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[lleksam]

Hi All

I'm new to boat building but have been building various models for some years now for my first venture I chose the Riva Aquarama a boat I have loved for may years. I found a set of 10:1 plans here http://www.replicaplans.com/RivaAquarama.html to make, I had a local roof truss print the plans on A0 and A1 paper for me, I Think I have decided to go with 2 Brushless motors (this is what my post is really about) Driving contra rotating Props have chosen STD/1415/3 Right and Left hand from http://www.prop-shop.co.uk/index.php?section=store&sub_section=product_detail&id=859&product_type=37 Amati Models make a "Fittings Kit" that seems to be about a similar scale that I think I will buy when time comes or they come into stock at Cornwall model boats  Enough of the project down to the question

I cant seem to get my head around brushless motors, can anyone help me choosing motors please I would like a reasonable turn of speed, but not record breaking, what Kv would i need, what size, I think they would need to be "INRUNNERS" to get cooling, I think I would like to use a mixer as well bearing this in mind can anyone help me please?

Thank you in advance
Steve

[Martin (Admin)]

This might be a good starting point:  http://www.modelboatmayhem.co.uk/forum/index.php?topic=13538.msg130068#msg130068

[lleksam]

Hi Thanks for that Martin was a great help

Have decided on a pair of 1500KV + - a few hundred, something with a size of about 36mm diameter  with either a 4 or 5mm shaft,  but the choices in inrunner seem limited so may have to go for outrunner. I keep going back to this one http://www.westbourne-model.co.uk/tornado-thumper-v2-3536-5-1450kv-12012-0.html

If any one thinks I'm making mistake or can recommend another good motor PLEASE PLEASE say, as I said I'm new to the marine side of modeling and really new to these new fangled 3 phase motors,

Thanks

Steve

[ukmike]

Hi Sam
The first layer is Limewood aka Basswood 1.5 x 7mm.  The mahogany is 1.5 x 8mm.
Look here for inspiration. http://www.classicboat.com/classic-29Riva-Super-Aquarama.htm

If the model you are going to build is 10% scale then it will be about 84cm LOA. Will be quite heavy when complete, requiring a goodly amount of power to perform correctly.
The majority of model Aquarama models do not seem to emulate the correct planing attitude, most of them seen to throw water everywhere including inside themselves.
I believe it's a mixture of too much weight, not enough power and incorrect balance, my opinion of course.

The "Engine Room" of the model is really quite cramped and sealed tightly when the cockpit seat and sundeck are in place therefore adequate cooling has to be taken seriously.
My thoughts are these, go with the water cooled in-runners and speed controllers. Look here at these motors as they also have an internal fan. http://www.hobbyking.com/hobbyking/store/catalog/D480S-3200(1).jpg
Add cooling jackets. http://www.hobbyking.com/hobbyking/store/catalog/WCJ-B3656M.gif You can also buy a cooling plate for the ESC's if you don't want to buy ready made water cooled ones.

Mike.

[lleksam]

Thanks Mike for advise, will go with same motors as you, need to order them soon to see where they will end up in the boat. I started machining mahogany one of the stairs down today for the 10mm thick keel that is in my drawings, and a few other bits. take a look at drawings i have (link above) its a very different beast form yours,

Cheers

Steve

[lleksam]

Had a rethink on propulsion systems, where i work we have a 3/4 acre ornamental lake for me to play in, but unfortunately there are patches of underwater weed, so have decided to try a single 2340 Graupner jet driven by a Overlander BM 600-750 brushless in-runner, that i picked up at a local model shop yesterday, i ordered a water jacket from E-But last night and the jet from Cornwall Models. The thought did run through my mind that if this is not enough for boat I would throw 2 Graupner mini jets in one either side as well, idea quickly brushed aside, but may be fun.

started to machine "Stairs" down made 10mm  thick keel and quite a bit of 6` long 3mm thick 8mm wide planks, underestimated the amount of 4mm ply I would need so only managed to make the front 9 ribs, ordered more that was a strange order 900x300x4mm ply and a jet drive,


will take pictures soon

if any one has advise, ideas or just wish to call me a idiot please go ahead

Steve

[MikeA]

have you got the jet yet is it big enough for the boat?

[lleksam]

have you got the jet yet is it big enough for the boat?

Hi
No only ordered it last night, big enough?? unsure about that, its total length is near 1/3 of the boat, just hoping it develops enough power, I watched a video that had 2 in a much larger boat and possibly 3 times the hopefull weight of what i think this one will end up as, and it went like hell, still at planning stage at moment though, you think i may need twins? LOL

Steve

[MikeA]

it its 1/3 lenght of the boat i doubt it 

[lleksam]

after reading your comments I decided to check and i have serious doubts as to weather it Will actually fit in boat

Length approx. 250mm
Length incl. reversing mechanism approx. 290mm
Width approx. 58mm
Height approx. 70mm

i think i will have serious problems getting outlet under water, thinking laterally could i mount pump further forward and pipe in some nice kinky stainless steel the high pressure outlet to the back and put the steering nozzle on end of tube? as it is now just a few inches further back


Steve

[lleksam]

sitting here dreaming I also wonderd if I put a "Y" piece in could i feed 2 jet outlets, one each side, with a steering nozel on each.

Steve

[MikeA]

holy **** thats massive lol youl be draining the lake with that!!

The outlet on a jet pump doesnt need to be underwater it works by force. Every action has a opposite and equal reaction type thing.

http://www.youtube.com/watch?v=plI-pTt7fSs&feature=related