Drive Q ...

[Tafflad]

Putting this Q here in this sub-forum, as the drive sub forums are manufacturer specific ...

I am looking to select optimum engine & drive mix for next boat.
Which will be a 21/22' hull (Chaparral 216/226 current considerations) .... My use in in-shore salt water towed watersports ... majority of towing is in 18-26mph, acceleration and being to hold a constant speed is more important than maxium speed.


I have asked some Q's over engine on the relevant sub forum:
http://forums.iboats.com/showthread.php?t=520897&p=3520127#post3520127
to help decide on how many horses I need.

Would appreciate some advice over drives ...

I have had several Mercrusier Alpha drives ... how does the Volvo SX drive compare ?

Then the important consideration is do I consider the (not inconsiderable) extra spend on a B3 or duoprop.
If The spend is worth it ... is there a significant advantage in either B3 or Duoprop, which would then make the choice of engine for me.

 

[Don S]

Re: Drive Q ...

In your other thread you was considering fuel savings. Well the Volvo DP is what you want if you would like to save 25% over a single prop or the Bravo III drives. Even Mercruiser doesn't dispute the 25% fuel fuel effeciency claimed by Volvo.
Speed wise, the Bravo III drive is better in boats designed for going over 60 mph, for those up to 50mph the Volvo is better. The props have different diameters and pitch designed to work together where the B3's just use the same size, just counter rotating props. Works better for high speed. Getting on plane again is Volvo DP over B3.

Comparing the single prop Volvo to the Alpha drive, the Alpha is by far the least expensive way to go. By a lot.
Replacement drives alone, Volvo OEM 9K, Alpha clone with 3 year warranty, less than 2K.

Volvo single prop compared to Bravo. about the same in all respects.

Edit: Thought I might add this too, even though you are looking at a much smalleer boat. When I lived up in Ketchikan, we had two customers with 2 almost identical 28' Bayliner Cierra's. Both with Merc 7.4MPI engines, only difference was one was B2 with single prop, the other was B3 with dual props.
Out of the hole, they ran almost identical times. The BIII got a bit higher top speed, but the III had much better low speed control and reverse control.

 

[Tafflad]

Re: Drive Q ...

Thanks Don .... Volvo with Duoprop seems to be taking the lead.
Does the Duoprop have same smooth cone clutch as the SX?

 

[Don S]

Re: Drive Q ...

Yes, the uppers are the same, the lower is all that changes.

One note on the Volvo drives. The trim pumps have been a problem in the past, They had a plastic plug that was glued in that would come loose. No replacement part, so you have to pay 800 bucks for a new pump if not under warranty. Haven't heard about any problems with the 2011 models, perhaps they fixed it, I don't know. Something to think about for warranty offered.