Donzi 73 inch

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  • Lefty20671
    Junior Member
    • Jun 2023
    • 11

    #1

    Donzi 73 inch

    I am building a Donzi 73 inch sport fisherman. Going to run dual counter-rotating motors and props. Any suggestions on brushless motor/esc? Not trying to set any speed records, just want a nice scale speed of about 30mph.
  • fweasel
    master of some
    • Jul 2016
    • 4281

    #2
    That's a big hull, that will likely push a lot of water. While I have no experience building something that size, I would be starting with twin 56mm motors (TP5650 for example), lower kV (600ish), and higher voltage...10-12S.
    Vac-U-Tug Jr (13mph)

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    • Lefty20671
      Junior Member
      • Jun 2023
      • 11

      #3
      Thanks fweasel, I.m looking at the tp 56mm motor with 720kv. Would the ztw seal 200 amp esc be ok with those on 8s? Going to start small with the props and experiment with larger diameter. The real Donzi cruises in the mid 30's so I'd like this one to get on plane, and handle well. Thanks again.

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      • fweasel
        master of some
        • Jul 2016
        • 4281

        #4
        Yes, those ESC's will work on 8S at that kV, but they are the limiting power factor in the setup. You won't be able to go over 8S for battery voltage, and it you prop up, it may pull more current than those will deliver. If it's a budget issue, I would rather see you use water cooled MMX8S which have been known to punch above their weight, vs the 200A ZTW's. High voltage ESC's like the ZTW 300A G2 will give you plenty of current headroom, and allow you to run more than 8S voltage.
        Vac-U-Tug Jr (13mph)

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        • Lefty20671
          Junior Member
          • Jun 2023
          • 11

          #5
          So to water cool the mmx8s, just add a water cool plate, and leave the fan? Looks like they are out of stock as well.

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          • fweasel
            master of some
            • Jul 2016
            • 4281

            #6
            Stump Fab sells a water cooling plate and 3D printed cover to make the MMX8S a DIY conversion. You'll need a tube of thermal transfer paste as well. Sometimes they stock fully converted ESC's if you don't want to do it yourself.

            Cooling plate
            3D printed cover
            thermal paste
            Vac-U-Tug Jr (13mph)

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            • Lefty20671
              Junior Member
              • Jun 2023
              • 11

              #7
              Found it. Thanks fweasel, placed my order for the completed esc with Stump. I'll keep you up to date with the build.

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              • Peter A
                Fast Electric Addict!
                • Sep 2012
                • 1486

                #8
                With submerged drives you will want some low kv. Depending on prop size, I'm guessing around 60mm 3 blade, You will want to keep your rpm under 10k. submerged drives will load the motor/esc a lot more than surface drives.
                I am assuming that you are keeping with the scale thing in using submerged drives. Surface drives may not work too well or be very efficient at 30 mph.

                Just as an example, the speed calc with a 60 x 1.4 pitch prop, 400kv on 10s and 80% efficiency shows 28 mph. That is for a surface drive mono. Playing around withprops and cell counts should get you where you want to be. Yes you have two drives and props also so should be more efficient and give you good run time. You could possibly use the ZTW 300 esc or even the 150A HV esc if your amp draw is kept quite low. I'm thinking you want to be in the 60A range per motor. On 10s that gives you around just under 6 hp equivalent hp.
                NZMPBA 2013, 2016 Open Electric Champion. NZMPBA 2016 P Offshore Champion.
                2016 SUHA Q Sport Hydro Hi Points Champion.
                BOPMPBC Open Mono, Open Electric Champion.

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                • Lefty20671
                  Junior Member
                  • Jun 2023
                  • 11

                  #9
                  IMG_3884.jpgIMG_3867.jpgIMG_3897 (1).jpg

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                  • vvviivvv
                    Fast Electric Addict!
                    • May 2009
                    • 1076

                    #10
                    That's a beautiful hull,

                    Shame its a little late but a pair of out runners would of been perfect for this application.
                    Hpr 06 / 09 / 150 /185, Mhz Skater H45 hydro.
                    Uk SAW record holder

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                    • Lefty20671
                      Junior Member
                      • Jun 2023
                      • 11

                      #11
                      444487736_3798118733800687_6830635357553491548_n.jpg

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                      • Lefty20671
                        Junior Member
                        • Jun 2023
                        • 11

                        #12
                        Donzi 73 complete.

                        Not a speed demon, but a true joy to run. Maxes out at 29 mph on 6s with TP 56mm motors. I spent the extra coin on dual Castle Creations Hydra XLX2 escs.

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                        • fweasel
                          master of some
                          • Jul 2016
                          • 4281

                          #13
                          Absolutely beautiful. I'd love to see more pictures of the finished build, specifically the submerged drives, rudders, and setup inside. What props did you end of using?
                          Vac-U-Tug Jr (13mph)

                          Comment

                          • Lefty20671
                            Junior Member
                            • Jun 2023
                            • 11

                            #14
                            IMG_4138.jpgIMG_4140.jpgIMG_4167 - Copy.jpgIMG_4156 - Copy.jpgIMG_4133.jpg

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                            • Lefty20671
                              Junior Member
                              • Jun 2023
                              • 11

                              #15
                              IMG_4192.jpgIMG_4189.jpg

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