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Author Topic:   Prop for 17 Outrage
fdubois posted 12-31-2003 02:50 PM ET (US)   Profile for fdubois   Send Email to fdubois  
Just bought a 1995 Outrage 17 Commercial Products Division boat (former Virgina Game and Fisheries boat) with a 115 Mercury on it. Need a new prop badly so I want to go with a Stainless general purpose prop. Will be used on Chesapeake Bay for fishing and general exploring. Can anyone recommend pitch and diameter? Thanks. Frank
[Boat name is Isabel, insurance claim paid for her!]
jimh posted 12-31-2003 04:04 PM ET (US)     Profile for jimh  Send Email to jimh     
Executive Summary: 19 inch

Longer Answer:

According to the article in the Reference Section that predicts performance, you ought to be able to get about 42-44 MPH out of your boat and motor combination.

See:
Performance Prediction
http://continuouswave.com/whaler/reference/performancePrediction.html

I don't know what the lower unit gear ratio or maximum RPM of your motor happens to be, but I looked it up on the Mercury Marine Website.
http://www.mercurymarine.com/mercury_115_classic

Turns out you have a 2.07:1 gear ratio and maximum crankshaft speed of 5250.

I figure you will have a SLIP factor of about 6-percent if everything is just right. I use a figure of 43-MPH as the target. I then enter all this data into the Propeller Calculator available here on the website:

Propeller Calculator
http://continuouswave.com/cgi-bin/propcalc.pl

It tells me the pitch of propeller needed to produce a boat speed of 43 MPH with a crankshaft speed of 5250 RPM, a gear ratio of 2.07:1. and a propeller slip factor of about 6-percent:

Answer: 19-inch pitch

You leave the diameter up to the propeller designer, who has figured out what to use at that pitch that will fit your motor. He will know the limit of the diameter necessary to fit into the space on your motor and also what the proper diameter will be for that pitch.

I'd start with a Mercury brand propeller since they are some of the best and they also will have a very wide selection 19-inch pitch that will fit your motor. Also, most all of the Mercury propellers use a standard and interchangeable hub system, so you can buy one hub and try a number of propellers with it. Some dealers will let you test drive a propeller and return it--if you don't do anything other than get it wet.

Don't sell a BLACK MAX three blade propeller short. They gave a good account of themselves in a recent rather comprehensive propeller test on a Boston Whaler.

See: One Boat--Six Propeller/Engine combinations:
http://continuouswave.com/whaler/reference/190Nantucket.html

Marc posted 12-31-2003 05:13 PM ET (US)     Profile for Marc  Send Email to Marc     
Frank:

I have a 91' 17' Outrage with a 115 Mercury also. I have a 13.25 x 20p stainless steel Merc Laser II prop. This prop has worked well for me. I get about 40/41 MPH at WOT. At least that is what the GPS tells me.

I posed a performance question a while back and got a lot of good information that may help:

http://continuouswave.com/ubb/Forum3/HTML/002878.html

Marc..

jetfrank posted 12-31-2003 05:43 PM ET (US)     Profile for jetfrank  Send Email to jetfrank     
Great information! Thanks for the help and have a happy new year, I'll be putting around in Isabel tomorrow if the wind stops blowin. Frank
fdubois posted 01-24-2004 10:19 PM ET (US)     Profile for fdubois  Send Email to fdubois     
Well, Picked up a 13X19P reonditioned aluminum on ebay for around $50 and a Like New Laser II 13.25 X 20P Stainless for $150 (retail $490!). Creek and Bay are incased in ice so will try them out when the ice melts and I finished getting the boat lift in. Frank and Isabel

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