Sterndrive Decisions

I have a Yanmar 6 diesel 220 HP and need to purchase a sterndrive. I have no experience these. What are the pro and con with these? track records? Yanmar ZT350 it was changed to a different supplier for the ZT370. Bravo diesel 2 0r 3 ? Konrad recommends there 570 single prop. This is a single engine 27 planing hull cruiser. Single or dual prop advantages? Im in Asia and no service dealers, reliability is the key issue.
Thanks for any advice.
Linwood

 

I do not have any experience with a diesel sterndrive, however the Bravo 2 Diesel would be my choice. I had a 26 foot cruiser with a single 7.4L gas and Bravo 2 drive. That drive swings a huge wheel which geared properly would be ideal behind a diesel. I am pretty sure that there was a partnership with Yanmar & Mercruiser at some point. You might be able to look up the factory matched recommendations.

 

Bravo drives can be made to accept prodigious amounts of torque when used in 200 mph lake and river boats. Typically over 1000hp and comparable amounts of torque, you might want to contact some of the relevant performance shops and see how they beef up the drives. When you are a long way from any service techs or spare parts bulletproof takes on a new importance.

 

An Alpha can handle 220 HP, though the Bravo is a tougher, stouter drive. Bell housings and transom kits are available for you diesel.

 

Par, you'd be comfortable with a 6cyl 220 HP Diesel coupled to an Alpha? I wouldn't think they had enough strength to handle the torque. I guess some manufacturers did couple them to the 7.4L in lighter performance hulls. linwoodhardy what is the approximate displacement of the boat you are working on?

 

The naturally aspirated 5.7 LT is coupled to the Alpha regularly. It produces 225 HP, though the same engine as a Vortec (CFI or TPI) typically produces 260 HP and is also bolted to an Alpha, though seemingly equally to the Bravo, depending on application. A one ton 18' bow rider will have the 350 LT on an Alpha, while a 2 ton 20' cruiser will likely employ the Bravo with a 350 LT Vortec.

 

7228sedan the designer says 3000, I think its around 5000+ loaded, and thanks for the advice for me to make an educated decision.

 

It's easy enough to find the weight of your boat. If the designer says it's 1.5 tons, just guessing it's 166% heavier doesn't seem reasonable, even if his 1.5 ton figure is "light" displacement. In any case, it sounds like you'll want the Bravo anyway.

 

sterndrives are rated by torque not horsepower, I would not put any diesel on an alpha

 

Hi Powerabout,
Without wishing to be too contradictory the spec sheets which I only downloaded from the website this afternoon state that the Alpha will handle diesel engines up to 150HP The Bravo One up to 370 Hp
The reason I happened to obtain these is that I am investigating fitting a stern drive diesel 2.0L or 2.2L to a suitable hull. Thus obtaining the fuel economy of diesel which I understand can be up to 50-60% on petrol.

 

not a prob
I can see where Merc is coming from, they assume a 150hp diesel is a high revving 4 cyl.
Not a slow 6ltr perkins or Ford making less than 150hp but tons of torque.
A diesel being more fuel efficient is all up to the combination its installed in and how fast you run it.

 

My Decision

My ? from an earlier post on what drive to use. Yanmar would not sell me the ZT370 there latest version of the outdrive to use on my 220HP 6 cylinder diesel, there response was to buy a new diesel engine combination with the outdrive, Ouch. After much soul searching on what to do, Iv ordered from Kronrad Marine there model 540 sterndrive package. Thanks to all that responded to my question.
Linwood Hardy

 

Hi Folks,
I joined this forum in the hope that I could obtain some unbiased advice on what type of boat to buy. It will be something between 6M -7M family friendly with some fishing.
I have access to a jetty and intend to keep the boat in the water.
Now this is where I need help. I have been advised that if I am going to keep the boat in the water then I should not consider a stern drive. As this will be costly to maintain due to continual corrosion problems and general degradation of seals etc.
And that a proper outboard of 80-120HP is the best way to go as the drive/prop can be pivoted out of the water when not in use, and therefore kept away from salt water.
This all make sense to me.

My interest in a stern drive came about because I felt that deisel engines (such as the new Mariner series stern drives) makes for an almost 50% improvement in fuel useage for the 6-7M types. My intent was to find a Bayliner type boat which has many miles on the clock and at a good price. and do an engine transplant. I live in Sydney so I'm surounded by boats!!!

Any help and advice would be appreciated.