990mm Tunnel hull electric help???

[coan]

Hi Everyone.

I have a 990mm tunnel hull,the last ones to come with the old k&b 7.5 motors. I have converted the outboard to electric already and the rest of the boat.

Setup is: 1600kv outrunner turnigy motor
120amp turnigy esc
6s 65c Dinogy battery.
Octura 447 prop-I have a couple of props but I have only ran that one so far as winter is here in South Africa.

Boat is fast already but i haven't had a gps on yet. What is the cheapest way to go faster? New motor? New esc? New battery?

Thanks in advance

[JimClark]

I would say prop unless the batteries are pretty old with lots of use

[HTVboats]

Knowing the watt rating of your motor would really help here. The typical Q (6S) tunnels we race have 2 1/2 -3 watt motors. 1515 and 1520 cans, 40X74 and 40X82 mm. 1600kv is ideal for this application. With a 1521 Castle 1600 kv we use an M445 prop for heat racing. Stepping up to M545 and M645 will speed you up but cut run time and increase amp draw. Your X447 will kill your 120 speedy as it has too much blade area and diameter. I would recommend a T-180 either way.
Mic

[Fluid]

He means 2500-3000 watt motors.


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[coan]

Knowing the watt rating of your motor would really help here. The typical Q (6S) tunnels we race have 2 1/2 -3 watt motors. 1515 and 1520 cans, 40X74 and 40X82 mm. 1600kv is ideal for this application. With a 1521 Castle 1600 kv we use an M445 prop for heat racing. Stepping up to M545 and M645 will speed you up but cut run time and increase amp draw. Your X447 will kill your 120 speedy as it has too much blade area and diameter. I would recommend a T-180 either way.
Mic

Motor i currently have on is max power 1500 watt 1600kv 4 turns. Id have to go look at what other props i have. As far as i remember they are all octura and i think i have a x445,x645, x447 but id have to go look. I know the one on at the moment is a 447. Is there a chart as too what props do what? So for instance a x111 is torq and a x999 top speed.

[HTVboats]

For a 990mm hull (40") your motor may be a little under powered. Will work fine just not turn big props which is what you have. That said your motor will turn them just not for long without heat build up. Look at new props here on OSE and you will see the pitch and diameter listed. Higher pitch goes faster and diameter can load an engine, You need enough diameter for hookup (traction) and extra just eats power. With electric you can easily go faster with larger props but run time decreases and heat builds up. Your big speed may last a couple straightaways and then burn everything down. Start small, check temps and work up. 40-42 mm diameter would be a good start. X or M440 and X442.
Mic

[coan]

Ok so i ran the boat today and last week. Last week i ran a 645 prop and on 4s it barely lifted the tunnel out the water although i didnt go full throttle. On 6s it got going but also like half throttle to 80% for like a second. Today i ran the same prop it flew on full throttle but then it cuts out. Not sure what but im thinking the esc cuts power to the motor. Only happens just as the boat starts flying cuts power for a second and then i can go again. Get it back in and the motor is hot, esc is cold and battery is cold. Changed to my prather 230 prop and it looked like it was going faster but by then the battery was going flat as well. Only had the gps in on my last run when the battery was going flat and i clocked 52km/h. Now i want to upgrade the motor only problem is i stay is South Africa, no one here really sells boat motors and if they do its high kv or joysway. Now i use to import but with our current exchange rate it is almost double the price of what i paid for 3 years ago and postage is a killer as well. So what im getting to is what is the possibility of running car motors? Ive got a track and field 3.5t motor and novak 3.5t motor and a hobbywing 21.5t motor. Any advice???

Here is the video of last weekend- https://www.youtube.com/watch?v=msW6qvcwx1k

[coan]

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[Fluid]

If you mean a ROAR-type car motor then no, they are too low in power for that big boat. Your motor is probably cutting out due to the ESC not being able to keep up with the multiple outrunner. A larger, lower Kv outrunner would work much better. A larger diameter, more efficient prop could then be used - but I forget the largest which will fit on the K&B leg.

As a point of interest my 870mm catamaran runs a 46mm diameter outrunner with an 1100 Kv on 6S. Spinning an x455 prop it runs around 80 km/h.

Running 4S on a boat nearly a meter long is simply not enough voltage and a 45mm prop is too small.

Nice looking boat BTW!



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[coan]

If you mean a ROAR-type car motor then no, they are too low in power for that big boat. Your motor is probably cutting out due to the ESC not being able to keep up with the multiple outrunner. A larger, lower Kv outrunner would work much better. A larger diameter, more efficient prop could then be used - but I forget the largest which will fit on the K&B leg.

As a point of interest my 870mm catamaran runs a 46mm diameter outrunner with an 1100 Kv on 6S. Spinning an x455 prop it runs around 80 km/h.

Running 4S on a boat nearly a meter long is simply not enough voltage and a 45mm prop is too small.


Nice looking boat BTW!



.

What do you mean multiple outrunner? Do you mean multi pole? Im looking at upgrading to a 3000+ watt motor around 700kv- 1200kv. Just depends on what i can get. Prop wise i have four props to play with like a said its hard to get stuff here due to exchange rate and our post office sucks as a 3rd world country. Sizes are prather 230, 235 octura 447 and 645 i think.

While im waiting to see what motor i can get and afford for now im going to install my trim and tilt system i made that would work on a servo on a 3rd channel and the boat will go for a respray to its new Rockstar energy drink colors as well as i will get a cowel made by a local guy who builds 26cc f1 and black mamba boats. Already stripped the boat this afternoon to start fitting the trim system and then test all the with the boat running and then the new paint.

[coan]

If you mean a ROAR-type car motor then no, they are too low in power for that big boat. Your motor is probably cutting out due to the ESC not being able to keep up with the multiple outrunner. A larger, lower Kv outrunner would work much better. A larger diameter, more efficient prop could then be used - but I forget the largest which will fit on the K&B leg.

As a point of interest my 870mm catamaran runs a 46mm diameter outrunner with an 1100 Kv on 6S. Spinning an x455 prop it runs around 80 km/h.

Running 4S on a boat nearly a meter long is simply not enough voltage and a 45mm prop is too small.


Nice looking boat BTW!



.

What do you mean multiple outrunner? Do you mean multi pole? Im looking at upgrading to a 3000+ watt motor around 700kv- 1200kv. Just depends on what i can get. Prop wise i have four props to play with like a said its hard to get stuff here due to exchange rate and our post office sucks as a 3rd world country. Sizes are prather 230, 235 octura 447 and 645 i think.

While im waiting to see what motor i can get and afford for now im going to install my trim and tilt system i made that would work on a servo on a 3rd channel and the boat will go for a respray to its new Rockstar energy drink colors as well as i will get a cowel made by a local guy who builds 26cc f1 and black mamba boats. Already stripped the boat this afternoon to start fitting the trim system and then test all the with the boat running and then the new paint.

[Fluid]

Sorry for the typo, yes I meant multi-pole. At the high rpm you are running (near 30,000) and a high pole count some ESCs can lose the rotor position, causing cogging and shutdowns. So can excess timing advance.

Find out out the maximum diameter prop which will fit the leg without hitting the cavitation plate. If it fits, an x648 may be a good choice. On 6S and a Kv of 1100 you might hit 75 km/h with the boat trimmed well.

Over the years many have tried running a third channel trim adjustment on OPC craft, and AFAIK all abandoned it. Try it if you want, but my advice is KISS.



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