Thundercat 31 conversion build

[ReddyWatts]

First build and no smoke? Congratulations!

[lomdel]

First build and no smoke? Congratulations!

All those PMs of yours regarding FeCalc calculations helped a lot, you suggested the 13XL over the 10XL I had. I'm still not satisfied with the speed, but I'm working on it...
Is the Proboat Thundercat 31 hull renowned for slow speed or why do you think I can't get more outta this set-up (if you read the thread).
I'm gonna start propping up and I'm considering ordering a 12XL as well... The temps is my only worry. Its hitting 130F now...

[Steven Vaccaro]

From reading your posts, it looks like you want much more speed. Thats going to take a Neu motor or Larger diameter Feigao motor.

[lomdel]

Then I would opt for the 580 10L with the same ESC and 6S lipos driving a S225 prop (FeCalc). If only my budget allowed it...
Or a KB 45 9XL with a S225 prop...
The larger diameter (45mm) cans won't actually fit. The shaft too high from bottom of hull, hence an offset to the flex-shaft.

[DISAR]

If I were in your position I would try first the 10xl with the rest of your setup (6s1p (3800 20c), s215, etti 150a). You can see in the head of the river thread which is a similar hull to yours that they even use 9xl,6s1p, 42mm prop.
I am pretty sure that the 10xl will work fine and your speed will greatly increase. Run the boat in full throttle and after 30secs-1min bring it in to check the temps. if everything is ok, you achieved your goal.

[DISAR]

The FEcalc most of the times overestimates Amps. Use the "hydro" option which works for my boats which are cats and monos. According the FEcalc. with the 10xl, 6s1p, s215 you have:

89amps,1700watts,3.3mins

and speed according to OSE calculations abt 50 mph. I use the 9xl with 6s, 40-42 mm props and is fine, therefore the 10xl would be better (cooler).

[lomdel]

That is great news! I think that Reddy would strongly disagree, but I'll try your suggestion this weekend, Disar!

[DISAR]

Please try and I am 99.9% sure it will work. But please check the temperatures after 30 sec-1min just to be sure. Waiting for your news.

[Steven Vaccaro]

Remember the head of the river cat is not as heavy as the thundercat. In theory a 10xl will provide more rpm but less torque. If you do try it, start with a much smaller prop than the s215. I would start with a 40mm something 1.4 pitch. Either a plastic or metal.

[ReddyWatts]

The reason I did not recommend the 10XL to 12XL was because of the props and the 80 amp lipos you had already purchased.

[DISAR]

Reddywatts was right in his suggestions for a safe setup. With the 10XL you will be getting the max. of your boat, and as Steve stated if you have a 40mm prop. use this first. Please note also that your batteries will be at or close to their max. discharge capacity. If you have the 5000 use these ones first and see how things are going. If they are just warm then use the 4000. Anyway do not forget to check temperatures after 30secs-1min and run at full throttle as much as you can. Finally the strut to be as high as possible (bottom of strut level or higher than bottom of sponsons)

[lomdel]

I have a lot of options now, thanx guys.

My Pather 215 prop has been sharpened from its original 40,6mm down to 40,1mm, but the pitch is still 1,6. I'll stick to it with the 10XL for now, since I don't have easy access to smaller lower pitch ones. This I'll try with my soon to arrive 4000mah 25C lipos.
The 13XL I'll try with the larger S220 and X642 props as soon as they arrive.
I'll let you all know what the outcome of this expensive experiment is and which one produced the most smoke from my motors and ESC... lol

I can waterjet 4,5" stringer mounts for the 45mm can of a KB45 or the 580L, but it'll be a tight fit into the hull and I don't know wether the height offset to the flex-shaft can be overcome, except if I use these : http://www.finedesignrc.com/hardware/fdmflexcoupler.gif . They have a piece of cable in the middle. I actually have two that I ordered earlier, but I doubt if they'll be strong enough for the power of the bigger motors...

[DISAR]

From your current options (10XL,13XL) the 10XL will give you more speed with the 215, just watch out the temps of your batteries and motor. I believe that you know this page

http://www.offshoreelectrics.com/conversion.htm

If you at the bottom of it you can estimate the speed of your setup which is quite accurate and better than the fe calc speed estimation.

[ReddyWatts]

Ok lomdel, now your hooked like the rest of us. Go and see how much money you can sink into a boat to make it run faster. ha

[lomdel]

I already spent waaaaay too much! Remember the poll I posted a while ago : Does your wife know...? Mine have noooo idea...