Advice on V-Drive System

[naveganteamotor]

I am considering the buy of a Ferretti 36, with twin 3208-T Cat 320 H.P., equipped with Twin Disc V-drive marine transmission, so the engines are further aft. I would like to have your opinions about V-drive:
What are the pros of this system? Increased performance? Is it costly maintenance?
Thanks a lot!

[Chief Engineer]

I have worked on a boat with 3208s with vee drives.....

They were a real PITA to change filters/service the stuffing boxes.

They were too close together and access to the outboard sides of the engines was abysmal.

No complaints about the engines/gear....just poor thinking/planning

[naveganteamotor]

Thanks, Chief Engineer.

But are there any advantages of v-drive for a 36'?

[skipmac]

Advantages:

- better placement of the engines for weight distribution in the hull.
- give more horizontal angle of the prop shaft so more efficient drive.
- fairly simple design and usually pretty reliable (mainly familiar with the Walter V-drive)


Disadvantages:

- a little more weight
- one more thing that might break down
- a couple more hoses (the Walter wants cooling water through the unit)
- restricts access to prop shaft, stuffing box and potentially parts of the engine (depending on the boat, layout, beam, width of engine room, etc.)

[Pete7]

Do they absorb considerably more power than a straight through box? not sure, but I think they might. Worth checking before proceeding.

Pete

[skipmac]

Originally Posted by Pete7

Do they absorb considerably more power than a straight through box? not sure, but I think they might. Worth checking before proceeding.

Pete

I wouldn't call it "considerably more power". Certainly some but it would be very small. They are strictly mechanical so just adding a couple of gears and seals so just a little friction loss.

Maybe an engineer can tell us the numbers but I would be will to wager at least fifty cents that the gain in efficiency by having the prop more parallel to the water more than offsets any friction losses in the drive.

[capngeo]

I had a Borg-Warner unit on a towboat that was bullet-proof

[four winds]

On my Pearson the engine sits level in the boat. And the V drive output shaft is angled down as most boats are it seems.

I have considered that having the engine sitting level is the advantage. Engine is probably placed farther aft than normal as well.

The stuffing box looks hard to access to me, it's directly under the engine. Haven't had to go there yet.

[delmarrey]

Here is a link to some info on v-drives. Boat Mechanical Systems Handbook ... - Google Books