Duo-Prop lower's

[onesubdrvr]

Is there anybody currently running a duo-prop lower unit on their classic?

I was looking at the volvo website the other day, and they have a "repower" adviser, and they (Volvo), says a duo-prop will provide higher top-end speed, better cruise speed and better effeciency. Which leads me to the reason for my question, isn't that what we all look for?

For example, someone with an older 270, 280, or 290 drive, could move to a duo-prop lower pretty easy, and maybe pick up some speed.

What would be the negatives associated with doing this? Obviously one would be the more limited selection of props.

Thanks
Wayne

[Schnook]

I have a bravo three, which I guess is the same thing. I get an excellent hole shot and up on plane quickly-that helps efficiency. The dealer here told me I could probably get another 7-10 mph if I switched to an XR drive, and a couple of people told me I'd sacrifice top end with this drive. Once I get trimmed out I may get above 55. Once again, I'm new at this so I may out in left field, but I hope it helps.

[mattyboy]

I seem to remember a yellow and white newer 18 and a red and white 16 with a duo prop volvo dx i think not sure on performance numbers
I looked at a duo prop replacement for my 250 at the NY city boat show
5-6k is a big investment for an unsure return of investment in MPH

[Cuda]

I think the duoprop will hurt top end from what I've read.

[pantera24]

Do you mean like this.?

[pantera24]

Here's more info.
http://www.donzi.net/hull.cfm?id=117

[blackhawk]

The Duoprop vs SX is not the same as a Bravo 3 vs Bravo 1. If a duoprop loses any top speed at all it will be very marginal, maybe 1 mph. I have seen first hand 2 identical boats, one running a Volvo SX and the other a duoprop, and they were dead even on top-end. The duoprop accelerates harder and does not list when the drive isn't trimmed out or when you get big air. The downfall is prop selection and prop costs.

[onesubdrvr]

The Duoprop vs SX is not the same as a Bravo 3 vs Bravo 1. If a duoprop loses any top speed at all it will be very marginal, maybe 1 mph. I have seen first hand 2 identical boats, one running a Volvo SX and the other a duoprop, and they were dead even on top-end. The duoprop accelerates harder and does not list when the drive isn't trimmed out or when you get big air. The downfall is prop selection and prop costs.
Thanks, yeah, that's kinda what I was curious about, good info. Further questioning could be done 280SP vs 280DP, but, I'll save that for another day :biggrin.:

Thanks
Wayne

[JPR]

I had heard that the duoprop gives so much lift that it can be difficult to steer at higher speed - any truth to that or marine myth? I had a chance to buy a new xdp at a good price but was concerned about top end and steering.

[MOP]

When I had the Blackhawk on the Beast the handling was great to say the very least, it it cornered as if on rails equal in both directions and th hole shot was much better than anticipated. At 1K it planed off quickly with 5 on board proving the skeptics wrong, if my mouse motor made a little more power I would have taken Don up on his offer of trying the 27" BH wheels and might still be running it. Would love to find a real cheap 18 to put the BH on, we know how fast they can go!

Phil

[onesubdrvr]

You know something Phil,....

That's kinda funny,......I'd like to find a cheap blackhawk (transom / gimble / drive / etc.) to try on an 18!

Wayne

[Lenny]

You know something Phil,....

That's kinda funny,......I'd like to find a cheap blackhawk (transom / gimble / drive / etc.) to try on an 18!

Wayne

Driving Don's 18 with the BH was FUN to say the least. Just had to be on the throttle (off) instantly when jumping wakes and such. Not much different than the 22BH. One hop,...WOW ,... 2 hops,.. WHOLLY $UCK :eek:,... 3 hops, nothing left to chat about...

[onesubdrvr]

Driving Don's 18 with the BH was FUN to say the least. Just had to be on the throttle (off) instantly when jumping wakes and such. Not much different than the 22BH. One hop,...WOW ,... 2 hops,.. WHOLLY $UCK :eek:,... 3 hops, nothing left to chat about...
Maybe a cross between the optimum BH X dimension, and a standard X dimension, split the difference, maybe gain stability (not going to go completely vertical), but still gain some of the performance aspects of the drive??

Wayne

[mattyboy]

i think you guys are looking for this boat

It's Stevie Marr's runs like a scalded bull hamsta on railroad tracks with stock power ;)

[blackhawk]

Blackhawks and Duoprops are totally different animals. BHs are surface drives and are short and mounted higher. Duoprops are mounted at the standard X and are standard length. Apples and oranges.

BHs are fast but the trade off is rough water capabilities. Fast as hell in the consistant 2' chop but when you get in the big stuff or the slop where the boat starts airing out they are just too short.

[onesubdrvr]

Blackhawks and Duoprops are totally different animals. BHs are surface drives and are short and mounted higher. Duoprops are mounted at the standard X and are standard length. Apples and oranges.

BHs are fast but the trade off is rough water capabilities. Fast as hell in the consistant 2' chop but when you get in the big stuff or the slop where the boat starts airing out they are just too short.
First, quite right,..... I originally started this thread trying to compare (before I knew the model #'s), a Volvo 280SP and 280DP, because the Volvo website (while now updated for the Penta drives), states that a duo-prop drive gives greater effeciency, higher top speed, better cruise speed / etc. We kind of got off on a tangent I guess,....

As far as the BlackHawk goes, if one were to replace an old drive with one, having to re-do the transom, and since as is almost allways the case, performance and stability are a trade off, that's why I was wondering about splitting the difference in the X between the recommended X dim for a BH, and Stock.

Lovin the info guys!

Wayne

[mattyboy]

Do you mean like this.?

that's a wild looking setup a newer 290 upper and a dpx lower??? the one i saw had a standard 290 lower with just a longer shaft/s and the old prop cone that setup looks much more slippery

see that was my point for a 250 270 280 in order to get the full functionality of the drive it's not just the lower you need to change the transom plate to a 290 so you have trim then too a 290 upper

and again Stevie Marr's x 18 is a blackhawk 350 combo and that boat rides like it is on rails not sure where his x dimension is

plus if you look at that volvo setup that pantera posted someone with a standard 200 series would need to find another source for water a transom or hull water pickup

[Lenny]

Wayne, the BH on a 22 and a Bravo/Alpha on a 22 have the SAME "X" dimension. Only the BH boat HULL has about 1 1/2" missing from an angle starting 8' forward of the transom tapering back to the 1 1/2"...but, same "X" as measured at the transom.

Dons' boat runs fine, if you want FUN, it has it.

Before I cut a hole in my transom I would go and pay Steve M for a ride and make a deduction from there. There is 8" of prop centerline missing on a BH as compared to an Aplha/Bravo and THEN, I believe, Steves' is up 3 more inches...that makes 11" in prop centerlines difference :eek:

I have no idea how Steves' boat runs as I have never been in it, but at 78 GPS, and a 350 MAG MPI, you know it ticks far better than a Bravo/ Alpha.

What I would like to see, is the difference between IT and Don Cigs' 18 ride with the same drive. I know Dons', but would love to run in Steves...

:)

[MOP]

Not 100% sure but I think Don WAS running about the same ponies as Steve but going about 5-6 MPH slower. He is now going the "He Shall Over Come Route"! :biggrin.:

[Lenny]

MOP, Don is running 70.5 with a BH, stock "X" (14 1/4") on an 18 spinning both 31's and 29's I believe. Both end up equal- (ish) in top end put different sticky rates and holeshot and rpms. 350 MAG MPI. Same as Steves. But Steve has 7 GPS mph on him.

The ride is "FUN" :eek: in Donz.