View Full Version : Top speed to expect?
Kerick
08-02-2004, 03:49 PM
I have a 20 ft. Lund Alaskan dual console with a 90 hp Yamaha four stroke. The Yamaha bulletin says I should get 38 mph at 5800 rpm. All I can get is 25 mph at 5800 rpm. I have a Maxum bow mount trolling motor, three batteries, and a T8 kicker. Should I expect more, and what pitch prop should I be using?
How are you measuring your speed? If it is with the speedo on the boat or a depth finder, they can both be wildly inaccurate. The only reliable way to gauge speed is via GPS.
Bill Krejca
08-02-2004, 06:13 PM
I have the 20' with a 115 yamaha 4 stroke and get 43mph at 5800rpm. Prop is 17 pitch Yamaha stainless.
Kerick
08-02-2004, 09:14 PM
Sorry. Meant to include I measured the speed with a GPS.
What prop are you using now? I your weight evenly distributed on the boat? What hole is the motor mounted in?
You have approximately the same weight per HP as my Lund Explorer with a 70 HP motor. I wish I was getting 38 mph.
Unlogged T-Mac
08-03-2004, 01:04 PM
Is your 5800 at full throttle and trimmed out to best speed?
What prop do you now have on it?
BustaBiggun
08-03-2004, 01:07 PM
The yamaha bulletins say what prop they were using. They also say what elevation and load in the boat.
Hunt4Ever
08-03-2004, 05:20 PM
I have the 1800 Lund Alaskan with the 90HP Yammaha 4-Stroke on it and the best I've seen WOT is 39 mph. If you can get that out of the 20'er your doing better than I.
Questions
08-04-2004, 03:04 PM
Did you figure out why you only go 25mph at 5800 rpms, yet?
Like is there is a 13pitch prop involved?
Kerick
08-05-2004, 10:02 PM
My boat was at the lake, so had to wait to get there to see what prop I have. It's a 13 1/2 x 15 K. The prop in the Yamaha bulletin was a 13 x 19. Would that make that much difference?
What are you using to determine your speed? If it's the speedometer on the boat, those are never correct. Mines not even close to my GPS speed. The prop you currently have at 5800 RPM should be pushing you in the 34 MPH range. If your speed reading is coming from a GPS and your tachometer is on the correct setting, you have other problems.