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Hi, I have recently purchased a Precedent KD Perkasa kit 37" and would like to power it with a brushless motor, but being an Old F**t I know nothing at all about Brushless Motors or their relevant speed controllers or battery power. So I would like your input on what exactly I need, obviously I would like the model to have a fair turn of speed. Thanking you in anticipation of your much needed assistance. Little Charlie
This build is proving to be much more difficult than I had expected. 😤 I think I started this project thinking that all of the parts were ready to fit and glue. As I went on, it became clear that this is not the case. Due to this, and as detailed in the earlier post, I have had to break down the glue joints of the hull frame, and reposition after deepening some of the assembly slots. I have re-assembled the bulkheads, stringers etc. and then started to fit the side skins. This has proven to be the most difficult task so far. You need six arms. After several failures, removal of all of the fixing tape and then starting again, they finally started to look reasonable. I watched a time lapse video on you tube and he seems to do it fairly easily. Oh well. 🤔 Now that I was happy with the fit of the sides, it was time to start on the bottom skins. I started by trying to form chamfers along the keel centre joints so that they look reasonable. Then I once again applied tape to hold them in position whilst glueing with my other three hands, I wish. This only took two attempts. I must be getting better. I still have most of my hair also. Next, I tried to mount the motors onto the angled bulkhead. The front location was very loose so I made a couple of thin silver steel rings to improve the fit. They work very well. 😊 Next job was to fit and align the prop shafts. I decided to make these solid joints and avoid the use of universal joints. The first motor went straight on with perfect shaft alignment. The second was not so good. After two hours of fiddling with a packer, I finally achieved perfect alignment. Next job was to give good joint strength and make the hull water tight. Rightly or wrongly I use a lot of glue to give that perfect seal. I used epoxy for all of the skin inner joints and Stabilit for the outer seams and joints. I used the Stabilit around the shafts as well which looks a little messy at the moment, but I will tidy all of this up next. I will paint the inner Stabilit with white paint to hide a little. This weekend I will do a water test to ensure it is water tight.😱 I think after that I will fit all of the electrics, servo and speed controller. Then I will spray the hull and the main deck prior to fixing together. I would be interested to know what others think about when to paint, before or after assembly, especialy regarding the hull. Enough for now.🤐 I will try to speed up the build a bit now as I am expecting the new 46" Crash Tender to arrive soon. Wood!!! Love it.😊
Hi TJ, RE: RX battery. Any 4 or 5 cell (4.8 or 6V) NiMh of 1000mAh up will do. Use the biggest one you can without upsetting the boat's trim or reducing it's performance / planing etc. BUT: don't forget to disconnect the red wires between your ESCs and RX to disconnect the BECs in the mTroniks speed controllers!!! Also check that your RX and mixer module etc can handle 6V+! If not use the 4 cell pack. A fully charged NiMh will be significantly above 6V. Some modules; e.g. Action Electronics / Component Shop don't like that 😡 Alternatives are, esp if you need to save weight, 1 use ONE of the red BEC leads from ESC to RX, e.g. the centre one, and disconnect the other two, 2 Use a separate 5V UBEC module to syphon power off the drive battery for the RX, AND disconnect all three red BEC wires from the ESCs. Cheers, Doug 😎
Actually 4 pole , "Graupner HPD 2920-4000 High-end brushless motor Particularly suitable for: MiniMono, MiniHydro, MiniCats, MiniHydroplanes, aircraft with wingspan up to 1 m, off-road and on-road 1:12 Features ?Special CNC-machined housing for maximum heat dissipation ?High-efficiency 4-pole 12-slot brushless motor ?High-performance rotor with Kevlar reinforcement ?High-purity copper coils for optimised conductivity ?Extremely strong sintered neodymium magnets ?Intense torque at low weight Specification Operating voltage range : 4,2-16,8 V No-load speed: 29600 U/min All-up weight, approx. : 90 g Free shaft length: 10 mm Recommended controller: Navy V75 G7257 Output : 650 W Number of poles: 4 Permissible motor direction : R und L Nominal voltage: 7,4 V Case length: 30 mm Shaft diameter: 4 mm Case diameter: 29 mm Revolutions/Volt: 4000 " Taken from one Google, first response at Cornwall Models Boats!😉 Note. 650W, Nominal voltage 7.4V. No wonder it's a bit quick on 11.1V 😲 Cheers, Doug 😎
Hi I have just read your post about your tug, I am one of those who modified mine to two new motors:- A. Because the original gear box nylon pinion gears split and there was no way that one could get them to fix securely back on to the motor shaft, plus the fact that when initially refitted they would no longer mesh and if the motors stopped at the wrong point they would not restart they just jammed. B. I wanted to make the tug more manoeuvrable so fitted separate speed controllers to each motor enabling me to run one motor forward and one in reverse this with suitable rudder positioning allows the tug to rotate on its axis with very little forward or reverse motion. C. I was able to use a 6v 4Ah Gel type battery which gives a much greater runtime. As to the old gearbox I think that because the gears were split it was disposed of. Somewhere in my harbour here there should be some photo’s of the conversion. I am now using speed 300 motors with a 2.5:1 reduction position much further forward in the hull an I made extension shafts to the original fitted ones, and it all works. Hope this helps and perhaps explained the need to change the original setup. Graham
Hi Martin, BEC is the Battery Eliminator Circuit built into an Electronic Speed Controller. UBEC is a Universal BEC which takes power from the main (drive) battery and supplies 5V or 6v to the receiver. It can be a linear device. SBEC does the same job as a UBEC but is a so called Switched device which is more efficient than a linear. So functionally for our purposes there is no difference. Alles klar Herr Kommissar!? 😉 Cheers, Doug 😎
[Score: 5/10] 20"/600g Elke HF 408 Capable of 2mph Single Propellor (3 Blade) Direct Drive to a 6v (3 Blade) Powered by NiMH (7.2v) Batteries - Comments: This is a restoration project - my first radio control boat 'Elke', is a small fishing boat with plastic hull, a Graupner kit, purchased in Germany when I was serving in the Army there in 1974. I am restoring it for my grandson. It used to be a good runner with a 6v battery, small electric motor, two servos, one wired so it could move boat in reverse as well as forward. A good little sailor, light in weight and a good pond model. Had to be careful of wave height. Anyway, it has been in the garage for 40 years now so much to do. The inside is a bit of a mess and everything has a layer of dust. I will fit a speed controller and NiMH battery. But nothing too difficult so hope to have it finished for Christmas.
Correction on details of Hydro. Gordon tells me the boat is Japanese from the 1980's made by Gunze Sangyo . It has the original Mabuchi motor and mechanical speed wiper controller [gets very hot ! ] . The hull is fine glass fibre not plastic.
Guys advice please. Speed controllers for my boat , viper too expensive alternatives please for the johnson 600 motors please. I’m pulling my hair out trying not to have todown grade motors. Regards Terry Nobby
Doug, The 6volt battery is currently an NiMh battery not an SLA. The problem was that according to Mtroniks the minimum voltage to the ESC to adequately run the BEC connection is 6volts. That is why I was getting erratic control when the battery voltage was 5.6 volts. The action speed controller will work 2-12 volts and I am going to use a separate receiver battery as suggested by Dave Milbourn just to make sure. Regards Will
Help required please, I have two Graupner Jumbo 540 6volt motors in an eboat circa 1978, I had fitted an Mtroniks speed controller replacing the Bob's board only to find that when the voltage dropped below 6 volts down to 5.6 volts I was experiencing intermittent operation of the esc. I have been informed by Mtroniks that the minimum voltage for operation of the esc is 6volts. Graupner have also confirmed that the maximum voltage for the Jumbo 540 motors is 6 volts. Do I have any alternatives other than refitting the Bob's board?
[Score: 8/10] Capable of 6mph and a runtime of 60mins Single Propellor (3 Blade 25mm) Direct Drive to a 380 (3 Blade) Powered by NiMH (6v) 3Amp/h Batteries Controlled Through Mtronik 15 amp (5Amps) ESC - Comments: The boat is a Graupner kit from the late 1970s and has recently been updated with new Spektrum radio tx and Mtronik speed controller. and
Guys, hi I came down to hartsholme today to trial run the build and was made extremely welcome thanks greatly. Er motor widthThe motors are T4A from mobile marine they were extremely hot so prop size adjustment is needed. I am building again this time an inshore mine sweeper I have 50 mm graupner props on at the moment and am looking for a pair of motors to run off 12v LAB with 15 amp speed controllers per motor but cooler with out going to big I have 50mm per motor width allowance and 70mm length. I would like to keep up speed as inshore sweepers were fairly nippy 20knots real time. Is there any recommendations please ,apart from rebuild again. Regards Nobby
Hi Doug, I dread to think what a Proxxon version of a Jacobs chuck would run to. They seem to be outrageously expensive things. I only have a Proxxon drill because it was on a deal too good to miss, but the electronic speed controller went nappoo after a few weeks, so I cut it out and wired it direct, so it's flat out all the time. Having said that it has tolerated that for literally years since. I also use the Proxxon transformer to power my other mini tools, which are all the much missed and very reasonably priced Mini(Maxi)craft stuff. I have a circular saw, orbital sander and disc sander and all are plugged into the Proxxon power box when required. The circular saw must have cut miles of deck planking by now! Cheers, Martin