Waht's the Skinny on Volvo Duo-Prop?

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JoLin

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Looking at a boat tomorrow (24' Chris Craft) that has a 5.7 liter V-P duo-prop setup, vintage 1999. Are these good units, or are they so complicated that they're prone to breakdown, which I'm sure would be darned expensive to fix.

I've already looked at the propeller prices and suffered a mild heart attack.

Any experience out there?
 

mcleaves

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Re: Waht's the Skinny on Volvo Duo-Prop?

Looking at a boat tomorrow (24' Chris Craft) that has a 5.7 liter V-P duo-prop setup, vintage 1999. Are these good units, or are they so complicated that they're prone to breakdown, which I'm sure would be darned expensive to fix.

I've already looked at the propeller prices and suffered a mild heart attack.

Any experience out there?

Two comments:
  1. Volvo's are damn near bullet proof drives. Extremely low failure rates. Parts are a bit more expensive, but only if you need a repair which is rare.
  2. The Volvo DP is transforming to a boats handling and performance. Lower planing speeds, huge increase in hole shots, better fuel economy and a higher top end.

I have the advantage of going from a single prop SX drive to a DP on the same boat, so I was truly able to compare apples to apples. It was if I had a newer more efficient hull AND a bigger engine with the upgrade.

I'll never own a single prop on anything over 20' again.

Mike
 

QC

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Re: Waht's the Skinny on Volvo Duo-Prop?

I agree with above, but . . . If poorly maintained, any I/O can be a money pit regardless of manufacturer or design. Do a search on U-joint bellows, gimbal bearings just to familiarize yourself before you look at her. Could be awesome, but you should know a little more if you aren't getting a survey.,
 

JoLin

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Re: Waht's the Skinny on Volvo Duo-Prop?

Thanks, guys. If I decide to pursue it (It's really out of my price range unless the owner is deparate), a survey is the first order of business. Never having owned an outdrive boat before, I wanted to make sure I wasn't walking into a long-term maintenance and repair nightmare.

Sounds like they're as good as any, though, with no inherent design or manufacturing issues. That's good to hear.
 

gcboat

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Re: Waht's the Skinny on Volvo Duo-Prop?

Have to disagree, they are not as good as any, they are far better. And your hearing that from a guy that has spent lots of money on Merc and OMC outdrives. The DP is possibly the best drive system available on an I/O.

But you are correct on one thing, whack something with the props and your wallet will regret it. :)

Absolutely true !!! The best investment anyone could possibly purchase for an upgrade. Every now and then I see a set of 4's and 6's on ebay. Keep an eye peeled as they usually don't last very long. :eek:
 

mtnrat

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Re: Waht's the Skinny on Volvo Duo-Prop?

I went from a single prop to duoprop lower. I cannot fully describe the improvement. If you get a volvo duoprop you are getting the best IMO.
 

HT32BSX115

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Re: Waht's the Skinny on Volvo Duo-Prop?

I did it too.

I removed a 460 King Cobra with 340 crankshaft HP and replaced it with a 454 bravo III at 330 crankshaft HP (300 prop HP).

The propshaft HP difference is not significant.

The top speed is 3 MPH or so slower (dual counter-rotating props produce MORE drag. and you lose a little top-speed HP) but the hole shot and acceleration at any speed is spectacular!

And the slow speed handling forward/reverse is FAR better.

Yes the props will cost more. I bought a set of 26p props on ebay for about $600 ($1300 retail) and no one makes plastic props for a Bravo III or a Duo-Prop....but it's worth it.
 

Don S

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Re: Waht's the Skinny on Volvo Duo-Prop?

Don't compare a Bravo III to a VP DuoProp, not even the same catagory.
The Volvo props are different diameter and pitches designed to work together. Bravo uses 2 props. Both the same pitch and same diameter, and they don't work together that well at anything below 50 MPH. After that, the Bravo is better.
 

Lou C

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Re: Waht's the Skinny on Volvo Duo-Prop?

You're in Long Island so this is a salt water boat, yes? If you are mooring/slipping in salt water you might want to think twice about a sterndrive. Quite a bit more maintenance than an outboard which is what it looks like you have now. Most of the antifouling paints don't last the whole season so barnacles are a problem. If you get closeer to buying it make sure it was well maintained as far as the exhaust system goes especially, neglected exhaust on a salt water IO is a recipe for engine problems. The Volvo drive itself is one of the best out there, as long as you can get good local service.
 

HT32BSX115

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Re: Waht's the Skinny on Volvo Duo-Prop?

Don't compare a Bravo III to a VP DuoProp, not even the same catagory.
The Volvo props are different diameter and pitches designed to work together. Bravo uses 2 props. Both the same pitch and same diameter, and they don't work together that well at anything below 50 MPH. After that, the Bravo is better.


I have 2 sets of Bravo III props. 24p and 26p

The rear (outer) props are of slightly smaller diameter than the front (inner) props. 1.5" smaller to be exact.

They probably are the same pitch (they do have 24 and 26 respectively stamped on each set) but the blade area of the rear props are substantially smaller than the front.

I'm sure there are design differences between the VP and Merc props. I'm not going to argue those differences.

I will argue that any "duo-prop" drive will perform far better on any large boat than a single prop drive. (except for top speed.....but who cares about 3-5mph?)

My 21' sport boat performs at any speed (except for top speed) far better than the similarly powered, correctly pitched (SS prop) King Cobra I had...
 

Don S

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Re: Waht's the Skinny on Volvo Duo-Prop?

I have been lucky enough to operate 2 identical boats, both 28' Bayliner classics with 7.4 MPI engines. One with a Bravo 3 one with a 2. Top speed and time to plane were identical. Backing was a lot better with the duo prop.
I have also changed many boats with single prop Volvo to DP. BIG difference on planing time and top speed, also a conversion of a 460 Ford in a 28 Bayliner to a Volvo DP. HUGE difference from single prop stats.
Even the Merc tech reps say the B3 drives only exceed above 50 mph. They were designed for high speed.
 

billbayliner

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Re: Waht's the Skinny on Volvo Duo-Prop?

As with anything.............. Preventative maintainance is key to any mechanical device being consistant......

The Volvo Duo Prop is an amazing drive! I have a Volvo Duo prop, model C1, on my very heavy 1995 Crowline 250 CR... Over all length 26' 8''...

I only have a 5.7 (350) engine in it.... I would not be able to get on plane with any other drive with that small power plant.

Do not get me wrong, I have another boat with the Merc alpha 1 gen2 drive and love it.

But I must tell you, the "control" you have over your boat in regards to docking, etc, is amazing with the Volvo DP...

Not an expert, my my opinion....
 

HT32BSX115

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Re: Waht's the Skinny on Volvo Duo-Prop?

I definitely want high speed! I wish mine was faster but more speed always means more $$$!

I'll just have to be happy going fast in other things!
 

Maclin

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Re: Waht's the Skinny on Volvo Duo-Prop?

The VP DuoProp drive makes for great boating performance. The only downside is the expense when the props get dinged and need attention or replaced. In my opinion the 1-2 mph "loss" of top speed is not worth any thought at all. If you "race" another boat just like yours and they have just a single prop you will outpace them so much out of the hole that it will be a while before that "extra" mph shows up anyway. And I am here to tell ya that the holeshot alone will make you glad your boat has the VP DP drive.
 

QC

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Re: Waht's the Skinny on Volvo Duo-Prop?

Even the Merc tech reps say the B3 drives only exceed above 50 mph. They were designed for high speed.
Funny, but they (Merc) don't recommend them above 60 . . . Pretty narrow window. Almost all of the stock go fast guys run some derivative of a Bravo 1.
 

abj87

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Re: Waht's the Skinny on Volvo Duo-Prop?

Zero prop walk when docking is nice.
 

JoLin

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Re: Waht's the Skinny on Volvo Duo-Prop?

You're in Long Island so this is a salt water boat, yes? If you are mooring/slipping in salt water you might want to think twice about a sterndrive. Quite a bit more maintenance than an outboard which is what it looks like you have now. Most of the antifouling paints don't last the whole season so barnacles are a problem. If you get closeer to buying it make sure it was well maintained as far as the exhaust system goes especially, neglected exhaust on a salt water IO is a recipe for engine problems. The Volvo drive itself is one of the best out there, as long as you can get good local service.

Hi, Lou -

Believe me, I've thought MORE than twice about buying a sterndrive boat. I like outboards. Fact is, if one is looking for a USED boat, with a good-sized cabin, in the 24-26 foot range.... I haven't seen a single outboard-powered boat in 3 months of watching the ads. They simply don't exist within those parameters.
 

Lou C

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Re: Waht's the Skinny on Volvo Duo-Prop?

Just about everyone will tell you to go OB around here if you are leaving it in the water, as I said, the anti fouling paint not lasting the whole season can REALLY make a mess out of a sterndrive transom assembly, I had barnacles everywhere, even in the water intakes! But I let the yard paint the drive and I don't think they take the time to do as good as job as you could do yourself, that's what I'm doing next year.
I have stuck with it partly because the drive maintenance is offset by the simple automotive based engine that is easy and cheap to repair. Modern outboards are light years ahead of the old school ones in terms of smoke reduction, reliability in starting and quietness. But when something goes wrong, I don't think most driveway mechanics who know their way around a small block Chevy and a Quadrajet are going to know what to do with them. And if you can't find a good tech you are out of luck. As an example there are only 2 dealers certified by BRP to sell and service the ETECs here in LI, now is that not silly, we are surrounded by salt water!
If you do get it, really check over the exhaust system, bellows, gimble bearing etc. I pull the drive every fall and check for water in the gear oil, water in the bellows and gear oil leaks. I lube up the shift linkage and associated parts when I reinstall the drive in the spring and it's ready to go.
If I ever put a new engine in this one it will be closed cooled for sure, still you have to worry about the manifolds (check after 5 years probably replace). They all cost you money sooner or later!
 

JOE MAGIC

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Re: Waht's the Skinny on Volvo Duo-Prop?


HI-
I HAVE A CHRIS CRAFT 1988 AEROSPORT WITH A VOLVO DUOPROP
COUNTER ROTATING--I LOVE IT--YES PROPS WILL SEND YOU FOR A SPIN--
BUT WILL LAST LONGER AND COST LESS IN THE LONG RUN-
THEY WERE MADE FOR TORPEDOES---TAKE IT FROM THERE--LOL--
JOE.
 
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