Props for my Genesis to go 100 kmh+

[Cpt. Joe]

Hi there,
i would like to ask for your opinion, recommendations and tipps

I own a Genesis hull from HK
- screwed cover with foam seal (100%waterproof)
- Upgraded flex cable to 3/16
- upgraded cooling system
- LEOPARD 4082
- Turnigy Marine 180A ESC: external BEC, voltage protection disabled, 15 ° Timing
- 2 x 3s=6s 45-90 C discharge Nano Tech Battery packs 5.0 Ah

Props:
Octura M654: approx 75 kmh or 46mpH
Prather 230: approx 87 km / h or 54mph
With these Props ESC and motor are warm to the touch.
Battery packs are the warmest parts! But not really hot.

Under these conditions, I would like to change the prop to exceed 100 kmh+.

What prop would you recommend me. Maybe Prather S250 or a bigger Octura prop or maybe a cnc 3 or 4blade prop?
What about the torque with big props. I think the boat flips very quick with the Prather 230.
Evt. I will also mount the rudder offset. Depends on the size of the prop.
Your opinion and suggestions and experiences are very welcome.
Thanks in advance.
Greetings from Switzerland.
Cpt. Joe
Foto 27.05.13 20 03 44.jpgFoto 27.05.13 20 04 35.jpgFoto 27.05.13 20 07 05.jpgFoto 27.05.13 20 08 00.jpgFoto 27.05.13 20 17 38.jpg

[martin]

What kv is the motor.

[Cpt. Joe]

What kv is the motor.

1600kv.
Sorry, i forgot to mention.

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[Chilli]

I'm kind of surprised you only doing 46 mph with the 645. Your no load rpm is in the mid 30k range. I'm sure you have more speed in her. One thing you need to do is detounge the 645. That will get you some more speed

When you lay your hull on a flat table, is the bottom of the strut above or below the table top?

[Cpt. Joe]

As you can see in the picture it is about 1mm above the table top.Foto 27.05.13 22 18 17.jpg

[Cpt. Joe]

@chilli
what do you mean with detounge the prop?

[f1rogers]

with the 230 prop mine goes over 80mph. 2200 kv on 6s.

[Chilli]

@chilli
what do you mean with detounge the prop?

I was afraid you were going to ask that. LOL Detounging involves removing material the leading edge of the prop toward the front third of the blade. This is standard mod on the Octura X Series. The Octura M series comes with the tounge already removed.

http://rcboat.com/prop.htm Refer to the second section "Areas to Cut Prop" and Figure 2 for an explanation.

Try raising your strut up a few MM to unload the prop a bit more and see if that get's you a few extra KPH. Once we get the most out of your current set up, then you can start looking for a prop to get you to your taget.

[Cpt. Joe]

Hello,
theoretical that's not so far away:
80:22X16=58 mph
okay, difference is 4mph.

Maybe i have definetely to go for a bigger prop!? I can't increase the rpm with my 1600 kv.

[Cpt. Joe]

@chilli,
thanks for explanation for detounge the prop i will read it carefully.
Do you mean i have to raise the strut more, that should be in parallel to the underline of the boat i guess.

[martin]

Bring the strut up more as said so theirs a 3-4mm gap between the strut & table, your prop is running to deep in the water. This will allow the prop to unload more, the detounged prop will also allow the prop to unload further.

[Fluid]

As above you should be over 100 km/h with your current setup. A "larger" prop will probably only overheat things more. Loosening up the hull is probably what is needed, that or better cells - the hot packs are an indication of where your limiting factor is. Right now the low prop height is forcing the bows down, wetting the whole boat down. Raising the strut and perhaps moving the CG back should help.



.

[BajaOutlaw33]

I have basicly the the same set up as you except I have the stock 2075kv motor in right now. Im running the 3s nano tec 6000 25-50c batteries and a 36mm x 1.4p 3 blade cnc prop. Im running in the high 40mph range with my ESC @ 100 degrees my motor @ 98 degrees. I have the leopard 4082 2000kv or 2200kv in mind but havent decided yet. I just bought the 3/16 drive upgrade and a VSX 4018/3 40mm x 1.8P. Im pretty sure that setup will melt my 2075kv but I want to see how far I can push that little motor. I will let you know my results of my bigger prop. I like to run higher Kv motors with smaller diameter props. I know it draws more amps but I seem to get more speed out of my rig.

Genesis 1.jpgGenesis 2.jpgGenesis 3.jpgGenesis.jpg

[Chilli]

@chilli,
thanks for explanation for detounge the prop i will read it carefully.
Do you mean i have to raise the strut more, that should be in parallel to the underline of the boat i guess.

Good posts by everyone above. Yes, raise the strut but keep it parallel. Not only should you be faster, but as Fluid mentioned, your equipment will run cooler. If you start having blow over problems, you can then move the CG forward or add a little negative angle to the strut (rear down).'

Something else I just notice. Did you add a brass water pick up tube and run it along the back of the rudder? If so, that could be causing allot of extra drag. The back of the rudder needs to be flat so water can break away cleanly.

[TristanJones]

I ran a pair of 5s 5000mAh 65-130c nanno-tech packs (parallel) in mine, they were too heavy I think, but it got up and went alright, with a trackstar 3974 2200kv, m445 thinned and sharpened. I haven't put the GPS in it yet, but it seems to get along way faster than it previously did with the stock motor on 5s and I GPS'd that at 79km/h
They are very sensitive to COG and prop height Ive found. I have been having issues with my cheap nasty radio gear so haven't managed to get it up to full pace yet, but here is a vid of what Ive gotten so far.