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[stobby256]

Hi All,

I'm usually found on the flying sites forum.. I'm contemplating building a model powerboat over the next few months. I've got a great deal of building experience but I need pointing in the right direction.

Boat details: -

48" long, around 15"beam, mono 'V' hull. Construction is 3mm plywood with bulkheads etc in 6mm. The design was downloaded from a plans section in another (not quite as good!) forum. No details were given regards an engine or motor. That's it!

I have to design the deck and cabin etc but thats no problem, I think.

Questions: -

1) This will be electric so I'm aiming for 12V electrics, and a 700BB turbo motor...? Or shall I go for 2 motors? So thats one motor with a 6V pack either side, or two motors with a12V pack in the middle?
2) Where should I aim for for the CoG?
3) After the plywood construction phase, I take it the best way would beto glass cloth andepoxy resin?
4) Finishing - (a way off yet!) the usual primer, top coat and laquer.. Applied via a spray gun set up of course. Paints? Could I get this professionally done using 2K?
5) Electronics - Im used to 35MHz but I also have a 40MHz set up for another much smaller boat I made a year ago. If I go for 2 motors, is that two controllers? etc etc...
6) Suppliers - propellors? drive shaft? Rudders?

Ok enough for now. If there is anyone out there who could advise then please let me know!

Cheers,

Stobby

[David_S]

Hi Stobby,

Glad you found it, I think you'll get the answers you need faster here then on FS.

[Martin (Admin)]

Hi Stobby,

I assume it's a fast launch of some sort!?!?

1. 48" hull is a big log of wood, I would suggest 2 motors.
2. For a planning hull, "About" a 1/3 from the transom / stern.
3. If you are used to applying glass cloth and epoxy resin then that will give you a strong and durable finish.
    Make sure to paint / varnish the insides too.
4. Yep! Primer, top coat and lacquer - time on effort pays it own rewards here not the cost of the materials.
    "professionally done using 2K?" Yes but again, time and effort etc.
5. I would go for 2 controllers as you maybe drawing large currents with 2 x Speed700BB's... and it will help with steering!
6.  http://www.modelboatmayhem.co.uk/forum/index.php?topic=2607.msg25666#msg25666

[martno1fan]

Stick a strimmer motor in it if its for fun ,if you want real speed put a zenoah gpum in it.Sounds like the woody i built size wise?.mine had a 28 cc strimmer motor it now has a new home but she ran pretty well.
Mart

[stobby256]

Hi All....

I'm really appreciative of all  the help given here!

Mart - great idea about the strimmer engine! What does she go like or shouldnt I ask?? 

Martin...

Just some last questions. 

Rudders - how big and how many?
Im going for TWO 700BB's driven from 12v and two controllers. Will a single rudder do, or will two be better, one each over the back of each prop?
With two contra-rotating props, which way should they rotate looking at the stern?
What size propellors? Speed would be nice buts lets get realistic!
I aim to put two motors near the back and the 12v pack in the middle that should keep the CoG somewhere right.

That proably answers everything, until next time... :angel:

[martno1fan]

Hi the motor revved pretty well once i fitted a walbro wa 167 carb,speed was arround28- 30 ish.Ran for almost an hr on a  tank of fuel too and the motor cost me 15 quid new,theres a guy selling them on ebay now for 25 quid each still a bargain as its a great little motor.Heres a link to some videos of her running,is your boat the same or different?.Bare in mind i made a few changes to mine above the waterline by raising the sides at the transom a bit.Best rudder for a vee is offset to the right but if your going with twin props id go with one rudder central i asume you want surface drive?if so the last thing you want is a rudder directly behind the props .My boat cost me all of £200 to build and get running including radio gear not bad at all and she ran way better than those cheapy chinese things you see on ebay for about £400  .
here she is in rough water notice the flip at the end  ::)
http://www.youtube.com/watch?v=RIiugpqf2lw