Need help with prop size, and 3blade vs 2blade

[Amisol]

Hi,

I mesuared recently 228amp on my swordfish 240amp. And my motor capasity is max 5.500. Yesterday I had 7.800watt!!

I used a 2 blade 60mm pitch 1.4. Now I wanna try a 3 blade, but maybe go down to 52mm. Anyone who can help me here?

Thanks!!

[Fluid]

You have not given us enough information.
- exactly what hull
- exactly what motor size and Kv
- exactly what packs: cell make, capacity, voltage and C rating
- exactly what prop
- a photo of the stern from the side showing the position of the strut relative to the boat bottom.


.

[Amisol]

Its a 50inch fiberglass hull
Motor: 5692 (56mm) 4 pole, 1000kv
I think the motor is similar to leopard 5692
8-12s, I use 10s 5000mah 65c.
Motor max amp 140, and max power 5.5000w

This is the new prop I want to try:'http://rcmn.no/index.php?do=product&id=734

[Amisol]

Is this ok?

[Fluid]

Running 10S is too much for this big hull, to keep amp draw within reason it will need a small prop and not push the boat well. Better to run 8S and a larger prop. The link to the prop you want doesn't work, but on 8S the one in the photo (which looks like a Prather) should work if it is truly a 60 non 1.4 pitch ratio (Prathers are not). Just take it easy until your logging tells you it is safe. Really, that motor is an expert's motor on 10S in that big boat.

You would be better served to run a motor with a Kv between 700 and 800. Then you could run a larger more efficient prop on 8S or step up to 10S and run the prop you have.



.

[Amisol]

Okey. At first I used 8s. The motor was the same as I have now, but the ESC was Seaking V1 Series ESC - Seaking 130A-HV, 5-12s. One testround, and the esc and batteries totally damaged. Burst amp is 180a. It didn't hold for more then one round. What a piece of junk?

image.jpg

I changed the esc to Swordfish 240a II +, and was told by many that 10s draws less amps than 8s. And Joysway has written that this boat is good for 12s. But I'm never going to try more than 10s.

Here is the boat (hull)

image.jpg

Joysway says that if 10s is tried, you have to go down from 60mm to 55mm. But I kept the 60mm, since my ESC is much stronger than the stock. But since I had 229a last time, I'm going down some mm. And I want to try 3 blade, so therefore I wonder if 52mm is good enough?

This is the gas version of the boat, I have battery version: http://www.ripmax.com/Item.aspx?ItemID=B-JS-9112A

The prop I want to try, hope this link works, and its in norwegian http://rcmn.no/index.php?do=product&id=734

[Amisol]

This is my new setup.

image.jpg

And also included 2 seperate waterinntakes and each inntake has it own waterpump, so when I'm done driving, I let the boat stay in water for 3 more minutes for extra cooling of esc and motor:

image.jpg

[Steven Vaccaro]

Id try a 52mm 2 blade in a low pitch like the octura x452

[Amisol]

Id try a 52mm 2 blade in a low pitch like the octura x452

But i need a 3 blade for more stability. How far down dou you recommand? I thought 52mm was a ok size, compared to 60mm 2 blade?

[Steven Vaccaro]

It's tough to say, you really need to try it to see for sure.

[Amisol]

Ok. So if i try the prop for 2-3 minutes and try one big full speed, 3-4 seconds. Is this enough to damage anything? The esc? The motor?

[Peter A]

Amisol, what are trying to achieve with your boat? Are you sport running, racing or zoom zoom? This will have an effect on your outcome. While I have no experience with bigger Fe boats, guys like Fluid do. My thoughts however are that if you are heat racing or sport running you may get away with the SF240 on 8s but you may need to run 2P also. For speed runs you are probably going to need a SF300 and good batteries. While prop choice is going to make a difference in speed and run time other tuning on the boat such as CG, strut height and angle will all come in to play also. It just takes time testing and tuning to get it all just right.

[Fluid]

Where did you get the idea you need a 3-blade for "stability"? This is not rocket science, I have plenty of large boat experience and gave you my opinion, as did Steven; we are trying to help you. But you argue that someone else told you something different and Joysway said yadayadayada - but it was all obviously wrong as your burned up equipment attests. If you don't want to take the advice given you in this thread, why are you asking?


.

[Amisol]

Amisol, what are trying to achieve with your boat? Are you sport running, racing or zoom zoom? This will have an effect on your outcome. While I have no experience with bigger Fe boats, guys like Fluid do. My thoughts however are that if you are heat racing or sport running you may get away with the SF240 on 8s but you may need to run 2P also. For speed runs you are probably going to need a SF300 and good batteries. While prop choice is going to make a difference in speed and run time other tuning on the boat such as CG, strut height and angle will all come in to play also. It just takes time testing and tuning to get it all just right.

Hi,

I'm very new to this. Sorry. It's on my own - hobby racing - but of course I'm speeding to max the last 5 minutes of the batteries.

By 2P, do you mean 2 poled motor? I have 4, but I don't now what is means

I understand that it will take some test than, like Steven Vaccaro says, to find out if the prop is ok for this setup.

Thanks for answering!

[Amisol]

Where did you get the idea you need a 3-blade for "stability"? This is not rocket science, I have plenty of large boat experience and gave you my opinion, as did Steven; we are trying to help you. But you argue that someone else told you something different and Joysway said yadayadayada - but it was all obviously wrong as your burned up equipment attests. If you don't want to take the advice given you in this thread, why are you asking?


.

Like I mentioned to Peter, I'm very new to this. So very sorry for my many questions..but thanks for answering!!

Actually, Joysway said the same as you, start with 8s batteries. And this damaged the stock ESC and the batteries. That being said, I can't understand why Joysway produce this boat (and the Silverline) all over the world with such small ESC (Seaking 130A). I started to use 10s when I changed to SW240. Had three testrounds, and after the third, the results was too scary to continue with 60mm blade:



Because of this, I wanted to go down to 55mm, but instead 3 bladed 52mm. So with all respect, do you (as also Steven said), think I can at least try this prop for a testround, and then read the log, without damage any parts? Can I run full speed for 3-4 seconds just to see the results?