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[ashwooda]

Hi,

I have been building yachts for some time but wanted something to do when the wind drops, so this is my first powered boat and I know nothing about electrics, propellers etc

I wanted to build a boat which will go fast and be reliable, I will not be racing so I don't need to be the fastest boat on the lake, just as long as it is fun. I like wood so purchased a Dutch catamaran kit but it is woefully short on hardware advice.

The construction is plywood with glass inside and out. I have used 200g cloth on the inside for rigidity with two layers along the tunnel, the outside layer will just be 25g cloth for surface finishing and protection. The overall dimensions are 72cm by 21 cm (the ruler in the pictures is a 60cm ruler). The central compartment is 20cm wide by 16cm long with a maximum height of 6cm and minimum 5cm.

There is a buildlog available but it is in Dutch (http://www.xtremercboats.com/phpBB/viewtopic.php?f=3&t=15151). I have asked these questions there as well but it is a very old thread and I don't have high hopes of getting an answer, but there are some nice pictures in there. Any advice is welcome but if anybody can point me to specific items and suppliers that would be great. 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.

Thanks in advance,
Andy

[bj]

Take a look at HobbyKing's website. They have a boat called APPARITION of a similar size but no quoted prop diameter unfortunately. Other features may suit your hull.

[pompebled]

Hi Andy,

I'm currently digging through the link you provided, looking for the most succesful set-up for this design, as it's a lot of reading, it may be a while before I get back to you.

Maybe you should put up the pictures of your build on Mayhem too.

Regards, Jan.

[pompebled]

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_.html
A 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.html
http://www.hobbyking.com/hobbyking/store/__8937__Turnigy_Marine_180A_Brushless_Boat_ESC.html

5)  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.

[ashwooda]

Thanks so much for that Jan.

Time to spend some money :)

Cheers,
Andy