Mean Machine Catamaran (Sport)

[knpc]

It could be the picture, but the stuffing tube looks to have a abrupt bend instead of a nice long sweep. It could cause resistance that would lead to slower speeds and higher amps.

[Jeff Wohlt]

And cut off some of that rudder! You only want about 2.5" under the water. It is tappered and I don't use those but still I would remove some for sure.

[Brushless55]

I thing the CG needs to be moved back..

[Xfactor]

So the smaller the number 8xl has more torque than a 10xl? What is the max you can spin an xl motor? C

The lower kv motors have more torque.The 10xl has more torque.

[Rich]

well i ran my MM tonight and a got some good results, i moved both lipos back about 2 inches from the back, 125.57 amps, 1660 watts, temp of esc 114f, motor 85.8f, speed though was 36mph, my prop came off when i let off the throttle thats ok though it was worth it, I order some different size anyway.

> My tube is a bit excessively bent but i could not make it a sweep, do to the motor being at angle which it needs to be to fit under the cowl. The flex seems to be holding up, i don't see any where on the Teflon tube but time can only tell that story.

[BakedMopar]

580 6l and your only getting 36-40 mph? Something must be wrong.

[Rumdog]

Prop is WAAY too small! Need a gap between the strut and drive dog. Thatg bend in the tube could also be causing excessive drag,and amps.

[Brushless55]

I run my batteries all the way back in my MM
and for me that helped a bunch

[Jeff Wohlt]

Me too -- about 1" from the transom.

[DISAR]

me too

The amps are a little higher than they should be, I can say the following

a) You can reach higher speeds only with bigger prop, 445,645
b) Your amps will increase too and maybe the etti will let go...
c) I suggest to cut some part of your rudder, at least 1" ( I cut mine too and turning was same and better performance)
d) This is quite difficult to do but you should do it sooner or later, it is the stuffing tube angle. It creates unnecessary resistance BOTH water and friction (one cause of your high amps). You need a uniform radius from the point it exists the hull until the strut, no need to be straight only before the strut and motor 2" about. Lower the motor angle as well, pls see attached rough sketch
e) Batteries about 1" from the back

Speeds are relative and depends on many conditions (gps-water-chop-density-sea-fresh etc...) (I have never achieved the speeds mentioned here even with same boat-setup)

[Rich]

Well I fixed the flex tube problem, had to do some cutting and moved the water cooling jacket back to be able to move the motor down, I am happy with the way it came out. I will try it at the end of the week, ill let you guys know.

[Rich]

I ran the MM a few times with different setups,

First: grim racer prop 53 x 40, mini rudder, strut all the way up, 11.1 lipo

esc temp 119f, motor 83f

96 Amp, 1100 watts 36mph

Second: grim 53 x 40, mini rudder, 4s

esc temp 135f, motor 92f

166 amp, 2266 watt 43mph

Third: m445 prop, mini rudder, 11.1 lipo

Esc temp 138.5 f, motor 81.3

148 amp, 1675 watt, 45mph

Fourth: m445, long rudder (trimmed about 1" off) 4s, strut still all the way up with about 1 deg angle

Esc temp 182f, motor 96.7f

Amp 181.67 (WOW!) 2578 watts (WOW AGAIN) and the fastest speed yet 48mph!!

Just to let you guys know that i didn't do these in this order and the hull was well out of the water with these setups , but i do have a question on what i should have my etti 150 set to in terms of PWM with the 580 6l and the timing????

[D&D]

This is my new MM build, my first FE build:
Neu 1515 1y
Castle Hydra HV 180
Futabe PM3-X FAAST
Turnigy 4S-2P (5000MA @ 35-45C)

First Run water way too rough ran slow and discovered a couple of minor problems. Second run on X440-3 GPS @ 54.5mph. Third run on X442 GPS @ 55.5mph. Temps acceptable and the boat is running like it is on a rail - which is not to say I would go racing, but it is a nice sport boat at this point.

Don't know if I am posting the pics correctly, but here is my try:

[IMG]/http://forums.offshoreelectrics.com/album.php?albumid=196&pictureid=1997
[/IMG]http://forums.offshoreelectrics.com/album.php?albumid=196&pictureid=2000

[Rich]

Nice i like it! so your using two 4s packs wired in parallel? And which rudder are you using?

[D&D]

Yes, two 4S packs in parallel (4S2P). The rudder and strut are Speed Master 21s.

So far I've run a X440-3, X442, and a modified X445 with the strut at different heights and I can seem to get away from 55mph (54.5 to 55.5). I havn't done that much testing yet, but I am somewhat confused by the consistency of the mph. This is my first FE but I have built a ton of nitro Areaomarine cat boats, oh well, testing continues today if weather permits.

http://forums.offshoreelectrics.com/...pictureid=2000