P limited prop size

[chris reed]

Hi my name is Chris. I am new to fast Electric boat. I am buliding a P limited hydroWith a.Aqua craft motor on 4s batterys. what would s be some good props for heat racing.

[Fluid]

Hi Chris, welcome! Which AquaCraft motor do you have? Is it a brushless motor? Do you know the Kv (rpm/volt) of the motor? What is the type and capacity of the 4S battery? What is the size and type of the hydro? We need this information to give you the best answer.



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[chris reed]

The motor is a Aquacraft marine Brushless 36-56-2030kv.the Batterys are a pair of Hyperion G3 2s 45c 5000 ma. I will be using a seaking 180 esc.and the boat is a 30" whiplash.

[Fluid]

Okay! Our club members using that setup in various hulls have good luck with the Octura m445 and m545 props. I normally use a Grim Racer 42x66 that has been slightly cupped. All can work, just watch for heat. These are race-wining setups in our area as long as the rest of the boat is right - strut setting, motor alignment, CG, etc. Good luck!


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[lohring]

You might also consider an ABC S-15

Lohring Miller

[chris reed]

Thanks for the info. I will try your sugestion. Chris

[LuckyDuc]

An S-15 is not a good prop recommendation for a whiplash with a UL-1 motor. The likelihood of you having a meltdown is VERY high if you try a stock S-15.

[detox]

I wonder if a ABC 1816/3 would work. If I am faster than everyone else, I do not care if temps are high.

[Jeepers]

I tried a 1718-10-50 on my Whiplash the motor came back at over 200 degrees.

A stock bottom Whiplash will not take much over 445-545, a 447 can work but the boat must me trimmed properly and the motor/battery connectors will be hot.

A back cut 646 works but its not much faster than a 445 and connectors will be hot, also have not been able to get an ABC H5 to work well.


I have had really good luck running a Grim 42x66, A Prather 220 and a Prather 225.

Detox, you will mind that the temps are high the UL1 motors will not last long under those conditions, a few races at best, to high of temps and you will not even finish a race. Unless your pockets are deep and don't mind replacing a motor/esc every race.

[detox]

The motor is the fuse, so keep a couple extra. Keeping your hull weight low and adding steeper ride pads will allow a little more prop. Extend your prop to IMPBA max of 3" from stern to back of prop dog (What is NAMBA max?)

[Jeepers]

been there done that Detox, and in my experience the motor is not the only thing that fails the esc usually goes with it, been there done that too many times. also seen it happen many more times.

I have seen people take out 120-240amp escs on these spec motors when they fail.

My Whip has a modified ride pads and even then prop size for heat racing is limited and it ran best in competition with the 42x66

[detox]

I have not taken out a UL-1 esc yet, only motor.

[Jeepers]

lucky you!

hey by the way Detox I like your new Whiplash that you built.

[Chilli]

Detox, I don't see in the IMPBA rule book where where there is a max strut distance from back of the transom. I do read a maximum strut length of 3".

For you guys who want to try ABC props. Be carefull, as an ABC prop of similar diameter and pitch to a Octura prop will load up the motor significantly more.

[detox]

Detox, I don't see in the IMPBA rule book where where there is a max strut distance from back of the transom. I do read a maximum strut length of 3".

Sorry. I read that in the Nitro section


Sportsman 20 Hydro (Sport 20 Hydro)
Boat Specifications
1. Boat must be inboard powered.
2. Hull must be a three (3) point hydroplane configuration and resemble a limited or
unlimited hydroplane design of past or present. Hulls not permitted: outrigger,
modified outrigger, tunnels, or canard hulls.
3. Boat must have a name, or sponsor's name, or logo, or a racing number affixed to the
hull. (a local or national or fictitious sponsor name is acceptable).
4. Hull shall have a minimum length of 27 inches, and a maximum length of 35 inches.
5. If the bow is recessed behind the tips of the sponsons, that recess shall be no larger
than 25% of the overall length of the boat. (refer to Sport Hull Configurations)
6. Boat must have a driver in open cockpit or simulated enclosed cockpit.
7. A strut width no greater than 9/16 inch wide may be mounted either under the hull
or on the transom with the farthest end of the drive dog, as measured from the
transom not extending out more than 3 inches.
8. See Sport Hull pictorial for clarification of Sport Hull Configurations.