Twin out-board cat discussion

[F1 madness]

most of my good ideas are in the off topic section (skippies and kiwis)
check the last 3-4 pages youll see what i mean

ill have a butchers now

[K.R.Joye]

I think outrunners would do great on O/Bs.They are so hard to cool(properly) inside a boat Couple of things, i would suggest using counter rotating motors just to offset the torque moment givin off by the outrunners also run 3/16 cables. Last, your going to need some good 150-200 amp ESCs, meaning don't go with Hi-Models. Etti 150s should do the job for 6S. Keep us posted!

[F1 madness]

Thanks bud,so you reckon go with the 1100 kv on 6s,should be able to modify the out boards for 3/16 flexis.
Also what do you reckon to the overall size.

[K.R.Joye]

Thing is you can run big props with outrunners, I would say maybe up to a 450 with 4025/1100s. You maybe be ok with .150 cable considering you will probably be running count/rotating motors with 447R&Ls.

A 40" Cat hull should handle the 2P weight, besides you will need the ballast to keep from flipping backwards on starts.

[F1 madness]

Sorted im just starting the drawings now for parts needed to start putting it together,i think this is gonna be a fun and interesting build,and my biggest 1 yet LOL
will keep you posted on progress

[Fluid]

I run a Scorpion 4025/6 on 6S and it needs a lot more prop than an x447, even in a single motor 35" cat application. I know you want to run counter-rotating props, but you won't like the low speed from the x447s. Mine runs well on an x455, but if you want more than 45-50 mph you'll need either more pitch or more motor.

These motors are rated by Scorpion at 100 amps tops. I've run mine in the 130s and it doesn't get too hot, and in an OB application it may work okay. But remember that these motors are designed to run in an open helicopter and drawing over 100 amps continuous may shorten their life - or not.



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[F1 madness]

[QUOTE=Fluid;208671]I run a Scorpion 4025/6 on 6S and it needs a lot more prop than an x447, even in a single motor 35" cat application. I know you want to run counter-rotating props, but you won't like the low speed from the x447s. Mine runs well on an x455, but if you want more than 45-50 mph you'll need either more pitch or more motor.

These motors are rated by Scorpion at 100 amps tops. I've run mine in the 130s and it doesn't get too hot, and in an OB application it may work okay. But remember that these motors are designed to run in an open helicopter and drawing over 100 amps continuous may shorten their life - or not.

Cheers bud,which motors and props would you go for then if i wanted hit min 50mph

[BakedMopar]

I am not familiar with the O.S. lower unit but the K&B stub shaft doesn't allow for props with larger hubs (447's and up). Is there a way to lengthen the stub?

Edit sorry I meant OS lower unit.

[F1 madness]

I am not familiar with the O.S. lower unit but the K&B stub shaft doesn't allow for props with larger hubs (447's and up). Is there a way to lengthen the stub?

Edit sorry I meant OS lower unit.

not sure,if i cant get that size prop on the stub that come with the unit ill have some machined at my local engineers,whose a friend of mine,nothing is impossible

[BakedMopar]

Don't take it the wrong way. I was asking cause I would like to run a bigger prop on mine. I'm sure anything is possible if you have the resources.

[F1 madness]

Don't take it the wrong way. I was asking cause I would like to run a bigger prop on mine. I'm sure anything is possible if you have the resources.

not taken wrong way,whats the biggest prop you can get on the standard shaft.
(how long is the hub is the max)

[BakedMopar]

I can only get a 445 on. The 447 and up has a longer hub and I can't get the whole nut on. Not too sure inexact measurements but I can gt them for you later if you need.

[F1 madness]

I can only get a 445 on. The 447 and up has a longer hub and I can't get the whole nut on. Not too sure inexact measurements but I can gt them for you later if you need.

that would be a big help cheers bud,iv got some cf props the 42mm,45mm,47mm, all have the same length hub LOL

[Darin Jordan]

I can only get a 445 on. The 447 and up has a longer hub and I can't get the whole nut on. Not too sure inexact measurements but I can gt them for you later if you need.

If you replace the stub shaft assembly with one from Hyperformance Products, you'll have plenty of length, and a stub that will last a LOT longer than the standard K&B:

http://hyperprod.bizhosting.com/psa35.html

Cool project.... I'm going to be doing a dual outboard conversion on a ProBoat Miss Geico later this summer, but I'll be using dual ProBoat Stiletto Outboards on it with dual BlackJack or Stiletto power systems... Should be a fun project!

[BakedMopar]

Thank you very much for the info Darin! I use my outboard on my rescue boat and I would love to use a 447/3 on it.