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Hi, I can't profess to be a Tug expert but I believe the general rule is 'Low revs & Hi Torque'. I hope one of the tug fans here will pick up this thread. Also this forum might be useful to you; a discussion on kort nozzles & tugs 'Fixed or steerable'. https://www.rcgroups.com/forums/showthread.php?1536288-Steer... Good luck, let us know how it goes. Cheers Doug 😎
I recently bought a on Ebay 'stranded' vintage harbourtug which will be fully rebuild. (I actually bought a NOS hull, and old - but good build - superstructure and all the deckgear & fittings. Except for some essential parts... There's no kortnozzle/rudder and propellor. I would like to know what size of nozzle and propdiameter I should mount. Originally it was designed with a steering nozzle/rudder, but the only item which comes close is the fixed nozzle as used on the Robbe Happy Hunter salvage tug model.(which has twin nozzles) That nozzle would be fixed with a seperate rudder for steering. What would you advise? What alternatives are available? (Making a proper nozzle myself which actually works and looks to scale is out of the question.) Attached three photos: one showing original (steering nozzle) and teh other with this Happy Hunter fixed nozzle, and te drawing showing the design.
Scratch Built 1:32 scale Dover Harbour Board Tug, DHB Doughty. The main hull is a standard Damen hull purchased from Mobile Marine Models, see their website for Portgarth. the hull is fitted with 2 x T12 Motors for the main propulsion,2 x 60 degree kort nozzles for steering, with 2 x purpose made brass props. Also fitted is a 12v Graupner water pump for the working fire monitor and Fwd spray bar, 2 x Mtronks 15 amp ESC's, Futaba steering servo and Futaba 40 MHz Receiver. Approx Dimensions including fendering Loa 41" Beam 14"
[Score: 5/10] 31" Shell Pioneer Twin Propellors (4 Blade 35mm) Direct Drive to a 2x MFA940051LN (4 Blade) Powered by LiPoly (7.4v) 4Amp/h Batteries Controlled Through 3xViper 15A (5Amps) ESC - Comments: This is my first working RC build but here goes. A bit vauqe about the fiqures because we are still on the slipway. It is scratch built from the Phil Thomas drawing "Shell Pioneer" Twin prop with Kort nozzle steering, bow thruster, working fire monitors and lights. Throtle & steering control via Action Electronics P40E mixer. 2x 2S25C4000mA lipoly's. 6 Ch radio (4 used). draws around 4.5A hope to get 30min run time minimum. Third ESC for bow thruster.
Modified HegI Fairplay V tug built by My late Father. Mods include bigger 65mm Prop in a brass kort nozzle, working fire monitors, lights, radar, engine sound and grappling hooks to rescue nitro boats. Built 1980-81.
Alan you are right they are from another thread this was just a quick option I will try & get the trawler out later it is up in the garage loft & take some pictures for you, as I remember the motor was amidships to allow room for a 12v battery the servo horn is straight to the kort nozzle rudder arm pleased to help if I can Bob 👍
[Score: 10/10] 32" Al Khubar Capable of 7mph and a runtime of 90mins Geared Powered by Lead Acid (6v) 7Amp/h Batteries Controlled Through Action (10Amps) ESC - Comments: Built from the Model Slipway Kit. Very manouverable with twin steerable Kortz Nozzles.
I bought the hull from a friend who moulds them then built It from pictures I had taken of the actual boat In Blyth harbour It runs on a Graupner 700bb motor 12v battery Robbe Fixed Kort Nozzle with Rudder & 60 mm Propeller lights on a separate 6v battery & figures from Adrian Clutterbuck the ships cat was a stray
HI Barry & Mark Yes lack of knowledge of a particular model can make advice difficult. I have fitted kort nozzels to a couple of my tugs and I would advise using a template to ensure you get the nozzles absolutely central with the prop shaft. The Instructions with my Al Khubar suggested using a plasticard disk cut to the Inner diameter of the nozzle with a hole drilled In the centre to take the prop shaft (both need to be a tight fit). You can then attach the disc to the prop shaft and fix with nuts either side of the disc and align the propshaft to the nozzle. Try and make sure you get everything nice and square as the props should be a close fit, mine had a 1-2mm clearance all round. You may find that the hole In the hull needs to be widened to get the required result, mine certainly did, but you can use plastic padding to make good once finished. If I was doing another I think I would also test fit the motor to make sure of a nice straight drive chain. My Eldergarth had steerable nozzles so alignment Is more critical than for a fixed nozzle with rudder. Hopefully your plan shows the position of the prop relative to the rear of the nozzle as some props have an extension on the boss that might foul the rudder, I know from experience with my Al Khubar so I suggest you try your prop In position before you finally fix. Hope this will help Barry fit the Korts succesfully. Dave
Hello all. This Is a scratch built boat from a fiberglass bare hull that I purchased. The purpose of this build Is to give me a toy to play with at my cabin at Langdale BC. This Is on the ocean and many log tows go past here so there Is a scandalous amount of logs In the water that we burn as firewood on beach patio and our fireplace. The tug will be used to push these back to shore where I can reach them with a pipe pole, and hoist them up with my crane. The boat will be very crude In Its finishing, and have very little detail, and the "house" will only roughly represent the tug I am modelling It after. In fact I expect to place a handle on It so I can handle It like a suitcase. It Is 45" long and single screw (3.75" four blade prop) I am using a steerable Kort nozzle I built and has a rudder on the nozzle as well.
Hello Dave, and thanks for your help. The motor Is actually a MabuchI RS-755VC-4540 and Is rated 50 watts at nominal 18 volts, but available to operate at 9-32 volts. 18 volt loaded speed Is 7500 rpm, so I hope not to need all 18 volts to get the power I need. As I understand It, the loaded rpm will drop with proportionately with the volts, so a 9 volt pack would be 3750 rpm, for a final speed of 1500 rpm. 12 volts then would be a final full speed of 2000 rpm. This still seems high to me but perhaps as we scale down things speed up? Yes very much want good "very slow" performance, so I think I will go with this brush motor package, and see how It goes. Does 12 volts sound like a good place to start? Motor stall current at 18 volts Is 22 amps, (full load Is 4) and I suspect that as the volts used drop, the amps drop faster, so I suspect that at 12 volts, a 30 amp speed controller would be lots?. By the way, my stern tube Is fully submerged and well below my waterline at both ends as I wanted the thrust to be In line with the boat. My stern tube has no seal, just a brass bushing on each end. Being salt water I want things pretty tight so am considering taking out the bushing on one end and replacing It with one I machine, that gets bigger on the motor end and has a machined area such that I can fit a 1/4" X 1/2" double lip seal for positive sealing. Fill the rest of the tube with waterproof grease mixed with some oil so It does not get too thick? Futaba 4 channel radio the "go to" radio? I would like a non returning stick for fast and slow, as well as non returning (not sprung back to middle) for the steering as when pushing objects, one often has the steering off center for quite a length of time. I tried to add a picture of the nozzle, but so far It does not look to have worked. Also wanted to show a picture of the keel and "Jaws" on the bow. The keel Is 1" thick X 3/4" stanless steel bar, and acts as a shoe for the Kort nozzle. At the bow the jaws are this same stanless steel bar, but with angled jaws ground Into It so one can "dig In" to a log and push It for the end or side. Thanks again for your thoughtful reply. Steve
Hello folks. I have a 15 year old, 44.5 Inch fiberglass bare tugboat hull, and marabouchI 4540 brush motor that has a very nice enclosed 2.5/1 reduction gear and 3 3/4" four blade propeller. I have machined a Kort nozzle from rotocast bronze. I plan to use lots and lots of batteries as I need ballast anyways, and want a good long run time. The tug will be for play, but will also be used to go out and push In logs to the shore, where have a crane that I can then lift them up for cutting Into firewood. (Salt water) So I wonder If I should swap this motor for a brushless? I would like to use a very large motor and not run It as hard, so the model Is powerfull enough for pushing 1000 lb logs around. Also just not all that Interested In changing brushes and overheating problems. Also would like as low a speed shaft speed as Is reasonable. So buy a very large motor and feed It lower volts? Get lower shaft speeds too? Is this 50 watt 4540 plenty of motor, that will last quite a long time and I should not change anything? Batteries,.... I don't want to have to be a battery expert, leave them In the correct state of charge, or have a masters degree In battery charging. Need weight anyways, so what battery should I be using? Speed controller? Need a special one for brushless, and I don't have any gear yet so I would like to get what will work best, even If that means sticking with the brush motor. Cost Is less an Issue. Thanks for any help you might have. Steve
Building a model of this anchor handling/ rig support vessel. Having difficulty In determining how the stern and the Kort nozzle support bracketry Is shaped and Installed. Has anybody and photos or sketches showing these arrangements? Thanks