Part 1. Ideal conditions; nearly 30°C, cool Bier at hand😜 Sea Scout built by Dad in the early sixties with a Taycol Target and 6V lead acid wet cells (very wet😡). Renovated and dragged into the 21st century over the last several months 😉 See Build Blog 'Sea Scout 'Jessica'' for details! Motor: Propdrive 2830, 1000kV, 30mm 3 blade Raboesch prop. Quicrun 16BL30 (30A) ESC with BEC. Tested with 3 battery types, all started with 99% measured capacity- 1. NiMh 4.2Ah 7.2V, nom. 408gm. Result: Speed sedate (OK 😉scale river cruising!) No planing. Max current: 3.6A End status V / capacity left: At end of short run ca 3 mins. 7.78V 99%. 2. 2S LiPo 4.0Ah 7.4V nom. 257gm. Result: Speed still sedate but due to lower batt weight at least the forefoot came out of the wet stuff! Max current: 4.1A End status V / capacity left: At end of short run ca 3 mins. 8.25V 93%. 3. 3S LiPo 4.0Ah 11.1V nom. 315gm. Result: Now we're getting somewhere!!😁 Good speed, manoeuvrability and planing 😊 Max current: 7.5A End status: 11.95V 74% after several long runs, ca 20 mins total. Estimated (extrapolated) endurance on a 4Ah LiPo around one hour - mostly 'full bore' - 'Pedal to the metal man' 😊 See also: https://youtu.be/oMUlSOaAREM The competition! https://youtu.be/zPgYicA0yGw Final run. (Beer was getting warm😁) Cap'ns log entry: Boat dead-weight w/o battery: 1.8kg. Spray rails to be added!😲 Slight list to port to be trimmed. Rudder servo to be reversed!!😲 Keel protection to be added: some scratches and flaking from stony sloping shore 🤔 Summary: much as expected👍 Forget anything less than 3S. Anyone want to buy a batch (4) of new 2S 4Ah 45C Lipos? 'One careful owner'! Happy boating people, Cheers Doug 😎 PS Many thanks to Camera girl Gisela 👍 Recorded in 1080p HD.
Right chaps, firstly many thanks for your suggestions. I won't be doing LiPos, because the charging is too complicated for me. I can't read the instructions of my fancy charger so it remains in its box. I forgot that I can get NiMhs in sealed packs, so that'll be something I get hold of, although the shop had more out of stock than in! Secretary, I liked the look of that servo you linked me to and will be getting one. Norman, I have today picked up my Spektrum DX5e from my daughter's place where it was in store. I found it whilst looking for something else as always! I already have the Orange Rx and can now try binding it, when I have some batteries for both items. I also have 27meg gear, three different lots and WILL be using it in my classic speedboat models. I waste as little as possible! I have now settled on a continuous loop for the sail control, which doesn't need spring tension, though haven't decided a good way to attach the sheets to the loop or how to tell when the loop has gone as far as it dare before getting a bit mixed up. But I have sorted out the plank system by making one section trap a second, both of which can be removed separately. I found a gear and shaft out of an old printer which I chucked in the lathe and turned a groove in for the loop line. Then I found a use finally for that 6mm ball race I've had in my drill drawer for years! It was an interference fit on the shaft. I had some PTFE plate for another task and in some spare I made a hole that the ball race pushes into a treat, below it an identical plate supports the other end of the shaft, PTFE being very low friction. All this levels the return "pulley" with the servo drum. I only have a limited length of run for the loop line, but it should be enough. It's all I got anyway. About 10" between pulley and drum centres. If I attach the sheet part way down the boom instead of the end I should have enough movement. So, progress. My son-in-law supplied some bike gear cable for the rudder actuation as the rudder stock is at an extreme, typically cutter, angle. A hunt through the supplies (Pringles tins) gave up enough aluminium tube to guide the cable. Alas, I installed with lots of epoxy the rudder tube and it turns out to be 4.5mm bore! Gawd knows where that came from. The tube built into the back of the rudder itself is 4 mm. So that'll be some lathe work ahead. All good fun between the gardening chores. Cheers, Martin
Hi all, Whilst I can make almost anything, I have absolutely no idea how to install modern R/C gear in a model, much less a yacht. I have an Orange Rx which has 6 channels for some reason, but I only need 2. BTW, when did functions become channels? I grew up with proportional being 2 channels per function. Anyway, that's a 2.4 doodah. I have a GWS sail winch a drum jobbie. I also have a few different servos for the rudder, but I don't know what voltage they are. I will stuff 4 pen cells in a holder and therefore get 4.8 volts, is that right? This will all fit a treat on a removable piece of ply which I can secure with a slider at one end and a wingnut at tother. Said ply with all gear will slide through the main companionway with that item removed. So, how do I know which servos will work for steering? Will they work with a 2.4 Gg set? Or must I buy new? Will the Rx be OK sited near the battery pack and servos? And how the hell does one "bind" the Tx to the Rx? I've had the Tx for 3 years and it ain't yet out of its box. It's a Spektrum Dx5e. I'm using NiMhs in the battery pack as I don't understand LiPos and will only be using the yacht occasionally. And I can charge NiMhs with a wall charger. I have fancy metallic blue thing that does everything, but the Chenglish instructions defeated me, so it hasn't been out of its box either. (Get the impression I ain't big on working models, folks?) Any info/instructions/encouragement gratefully recieved. And anything helpful about rigging the damned thing under the deck is welcome too! No idea where to start there. I have very limited space through companionways and deck lights which are all removable, but smallish, if evenly spaced. Cheers, Martin
Oliver Tiger and Gannet? Oh be still my beating heart! I remember seeing a Gannet and a Channel Island Special at Victoria when I was a kid with my Dad. Even he was impressed. And Olive Cockman had a Westbury Seal she'd built herself and fitted in a large cruiser, which she used for straight running and steering, where you nominated a spot on the lake side and set off your model with a fixed rudder. The nearer you got to your nominated spot the more points you got. Never hear of it these days. R/C doesn't appeal to me apart from steering a yacht, although free-sailing is still appealing to me. I have engines, but I haven't got any in a boat as I could never get the things to start. I just like having them around and running them screwed to an outbuilding, when they'll run! I can't be doing with all the fuss of LiPos and charging them properly. Too expensive, so it's NiMhs for me, charged in a wall charger. but it's really building stuff I like to do. Martin
Hi Richard, if the charger was good for the original battery and both are NiMH it will be good for the new one as well. One thing bothers me slightly: what does 'Sprint' charger mean? Just a name or does it only do fast charging at high current? Which is not recommended as it shortens the battery life. 😆 Which charger is it? All the best, Doug 😎
give up and go home! Oh! I am home 😁 Since I need access to the rudder the after deck has to be made as a removable hatch. Would you believe at the last refit (25 years ago) I actually managed to shoehorn the RX and RX NiMH battery in there as well!? Pic 1 shows what it looked like when I started this refit, after 20 odd years in the cellar 😲 Anyway, I wanted the deck to be mahogany to match the cabin roof and as a hatch it was obvious that it would need a subframe. Pic 2 to 5, had to open a new bag of chomp chomp clamps 😉 Trial fit Pic 6. SFSG! Under side was sealed with two coats of EzeKote and fixings added; neodymium magnets at the forward edge, domed captive nyloc nuts glued into the under frame at the aft edge. Pics 7 & 8. These will then accept 4mm studs screwed into Riva style fuel filler caps to hold it down and (hopefully) keep it watertight. Mahog was then finished in the same laborious and patience testing process described above (or is it below😲) for the cabin roof and decks. Pic 9 shows it screwed down with normal 4mm 'Camembert' head screws - Why? see below 😆 Finish was OK.. BUT After leaving screwed down overnight a hairline crack had developed 😡 Pic 10. Also, I didn't like the 3mm fillets between the hatch deck and the main deck, and was wondering what to do about the lip on the bulkhead at the rear of the cockpit. There was a chunk cut out in the middle. This was where in the old days we had a tiller bar to set the rudder for Free Running on a great circle (Radnor Park Lake in Folkestone - side note for Graham P74, probably before he was born😉) Sooo .... machined the lip away, removed the 3mm fillets, made a cardboard template for the new deck-piece and tomorrow is another day. Wonder what I can muck up then !!?? 😊 G'night all, ciao Doug 😎 Oh yes the Filler caps - drilled them on the lathe for 4mm thread clearance, dug out the tap set, selected 4mm 0.7mm pitch ..... Oh S..t, only a tapered tap which starts cutting at 5mm. Hole in the cap is only 5mm deep.😡 Immediately ordered 4mm parallel machine tap, should be here on Wednesday. No sweat, should have deck hatch Mk. 2 finished by then 😎
OK, the steam genny could take some serious current! What batts are you planning to use? The three light circuits will draw (worst case) around 150mA all together. More likely about 75mA so a 5000mAHr batt would last with lights alone about 1/2 to one week! The batt would hardly notice them 😉 If you use a 7.2V NiMH for the lights alone, with a 60Ohm resistor in each circuit, then a little 1000mAH batt would last between 6.5 and 13 hours! Should be enough for even the hardiest sailor 😁 Now 03:15 here so 'Doug's Electronics Shop' is closing for the day. Tomorrow is another one, ciao Doug 😎
Hi again, I recommend that you use three circuits of 3 LEDs each. If your main battery is 12V (or 11.1V LiPo) you can then use a 120 or 150Ohm resistor for each circuit. Lower value resistor = brighter light! With a NiMH at 7.2 V use 60Ohm resistors, with a 7.4V LiPo use 68 or 75Ohm resistors. 1/8th or 1/4 Watt resistors will do. Have an illuminating time 😊, cheers Doug 😎
[Score: 9/10] 58"/9000g MTB741 Fairmile D Capable of 9mph and a runtime of 65mins Twin Propellors (2 Blade S Type 40mm) Direct Drive to a Graupner 700BB 12V (2 Blade S Type) Powered by NiMH (12v) 9Amp/h Batteries Controlled Through MTroniks 30A Tio x 2 (10Amps) ESC - Comments: 1/24 Scale. Scratchbuilt from John Lambert Drgs & photos. It took 3.5 years. Plywood bulkheads, pine stringers & balsawood planking, then fibreglassed. Superstructure balsawood. Guns scratchbuilt from tinplate and brass. There are 2 motors and drive trains powered by 2 x 9cell NiMH D cells x 9Ah. 6 pdr guns rotate. 20mm oerlikon rotates and elevates. Radio is Futaba 2.4 GHz
Thanks for your responses, please note this ESC does not have a brand name (generic Chinese job) and it didn't have any mention of a card on the instructions. Anyway I tried it on 2 cards I have got and they did not work, resorted to sticks and code tones to turn off the break function. Boat ran well if a bit too powerful, may use 7.4v instead of 11.1v Features: 200A Brushless ESC with 5V/5A SBEC Water cooling. Waterproof design(Need to use 704 silicone rubber by yourself). This super simple boat series comes with a limited range of programming functions and are designed to be plug-n-play. A perfect ESC for those looking for something simple to use and economic. Specifications: Cont current: 200A Burst current: 230A BEC model: Switch BEC output: 5V/5A Recommend battery: Li-ion/Lipoly 2-7S;Ni-MH/Ni-Cd 6-20NIMH Cooling: Watercooled ESC weight: 124g ESC size: 92mm * 40mm * 22mm Please note only cost £17 at the time , now £32 (4/2018) via Amazon
Hi MB, can only say what I have which works and I ain't set the house on fire yet 😉 Not surprisingly for someone living in Munich both mine are from German companies! Robbe Power peak Uni 7 and Graupner Unimat 14. There are later versions of both around nowadays but you can still find these on Amazon / Ebay etc. Both of them have automated programmes for various Lithium types, NiMH / NiCad (not recommended these days!) and SLAs. Robbe is now defunct and their Marine stuff taken over by Graupner and marketed as RoMarin! Pics also show the Balancer Adaptor Boards, necessary to connect the balancer cable of the battery. This ensures that each cell is equally charged 😊 I also included in the pics the little battery Capacity Testers I use. They cost around a tenner and are very useful for checking the capacity before a run or charging, as well as the voltage and capacity of each cell, which gives an indication of the battery condition. I found some duff cells with the tester in a few batteries I'd only just bought 😡 When looking for / buying a charger look also for a LiPo Safe bag to charge them in. E.g. LiPo Guard. Charger may cost 50 quid upwards depending on how many charging outlets you want and how many Bells & Whistles. But I get on well with these two 😉 I like the Robbe version cos I can charge two LiPos at the same time. Also in the pics are a few of the charging cables I made up with gold 4mm bullet plugs for the charger end and Tamiya and BEC (for my Plastic magic stuff!) at the batt end. Such adaptor cables are also available 'ready made' but I just like fiddlin' 😊 Hope this helps, Cheers Doug 😎 Nearly forgot! Can't say for sure what current your motor will draw cos I don't know all the other details, but a 40" boat will need some shove! So I wouldn't go below the 5000mAH if you want a half decent run time. A 40" boat can carry a bit of weight! And batt power is more useful than pure ballast 😉 Recommend a little Wattmeter to check the max current draw - see last pic. Basic theory! A fully charged 5000mAh (or 5AH) batt can theoretically deliver 5A for one hour, or 10A for half an hour and so on! Say your set up draws 20A with the 'pedal to the metal' then a 5000mAH batt will 'theoretically' last 15 minutes. Theoretically cos other factors are in play; initial charge state, temperature, internal resistance of the cells, cable losses etc. The latter is why I only use gold connectors! The higher the batt capacity the higher the price and weight. So suggest you start with the 5000 and see how (long) it goes. Then check the weights of higher capacity batts (and the bank account / management approval😉) Bon chance mon ami!
Hi MB, Attached are two extracts from the official USN Bureau of Ship plans for an MTB. Kindly sent to me by the colleague I bought the PT Boat from. Also a pic of the forward (starboard!) gun tub on a model, showing what can be done these days with some photo etch upgrades😉 Not mine I'm afraid🤔 I get the impression that the Aerokits version is somewhat stylised. Have fun, cheers Doug 😎 BTW: If you don't want to tackle LiPos just yet you could use Hi Power NiMH. LiPos do involve some investment when you first start using them: Lithium safe charger, relatively expensive battery packs and LiPo safe ESC. The latter can be preset to stop if the LipO is discharged to it's lowest safe voltage, i.e. 3.2V per cell. Below that the LiPo cells will most likely (99.9%) be irreparably damaged.😡 Cheers Doug 😎
Evenin' Gerry. OK understood. So I assume you have no electrical equipment, experience or components available. Correct? For an 'electrics novice' I am inclined to recommend you start with standard brushed motors and NiMH batteries. Cheaper and easier to manage for a novice. In which case 3 x 380/385 motors with 3 x 25mm 3 blade screws would be a good start. Can send some info on a suitable dual+1 ESC and rudder mixer tomorrow, getting late here in Munich now 😲 Don't worry there's lots of clever (been there dun that) guys here who'll help you through 😉 More later when I've cogitated a little 😊 One final thought: don't finish planking/skinning the hull until the motor mounts and prop shaft hull breakthroughs are sorted out and trial fitted for alignment. Doing that on a completed sealed hull is a pain in the you know where🤔 cheers Doug 😎
Hi Gerry, welcome aboard 👍 Don't mind some of our crustier Fleet Admirals😉, they mean well and have a wealth of knowledge 😉 First some basics (and forgive me if I'm preaching to the converted but the query was a bit bald to say the least!)! - 1 What experience do you have with RC boats? 2 Brushed or brushless motors? Are you aware of the pros and cons? 3 Battery: are you thinking NiMH or LiPO? Are you equipped for LiPOs, i.e. appropriate charger? 3 I assume you mean the ELCO 80 foot Patrol Torpedo Boat (PTB)? Which at 1:32 would give a model of around 30 inches. Please confirm or let us know what original type the model should represent. 4 Are you scratch building from a plan, or from a kit? If a kit which one? Maker? Sorry for all the questions, but it's like computers; nothing in = nothing out!🤔 Some general rules (I know, rules are made to be bent til' they break!😉) If you go brushed motors there is a neat dual ESC + rudder mixer on the market where you can also connect a third separate ESC for the centre motor, to give that extra OOOMPH at Full Ahead 😊 If you go brushless the basic rule is props no larger than the diameter of the motor. And use an out runner, good torque and SHOVE! Inrunners are mostly for the fly boys 😉 Guideline: last year I bought a 28" LoA model of an ELCO 80 footer PTB from another member. It's fitted with 2 x 28xx brushless motors and 30mm 3 blade screws and 2 x HobbyKing XC-10A ESCs. The builder who sold it to me said it is 'almost uncontrollable'! Whatever you do have fun with it, but if in doubt ASK, before you dump money in the boating lake! 🤔 Good luck and best regards, Doug 😎