19' Lowe Deck Boat with johnson 88 need prop advice

[big boat little motor]

Hey all,
I got a new to me 97 Lowe LS1900 deck boat with an 88hp Johnson outboard. The rig has seemed woefully underpowered reaching a crowd pleasing 27 mph on the pital. The Tach had been reporting errantly so I did not really know where WOT was with the prop that came with the boat. After Fixing the rectifier the tach said that WOT was 4300. I pulled the prop to understand what was going on and I found out that the prop was an 11x21 which seemed like way to much prop for that small of a motor. I looked at the prop wizard and they were recommending a 13 3/4X15 prop. Does this seem reasonable? And would any one be willing to venture a guess as to what top speed might be for this boat?

Thanks
BBLM

 

[hwsiii]

Re: 19' Lowe Deck Boat with johnson 88 need prop advice

Big Boat, I ran some numbers through my program on your boat and these are the results. I show the boat base weight at 1,500 pounds and the motor with a recommended WOT RPM between 4,500 and 5,500 and a gear ratio of 2:1, PLEASE check these to be sure I am right, if these numbers are wrong then my answers are wrong. I show you should be able to run at about 32 MPH at WOT. Right now you arae showing a Prop Slip of 37% with that small diameter and large pitch prop.

Boat and Motor

Prop Picker

Prop Change

H

 

[big boat little motor]

Re: 19' Lowe Deck Boat with johnson 88 need prop advice

wow that is impressive. Your weight's look very accurate on the boat motor and type of gear we drag around. The range from he service manual is 45-5500 rpm with power ratings taken at 5k. This makes me think that this would be reasonable then to get the 13.75x15. I just wanted to make sure that I wasn't making a mistake as no one here has a demo program.

Thanks
BBLM

 

[hwsiii]

Re: 19' Lowe Deck Boat with johnson 88 need prop advice

You are making the right decision, and you will be very happy at the difference in the hole shot and the time to plane. And you are very welcome.

H