[golden_fox]

Originally Posted by CODOG

Most gearboxes reduce the input / crankshaft RPM, via internal gearing, resulting in a lower output / propshaft RPM. There are some minor losses in power between input and output due in part to this gear train. Most modern V-Drives are variants of their equivalent parallel output and down-angle brothers, and share basic case design and much of the same gear train components too....the only real difference is that in a V-Drive configuration the input and output shafts are on the same face of the gearbox casing....the power losses for each configuration are all but identical.
There is a slight weight penalty to pay for with the V-Drive layout due to two additional shaft flanges, Cardan shaft, additional (usually heavier) mounts and in most cases an engine bell housing.
Against that, common benefits are...
The ability to move a large mass further aft (useful if applied to fast planing craft requiring an LCB biased aft)
The dramatically shortened propulsive machinery installation space required, as the engines are aft of the gearbox instead of fwd of.
In certain cases, the option of ridgidly connecting the gearbox to the propshaft, without the need of a flexible coupling to take out the inherrent shaft bending tendency of a flexibly mounted engine and close-coupled gearbox.
In certain cases, the benefit of designing a drive train that can transmit thrust directly to the boats structure, rather than through a flexibly mounted engine and close-coupled gearbox.

thanks CODOG.....very precise explanation.....certainly very helpful!!