Yes, in inboard installations, and with high confidence elsewhere as well.
An inboard marine gearbox is heavy and expensive (over 50 Hp).
And very rugged.
Its also cooled.
The heat is part of the inefficiency.
The gears are so heavy, because the propeller is an impact load.
This is a rule of thumb from manufacturers.
Compared to auto applications, the gearbox is sized for about 5x more hp
than a similar auto app.
Ie a 50 Hp marine gearbox is designed with the same loads as a 250 Hp
truck one.
Thats beause a very heavy load (boat, with load, moving fast ie with
lots of inertia) hits the propeller, and through the gearbox the engine
mounts, continuously.
Thus these heavy, continuous impacts due to wave action, make it
necessary to have very heavy gears to get the components to last.
(Likewise the marine engine is far more highly loaded than a similar
power auto engine, for example.
Thus marine engines are very much heavier than the auto app ones.)
Is this what you refer to ?
http://www.marinepartseurope.com/en/volvo-penta-explodedview-7744050-44-18192B.aspx
Mechanical efficiency in any gearset is seldom high.
2.5% in losses is far too low, as a low end expect 10-20%.
Anecdote:
A toothed belt transmission if very much more efficient, around 97%.
On 12/09/2014 12:39, Bendik Vignes bendik.vignes@yahoo.com
[electricboats] wrote:
> 1/3 of the energy wasted in the drivetrain: Are you referring to
> inboard installations? If so, such high drivetrain losses are really a
> lot more than I have estimated in my project!
--
-hanermo (cnc designs)
Posted by: Hannu Venermo <gcode.fi@gmail.com>
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