Prop size questip

[pribco]

What would be a good starting point for prop size on this setup.

Dumas40 deepve boat-32 inch
1300kv brushless
120 amp esc
2 lipo 3cellbatts in series--
surface drive
flex cable

Am looking for good safe size prop, not necessarily fastest.

Thanks

[m4a1usr]

A X440 could work but I dont know the motor you are planning on using. If its a big outrunner then your probably alright. Your esc is right on the edge.

John

[Boaterguy]

yeah, start with an X437 and move up. if it's an OR the 440 should be acceptable.
Think about getting a T180, they are only 70 bucks or so and from what I've heard they work great. another option is to get those SS 200's, get two of them just in case and you still pay the same as a t180.

[pribco]

Thanks, guys--

Motor is an OR but medium size--specs call for 75 A esc.

Not looking for great speed, but get up on plane, plus whatever.

Boater guy--where can I find the T180 and SS200??

BTW--I have a 42mm and a 45mm prop--I guess these are to big??

[Boaterguy]

SS200: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14500
T180: http://www.hobbyking.com/hobbyking/store/__8937__Turnigy_Marine_180A_Brushless_Boat_ESC.htm l
the 42mm might be good for SAW runs if you want to, although prolonged running will be a big strain on the components.

[LarrysDrifter]

I would go with the 180amp speedo. You can get it from the OSE store-which is preferred since Steve will aid you in warranty if something goes wrong. With the 1300kv motor you plan to run on 6s with, I would try an Octura X447/3. That also depends on the outrunner temp too, since they tend to run hotter than an inrunner with a cooling jacket. You might want to get an X445 prop too. I have a feeling you wont be using that motor too long though, since temps might be too high for your liking. A more reliable motor would be a Leopard 4082 1500kv on 6s with the above mentioned 3 blade prop. I could be wrong about the outrunner, but from my experience with outrunners in mono's, they get hot rather fast and hinder run time rather quickly after putting the boat in the water-even with a small maiden run prop.

[LarrysDrifter]

yeah, start with an X437 and move up. if it's an OR the 440 should be acceptable.
Think about getting a T180, they are only 70 bucks or so and from what I've heard they work great. another option is to get those SS 200's, get two of them just in case and you still pay the same as a t180.

Why buy two of these esc's with the higher probability one or both will blow when you can get one 180 and have it last a long time? Makes no sense to buy two cheap speedos,expecting one to fail and use the other as a back up, only to have it fail too,then your out 2 speedos, when you could have spent the same money on 1 good one that will last.

[pribco]

this is the motor--

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11182

[LarrysDrifter]

I have never run that motor,so I cant say how it will do. Someone else who has might come in and give you advise on it. My opinion is to get an inrunner.

[znus]

Dunno the specs on your lipos but in series they might have a hard time delivering the amps needed.

[785boats]

Pribco
I don't have the 1300kv version but I do have a couple of the 2200kv version that i run on 4s & a 40mm prop The water cooled motor mount keeps them cool enough. That's in a 25" & 27" mono. Not much of a comparison, I know, but it might give you an idea.
But here's a word of caution.
That little circlip that holds the shaft into the motor is in a very shallow groove. It takes all the force of the prop & I've had one twist out of the groove.
You need to run a thrust bearing that puts the load onto the motor mount, to take the load off that poor little circlip. This goes for all those Heli type of motors I reckon as they are not set up to absorb end loads in the bearings. Only lateral loads.
All the best.
Paul.

[pribco]

Crap-one more thing to be concerned about-

Where do I get thgrust bvearing?? Install??

[785boats]

Steve sells them here at OSE.

http://www.offshoreelectrics.com/products.php?cat=Motor+Thrust+Bearings

Paul.