Motor and Prop Survey 2020 Update

[Colin BishopModerator @colinbishop34627]

Article in forthcoming Special Issue oif Model Boats

[Colin BishopModerator @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

[Robin LeeParticipant @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

[Colin BishopModerator @colinbishop34627]

That’s great Robin, exactly what I am looking for.

 

Colin

[Robin LeeParticipant @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:

 

[Mark Beard 1Participant @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.

[Francis MacnaughtonParticipant @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

[Gareth JonesParticipant @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

[Gareth JonesParticipant @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

[Gareth JonesParticipant @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)

[Colin BishopModerator @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

[Gareth JonesParticipant @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

[Gareth JonesParticipant @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.

 

 

 

[Queequeg QuintParticipant @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.

[Queequeg QuintParticipant @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!

 

 

[Queequeg QuintParticipant @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!!!

 

 

 

[RedPandaParticipant @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

 

[Colin BishopModerator @colinbishop34627]

Thank you for your contributions guys, the information is really useful and there are some superb photos too. Keep ’em coming.

 

Colin

 

 

[Laurent Gontier-VersaillesParticipant @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

[Colin BishopModerator @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

 

[Guy Bagley 1Participant @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

 

http://img508.imageshack.us/i/dscn2503s.jpg/

[Robin LeeParticipant @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

 

[Francis MacnaughtonParticipant @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!

 

[Francis MacnaughtonParticipant @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!

 

[TankermanParticipant @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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