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Prop Pitch for High Altitude Lakes???-gctid380188

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    Prop Pitch for High Altitude Lakes???-gctid380188

    Friend today told me (a newbie boat owner) that I should put on a different pitch prop for boating at high altitude (Lake Tahoe elev 6500). Current prop is #832832A45P21. Does this mean pitch "21?"

    I was hoping to launch tomorrow. I was planning to launch tomorrow for entire summer, so am looking forward to any advice you can offer.

    Thanks in advance for your help. Jerry

    2006 175 Bayliner BR, 3.0 Alpha 1, 135h.

    #2
    Jerry, water doesn't change consistancy, air DOES. I would think that carb mixtures and/or octane ratings might be changed for higher altitudes but not the prop. Much like your car at high altitudes. Others on here might know better than me but it's gettin' late and your launching tomorrow. Enjoy your summer..

    Chris

    Comment


      #3
      Less air density at high altitude means that a naturally aspirated engine will not produce the same power as it will closer to or at sea level.

      This may require re-jetting.... but give it a try first, but understand that it will never perform as it does at sea level.

      High Altitude boats are gear differently than boats used at/near sea level.

      The correct way to do this, would be to re-gear for the altitude. Merc can suggest a ratio.

      Your only other option will be to prop down, and try it.

      Be prepared that some form of adjustment will be required.

      .
      Rick E. Gresham, Oregon
      2850 Bounty Sedan Flybridge model
      Twin 280 HP 5.7's w/ Closed Cooling
      Volvo Penta DuoProp Drives
      Kohler 4 CZ Gen Set

      Comment


        #4
        You live there; did you buy the boat there? If yes, then chances are the boat is all set to go. If not, you need to try it out. Read the owners manual for the engine, find out the rpm range. If the boat hits that, you're OK, all done. If not, try another prop. If that doesn't work, is it carbed? then re-jet. All these things can be done after launch...
        Jeff & Tara
        (And Ginger too)
        Lake Havasu City, AZ

        2000 Bayliner 3388
        "GetAway"
        Cummins 4bta 250s

        In memory of Shadow, the best boat dog ever. Rest in peace, girl. July 2, 2010

        Comment


          #5
          Go into the local marina explain to them you need to go down in pitch and see if they will lend you 2 props a 19p...and a 17p. Try them out see if you will reach recommended wot" will be posted on your engine ". Keep the 21p as a spare onboard you should have one anyway.

          There is a website that will allow you to try different pitch props for a small fee maybe someone else may know the address at this moment i am having a senior moment.
          Be good, be happy, for tomorrow is promised to no man !

          1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

          '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

          Manalapan N.J

          Comment


            #6
            jeffw wrote:
            You live there; did you buy the boat there? If yes, then chances are the boat is all set to go.
            + 1
            Rick E. Gresham, Oregon
            2850 Bounty Sedan Flybridge model
            Twin 280 HP 5.7's w/ Closed Cooling
            Volvo Penta DuoProp Drives
            Kohler 4 CZ Gen Set

            Comment


              #7
              for a 17 footer you will be ok, I think. I had a 1950 cuddy with the 4 cylinder back in the 90s, and it ran ok in Tahoe, and really good at sea level. The 25 foot cruiser would not plane out at Tahoe, and needed rejetting AND a prop just to barely plane.

              Comment


                #8
                Been there, done that! Unless Merc has changed their thinking, they advice to re prop, not re jet.

                I've had it happen to 2 boats, both purchased at sea level, and ultimately ran around 3500' Doesn't seem that high, but there was a big difference in performance. I ended up going down to a 14 1/4 x 17, 4 blade ss from a 21P aluminum, and the boat came alive. Rpm are within spec, top end is decent (more than I'll ever use) and fuel economy is 6.8 g/hr @ 28 knts with a 70% load.
                Bob Hawes.
                Kelowna, B.C.
                1998 Trophy 2052 WA
                4.3 Vortec, A1 G2

                Comment


                  #9
                  Tbanks all for your thoughts and advice. jerry

                  Comment


                    #10
                    I think a 19 pitch on your boat would have been the sea level pitch for water sports and all round boating. You probably need to go down to a 17 for Tahoe. If money is an issue start with a 17" pitch. If your a new boater, Lake Tahoe can get very rough suddenly. It's a big water lake and your boat is a little small for the conditions that often happen in the afternoon. You will see a lot of 26' plus runabouts on this lake for a reason.

                    Comment


                      #11
                      Hi,

                      We've been boating at Tahoe since 2003. Our Bayliner 1950 with a 5.0L V8 came with a 14x21 installed on it. Never ran it at sea level, but it couldn't pull WOT at Tahoe's elevation, and was generally sluggish. The second season we put on a 14x17 prop, and it was like night & day. Also, there's some really good marine dealers on the North and West shores that are very helpful, and can certainly give you good advice.

                      As far as the size of your boat, use caution if you venture out on the lake in the afternoon. The winds can come up quickly! Carry a VHF radio, and monitor the wind direction and sea conditions. The East winds are the worst! Waves on the lake can easily hit 4-6 feet on high wind days. We also have two bilge pumps, and we have a Vessel Assist membership.

                      Our first boat was a 17 footer, and was definitely too small. Our current 19 footer is better, but I'm still very careful when I go out!

                      Rick

                      Comment


                        #12
                        I have a 1986 1950 cuddy with a 5.0 V8 Chevy with Volvo Penta 200B.

                        It has a 3 blade aluminum Solas 14.5x19 prop.

                        I am getting a top speed of 35 mph at sea level with a WOT RPM of 3500.

                        It has plenty of torque & gets on plane easily without trim tabs.

                        I would like to know what I could do to increase the

                        top speed. I was told by the prop dealer it should have an RPM range of 4200-4700. I was expecting a top speed of 40-45 mph.

                        Comment


                          #13
                          The problem of bringing back a old thread with a completely different topic, people won't see it.
                          Be good, be happy, for tomorrow is promised to no man !

                          1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

                          '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

                          Manalapan N.J

                          Comment


                            #14
                            That vintage Volvo outdrives performed best with OEM Volvo props. Seems a 15.x17 or 15x19 would be in range. I ran a 15.x19 elephant ear on my 84 2150 Capri with 225 HP Volvo. Boat topped out at around 44 MPH.

                            Are you sure that you are not down on power. Have you looked at plugs and done a compression test? Bottom clean?


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