Blog

WWII Italian MAS 562

Skinned the frames added deck and splash rail also started on cabin and superstructure, added rudder and installed twin brushed Graupner 600 motors via Graupner style direct couplings. Motor mounting system through a bulkhead gives extra support to motors which mount on to end of the shafts. currently adding a rudder servo mount, as rudder is a close copy of the real boat's and still functional.

6 years ago by CB90

Blog

Command Boat 90

Scratch built at 12th scale from pictures and profiles of the internet. The boat was originally built in Sweden a class of fast military assault craft originally developed for the Swedish Navy by Dockstavarvet Speed: 40 knots (74 km/h) Draught: 0.8 m (2 ft 7 in) Length: 15.9 m (52 ft) Overall; 14.9 (48') Complement: 3 (two officers and one engineer); Up to 21 amphibious troops with full equipment Armament: 3 × Browning M2HB machine guns; 1 × Mk 19 grenade launcher; 4 naval mines or 6 depth charges . The Model I was attracted to this boat due to its great performance and maneuverability, this was mainly due to the use of twin water jets as the main propulsion, this is a trade off with efficiency. So my start point was to collect as much information as possible about the boat this involved collecting pictures and profiles of the craft from various sources. http://www.dockstavarvet.se/products/combat-and-patrol-boats/combat-boat-90-h/specification/ Eventually I found some plans of sort :- http://laurell.today/boats/combat/plans.html My Dad was a boat builder in the days of wooden yachts, and had showed me how to make plans and frames from a line drawing. I went about this first by creating a prototype about 24 in long out of light ply. I then created full size plans of the model to be made. Pictures of small prototype finally painted plain green. The Main model Used my computer to print out the frames onto paper, cut them out and used them as templates for the ply ribs. The construction was simple chine style, with 1.5 mm ply. I tried to build jet drives but failed to produce a effective unit. So reverted to propshafts which worked out well with better control and the boat can spin on it own axis by putting one engine in reverse the other in forward and adjusting the s. That it for now, hope it was of some interest

6 years ago by CB90

Forum

RC circuit

Am considering changing my Dumas pushboat San Pedro from single motor control to twin control to improve manueverability. I also plan on installing flanking rudders at the same time. I am going for a 6 channel transceiver setup. Have not been able to find any diagrams for what is needed or wiring involved. Any assistance would be gratefully appreciated!

5 years ago by Mariner85

Directory

(Fire Boat) Fireboat

Recently acquired Fireboat that needs refurbishment. Existing loose single shaft removed and twin shafts and rudders fitted. To fitted with twin (possibly brushless) motors, each with its own battery and controller. Updates to follow. (5/10)

5 years ago by Welshsailor

Forum

de Mist Naval Tug

Thanks for info Doug. Unfortunately several of the websites get error messages or have dropped access to the address. I think the Sturrock plans route seems to be the way to go (a pricey plan though for our horrendous currency exchange rate!) and was the source of the Ralph Wilmot model. Looking at some of the pics of the rudder layout when she was on the hard pending being put into the Maritime Museum, she had twin props and s...Sturrock didn't have s so obviously was built to the Sturrock plan. I have sent off a few emails and await any further guidance/info before I make any decisions. Thanks Glyn re Durban Club. I have mailed a member too.

5 years ago by Joburg-sailor

Response

BRAVE BORDERER

Hi I once saw a boat called a Telectra perform . Hard chine hull nothing unusual. This planed as flat as a pan cake even in fast turns . it was unusual in having a central single screw close to the transom but with s mounted as far away from the prop as possible . So no propwash over the rudder Cheers Ian

5 years ago by TOWN3810

Response

HMS BRAVE BORDERER

Rowen, here are a couple of things that may be of use to you (and others). The battery alarm will save you worrying about running out of steam as they can be set to beep at varying voltages to warn you of low battery, just put one on each batt balance lead and when one goes off (when an individual cell drops below the set voltage) it means start heading back. These can be picked up on Ebay for a few dollars. I use them on my planes as well and are audable from around 100m (these twin horns are the best) Secondly, re your ESC switches, these electronic switches (AliExpress) are great for this sort of thing (as long as you have enough aux switches on TX ) You can link them with a Y cable to work together or use them independantly for anything, (lights, pumps etc, - they can be operated by TX rotary switches as well) The ESC and 2000kv motor (HK) are the ones I am using in my ASR model and will work smoothly down to a crawl, the purple 1980 kv seems to have superseded these but I think they will be as good. The props are from Ali Express and are resin and available in L and R hand, are only a few bucks and perform perfectly while looking quite scale(ish). I painted them with an acrylic bronze which seems to have stayed on pretty well. Model weighs 2.8kg and will run at more than 10mph flat out with this set-up (using the 26mm L+R) props) which is silly speed and that's with 2x 2s 2200mah lipos (which will last till you get sick of it and still have 60% left) I was just looking at your Daman set-up and noticed the wiring method from the batts to the ESCs. You might want to make your batt to ESC connections direct to your ESCs (as per original ESC lead length)as your capacitors may get a thrashing (spikes) due to the extra length/ resistance you have there. There is a general rule that you don't lengthen the batt to ESC wiring without adding a 220mf capacitor of same voltage as the ESC for every 4"of extra wire length (ESC to motor - not so much). Might want to check this out in case you fry your ESCs You probably have thought of this but thought I'd mention it, 'just in case' Might help with your modulation as well. Have chucked in a vid of the HSL manouvering (first trials so wasn't perfect) and also the MTB (brushed) which I have just converted to a twin system (was twin but single Electronize unit) plus a sound unit. You may know that you can use as many RECs (bound to the same TX) for various purposes on the same boat (have run 2 boats together from the same TX) Might get you round the mixed brushless/ brushed problem with a bit of thought. Have you thought of changing your old HK silver 6DF TX to twin throttles, it's a piece of cake(as is the TGY 6x), just remove the aileron/rudder centering spring and make a friction plate as per throttle stick, and use the elevator channel as your other throttle. Set your ESCs and you can then use a twin system giving you perfect control. Saves a lot of hassle.

5 years ago by jbkiwi

Directory

(Other) A577

This model belongs to a friend of mine who had this in his attic where it got damaged and its condition deteriorated, he asked me if I would refurbish it. This is a static model and I have submitted this to help to show the variety of craft that the RAF Marine Branch operated in the 68 years of its existence. The Armoured Target Boat was the brainchild of the Air Ministry's "I've had a good idea" Department. The requirement was for a target boat that could be bombed from the air with practice bombs. The 40ft Armoured Target Boats were developed from the slightly smaller 37.5ft ATBs which had been designed by Scott-Paine and others at British Power Boat in 1932. A couple of years later, in 1934, whilst bringing the first of the 64ft HSLs into service, it was realised by the Air Ministry that the condition of the aircraft had been advancing and that it was necessary to provide additional protection to improve the first type of Armoured Target Boats (the 37.5ft type). T.E. Shaw suggested to Scott-Paine that he should increase the length of the 37.5ft type to 40ft and fit s. in addition the Air Ministry prepared a new armour plating arrangement which gave separate protection for the crew and engines and coxswain. There was a further alteration to the forward bulkhead which resulted in it being changed to vertical instead of raked fore and aft to overcome the new conditions for bombing. A long series of trials were carried out with the ballast with the 40ft type launch and eventually it was approved. The 40ft thus became the standard type Armoured Target Boat (ATB). The first batch of 15 craft of the 40ft type were ordered in 1935 with further batches being ordered in 1936, 1937 and 1938. A further addition was the introduction of a 3rd engine, this helped to maintain a good speed on the ranges, and helped to counterbalance the the boat as it had been found that in a tight turn the 37.5ft ATB had a tendency to roll over. (5/10)

6 years ago by colindavies

Response

BRAVE BORDERER - BRUSHLESS SUMMARY

The only thing you might have to watch out for is back feed from the pump out the aux tube (when moving) if you don't set up the y joints (must be y not T ) to create a venturi effect from the pump side. Doesn't matter standing still but at speed a T junction might reduce the flow as the flows will be fighting each other slightly. The beauty of the twin system is that if you are running a lot at high speed you could turn the pump off to save power. The best place to position water intakes is I have found is directly behind the prop (I usually just squash the brass tube slightly, fair it, cut it off at 45 deg and set it to just sit in the prop wash). At lower speeds especially, the prop will help to push water into the tubes rather than just relying on speed alone. Never had a problem with pickups interfering with rudder effectiveness as long as you fair the pickups nicely

6 years ago by jbkiwi

Response

Must get the skins on before I pull all of my hair out!!

Hi Pete, Basically yes. There are some other tricks with twin screws, not least engine assistance using a twin ESC with rudder mixer. Also the screw rotation makes a slight difference, and the rudders are usually slightly offset from the shafts, depending on the screw rotation. Are yours turning outwards or inwards? Referred to the top of the screw looking from aft while going forward. Cheers, Doug

6 years ago by RNinMunich

Response

Must get the skins on before I pull all of my hair out!!

Thanks Doug. Does this apply to s also. Thanks.😊

6 years ago by MouldBuilder

Response

Must get the skins on before I pull all of my hair out!!

Is there a correct angle, plus and minus of centre, that a rudder should move. If there is a norm, is this the same for s or is there a different set of rules.🤓 Thanks.😊

6 years ago by MouldBuilder

Response

Friday's Child Fairey Huntsman 31

They are a great looking craft, I am restoring one myself, please be aware that red paint may contain lead, so wear a mask while sanding. My restoration is of a old Fibre glass hull I intend to install s and motor shafts and go brushless, I am building the superstructure from scratch with some help from old plans. I want to have a swordsman type cabin.

6 years ago by CB90

Directory

(Working Vessel) Cygnus Revenge 38

Models by design Cygnus Revenge 38. Made strong to tow lures. Twin screw, twin esc, . Nice speed on the water, not excessive! and very stable in chop. (Motor: 800) (ESC: Mtroniks 40 x2) (8/10)

6 years ago by Bucaneer16

Response

BRAVE BORDERER

Starting a bit backwards here as have posted more recently with some ideas. if you are going to have a twin brushless system using 1 REC, you probably should have twin 2200Mah 2s lipos, a power lead (I use a JST plug set) taken from the input leads of ONE ESC (not the batt leads) (I break into them and solder the JST leads on ) run those to a UBEC and then to your REC switch then to your receiver. if your ESCs have a built in BEC, withdraw the red power wires from the BEC receiver plugs and tape them back as you now don't need the power from these. if your TX is 2 stick 4/6ch etc and is capable of being changed to 2 throttle sticks (provision for ratchet strip - copy if necessary - on opposite gimbal - ie using set up as mode 1&2 throttle) you can use the existing throttle and elevator stick to give full independent control with either rudder or aileron Ch for rudder. The Chinese ESCs I use have a power switch as well as BECs which is handy. I would keep the brushed system separate from the brushless altogether with its own battery (or try power from the other batt as described above) otherwise you may be trying to mix 3 phase and single phase at some point. if you are using 2.4 you could use another paired 3ch receiver (does work, as mentioned in my later post) to only run the brushless throttle from a rotary sw on your TX (if you have that )

6 years ago by jbkiwi

Forum

three model live steam boats for sale

Only the open deck boat for sale now, fitted with a Wilesco d46 boiler and twin cylinder engine. Servos for speed and rudder. This boat runs on gas from a small gas cylinder which gives around 15 to 20 mins running. Looking for £170 collection only. Some people have asked about a boiler test and I have looked into this as I will never understand why it needs one, 19psi, there is more pressure in a coke can. Anyway to get a test it needs a pressure test. Or just buy a new boiler off eBay for £55 pounds. This is collection only from Yeovil

6 years ago by terry1956

Response

Range Safety Launch?

I agree Donnie, I did just that (turning inwards seen from behind for moving ahead) on my twin screw single rudder destroyer. it made it much more responsive to the helm😉 Same with my long thin U26 Type 1A U-Boat. I am making the same changes to my Belfast cruiser, 4 screws, and the Graf Spee, twin screw. Both with single rudder. On my twin screw / PTB they turn outwards. Cheers, Doug 😎

6 years ago by RNinMunich

Directory

(Naval Ship) Battleship Missouri

Modified Sterling model kit, scale drive 4 shafts. s, smoke and cannon sound module. (Motor: 6 volt) (ESC: Hitech) (5/10)

6 years ago by Mikep

Forum

RE ads90's Vosper Firefloat

Hi Neil, Looks like a somewhat simplified Range Safety Launch to me, the 43ft version from 1955 - , but the number is dead wrong. http://www.rafboats.co.uk/rsl43.html Scale between around 11 - 12 to 1. LoA - 11.7 Beam - 11.1! Twin props should ALWAYS turn in opposite directions to counteract the so called prop walk which otherwise shifts the stern sideways in the direction the props are turning - seen from behind when the boat is moving forward. the jury is still out on whether they should turn outwards or inwards; with respect to the top of the prop when going forwards and seen from behind. Separate motor control (so called 'Tank Steering') is great for slow speed manoeuvrability and very sharp turns at speed (to be used with caution!), but is not easy and needs a lot of practice! A twin ESC / Rudder Mixer is easier😉 For scale; 3 blade props. Suggest you start a new thread for this. Ciao, Doug 😎

6 years ago by RNinMunich

Forum

What do you do when...

Its possible we have all had this issue.. boat in the middle of the pond not working, I used one of the other boats I have to retrieve it, not very easy.. I am thinking of building a rescue vessel, square(ish) front, twin prop's and rudders tucked out the way for reversing and with soft rubber edging all around it to push or even guide (if damaged rudder) any boat back to shore.. or is this going a bit far?.. your thoughts or what you do when or if this happens when your out on the pond?

6 years ago by Steve-Teresa

Forum

Warped wood

Hi John, yep, as mentioned above I know them and have some of their modules. Sonar sound (pinger) for my destroyer, twin ESC with rudder mixer, will probably also go in the destroyer. With a 12:1 LoA to beam ratio she needs all the help she can get for a sharp turn 😉 Delivered pronto to Munich as well 😊 Well made and highly recommendable 👍 Their documentation is also superb, 5 stars! Phew, just finished stripping the PTB hull, now I've got two hulls to sand, seal, strengthen and paint! All go folks 😁 Cheers all, Doug 😎

6 years ago by RNinMunich

Forum

LED Tug Mast Navigation Lights

Afternoon Pete, Not awesome 😉 just 'Been there - Done that'! Albeit on older versions. So; now we're getting somewhere. Good idea with the connector 👍 I plan to do that with mine as well. I took it apart to investigate adding smoke, lights and sound. And possibly a twin ESC rudder mixer. Project got shelved when I got deeply involved by a couple of renovation / conversion jobs. 🤔 You've inspired me to bump her up the 'To Do List' a ways 😉 Now we should be able to trace the wires back to the circuit board😊 Will send a Step by Step procedure tonight. Gotta go fix a rotten fence now 😡 Cheers Doug 😎 PS: I was also impressed with the quality and fit of the mouldings. Good tooling 👍 PPS: You may find this thread useful https://model-boats.com/builds/view/34234?goto=34235 Neil has also been down a similar road. 'Jarvo' as well, who came up with some useful tips, esp re locations of hidden screws😉

6 years ago by RNinMunich

Blog

Scudder

Vic Smeed plans of a rather ugly twin pontoon hydroplane air driven. Runs a 35 ic but will have a brushless 300w turning a 8x6 electric pusher. Water rudder pivot fwd of prop thrust line. Photo shows most of the detail with styrofoam flotation built in

6 years ago by Grumpy1949

Forum

Any clues?

"This is certainly NOThe the model of a Thames or Coastal barge hull" I had come to that conclusion. Researching typical twin masted vessels with that sort of beam (thereby ruling out most schooners) it could be a Brixham Trawler or some kind of ketch. One suggestion was a Moray Firth Scaffie but I need to go to one of the local museums to see if there is a model or a drawing. Interesting clue - the rudder post is carried above the deck. I guess half the fun is trying to see what I can make of it and then get it on the water.

6 years ago by aanside

Blog

H.M.S. BRAVE BORDERER

Just to clarify. Shipping was only 7 days to Canada, manufacture slightly longer. Examined the hull closely and was pleased. it is dimensionally accurate and robust, but light. it had also been reinforced in strategic areas and trimmed to the correct deck line. My many questions to Christian Sheppard – Capurro of MTBHulls were quickly and knowledgeably answered. A company I would recommend others. Reviewing the build blogs and U Tube videos of the both the Brave and Perkasa models, shows most use either single or twin screws. The original vessel had a triple screw contra - rotating layout. Experience from others suggests the third screw just adds weight and complexity, but little to the performance. Nevertheless, it was how the Braves were built, so that was how it would be. Christian gave several suggestions for other modelers who have built this vessel. Contacted them and was readily provided with information and advice. The finished weight of this model is important and a target of around 6 lbs recommended for a 1:32 scale version. This is to achieve the potential performance. Plans for drivetrain are 3 x 2835 4500kVa brushless motors, direct driving 3 x scale 3 blade 30mm screws. Decided use a single Li-Po battery for the best performance with minimum weight. It was suggested three batteries, each powering a single motor would be the best layout. After some research, concluded this would introduce a weight penalty and was discounted. There are various ideas for the best drivetrain. Unfortunately none for triple screws. Decided the best approach would be to fit the bare hull out as planned, then try it. Leaving all the finishing features for later. A contact in Australia had already done this using a single screw layout and kindly sent pictures of his hull layout and then under test. Very informative. The positions of the rudders, propellers and shafts are established by the scale dimensions and were permanently installed. Everything else was to be temporarily fitted, so it could be moved or replaced if necessary.

6 years ago by Rowen

Response

British Air Sea Rescue Launch

Hi I also went and got this model, that would have been about 18 month's ago, I have still not finished it. Could not get anything to fit right, so in the end I just went for it, along with twin props, 😱 just hope that it will work O.K. FRED

6 years ago by Fred

Forum

Graupner ranzow refitting

here we have some pics of the electrics as requested the first pic is of the mtronic 650 motors for main drive. second pic is of the control. the third pic is of the water proof voltage dropper and connections for 5v power supply to some of the aux, Ron

6 years ago by kmbcsecretary

Directory

(Racing Boat) Interceptor

Zoom 1 (Interceptor) Mono boat. Built from a Glassfibre hull, brought on Ebay for £35 the hull is a slim mono racing type with a self-righting side cabin it runs a 1400W 14V 2958 4200KV Brushless Motor and 29-S Water Cooling Jacket with additional air cooling fan. I did not want to use a flexi drive as high maintenance and prone to failure so the shaft runs via two universal joint one at each end. the propeller is a 38mm copper alloy The ESC is a 200A and water cooled the s supply separate water one for the motor and one for the ESC. The rudder are positioned to reduce prop-walk and are hinged to prevent damage if hit a object in the water and ride adjustment. Turn fins and trim tabs for ride adjustment were provided by a spares kit for another boat. also foamed and added an inner sealed hatch, a rubber bump strip and safety loop. The Boat is fast and over-powered used at half throttle, may use a 7.4v lipo instead, the self righting works well. 20th April 2018 while running on 11.1v the boat stopped, no response on retrieval it was found that the manufacturers battery connector had melted and the connection lost see later pictures. the battery was made by FLOUREON and was a 35C with 5500mah capacity the 80A fuse had not blown. (Motor: 2958 watercooled) (ESC: Unknown 200A) (8/10)

6 years ago by CB90

Forum

THE VOSPER 46'' CRASH TENDER KIT BY VINTAGE MODEL WORKS

Currently building this kit but would like to fit it with twin props. Does anyone have the hull measurements for the prop shafts exits and the rudders.

6 years ago by VOSPER21

Forum

THE VOSPER 46'' CRASH TENDER KIT BY VINTAGE MODEL WORKS

Hi Vosper21 Welcome to the forum. I put a single motor, shaft and rudder in my fireboat so I don't have any first hand experience of a twin drive system but I would think that the shafts should exit the hull at the same points as the single shaft but equidistant from the keel. Similarly the rudders should be directly behind each prop. There are members on this site that have done a twin drive system on the 46" model that can offer more informed guidance, hopefully they will chip in with some good advice. Over to you chaps ! Please consider doing a build blog to document your progress. Good luck with the build. Robbob.

6 years ago by robbob

Forum

Flyer 15, racing hydroplane

thank you boaty thought i might put small twin brushless motor and use a mixer to save trying to fit a rudder.

6 years ago by BigAlio

Media

SRN 4

An old favourite from my hovercraft phase. Runs really well on land and especially water. Although no reverse, it will auto-rotate on the hover, so when pointing in the desired direction on with the propulsion with the brushless motor and away she flies. Realistic in operation. Looking a bit work worn now. Could do with up-dating with Lipo batteries which would make it even lighter. Seen here with lift motor running with skirt inflated. Steering interesting, with twin air rudders. Must get some videos of the action.

6 years ago by Gascoigne

Forum

Fairey Huntsman & Swordsman

I dont uses mixes, but do use exponential and rates (spektrum dx6i) with my twin screw brushless 4 foot fireboat. When at speed rates on, then it turns nicer, no roll, when going slow rates off so turns are sharper, if that makes sense. Mixing the throttles.. interesting not thought of that, but it will lose power/speed. We use mixing on planes for taxiing, particularly on water, but once airborne its off. My avatar has this as the cheapo motors just wont balance so it compensates for this on the water. With the boat its easier to control with rudder input. I like the thinking though!😁

6 years ago by pmdevlin

Forum

Fairey Huntsman & Swordsman

Does any one have experience of models with twin motors in the Fairey Huntsman and Swordsman? (Or any boat) Would like what size the model was - what motor(s) were used and prop sizes, and was there any 'mixing' of motor control with rudder control.

6 years ago by AndyG009

Forum

Airboat - one rudder?

From what I have seen of Airboats (including several in Florida many moons ago 🤔) two rudders are predominant. Offset s seem to be smaller, not so long front to back and single rudders huge and seem to have been used only on very early versions of airboats. Must be a reason why they evolved to slimmer s. My guess is better response with less braking effect and consequent loss of speed in turns and / or less effect from cross-winds. Whatever, have fun with it, but watch out for the alligators 😲😉 Cheers Doug 😎 PS can highly recommend a visit to an alligator farm 😲😲

6 years ago by RNinMunich

Forum

Airboat - one rudder?

I would have thought that, every thing else being the same, 2 rudders will probably, maybe, give twice the turning effort, possibly. Does the position of the rudder(s) in relation to the thrust of the prop affect the effectiveness of the rudder though? A single rudder immediately behind the centre line of the prop will have the max air flow at the top and bottom of the rudder blade, so presumably behaves differently to s on either side of the centre line where the max thrust would be in the central part of the blade. (I think!) The other option is of course suck it and see, and change it if needed. Hard to believe I know, but I am not an aerodynamicist! Chris

6 years ago by octman

Directory

(Working Vessel) Aeronaut Pilot LKBM 04

Took me 7 months to build. Has twin esc so I can control each prop individually, s, a sound system, horn, working anchor windlass, 4 individually controlled lighting setups (cab / dashboard lighting, navigation, pilot and search lights), spinning radar etc. She gets up well on a plane, probably a bit over powered! (Motor: Graupner 600 speed) (ESC: MTroniks) (9/10)

6 years ago by Skipper44

Response

The Vosper 46” RAF Crash Tender Kit By Vintage Model Works

Hi Mate and welcome to the forum, (mad as hatters!!!) I have built the 46" and before you get to far in you need to decide if your having single or twin motors, and rudders, that way you dont fall foul of bulkheads, and shaft mountings, mine has Graupner 700bb motors on 3s lipos, but i am up-grading them to brushless soon, have the new ESC,s and the motors are on order. Great model to build and sail, attracts a lot of attention. Mark

6 years ago by jarvo

Forum

Props

Hello Doug Thanks for all of the useful information and yes it is a 'Black Art' and I have been party to some heated debates regarding props on large passenger carrying boats. I was highly amused by the link to 'Raboesh' which if it wasn't a Chinese company should have been. The model I am building is a Rother class lifeboat which will have twin props and a single rudder and I have read that due to the limited swing of the rudder the turning circle of the boat is much improved by having independently powered motors. Not at that stage yet still early days of the build. Thanks again and best regards Chris G

6 years ago by ChrisG

Forum

Props

Hi Roy, Happy New Year 😉 Twin screw rotation is case of 'Horses for courses'! It's a Black Art and much depends on the hull shape, especially at the stern and the orientation of the rudders to the shaft lines. What you write is correct for slow, short fat displacement hulls, like tugs and rig supply ships etc needing good slow speed manoeuvrability. Especially those with one rudder per shaft. For long thin hulls (naval ships) and deep V and planing hulls (Fast launches and power boats etc) inboard turning screws are preferred to concentrate the thrust behind the centreline of the hull instead of dissipating it out into the open water. it also concentrates the thrust onto the rudder when only one rudder is fitted on the centreline. Outboard turning screws tend to push the stern up and bow down. inboard turning tends to suck the stern down and raise the bow. So making planing easier. You only made one mistake in your description: "when using the props to assist a turn, i.e one prop turning clockwise and the other anti-clockwise". The props turn in opposite directions when both are running ahead, or both astern. When turning, one ahead and one astern they then both turn the same way thus producing the combined side thrust. I was advised to use inboard turning props on my H class destroyer (twin screws single rudder) by an ex RN Captain I met at the local lake here in Munich about 30 years ago! @ Chris: What type of boat / ship are you building? Cheers Doug 😎

6 years ago by RNinMunich

Directory

(US WESTERN RIVER TOWBOAT) ILLINI LOYAL

ANOTHER ON THE WAYS: SALVAGED DUMAS ABS HYDRODYNE HULL, 35 X 10 X 2" ORIGINALLY IN THE AMERICAN BEAUTY KIT. MY INTENT IS TO SCRATCH BUILD FROM THIS HULL, A SINGLE-DECK TWIN SCREW LINEHAUL TOWBOAT WITH A FUNCTIONING TELESCOPING PILOTHOUSE. THEY ARE COMMON ON THE UPPER ILLINOIS RIVER WHERE THERE ARE FIXED OVERPASSES OR LOW OBSTRUCTIONS SPANNING THE WATERWAY. THE DES PLAINES AND CALUMET RIVERS IN THE CHICAGO AREA ALSO HARBOR THESE PUSHBOATS. THE PLAN IS TO KEEP HER LIGHT WITH A LOW CG, BUT POWERFUL ENOUGH TO PUSH SOME SCALE WEIGHT; I RECKON 775 MOTORS WITH 50MM 5-BLADE WHEELS WILL SUFFICE. THIS BOAT WILL BE STEERED WITH STANDARD RUDDERS, NO FLANKING RUDDERS, BECAUSE I WANT TO KEEP IT SIMPLE. (K.I.S.S.) I AM STILL BRAINSTORMING THE SYSTEM FOR RAISING/LOWERING THE PILOTHOUSE; POSSIBLY A SERVO WINCH & CABLE OR LINEAR SERVO. A PNEUMATIC RIG IS ALSO A POSSIBILITY I RECKON. SHE WILL BE WEARING THE ORANGE TRIM AND MIDNIGHT BLUE PAINT SCHEME OF MY SHOP-ILLINIWEK MARINE SCALE SHIPYARD. I USE LIGHTHOUSE LED's & MINI SWITCHES FROM THE SEATTLE AREA EXCLUSIVELY, 9V, 3MM. HARBOR MODELS 1.5V WORKING RADAR & MAYBE A 6V WORKING DECK CAPSTAN WILL BE ADDED. SHE IS MY 5TH ADDITION TO THE ILLINIWEK MARINE FLEET, AND WILL OF COURSE PUSH AHEAD THE MATCHING BARGES. GO FIGHTING ILLINI! (Motor: 775 JOHNSON TYPE) (ESC: DIMART 320A FAN-COOLED) (8/10)

6 years ago by circle43nautical

Response

Electronics Down Below (5)

Hi Neil, You read too much!! 😉 Before you give yourself the work of altering the rudders see how she performs with the twin ESC & rudder mixer. For slow manoeuvring, especially in reverse, I'm pretty sure the rudders will be almost irrelevant, apart of course for controlling the mixer and hence motors. If you use the P94 in Mode 3 you can spin the boat on it's axis😉 The guys with small rudders in front of the props most likely don't have twin ESCs and a mixer. Two maxims: Why complicated when simple works! If it ain't broke don't fix it! I intend to 'suck it and see' first. Whatever you do have fun with it, but don't 'over engineer', cheers Doug 😎

7 years ago by RNinMunich

Directory

(Other) CG-40564

DUMAS 1:14 USCG 40' UTB. REPRESENTING US COAST GUARD UTILITY BOAT CG-40564, WHICH CAPSIZED DURING A RESCUE ATTEMPT ON THE COLUMBIA RIVER BAR ON 17 JAN 1961. HER CREW WAS FORTUNATELY RESCUED. SHE WAS ASSISTING CG-52301, A 52' TYPE F WOODEN MLB, WHICH FOUNDERED WITH THE LOSS OF ALL HANDS. IT REMAINS THE WORST SMALL BOAT RESCUE DISASTER IN COAST GUARD HiSTORY. THIS IS AN UNUSUAL SCALE BALSA PLANK-ON, COVERED BY 2 OZ FIBERGLASS. I USED MINWAX POLYURETHANE FOR AN ALTERNATE TO RESIN, WHICH TURNED OUT WELL, AND CAN BE DONE WITH MINIMAL VENTILATION. WITH BIRCH PLY DECK & CABINS, 1/8" SCRIBED SHEATHING COVERS THE DECK BOW TO STERN AND MAHOGANY TRIM LEFTOVER FROM ANOTHER DUMAS KIT IN MY SCALE SHIPYARD. STOCK D/C FITTINGS WITH SOME SUPPLEMENTAL PREMADE AND HANDMADE ITEMS. SHE FEATURES TWIN RABOESCH 4-BLADE WIDE FLUKE WHEELS AND MATCHING RUDDERS; WORKING HATCHES WITH STOWAGE AREA FOR ANCHOR & TOWLINE, LIGHTHOUSE 9V LED NAV LIGHTS AND FLASHING LED LAW ENFORCEMENT BLUE LIGHT (RC CONTROLLED). I'M ADDING A MOUNT FOR A SCALE BROWNING M2 50 CAL THAT I WAS ABLE TO PRODUCE ON MY 3D PRINTER. THAT'S AN ADVENTURE IN ITSELF. THIS WAS MY FIRST REAL PLANK ON BULKHEAD, AND BALSAWOOD CAN BE A LIL TRICKY, BUT WILL ALWAYS BE THE STANDARD OF WHICH I COMPARE ALL MY SUBSEQUENT BUILDS. MY FATHER BUILT RC AIRCRAFT, AND ALWAYS PREACHED THAT YOU SHOULD OVERBUILD IN ORDER TO SURVIVE A CRACK-UP AND FLY ANOTHER DAY! THAT'S MY CREED WITH BOATS. OVERBUILD!!! THANK YOU DAD! BTW-FYI-MR. ARNOLD PALMER WAS A US COAST GUARDSMAN (YM3) 1950-53 (Motor: 775 JOHNSON-TYPE 6-12V) (ESC: HOBBYWING) (9/10)

7 years ago by circle43nautical

Forum

Twin motor control problem

Dave, mtroinks have switches, so maybe when it had the pair of vipers, they where for the esc's? I would disconnect the red signal wire from the receiver end on the "y" harness, and use a separate 6v receiver supply, I have a number of twin screw setups, with a cheap battery monitor, if the esc fails, you still at least have rudder control, if the feed esc goes down, power is lost to the receiver, ensure you have a failsafe set at zero throttle. With spectrum, its usually automatic, unless...... you have reversed the throttle! that means you throttle will go wide open in event of esc failure. Easy test, on the bench, all set up to go, make sure all the props etc are clear, just turn your transmitter off, see what happens, nothing should! Have you done the range test? you might have been lucky having it go in reverse, Also, the gunner that is holding the esc wire, is he wearing a Teflon glove? His hand might get hot

7 years ago by pmdevlin

Forum

Twin motor control problem

I wanted total motor control on my large, heavy twin screw harbour tug. The rudder is pretty useless serving only as a sort of trim tab so I went the simple route: Each (brushed) motor has its own ESC and independent power supply so left and right Tx sticks control their appropriate motor. By doing this I am able to have one full ahead, the other full astern, to turn on the proverbial sixpence or for slick docking alongside

7 years ago by Robin Stobbs

Response

Question- Prop rotatio direction?

Quite correct Skydive, 👍 go to the top of the class 😉 Conventional wisdom is that you will get better rudder effect if the port prop turns clockwise and the starboard prop anticlockwise. Although with s this is not so critical, as it is on my twin screw - single rudder destroyer and Graf Spee. Main thing is opposite directions to cancel the rolling torque the motors create. Cheers Doug 😎

7 years ago by RNinMunich

Forum

Propulsion Hegi Revell Fairplay V tug model

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.

7 years ago by Radiosailor

Forum

Rudder Position

The rudder not being in line with the shaft line would not cause it to go round in circles. As long as the rudder is parallel to the shaft line the boat will go straight ahead. Most modern twin shaft / rudder designs today have the rudders set slightly inboard of the shaft lines. The swirl around the intake pipe might have more effect. But nothing you can't correct with the trim on the TX. Doug 😎

7 years ago by RNinMunich

Media

pt 109

a 30"scratch built pt. boat, I built hull from .8mm ply using a resized eezebilt 20" plan. the deck fittings were copied as best as I could from photos and drawings found on line. powered by 2- 2200kv brushless out runner motors through 2 20 amp speed controllers. twin contra rotating props s fast and light a pleasure to build 2

7 years ago by basilsdad

Response

The electrics, drive & radio

Hi robhenry Thank you for your complimentary remarks. I didn't really consider building the boat with twin motors and rudders as I wanted to build the kit 'out of the box' to a great extent and also because I was rediscovering the hobby and all of the new technology and techniques that it now benefits from. With the experience I and knowledge that I have now gained I would be not so hesitant to consider such things. I'm grateful for your contribution to Mike's data on the RAF boats as it will have no doubt filtered down to the benefit of my boat build. As I have discovered, surprisingly little information on these boats exists or has been made public despite their popularity with model builders and it would be a great thing if everyone were to pool their knowledge and resources to try and redress this situation. I will certainly try to photograph the boat in action if I can manage the controls and a camera at the same time 😁 Rob.

7 years ago by robbob