I am sorry to say but no, you are not right.
I build the hull's myself and we have 23ft boats with twin outboards on a hydraulic lift on the back, this is 500kg on the back (outside the boat).
When I builded the boat, I builded for inboard diesel, with all the structural strenght and flotation...
I want to increase speed to lower the torque. Years ago we had yanmar 350HP on bravo drives and I never saw one holding together longer then 30 hours.
The bravo's can handle power and RPM, not torque
I want to use a cummins 12V 5,9 diesel engine to replace a blown chevy 540 BB. the diesel engine puts out 500 HP at 3000rpm with 945lbs at 2000 rmp.
If I would use a speed increaser gearbox of 1 to 2, I convert this to 1000HP at 6000 and 472ft lbs at 4000 wich actually lies close to my BB...
I am a high perfomance boat builder in Europe. With our feul prices we have tons of clients who are asking us for dieselpower.
We want to use a bravo style drive, because almost every boat is equiped with this style of drive. The known problem is that these drive cannot handle the massive torque...