Motor and Prop Survey 2020 Update

Motor and Prop Survey 2020 Update

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  • #3665
    Colin Bishop
    Moderator
      @colinbishop34627

      Article in forthcoming Special Issue oif Model Boats

      #28911
      Colin Bishop
      Moderator
        @colinbishop34627

        MyHobbyStore have commissioned another Model Boats Special Issue for next year and this one will be a combination of recycled plan features going back to the 1980s plus a series of articles on what might be termed ‘Model Boating Basics’ which will be aimed at giving people advice on the issues which come up again and again on internet forums from new or less experienced modellers.

        I’d like one of the articles to be about Choosing Motors and Props as this is something which a lot of people find difficult. There is no magic solution to this and any ‘scientific’ based method involving calculations could be a turn off, people basically just want to know what will work in their boat. So the idea would be to give some general advice on things to take into consideration supplemented with a series of ‘benchmark’ setups for actual typical boats drawn from practical experience. If your boat is very similar in its characteristics to one of these benchmark model setups then you can be reasonably sure it will work for you too. If it is somewhere between two benchmarks then at least you will have bracketed the range of possible options.

        So I am inviting Members to use this topic to post details of their boats where they have a good working motor/prop/battery setup. If possible, also post photos of the model in action and of the interior layout as some of these could be published in the magazine. If you would prefer to PM me with details of your boat, that is OK too.

        Assuming that I get a good response, it will be summarised in the magazine for the benefit of all.

        The list of parameters that I have identified is as follows. We need all of them to do an effective job.

        Boat Name
        Type:  ie. tug, destroyer, cabin cruiser etc.
        If a Kit – which kit?
        Length (mm)
        Beam (mm)
        Draught (mm)
        Weight (Kg)
        Number of propellers
        Motor(s) used. (specific rather than generic i.e. Not just ‘540’ but ‘Dean’s Kondor’ for example so we know exactly which motor is being referred to.)
        Propeller type and description: i.e. 2 blade/3 blade/4blade etc. conventional or racing
        Propeller diameter.
        If geared drive what is the reduction ratio and are gears or belts used?
        Battery type and capacity.
        Approximate average running time obtained. 

        Please don’t use this topic to ask questions about which motors to use, it is intended for gathering information only!

         I look forward to lots of responses!

         Colin

        #28915
        Robin Lee
        Participant
          @robinlee31938

          Hi Colin,
          I’ll have a go at this request. One of my favourites a Dean’s Marine HMS Kelly.
           
          Boat Name: HMS Kelly
          Type: Destroyer
          Dean’s Marine Kit (more or less!)
          Length: 1120mm
          Beam: 125mm
          Draught: 50mm
          Weight: 3.8Kg
          Number of propellers: 2
          Motors: Deans Marine Kondor
          Propeller type: 3 blade conventional (kit parts)
          Propeller diameter: 30mm
          Drive: direct
          Battery type: one for each motor Sanyo 7.2volt Nicads 2000mAh
          Running time: at least 2 hours at half throttle
           
          Some photos:
           
           


           
          Quite difficult to get all the info together but can do more if wanted?

          Robin

          #28917
          Colin Bishop
          Moderator
            @colinbishop34627
            That’s great Robin, exactly what I am looking for.
             
            Colin
            #28922
            Robin Lee
            Participant
              @robinlee31938
              Hi Colin,
              Another model:.
               
              Boat Name: Tsekoa ll
              Type: Navigation Aid maintenance
              Model Slipway kit
              Length: 840mm
              Beam: 228mm
              Draught: 60mm
              Weight: 6.8Kg
              Number of propellers: 2
              Motors: 545 type – Electronize 545-12 (marginally underpowered but is very subjective)
              Propeller type: 4 blade conventional Prop Shop 1517/4
              Propeller diameter: 38mm
              Drive: direct
              Battery type: one for each motor Led Acid Gell 6volts 4Ah
              Running time: 2 hours 
              Some photos:
               

              #28925
              Mark Beard 1
              Participant
                @markbeard1

                I don’t want to clog this thread up with non-data posts, except to say how excited I am to see this info being published.  If enough people post their info as Robin has, we are going to get a superb database of empirical results which will really help new builders (like me) to get their models correctly powered from the outset.  Although I don’t have results to post, I look forward to offering some analysis or reduction of the data to some sort of usable form.

                #28942
                Francis Macnaughton
                Participant
                  @francismacnaughton39461
                  Colin,
                   
                  I would suggest that at least some indication of overall performance of the model with that power installed in comparison against the performance of the prototype would also be useful.  This especially true for higher speed types like warships, speed boats and MTBs.  Perhaps something along the lines of either:
                   
                     a)  Achieves prototype maximum speed    or
                   
                     b)  Exceeds prototype  maximum speed    or
                   
                     c)  Cannot match protype maximum speed
                   
                  Ideally this should be done by comparison of the model wake pattern with the original’s but I would suggest that even a subjective estimate such as Robin’s above would be better than nothing.
                   
                  Francis Macnaughton
                  #28951
                  Gareth Jones
                  Participant
                    @garethjones79649
                    Since I have started to keep a very similar database of my own models for the same reason I suppose I had better submit the details.  (Maybe Colin has borrowed my idea?)
                    Here is the first one then.
                     
                    Name   TID13 (I know there never was a TID 13 in real life)
                    Type       Tug
                    Scratch built, ply plank on frame hull
                    Length    900 mm
                    Breadth    230 mm
                    Draught   70 mm
                    Weight   6.4 kg
                    Propellers   1
                    Motor   Graupner Speed 900BB torque (type number 6373)
                    Propeller type 4 blade Rivabo brass general purpose (apologies to Glynn Guest, I dont know the pitch)
                    Propeller diameter 55 mm
                    Direct drive, no gearing
                    Battery 12 volt 7 amp hour lead acid
                    Duration not known but well over an hour
                    Performance    significantly over powered with this motor – it will almost plane.  However the propeller is slightly large for the motor, prop speed at max power is 3150 rpm. free running speed of motor is 6500
                     

                     

                    Edited By Gareth Jones on 22/11/2010 09:01:20

                    #28952
                    Gareth Jones
                    Participant
                      @garethjones79649
                      Here’s the next one
                       
                      Name    Daisy II
                      Type      Armed drifter
                      Kit    Mountfleet Osprey
                      Length   1100 mm
                      Breadth   250 mm
                      Draught   90 mm
                      Weight   8.5 kg
                      Number of props 1
                      Motor   Graupner Speed 720B torque (type number 6372)
                      Prop type 4 blade brass Rivabo general purpose
                      Diameter 70 mm
                      Direct drive, no gearing
                      Battery 12 volt lead acid, 5 amp hour
                      Duration over an hour
                      Performance,  good realistic scale speed.  Propeller size is a bit large for the motor. At full power prop rpm is 1530 compared with free running speed of motor which is 4100 rpm

                       

                      Edited By Gareth Jones on 22/11/2010 08:43:06

                      #28953
                      Gareth Jones
                      Participant
                        @garethjones79649
                        And here’s another.
                         
                        Name     Walbut Dream
                        Type    Narrow boat
                        Kit      Scratch built using Deans marine hull (still work in progress as the photo shows)
                        Length   1060 mm
                        Breadth   180 mm
                        Draught   60 mm
                        Weight   8.3 kg ballasted to estimated completed weight
                        Number of propellers   1
                        Motor   Graupner Speed 500E (type number 1788)
                        Propeller type 3 bladed brass Rivabo general purpose
                        Prop diameter 40 mm
                        Direct drive, no gearing
                        Battery    7.2 volt  2600 mah NiCad
                        Duration not known but probably about an hour
                        Performance   slightly over powered for a narrowboat.  Propeller is slightly large for motor size.  At full power, prop rpm is 3040, free running speed of motor is 7200 rpm.
                        The model has a bow thruster but in practice it is not required as turning performance is excellent using rudder alone (surprisingly perhaps)

                        #28954
                        Colin Bishop
                        Moderator
                          @colinbishop34627
                          Gareth,
                           
                          No I didn’t pinch your idea it’s a case of great minds think alike. I have had this in mind since July but your posts pre empted the formal decision of MyHobbyStore to go ahead with next year’s Special so I wasn’t in a position to ‘launch’ before then!
                           
                          Obviously the more boats we have then the more useful the data will be. My proposed article will cover general advice and publishing the benchmark data but wlll stop short of attempting to draw any theoretical conclusions for selecting motor/prop setups. If the data helps you and Billy move forward in this area then I’m sure Paul Freshney would be interested in publishing it in the regular magazine.
                           
                          Francis, you have made a good point but the assumption will be that we are looking at benchmarks where satisfactory ‘scale’ performance is a given. Defining this can be a bit of a minefield in itself and can be somewhat subjective to say the least.. The wake patterns in Robin’s excellent photos demonstrate satisfactory performance very well which is one of the reasons I asked for photos.
                           
                          Thanks for your help to date everyone, and keep them coming!
                           
                          Colin
                          #28955
                          Gareth Jones
                          Participant
                            @garethjones79649
                            Its fine by me Colin. I agree, the more information there is in the database, the better the possible match and the greater the number of people who will benefit.  Heres the next one then.
                             
                            Name    PT602 Snogg
                            Type      PT boat
                            Kit         Originally I think the hull was a Keil Kraft or Aerokit
                            Length   1020 mm
                            Breadth   280 mm
                            Draught   40 mm approx
                            Weight   6.3 kg
                            Number of props    3 but only 2 are driven, the other freewheels
                            Motors    2 off, Graupner Speed 700 (type number 7307)
                            Prop type      3 bladed brass Rivabo general purpose
                            Prop diameter      30 mm
                            Direct drive, no gearing
                            Battery      2 off NiMh, 9.6 volts, one is 2600 mah the other 3300 mah, the only reason they are different is because they happen to be what I already had available
                            Duration    around 15 minutes, depending on how much space there is to plane around the pond.
                            Performance      Excellent, planes well,  now better than with the 2 Speed 600 motors as originally described in Model Boats.  Present motors run much cooler.  Motors are well matched to propeller size, prop rpm at full throttle 9240 compared with motor free running speed of 14600.

                             

                            Edited By Gareth Jones on 22/11/2010 13:35:40

                            #28958
                            Gareth Jones
                            Participant
                              @garethjones79649
                              And heres the last one for now.
                               
                              Name   Onion barge E
                              Type    Springer tug
                              Kit   Scratch built (by my wife Elizabeth)
                              Length   460 mm
                              Breadth   200 mm
                              Draught   85 mm approx
                              Weight   3.9 kg
                              Number of props 1
                              Motor   Graupner Speed 500E (type number 1788)
                              Prop type   3 bladed brass Rivabo general purpose
                              Prop diameter   40 mm
                              Direct drive, no gearing
                              Battery 7.2 volt NiMh, 4300 mah
                              Duration around an hour
                              Performance   A little underpowered but fine as a ‘have a go boat.’

                              Motor gets a bit hot after long periods, prop is a little too large for motor.  At full power prop rpm is 3250 compared with motor free running speed of 7200 rpm.
                               
                               

                               

                              #28992
                              Queequeg Quint
                              Participant
                                @queequegquint38270

                                Name of vessel: The Ambassador

                                Hull type: Lobster boat
                                Hull: fiberglass, plus wood freeboard to allow the boat to carry more weight
                                Length: 35 inches
                                Width: 12 inches
                                Draft: 5 inches
                                Motor: MFA Como Torpedo 850, geared down with belt drive: 2.1:1
                                Prop: 65mm 4 blade brass
                                Weight, with 12volt 12AH battery: over 12 lbs (American pounds)
                                Run time: about one hour with aggressive driving
                                 
                                In this video, the camera is on board one lobster boat, trying to chase the Ambassador.  You can see how fast the Ambassador’s motor/prop setup is.
                                 
                                 
                                 
                                 
                                In this next video, the camera is inside the Ambassador.  You can hear how this motor sounds  Note: in the beginning, you hear the humming of two cooling fans (one for the motor, one for the Viper ESC).  Not sure if I really need them, but when I first got into this hobby seriously 2 years ago, I smoked a motor in the Orca.  Been fearful of doing that again ever since:
                                 
                                 
                                 
                                 
                                In these pictures you can see the veritable miracle that is the way I mounted this motor. I can’t believe it works but it does perfectly.
                                 

                                 

                                 

                                The motor is bolted to 4 wood blocks which are cold welded to the hull (at an angle!!!!)  It actually works I and use this boat alot! 

                                 

                                The only thing I had to do was add some cold weld to the universal joints beause they started to separate.  Also, my prop came loose once, but I caught that before I lost the prop and added some extra lock tight!
                                If anyone can tell me, I was wondering if I can squeeze out some more thrust by switching to a 5-blade prop….  Same diamaeter becuase I can’t fit a bigger one down there.
                                #28993
                                Queequeg Quint
                                Participant
                                  @queequegquint38270
                                  Here is a picture of the propwash of the Ambassador.  This is a “still” from a video.  I had the camera near the stern of the Ambassador, filming the Orca.  But I got a really nice picture of the Ambassador’s propwash.  I had a crane mounted on the Ambassador; you can see it at the top of the picture.  I think this is full throttle. 

                                   
                                  The Ambassador is by far my heaviest boat, but it is also the fastest!
                                   
                                   
                                  #28997
                                  Queequeg Quint
                                  Participant
                                    @queequegquint38270
                                    Here are some nice action photos of the Ambassador.  These photos are taken from the Illusion as it chases the Ambassador.  Notice the massive wake made by this mighty vessel!!!

                                     
                                     
                                     

                                    #29011
                                    RedPanda
                                    Participant
                                      @redpanda
                                      Hi Colin, my contribution as follows:

                                      Boat Name:                 Norseman
                                      Type:                        Tug
                                      Kit:                            RTR Heng Long / NQD Seaport Workboat
                                      Length (mm):             570
                                      Beam (mm):               185
                                      Draught (mm):            60
                                      Weight (Kg):              2.557
                                      Number of propellers:   1
                                      Motor(s) used:            Turnigy 2822-1200 brushless outrunner
                                      Propeller type:             Graupner 3 blade black plastic conventional (rounded blades)
                                      Propeller diameter:       50mm
                                      Gearing:                      No gearing
                                      Battery:                      LiPo – Turnigy 2S 30C 4000mAh hard case 4mm gold connectors
                                      Running time:              Not yet verified but setup pulls 7.00A max so 34mins at full throttle all the time.  Allow max 80% capacity usage and 60% average for throttle and I would expect about 45mins

                                       

                                      #29012
                                      Colin Bishop
                                      Moderator
                                        @colinbishop34627
                                        Thank you for your contributions guys, the information is really useful and there are some superb photos too. Keep ’em coming.
                                         
                                        Colin
                                         
                                         
                                        #29017
                                        Laurent Gontier-Versailles
                                        Participant
                                          @laurentgontier-versailles47241

                                          Name    Proteus
                                          Type     cargo ship
                                          Kit         no kit here, fully scratchbuilt
                                          scale     1/100 
                                          Length   690 mm
                                          Breadth   95 mm
                                          Draught   45 mm 
                                          Weight   2 kg
                                          Number of props  1
                                          Motors   1 set from Graupner, reference 1147, with a Speed 280 motor & a reduction gear 2 to 1
                                          Prop type : Rivabo general purpose type, 4 blades, shaped to suit my model
                                          Prop diameter      35 mm
                                          Battery      Ni-Cd, 4.8 volts
                                           

                                           

                                          Regards,

                                           
                                          Laurent 

                                          Edited By Laurent Gontier-Versailles on 28/11/2010 22:27:30

                                          #29369
                                          Colin Bishop
                                          Moderator
                                            @colinbishop34627
                                            This topic seems to have come to a bit of a halt and I was hoping for a few more benchmark setups we can use.
                                             
                                            So, in the hope of getting a further response I am offering an Ektronix 2.4 Gigahertz 2 channel TX/RX combo as a prize.  See photo below.
                                             
                                            If we get at least 25 posts with the details I have requested then each post will be numbered and I will draw a winner. The more setups you post the more your chances of success!
                                             
                                            All existing posts will be eligible.
                                             
                                            Deadline will be 31st January.
                                             
                                            I look forward to your contributions!
                                             
                                            Colin
                                             

                                            #29371
                                            Guy Bagley 1
                                            Participant
                                              @guybagley1
                                              Name     ‘ LADY LOUISE’
                                              Type    NORTHUMBRIAN COBLE
                                              36 INCH COBLE HULL FROM ORION MOULDINGS
                                              Length   36 INCH
                                              Breadth   9 INCH
                                               
                                              Weight   7 KILOS
                                              Number of propellers   1
                                              Motor   MODEL MOTORS DIRECT 555
                                              Propeller type 3 bladed brass Raboesch
                                              Prop diameter 35 mm
                                              Direct drive,
                                              Battery    7.2 volt  4300 mah NiCad
                                              Duration  90 mins
                                               
                                              #29385
                                              Robin Lee
                                              Participant
                                                @robinlee31938
                                                Could not resist the lure Colin.
                                                 
                                                Boat Name: Z38
                                                Type: Destroyer
                                                Dean’s Marine Kit (much enhanced&nbsp 96:1
                                                Length: 1320mm
                                                Beam: 132mm
                                                Draught: 45mm
                                                Weight: 4.2Kg
                                                Number of propellers: 2
                                                Motors: Deans Marine Kondor
                                                Propeller type: 3 blade Caldercraft R3-B1
                                                Propeller diameter: 30mm
                                                Drive: direct
                                                Battery type: one for each motor 8.4 volt NmHi 3300mAh
                                                Running time: at least 2 hours at half throttle
                                                Performance: Due to twin rudders (somewhat overscale) very manouverable for this type of model. Speed is more than scale so would recommend using 7.2volts rather than 8.4 volt batteries. I am defining scale speed using the classic prototype speed divided by square root of the scale e.g 38knots divided by square root of 96 = 3.87knots
                                                 

                                                #29476
                                                Francis Macnaughton
                                                Participant
                                                  @francismacnaughton39461
                                                  Boat Name           HMS GLOUCESTER 1/32nd
                                                  Type:                  Modern RN destroyer
                                                  Scratchbuilt
                                                  Length (4400mm)
                                                  Beam (498mm)
                                                  Draught (120 mm)
                                                  Weight (about 130Kg) – over half of this is batteries or ballast
                                                  Number of propellers 2 
                                                  Motor(s) used. (Aqualisa 1/4 HP 24V water pump motors rewound to 24 turns 24 SWG)
                                                  Propeller type and description: i.e. Propshop 5 blade conventional
                                                  Propeller diameter  5 inch
                                                  Geared drive with 30:64 reduction using nylon gears
                                                  Battery type and capacity 2  32AH gel type lead acid.
                                                  Approximate average running time obtained.  Battery power sufficient to allow operating at full speed for about 75 minutes before performance starts to tail off.

                                                   
                                                  This model was built to break the Guinness World record for the distance travelled in 24 hours- achieved 121 .6 miles on 5 May 2002 which is believed to still hold.
                                                   
                                                  Speed controller is a resistance network progressively reduced in effect by a servo arm operating microswitches until the batteries are directly connected to the motor at full power.
                                                   
                                                  Model can do 8.3 feet per second with both motors drawing about 6 amps which is not scale full speed but is close to the maximum economical cruising speed as determined from the appropriate hydronamic formula.  See MMI November 2002 for more details.
                                                   

                                                  With Guinness certificate


                                                  Motor gearbox and shaft arrangement
                                                   
                                                  Motor controller
                                                   

                                                  Still working on addiing fittings!

                                                   

                                                  #29481
                                                  Francis Macnaughton
                                                  Participant
                                                    @francismacnaughton39461
                                                    LCT Mk5 1/72nd
                                                    Type:  Landing Craft Tank
                                                    Scratchbuilt
                                                    Length (460 mm)
                                                    Beam (130 mm)
                                                    Draught (13 mm)
                                                    Weight (0.55 Kg) Including 4 tanks!
                                                    Number of propellers 3
                                                    Motor(s) used. (Cheap mini motor FF-030PN similar torque to servo type)
                                                    Propeller type and description:  3 blade plastic from Airfix Vosper MTB conventional type
                                                    Propeller diameter approx 12mm .
                                                    Direct drive
                                                    Battery type and capacity 4 AAA .
                                                    Approximate average running time obtained – probably well in excess of 1 hour but not well suited to large open waters.

                                                     
                                                    2 channels used for speed control via servo PCBs
                                                     
                                                     
                                                     

                                                    Current props probably too small as rather slow and aiming to replace with larger size/steeper pitch but choice around this size is very limited!

                                                     

                                                    #29605
                                                    Tankerman
                                                    Participant
                                                      @tankerman
                                                      Colin, the following details are the set-up that I have used in my models for more than thirty years and have never found cause to alter them.
                                                       
                                                      Ship name: M.V.Ballyloran
                                                      Type: Motor Collier
                                                      Kit: No,scratch built – Jim Pottinger plan
                                                      Length: 1397mm
                                                      Beam: 216mm
                                                      Draught: 89mm
                                                      Weight: 16.4kg
                                                      No.of Props: 1
                                                      Motor: Decaperm Geared, 12Volt
                                                      Prop.type: 4 blade, merchant ship type, cast brass.
                                                      Prop.dia: 42mm
                                                      Geared: 2.75:1, integral with motor bedplate
                                                      Battery type: Sealed Lead-Acid 12Volt – 8Ah
                                                      Duration: Not known but in excess of three hours at scale speed
                                                      Performancecale speed at about half throttle with ample reserve for heavy weather

                                                       
                                                       
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