Offshore Prop Size and Weight Distribution
 

I know props is all about testing but I'd like to have your view so at least I test less variants :)

Hull: Deep Vee Fiberglass, 35 inch, (Powerboat P1 design, stepped hull)
Engine: 2045KV
ESC: MAX200A
Lipo 4Cell, 5200 MAH

And what is the ideal center of gravity for brushless offshore mono? Would it be same with a gas engine?

RE: Offshore Prop Size and Weight Distribution
 

i would say start with a 42 mm prop and work up from there just to be safe. As for center of gravity, the accepted starting point of a mono is around 30% so for your 35 inch hull that is 10.5 inches forward of the stern. Adjust accordingly to water conditions and what the boat actually does when you get it on the water. A data logger is your best friend in this hobby, temps don't tell the full story, you may think things are running fine and cool on one size prop so you decide it's ok to go to the next size bigger and then... smoke on the water. You may be able to run up to a 47mm prop, just remember when ever you prop up run for no more then 30 seconds before you bring it in for a check. Set a clock and don't ignore it.

yeaa this is so fast with this new prop i'm having soo much fun its running good i don't need to check temps.... magic smoke comes out 100 bucks wasted.

RE: Offshore Prop Size and Weight Distribution
 

Makes no dif what your boats powered by wether it be gas or electric however rule of thumb is usually the more power the further forward it needs to go.The only way to do it is to test test test on the water and adjust from there.
Mart

RE: Offshore Prop Size and Weight Distribution
 

Not enough information to give a decent answer. We need to know:

Exact motor - brand and size and number of poles. Kv alone is useless.
Esact ESC - some are "better" than others
Exact cells - brand, "C" rating, 1P or 2P

CG will probably be between 25% and 30% but will depend on where the step is.




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RE: Offshore Prop Size and Weight Distribution
 

Hi Got RPM,

Information and photos added. Motor came with the boat and I bought the ESC/battery separately. They are definitely at low cost range :)

Engine Brand:Topedge 3660-09 (named as Ultimate Brushless for this boat) 2045KV Inrunner, rotor length 30mm, motor internal resistance 0.016Ω, 9.6-18V, Shaft size: Dia 5 x16mm

ESC: SKYWING watercooled:
Brushless Motor Speed Controller ESC PRO - SW-200A - 200Amp Firma Sky Wing
5 V / 5A BEC
Programmierbar
• Size: ca. 75 x 41 x 25 mm
• Constant Current: 200A
• Max Current: 240A
• BEC output: 5A
• Input Volt: 11.1 - 22.2V (3-6 LIPO / 6 - 18 NIMH)
• Low-Voltage Cutoff: Auto detect and set
Advantage of Sky Wing Speed Controller
• Low resistance
• High rate PWM
• Low torque start
• Soft start ramp up
• User programmable brake
• Auto motor cutoff with reset
• Throttle range self-adjusting
• Auto shut down When signal lost - temperature protection

Lipo: Hobbyfans, 4Cell, 5200 MAH, 45C


CG will probably be between 25% and 30% but will depend on where the step is: Hull length is 88 cm and first step is at 18 cm, second at 28 cm. I will place the battery either vertically right behind the motor but sacrifice for higher CG or place at center horizontally but weight distribution will be a little more forward.

RE: Offshore Prop Size and Weight Distribution
 

I also have a question if I can use high temp silicon for waterproofing the ESC? As it is watercooled, would be ok?

RE: Offshore Prop Size and Weight Distribution
 

Thats what we use for cooling esc,s gas motors exhaust systems etc.
Mart

RE: Offshore Prop Size and Weight Distribution
 

I meant using the silicon gasket paste (high heat) to fill in the locations where water can enter?