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.

1989 15 SS 70 hp 2stroke prop?
captjp	#1  Posted on 08/16/15 - 10:29 AM
Member Posts: 18 Comments: 0 Joined: 10/01/13	What's the recommended prop size for 1991 yamaha 70 2 stroke on a 1989 15 SS?
captjp	#2  Posted on 08/21/15 - 7:12 PM
Member Posts: 18 Comments: 0 Joined: 10/01/13	Any suggestion would really help. Size and pitch recommendations?
wlagarde	#3  Posted on 08/21/15 - 7:37 PM
Member Personal Page Project Albums Posts: 442 Comments: 2 Joined: 07/21/13	We need some additional information to help you: 1) How high is your engine mounted (see here: http://www.whalercentral.com/articles...cle_id=106)? 2) What is the gear ratio of your engine? 3) What is the WOT operating range of your engine? 4) What prop do you currently have installed (brand, material, diameter, and pitch)? 5) What is your current WOT rpm and speed? 1976 Sport 15 w/ 2005 50hp Nissan 2 stroke
mtown	#4  Posted on 08/22/15 - 5:25 AM
Member Personal Page Posts: 613 Comments: 5 Joined: 07/06/08	I have a 13 1/2x 17 Ballistic prop on my 70 Yamaha 2-stroke and have been very happy with it. The boat is a !964 16'6". Ballistic is made by Michigan wheel.
Phil T	#5  Posted on 08/22/15 - 10:43 AM
Administrator Personal Page Personal Album Project Albums Posts: 7043 Comments: 6 Joined: 03/26/05	I would go with a Yamaha K series painted stainless steel prop in 17" pitch. Engine mounted 3 holes up.
captjp	#6  Posted on 08/22/15 - 11:32 AM
Member Posts: 18 Comments: 0 Joined: 10/01/13	The engine is all the way down. Runiing 13x19 aluminum now. Wot is now 5800 rpm. Recommended is 5500 to 6000. Hitting 39 mph .
wlagarde	#7  Posted on 08/22/15 - 3:53 PM
Member Personal Page Project Albums Posts: 442 Comments: 2 Joined: 07/21/13	captjp wrote: The engine is all the way down. Runiing 13x19 aluminum now. Wot is now 5800 rpm. Recommended is 5500 to 6000. Hitting 39 mph . Your gear ratio should be 2.33 and the WOT 5000-6000: http://www.yamaha-motor.com/assets/se...5_1390.pdf. Confirm this is consistent with what your user manual says. Using the Mercury prop slip calculator (http://www.mercuryracing.com/prop-sli...alculator/) I calculate a slip of 13% which is high. You can use this app to get a general idea of what prop pitch is appropriate. Raise the engine 3 holes up and then lake test again and report back with updated data. If the engine aerates while riding onto the plane let us know that. Also be careful about over-reving the engine. The rpm should rise by about 150-200rpm per hole up (roughly) and the prop slip should decrease. I will defer to Phil on the ultimate prop recommendation as he is the "prop guru". Edited by wlagarde on 08/22/15 - 3:58 PM 1976 Sport 15 w/ 2005 50hp Nissan 2 stroke