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Astra 2404 torque rolls

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Astra 2404 torque rolls

Home › Forums › Beginners › Astra 2404 torque rolls

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  • 27 October 2017 at 02:15 #73843
    Wayne Clarke
    Participant
      @wayneclarke38583

      I have built 2 astra 2404 boats both 30 inches long. Both used the same electric motor,trim tabs etc the first had a x40 prop while the second is using a x45. Maiden run of the second hull with the x45 prop torque rolls up on its side to nearly 90 degrees to the water.if I shut it down it goes back to normal attitude. Would bigger trim tabs solve this or alter the prop size?

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      27 October 2017 at 02:15 #2730
      Wayne Clarke
      Participant
        @wayneclarke38583
        27 October 2017 at 08:39 #73844
        harry smith 1
        Participant
          @harrysmith1

          Hi Wayne

          Your problem is the x45mm prop, if you drop to the x40 as on your first boat, no problem.

          Or a less pitch x 45mm!!!

          Harry Smith

          27 October 2017 at 09:11 #73847
          ashley needham
          Participant
            @ashleyneedham69188

            I have not experimented to be sure BUT three blade props apparently do not give as much torque as two bladed ones, and presumably you could go down a size without sacrificing performance??

            Ashley

            27 October 2017 at 09:24 #73851
            Malcolm Frary
            Participant
              @malcolmfrary95515

              Every action has its equal and opposite reaction. The propellor wants to move the water, the water has more inertia than the hull, the hull turns. Bigger prop, more water expressing its inertia.

              If a faster boat is wanted, a smaller prop revving higher makes for faster moving water, and the hull going faster the other way, provided the motor can go there.

              27 October 2017 at 10:01 #73855
              harry smith 1
              Participant
                @harrysmith1

                Hi All

                I tested a 40mm 2 blade against a 37mm 3 blade both CNC props.

                Same boat and motor, also the same day.

                Using a GPS and AMP meter onboard.

                The 3blade used 5 more amps and was 2 km slower than the 2 blade.

                The 3 blade was faster on take off.

                Harry Smith

                29 October 2017 at 02:30 #73888
                Wayne Clarke
                Participant
                  @wayneclarke38583

                  If I fit larger trim tabs and use a s45 prop will that help

                  29 October 2017 at 08:24 #73889
                  Dave Milbourn
                  Participant
                    @davemilbourn48782

                    My Huntsman rolls quite badly with a 2-blade prop but this disappears when replaced with a 3-blade, but all-out speed is not important to me.

                    DM

                    29 October 2017 at 08:24 #73890
                    ashley needham
                    Participant
                      @ashleyneedham69188

                      Harry…but what about the torque???

                      Wayne. Those plastic props are cheap….get an X35 and X40, an S40 and S45 and bung it in the water. Ultimately that is the only way to answer your question.

                      Ashley

                      30 October 2017 at 00:46 #73901
                      harry smith 1
                      Participant
                        @harrysmith1

                        Hi Dave

                        I ran the Huntsman topless on the weekend and after a reposition of the battery it ran with no torque or roll problems.

                        Left and right turns very nice at speed.

                        I think may be as good as my mates Spearfish!!!

                        Harry

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