So, on to the questions:
1> Motor: Brushless seems the way to go but what size should I go for?
2> Batteries: I have a LiPo charger already but are these the best kind of batteries for this application or should I use NiMh? What size of battery should I pick?
3> Propeller: I have no idea about pitches and diameters and whatnot and I guess it is heavily dependant on the motor I use. Any advice would be good.
4> ESC: Again, probably very dependant on motor and batteries I suppose. Any suggestions welcome.
5> Drive train: I have no idea what hardware I need to go between the motor and the propeller
6> Cabling, fuses etc: I have no experience of fast electrics so again any advice would be welcome.
Hi Andy,
1) The motor used in one of the first builds is a Feigao 540-12L 2050Kv, running on 12 cells NiMH (now 4S Lipo), with a Graupner 45K (2318.45) prop this runs just under 50 km/h, which is rather sedate, as the design can handle about twice that speed.
(I have a 540 12L 2159 Kv with watercooling jacket lying about if you're interested).
Nowadays I'd go for a fourpole motor like this Turnigy (on 4-5S, where 5S is considered very 'hot'):
http://www.hobbyking.com/hobbyking/store/__17701__XK3674_B_2200KV_Brushless_Inrunner_19T_.htmlA watercooling jacket is required (preferably 60 mm long).
2) Lipo, either two, wired in series, one in each sponson, or a single pack on the tunnel, which requires the motor to sit very far forward, or very close to the transom, to be able to get the CoG right.
C-rate 35 or higher, capacity as much as will fit (longer runtimes).
3) With a Ø36 mm motor the Graupner 2318.xx series are a good starting point, once the boat is dialed in, think about a metal replacement (which needs to be sharpened and balanced).
4) Up to 4S a T-120, up to 6S a T-180:
http://www.hobbyking.com/hobbyking/store/__8946__Turnigy_Marine_120A_Brushless_Boat_ESC.htmlhttp://www.hobbyking.com/hobbyking/store/__8937__Turnigy_Marine_180A_Brushless_Boat_ESC.html5) A strut with either a 3/16 flexshaft, of a 2 mm wire drive and a rudder next to the prop, so both prop and rudderblade are close to the transom, which seems to work best on this design.
6) Silicone covered 2,5mm² wiring and 4 mm goldplated connectors.
Keeping the wires between the ESC and lipo's as short as possible.
Regards, Jan.