I had an MFA Spearfish in the mid 1990s and it was powered by an MFA Marlin or should I say underpowered. The Marlin was a good motor but was not really suitable for fast craft such as a powerboat or fast service launch like an M.T.B. I understand that MFA did an 850 which was for fast scale type models but in the end I put an Irvine 25 I.C in the Spearfish. At the time there was a motor called a Buhler which I think was Swiss . I used one😁 in my Perkassa running on nicads which performed very well. For the Aerokits P.T boat there are a lot of suitable brushless motors around and running on lipos will certainly give you all the speed you want.😁 Boaty
Mornin' John, agree re chromite, but still don't know what chroDite is! I only personally own the one Taycol Target. I got into this whole Taycol business while I was renovating Dad's old Sea Scout last year and decided I wanted a bit more Oomph so upgraded it to a 1000kV brushless, which gives goods results on a 3S LiPo. See the vids I've posted of the the 'Sea trials' (Lake Trials!?). So I decided to use the Target in the ancient Billing Boats Danish fish cutter I'm restoring and converting from static to RC. Figured the Target would cope OK with the plodding pace of a fish cutter😉 BUT, I wanted it to be reversible without cumbersome external switches or relays as recommended by Taycol / Keil Kraft in those days. After surfing around a bit a found a website where others had tackled the same problem. Looked at their solutions and refined them slightly. All I do is rectify the pulsed (square wave) signal from the ESC with a bridge rectifier (4 hi-current diodes in a bridge form in one package), apply the + and - outputs from the rectifier to the field coil so that it produces a constant magnetic field just like the permanent magnet of a canned motor. The two alternating (pulsed) outputs of the ESC are applied to the AC (~) inputs of the rectifier, which go + / - or - / + according to the command from the TX, I apply to the brush terminals just like a normal brushed motor setup. The output of the ESC is a train of either positive of negative going DC pulses. Pic 2 the positive train on the scope. Pic 3 the negative train. The larger and wider the pulse the higher and longer the voltage is applied and the faster the motor spins. So called Pulse Width Modulation (PWM). The gaps between the pulses are smoothed out by the inertia (flywheel effect) of the motor, and anything hanging on it - like a prop and a few million gallons of wet stuff 😁 Hey presto, a field coil motor that runs forwards or backwards on command 😊 Main thing is simply to separate the field coil from the armature coil (i.e. brush gear) so you can control each one independently. No rocket science but highly satisfying when it all comes together and works on the pond. OK, I'll look up Mr Lynch, wasn't he the Sarge in Z Cars 😁😁😁 Cheers, Doug 😎
Hi Steve im not sure now regarding motors as they have water cooling cans on but Surfury runs from memory a 1075kva motor Turnigy 160 A speedo watercooled on 2x2s 5200 lipo`s in series ie 14.4volts with 52mm mocom Alum prop approx 3hp. I think the Tornado has approx 2045kva motor same speedo + lipo`s x 50mm nylon prop both do scale speed to as fast as 40/61 IC and look great on our choppy water with just prop and rudder in the water. Both motors will take 6s if you like ballistic? All gear from Hobby king. Try the IC first, post some pics please
many thanks Vortex for info i will think of going brushless(i do have a Merco 61) where would a good starting point be for brushless 🤐if i can be so bold to ask you only recently got back into r/c boats so brushless /lipo is abit new to me regards Steve
W1 by jbkiwi Chief Petty Officer Posted: 3 days ago
This is my scratch built 36" RNZAF British Power Boat 64' HSL (arrived in NZ 1940). I actually went on board this vessel in 1968 when it was still in original form (the RNZAF having disposed of it in the 50s) This vessel is still around and has been recently re modelled (2nd time since early 70s) and I was lucky last year to have met the present owner and go on board (2nd time in 49yrs!)and take a few photos. The vessel was modified a number of times by the RNZAF over the years (air intakes, removal of the fore deck machine guns, wheelhouse turret etc so I sort of went in the middle. I found a few drawings of the type in an old mag which had side and top views plus the bulkheads and their positions, so I took them along to a copying shop and kept enlarging them until I had the desired proportions. This worked out quite well and using a few methods from other models I had built, managed to frame (ply) the hull and then fully strip plank it in balsa. It was then fiber glassed. The deck is ply, lined and varnish stained. The wheelhouse is varnished balsa with the top removable for access. The wheelhouse interior has detail such as controls, instrument panels, skipper, steps to wardroom etc but is not too detailed as it is not seen. The boat has full lighting by remote switch, lights are all LED. The propulsion side has dual everything (motors, ESCs, sound units), would have had 3x but ran out of space! Motors are 28mm 2200Kv water jacketed in-runners (cooled by remotely switched pump) using 30A Chinese ESCs (have 5A BEC, Fwd and Rev). Twin sound units are 'GT Power' car units which have around 40 different sound selections, from Cosworths to diesels and are computer programmable (as well as manually on the unit ) for various functions. I am using one of the v8 sounds (8 cyls short in my application) which I think is as near as you are going to get to 3 Napier Sea Lions (for which there is obviously no sound available) They 'start' 'Idle' and are fully proportional in fwd and rev and can sound quite realistic (will attempt to put up a vid later). Batteries are 2x 2200mah 2s 20c LiPos which will last around 2hrs at least of sailing (they also run the sound units) Still have a few small things left to do (have just made wheelhouse air intakes) but don't want to get too fiddly. Just want to keep it a practical model.
I bought an Italeri PT109 kit in 2011. It took 4 months to build as I had other projects on at the time. I notices the high quality of the parts, especially the hull and the actual paint finish was very easy due to it being plastic and got the nearest colour match by using Humbrol spray acrylic of Grass Green with Regency Red acrylic for the waterline and below. Difficult decision was as to build as a triple screw to maintain scale or go for the single screw. I eventually went for the latter with just one rudder. Power was by a 480 brushed flight motor with a 30 amp esc which was a bit over the top as power was by a 2200mAh 2S Lipo but the esc was the only one they had in the shop. Getting the motor installed was very straight forward as it was done before the deck was fitted but I had to make the aft cabin detachable for access to taking the battery in and out and also lubricating the propshaft .The boat performed well at scale speed but got slightly out of shape when full power was applied, appearing more as a fast electric. Overall the boat was ideal for smaller ponds (providing it was not running flat out). The outcome was a well detailed model that appeared like the real thing on the water but I would not recommend sailing it in rough conditions.. Boaty😁
I can work out scale speed as well as anyone. I am glad that your Model Slipway Tamar worked well for you with a pair of 600Eco motors, but many other owners changed their motors not long after the model was brought into use. You don't need high Kv brushless motors, or 4s LiPos to get scale performance with this model. The addition of a bow-thruster is well worth the effort and cost.
Like many people, I originally built a Model Slipway 1:16 Tamar with the recommended brushed motors. Most of us switched to brushless motors for a number of reasons... 1. short battery duration using NiMHs, or an SLA with brushed. 2. These ALBs have an on-Service speed of 25+ knots and for scale speed, only brushless motors and LiPos can sensibly provide the power and duration. Model Slipway converted their demonstrator to brushless.
Built originally in 1973 from a modav kit and powered by an Enya 35bbiii. Now running a 3548 brushless motor and 5800 3 cell lipo. Model in video was running an x35 prop with +/- 20 degrees of rudder, very sensitive on turns. Today's run was on x40 prop considerably faster with reduced rudder throw of +/- 15 degrees. Current draw was 30 amps max watts 376. Still too sensitive on turns.
I was hoping to get the Wavney on the water yesterday, but the weather gods put paid to that! Anyway, today was the day, so after adding almost 2kg of lead ballast fore and aft to get her on the waterline, it was off to Needham Lakes near Stowmarket, Suffolk. The initial sailing report is that she looks fantastic on the water despite it being a little choppy in the wind. The motors, ESC's performed perfectly, steering needs no adjusting and and at full tilt looked scale with a really nice bow wave. After 20 minutes of sailing which only dropped the 3S lipo down my 30%, all was well apart from a tiny little bit of water ingress at the back near the rudders. I can only put this down to water ingress from high speed passes as the bow wave created a little puddle of water on the rear deck. I know the hull is watertight as she was sat in the hot tub for an hour this morning and was as dry as bone following that. Will have to look at sealing the removable rear cabin as I think thats where the water got in?
Yes, I'd like to know that too! Please post links where you found them. I'm intrigued by batteries which seem to contradict the chemistry used in them😲 LiFe (LiFePo4) cells have a nominal voltage of 3.2V. Li-Ion have a nominal voltage of 3.6 to 3.85 V, They are a derivative of LiFe, which simply defines the metals used in the positive terminal; lithium + a Ferrous compound and carbon. Used in electric cars, military and aerospace. LiPo (Lithium Polymer) have a nominal cell voltage of 3.7V. They are also a variant of LiFe. The 'polymer' part simply refers to the material of the separator used to prevent electrode particles passing from from one to the other. It only allows Ion exchange, i.e. current flow. Hence in effect you can regard all of these rechargeable Lithium types as 'Li-Ion' batteries. Used in Laptops, notebooks, mobile phones / tablets etc, and of course RC models😉 There ARE 1.5V Lithium batteries, Li-FeS2, BUT they use Lithium metal as the anode and are NOT rechargeable!! Nominal voltage 1.4 -1.6V. Used as a high current, long storage life substitute for alkaline AA and AAA cells providing about two and a half times the energy of the alkaline. Similar not rechargeable chemistry, using other compounds of manganese (most common), copper, iron to name but a few, is also used in typical 3V Lithium button cells. 1.5V rechargeable suggests to me an alkaline battery, produced by RAYOVAC some years ago. I still have a few of their C size cells kicking about. Don't have a very good 'power to weight ratio' compared to modern LiPos though.🤔 Cheers, Doug 😎
scratch built, with out board motor,2 blade prop, 30 inche long, still need to install nav lights, chairs are from doll house, runs on Lipo battery, runs and turn excellant, and no that is not a beer in his hand it's a bottle of coke
Hi Ira, Aha! the 1/20 version. So she has some carrying capacity👍 Here's a recommendation from RC Groups- "I have a 1/20th Elco hull based on a John Drain keel and bulkhead kit from Australia. It is powered by three 3548 770KV outrunners turning 1 1/2" three blade props, three separate ESC's, and three 3500mah 4 cell LiPo battery's. Running weight is 16 lbs., capable of speed far in excess of scale, run time is great. " Sounds good to me! For reference; I have a 28" version, being renovated and upgraded. It has 2x 2832 brushless driving 3 blade 35mm props. Guy I bought it from said it was too fast for him! I'm considering adding an independent centre motor, a simple brushed job for slow cruising / manoeuvring. So the above seems reasonable for a 4footer of 16lb. Cheers, Doug 😎