachting story follow this link.

For the Vibatagare.com story follow this link.

[Raceman]

Man, that looks like prop destruction waiting to happen to me.

[CUDA]

far out Talk about going out side the BOX.

[Raceman]

I'm sure 75H has some pics at his fingertips, but there were some tractor style racing gearcases back in the 1930's or 40's. Apparently they weren't real successful since they died out. May be a case of "those who don't study history are destined to repeat it".

[Binger]

is there a formula for the mass of air and or water at a certan speed?

[Trikki1010]

Originally posted by Raceman
Man, that looks like prop destruction waiting to happen to me.

Bingo, If that is for larger boats, they usually travel waters laden with debris. Nice to put your prized possession out front

I understand more force on the prop without the laminar flow disruption from the case, BUT

Maybe this is a new program to get into the "prop replacement" business

Will they offer a "WEEDLESS" prop

[Markus]

I read the original article in the Swedish magazine

http://www.vibatagare.com/vib2004/vi..._vib12_04.html

A couple of points:

1. This is from the company that introduced the sterndrive
2. It is an inboard replacement
3. It is for big, slow boats. At the press event, they showed a boat with the doing 37 knots with this drive whereas another boat of the same model with the same engine and a straight shaft did 31 knots. Quite impressive.
4. The propeller is less protected indeed, but if you hit something big, the drive will just shear off without damaging the hull

[Trikki1010]

I read the original article in the Swedish magazine

The propeller is less protected indeed, but if you hit something big, the drive will just shear off without damaging the hull

Jag forstar inte

I'll let ya know what that says in 6 months, when I finish my course is Swedish tach sa mycket.

I have relatives in Boras, but still can't catch it all

Comforting to know they'll shear off, that'll be a service $pecialty. I did figure it was for barges.

I hope that bellows is above water, otherwise it'll make a gimbel bellows' look like an angel

[Bruster]

Originally posted by Markus


A couple of points:

4. The propeller is less protected indeed, but if you hit something big, the drive will just shear off without damaging the hull

Now that makes me feel a lot better. You will just never know how bad the propellers are screwed up, 'cause they will be laying on the bottom with your prized lower units!

[Mark75H]

The only thing new here is the combination of these components.

Volvo did not introduce the sterndrive, they "re-introduced" it. Johnson made and commercially sold sterndrives around 1930. The early 60's Volvo/Wynne/Strang sterndrives were the first sterndrives with major commercial success for higher power boats. Just like the Merc ads that led people to think Merc was the first outboard to exceed 100 mph, you have to carefully read the text which is intended to mislead you: even later Merc copywriters were confused by the Merc ad and for a while had the misinformation on their website (until I pointed it out ) If there have been ads claiming Volvo made the first sterndrive .... Volvo's ad writers have also fallen prey to their own propaganda.

The first contrarotating props also came out in the 1930 era, 5 years after the first the first forward facing "tractor" prop design.

In the 1960's OMC made a thru the bottom sterndrive-ish unit with a 2 cylinder 2 stroke powerhead inboard called a "Saildrive". I think the whole thing, powerhead and all, rotated inside the boat to steer.

Here is a 1930-ish Caille tractor from the back cover of "Century of Outboard Racing" by Kevin Desmond

[Markus]

Bruce Hazecamp wrote

Now that makes me feel a lot better. You will just never know how bad the propellers are screwed up, 'cause they will be laying on the bottom with your prized lower units

The drives will just shear off, but there will be no leak in the hull. The intended buyers don't care how badly screwed up the propellers or get or what happens to the drive as long as their 2 million dollar boats don't end up on the bottom.

[stylishskier]

good point markus, with a direct drive config if you hit something, the shaft is going to wreak havoc on everything under the boat. If the drives shear off then maybe they could be recovered or replaced for what say 30k a piece
if you hit something with a direct drive with a HUGE shaft and prop and rip a hole in the bottom of the boat, whats that... probably 2-300k in damages atleast considering if what you hit is bad enough to cause the engines out of alignment etc.
Looks like a good idea for the motoryacht market, but not hi-perf...

[Capt.Insane-o]

Interesting indeed, they are mounted through the hull by the looks of them.Underwater exhaust too, kewl.

[Markus]

Looks like a good idea for the motoryacht market, but not hi-perf...

And motoryachts is the intended market.

[Mark75H]

This should be a major improvement for most large motor yachts. Not only will they benefit from the dual prop effiency, they would also gain a major improvement in prop angle for efficient thrust. Normally inboards are stuck with a shaft angle that points down like negative trim angle.

Except for being fully under the boat with the props in front I don't see a big advantage over their own sterndrive. Maybe that's it.


As far as prop damage ..... the props would be the place they always were .... I don't see any increasaed potential for prop damage over the inboard arrangement they are intended to replace.