1. Use the full 4 digit year for everything you are asking your question about. Example: 1962, 1988, 2000, 2011
2. Include the correct name of your Whaler model. Example: Montauk 17, Montauk 170, Outrage 26, Outrage 260
3. Include the length when necessary. Example: 16, 17, 18, 20, 22
4. Do not post your email address anywhere on this site as it is already in your user profile.

1985 Sport 15 with a Yamaha 70 ELTK...Props?
onejaboney	#1  Posted on 06/22/09 - 8:42 PM
Member Posts: 1 Comments: 0 Joined: 06/22/09	I run this boat at 8000 ft in Colorado and just installed a new 15 pitch prop and it still doesn't plane or rev. My tach is broken but I wonder if a 11 pitch is what I need? Some guys at the marina in Grand Lake run a 11 pitch prop on their 40 hp four strokes and they work great. Any help with tuning for altitude would help.
Joe Kriz	#2  Posted on 06/22/09 - 9:13 PM
Site Owner Personal Page Personal Album Photo Albums Project Albums Posts: 11447 Comments: 452 Joined: 03/18/05	You may need high altitude jets. Talk to your dealer. Anything over 5,000 feet in elevation most likely needs a jet change or computer calibration depending on engine. Edited by Joe Kriz on 06/22/09 - 9:14 PM
theo	#3  Posted on 06/23/09 - 7:44 AM
Member Personal Page Posts: 252 Comments: 0 Joined: 08/26/08	Was the motor sold new in CO? If so it should already be jetted for altitude. If it came from out of state, I agree it could be running rich. Ted 1985 15' CC, 1994 60 hp Merc (Wednesday built), 5" jack plate
Tom W Clark	#4  Posted on 06/23/09 - 7:56 AM
Member Personal Page Posts: 4280 Comments: 7 Joined: 09/30/05	As we all know, engines loose power with altitude where the air is thinner and there is less oxygen. At 8000 feet a 70 HP outboard is going to perform like a 50 HP outboard at sea level. We know that 50 HP on a Sport 15 should push it to about 35 MPH. I believe the Yamaha 70 uses a 2.33:1 gear ration so with its 6000 RPM redline, that suggests you would need a prop with about 16" of pitch. If you're running a 15" pitch now and the boat will not go, there is something else wrong.