Speed question

[sds888]

Just making sure I don’t need to change anything. I use to have a G3 1756 SC with a 50 hp yahama boat weight around 900. It would go 35-36 mph. Just bought a Crestliner 17 Storm with 60 hp mercury boat weight around 680. The most I can get out of it is 32 mph. Not that I really need to go any faster it just baffles me. Any thoughts?


Sent from my iPad using Crappie.com Fishing mobile app

[Fishhunter]

If the Crestliner is wider there will be much more drag on the bottom of the boat. I but the Crestliner is rated for at list a 90 hp.

[sds888]

Thanks Fish. Mine is rated max 60 hp. The G3 is one inch wider.


Sent from my iPad using Crappie.com Fishing mobile app

[sds888]

I’m also thinking I’m using a lot more fuel but that might be the bigger engine or it just might be in my head.


Sent from my iPad using Crappie.com Fishing mobile app

[wannabe fisherman]

Prop size maybe ?

[Cray]

Lots of things go into the equation when it comes to boat speed. Like WAnnabe said first thing is prop size, next is RPM. Gear ratio in lower unit, motor height. Was old motor 2 stroke and new motor 4 stroke. Do you have a Tachometer if so what are Max RPM's. Im betting your spinning a prop that is to small at high rpm or to big a prop at to low RPM's. Either one of which would cause lower speed and higher fuel consumption. You may be ok with speed but if either of these is off it dosnt do your motor any good in the long run. Need to have it run with full load in middle of recomended rpm range for best fuel economy and engine life.

[sds888]

Thanks Cray. Both were 4 stroke. I’m running at around 5700 RPM at full throttle.


Sent from my iPhone using Crappie.com Fishing mobile app

[sds888]

Maybe some pictures to help.


Sent from my iPhone using Crappie.com Fishing mobile app

[Central Minn]

Have you had some one look at the calvitation plate when your at WOT trimmed up, it should be running right at the waters surface. By the pictures it looks like the motors is set to low,but it could just be the angle of the pics.

[Cray]

Motor looks pretty close to me especially for aluminum prop. If I could afford it I might put a stainless on it and raise one notch on transom. That would gain you 2-3 mph but to me it's not worth the the extra money though. My next question is on mph, was both measured on GPS or a boat mounted speedo? 32 with that set up and loaded boat is not bad in my opinion. Plus I feel as you run it and get motor broken in you fuel economy should improve some.