Mr Gadgets

Weight and power are factors in the equation. End result is WOT rpm's the motor is rated for. You prop and gear for an end result. In my opinion, the prop plays a big role in which gear ratio you choose. If your combination requires say 5500 rpm, and you have a light boat, the prop will be a larger pitch number. Heavy boat will require less pitch to aquire that 5500 rpm. Lets say you can turn 6000 rpm, now that light boat may not pull it with 600 hp with a 34 P prop. But if you have 1000 hp, you may end up with a 38 P prop and might consider a gear change to 1.35 ratio to keep the 34 P. My questimations are not proper math (Not implying that the switch from 1.5 to 1.35 is handled by 4" pitch change, etc).
I have always considered the prop that may work better at a maximum rpm and see where the gear ratio lands. If it ends up a 1.35 puts me in the sweet spot for a certain type of prop then so be it.
Now a lot of people have experimented with different gear ratios and props and come to different conclusions. To say that one ratio works better than another depends on a lot of factors in each instance. But a heavy boat versus a light one, will move the numbers down the scale ( lower ratio/smaller prop). More power versus less will move the numbers up the scale.
So yes, weight does play a factor in the equation. Will one ratio have more bottom end than another, I think it depends on what prop you use with the different ratio. Are there issues with the size of the gears, maybe so. I would suspect some people that have experimented can speak to that. How much difference there is with ratios, could be compensated with the right prop in most cases..
Just my .02..
Hope that helps your thoughts.
Dick

deathdealer

I know reviving a very old/dead thread but someone may want this info for the future. You can 100% run a bravo shop lower, a imco sc lower, or a bravo standard blunt nose lower on a bmax. The vertical shaft must be bmax specific in either std length or -2 length. So if you want to run a -2 imco sc on a bmax upper you need the -2 bmax bravo shop vertical shaft, same for std length imco sc on a bmax, need the std length bmax vertical shaft. You MUST drill a secondary water hole to feed the upper cap bearing or it will grenade in short order due to chasing oil out of the upper cap bearing. 100+ hours on the std length sc lower on a bmax 1.30 upper with std length bmax vertical shaft with added water passage hole.