Out drive ratios

[Century riviera]

My boat has the mercruiser 3.7l 190hp motor. What gear ratio should my drive be?

 

[JoLin]

https://www.sterndrivereplacement.c.../alpha-one-gen-1/complete-sei-106/gear-chart/

 

[Century riviera]

That's the info I need. Thanks

 

[Century riviera]

Found a drive in excellent shape. 1.81 ratio. Using the prop I had (14.5×17) 4 blade. The engine was revving over 5000 rpm. Found a nice stainless 21p 3 blade prop, now wot rpm is 4600-4700. Perfect! Top mph is only 47.5. I was hoping for more from 190 hp engine in a 5 meter boat. Would a 23p make the boat go faster or just lower the rpm?

 

[achris]

Just lower the revs... X horsepower will push y boat at z knots. Only way to go faster is get a bigger engine (or a smaller boat)...

190, fairly tired I suspect, crankshaft horsepower is doing well to push a 5 metre boat to 41 knots.. My fairly new 220 propshaft horsepower pushes my 6 metre boat to about 42 knots....

Chris........

 

[Scott Danforth]

If you want to go faster....you need more motor