Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: What pitch prop are being run on 90 HP Mercs?
Posted by trip313 on 05/14/12 - 4:27 AM
#1
I have a 1989 Super Sport 17' with a remanufactureed Merc 90 (3 cyl). I am working with Bblades on purchasing a SS prop for it (looks like a Trophy+ 17"P). I have run the prop on the boat with a hand held GPs and got 37 MPH @ 5600 RPM. Does this sound right to anyone else running a 17' hull with a 90 HP outboard on it? I was expecting the boat to be runing over 40 MPH.
I know I am giving up a little top end with the four blade prop. I am simply wondering what others with 90 HP & 70 HP are getting for top speed and what pitch props they are running.
Thank you.
Trip Thomas
Posted by awayland on 05/14/12 - 6:00 AM
#2
Not quite the same hull but Mercury Light speed 13-1/4" x 20" 5500-5600RPM 44mph flat calm trimmed out and porpoising like crazy
Posted by Tom W Clark on 05/14/12 - 6:44 AM
#3
No, you do not want a 17" anything and you do not want to run a Mercury Trophy Plus propeller on a classic 16'-7" Whaler with a 90 HP Mercury.
The best props for that boat/motor combination are the 13-1/4" x 20" Mercury Laser II (same as the Quicksilver Lightspeed) or the 13-1/4" x 19" Stiletto Advantage 4.25 (same as a Turbo 1).
37 MPH is w a y too slow, the boat should do 42-44 MPH. Be sure the motor is mounted three holes up on the transom.
Posted by mtown on 05/14/12 - 7:26 AM
#4
Don't want to hijack your thread, but I just put a 12 5/8" x21K prop on my son in laws 1979 Montauk yesterday. He has a Mercury 90hp 2 stroke installed 1 hole up. To the best of my knowledge the prop that was removed was an aluminum 13 1/4" with 17 pitch. The boat ran fine with that, but I recommended the stainless which I had from a Yamaha 2 stroke 115 and gave to him. The yamaha had been on my 1985 18' Outrage and was from dealer that way, and performed well. The boat is still on trailer so we have not tested yet. Any predictions?