Dumas sk daddle 2

[adam beck]

Hello guys not sure if this is the correct place but I need some help. I originally planned to run a nitro motor but have changed my mind and want to build it with a brushless drive train. I am thinking of running a 1800kv 36x74 brushless motor.. I am looking at a submerged drive. I think I want run a wire drive set up with a three blade prop. What hardware would you guys recommend? And what size prop? Do you guys see any problems?

 

[larcor69]

I built one of them that's not complete yet I really want to run a four stroke engine in it always keep my eyes out for a decent used about a 60 or 70 size four stroke

 

[RaceMechaniX]

Hello Adam,

Are you looking for a power system that just cruises around or something a little spicier?
Do you have batteries already? or any of the other components?

 

[Jerry Dunlap]

For batteries, I would recommend 2 2S 5000 mAH packs hooked in series. This would allow you to place the batteries on each side of the motor. A transom mounted strut would allow for prop depth/angle adjustment. Hardware for a 20 deep vee would work. Personally, I'd go with flex cable drive.
JD

 

[adam beck]

For batteries, I would recommend 2 2S 5000 mAH packs hooked in series. This would allow you to place the batteries on each side of the motor. A transom mounted strut would allow for prop depth/angle adjustment. Hardware for a 20 deep vee would work. Personally, I'd go with flex cable drive.
JD

I have two 2s 5000mah packs so that works. Yes to the spicier side of things we have a large lake in the center of our town so I have plenty of room. Why the flex cable? From what I have read these have to be removed after every run. This of course could be misinformation. I have found another thread that said an actual 440 3 blade would be something to try. I have to learn how to balance and sharpen props. I also have a 150 amp 2-6s esc not motor or hardware as far as prop shaft,stuffing tube, strut,rudder or

 

[adam beck]

Hello Adam,

Are you looking for a power system that just cruises around or something a little spicier?
Do you have batteries already? or any of the other components?

Something a little spicer but not crazy I have a couple 2s batteries 2 2200 mah and two 5200mah I have a 150 a 2-6s water cooled esc but nothing elee

 

[RaceMechaniX]

So you can easily make a 4S 5200mAh setup with those cells and run the 3674 size motor with a KV in the 1500-1900 range. That will not tax the ESC beyond it's 150A limit and you can up to make it plenty fast.

Definitely go with a flex cable, .150 with Teflon tubing and a 3/16" stub shaft will work nicely.

 

[Jerry Dunlap]

I have two 2s 5000mah packs so that works. Yes to the spicier side of things we have a large lake in the center of our town so I have plenty of room. Why the flex cable? From what I have read these have to be removed after every run. This of course could be misinformation. I have found another thread that said an actual 440 3 blade would be something to try. I have to learn how to balance and sharpen props. I also have a 150 amp 2-6s esc not motor or hardware as far as prop shaft,stuffing tube, strut,rudder or

You can remove the cable after you have finished running for the day and grease/oil it at that time. A motor I have had success with is the Dynamite 2000 Kv from Horizon Hobbies.
JD

 

[adam beck]

Thanks for the info guys. You guys recommend a place for the strut and rudder? I have looked at the speed master stuff. I am gonna make a turn fin for the bottom and possibly some trim tabs. I have access to a ton of stainless strapping at work of various thickness and widths thanks again for all your help.

 

[Grimracer]

I would do a sub surface drive with a hard shaft... (maybe wire drive)

I would set the leading edge of the prop 15% from the transom and to starboard about 3/16 inch.

If your not racing the boat this is have the best FUN factor! The boat will accelerate like crazy and not blow over as easy doing it!

Grim

 

[adam beck]

Grim racer i appreciate the advice on the set up. What about center of gravity? Nothing is mounted yet so if a can set it up right the first time that would be great. Does a wire drive set up need the same maintainace as a flex cable. Hard drive you mean solid shaft in a stuffing tube with a u joint at the motor correct?

 

[Grimracer]

Adam,

Thanks for the questions.

I would start with the CG at 30% from the back.. (it might be a tick nose heavy but with FE you have GOBs of power).

Wire drive and cable are about the same to me.. I remove every 5 or so runs and re-lube

I do mean a .187" hard shaft with a coupler.. NOTE.. it has been my research that a U-JOINT typically is not designed for high RPM (I am surprised they work at all in RC boating...LOL) .. A cruciform joint is better but not by much.. I would go old school and make a HARD coupler.

Grim

 

[adam beck]

Grim could you explain what a hard couple is. And with a hard shaft the only adjustment I would have would be something trim tabs if I put them on. What are the bennifits of the hard copper over the flex or wire drive. Thank you for answering all my questions. I really appreciate it The setup and the building are the most fun for me. Does the octura 440 three blade so about right

 

[Grimracer]

Just a shaft coupler made to setscrew to the hard shaft as well as the motor shaft..

With this you have no need to make shaft angle changes.. truth is you will not have to worry about prop depth all that much either..

Tuning will be
Prop (440 is a good start)
Rudder
Trim plates
Turn fins
If the boat has a turn fin center of the keel, under the hull, USE IT!

Grim