Any pros/cons going from a 1.5 to 1.36 on a relatively slow boat? Turning damaged 28 B1's to 5,000 with the 1.5's with a max of 74.3.

Probably just make it lazy pulling out.

+1,, you will loose the snappyness in the boat..in other words it will take more time to reach speed,if you could even reach the speed mentioned..

even with a smaller wheel?

Yes,

Been There Done That!

You my gain a little top end, but you will loose torque.
I did this on my Nordic and wound up switching back.
Your prop will be spinning faster but with less power to push.

1.50 w/b1 28 pitch 77-78 mph consistantly reguardless of load.

1.36 w/b1 26 pitch 79-81 mph inconsistantly and more sensiitive to loads in boat.

Keep this in mind also, you are now spinning your propshaft faster which means more stress on you lower unit. I had to have mine rebuilt after 2 years with the 1.36 set-up.
You will also need to play the prop game again to find what works best.

turning damaged 28 B1's? what would it do with undamaged ones? you change ratio you are buying props anyway...

Maybe 2-3 more undamaged.... But who knows. I have a slight bearing noise in a drive so I buying a used set off a friend. Maybe I'll take my 1.5 gears out and throw them in the other cases and repair/lab the 28's.

Thanks for everything.

Can someone explain this in better detail?

For example, I have 1.65 drives on my 28 ZX (6.2's). but the 350 Mag boats have 1.5 drives. The prop pitch on the 350 is 23 and on the 6.2 it's 25.

Mathematically it's a wash. I have noticed differences because, what I think, prop diameter differences but that's about it.

With this 1.36 / 1.5 question it is almost the same. The MPH changes only by 2 top end with the 1.36 with a reduction in prop pitch by 2 inches.

The final work load at top speed will be near the same, however getting there will change with the new gear ratio.

Think of your old ten speed bike, you could put in it top gear and spin the peddals slower but harder to have that top speed. You friend is next to you peddling faster in a lower gear but going the same speed. You both stop and don't shift, then take off from the dead stop? Who has the easier time getting that bike back on plane?