Let's See How Smart Everyone Is...

[Doby]

Motor suggestions please;

Requirements;
1) Brushless outrunner
2) Relativily inexpensive
3) Power will be a 2S 5000mAh 20-30C Lipo
4) Pushing a 56" mono, 13" wide
5) Weight of boat will be approx 30 Lbs
6) Turning a (approx) 35mm prop.

Lets hear your suggestions.

[BakedMopar]

I should give my mouse DeCon for clicking on this thread.

[Boatman]

Sad thing is if we could get someone to machine and produce a quality transmission (geared) for us that would be possible. Some of those heli's are getting pretty big and powerful.


Edit: Your speed goal was not given. :)

[Flying Scotsman]

Not cheap....A Honda 50hp outboard...might be a little heavy on the transom though

You have to use a transmission and a larger 3 bladed prop...speed 5mph ...smart ass Douggie.
Edit
or a motor with about 100kv... and two dogs with a towing rope.... speed 1.5 mph... double smart ass Douggie....Love you Doby

Douggie

[domwilson]

I would start with a 32' cat. Twin 850 hp engines and a good tow rope. Should get you over 50 easily...

[Doby]

Ironically, this is for an actual project of mine....speed expectations will be around 5Mph.

[Jeff Wohlt]

If those are your speeds then a good, cheap big outrunner with 6S could get you there with a big prop. What is it a kiddie ride..LOL.

[befu]

Motor suggestions please;

Requirements;
1) Brushless outrunner
2) Relativily inexpensive
3) Power will be a 2S 5000mAh 20-30C Lipo
4) Pushing a 56" mono, 13" wide
5) Weight of boat will be approx 30 Lbs
6) Turning a (approx) 35mm prop.

Lets hear your suggestions.

5mph? Will it even get on plane? Or is it a displacement hull. 30 lbs is really heavy for a 56" mono. Heck, even the old dumas 55" hull was about 9 lbs and that is one of the heaviest boats I have seen. Nice, but really heavy.
I wouldn't think it would be that hard. Why do I say that?

Back in the old gas days before zenoah and modified homelites, you could get a large heavy boat going mid 20's with a cheap weed eater. Some faster, but I remember this 55" cat that we made out of a dumass 55, cut in half and used marine 1/4" ply for the sides and tunnel. I think it weighed in around the mid 20's. We pushed it with a stock 25cc weed trimmer, was slow and slugish but it planed out and probably went low to mid 20's. Used a larger prop, maybe 482 to 472 octura. Those weed trimmers only put out about 3/4 to 1 1/4hp.

So, onto your idea. 30 lbs is really heavy, not sure it will plane at 5mph. But on 2s and a x482 prop, 300 kv gives a theoretical of 9.5 mph, which should put you close.
http://www.hobbyking.com/hobbyking/s...idProduct=5204
This is a 50mm dia outrunner at 270kv and it is on sale at $26. The problem is the wattage available on 2s. 7.4v at 60 amps is only 444 watts, or 6/10 hp. Might work for 5 mph.

Here is a 63mm outrunner, 235kv for $45
http://www.hobbyking.com/hobbyking/s...utrunner_235Kv

A 50mm turnigy, $40 and 270 kv
http://www.hobbyking.com/hobbyking/s..._270Kv_/_2100W

I think it is doable, but need more information. What hull are you looking at? Planing or semi displacement? Like a sport fisherman? Maybe twins would be in order. Is that battery set and only one? What run time or are you looking at 3-4 minutes for up to 700 watts available? Doable, but that is a lot of amps for a 2s setup, and a lot of weight for a 56" boat.

Sorry for a lack of emoticons or quips in this post, kind of broke with the above tradition on this one.

Brian

[Doby]

Thanks Brian, thats what I was looking for.....kind of...

This is what it is going to power..........as an auxillary motor

[befu]

Oh, that changes everything. Yeah, I would think that would work out no problem.

I have seen a couple of discussions over on rcgroups on the scale section about how much power to put into a given hull. They even had equations with variables and technical sounding stuff! They might be able to help you out there.

You have a very efficient displacement hull there, should be easy to power with a 2s battery and have it motor around for a long time.

Opps, just noticed the 35mm prop, missed that the first time around. You are going to need a much smaller outrunner. I wonder if one of those mystery 2836-1700 kv with 30 amp esc would work for this? They turn a 35mm prop on the cracker box easily. They also make a 1000 kv version which might be better.

Sorry I missed the 35mm prop detail.

[Jacked1]

Just get a cheepo drill for 20 bucks on ebay and you could use the chuck to go strait to the drive shaft.

I used two for my 2nd version of my old pos villian when i was 12! Didn't use the chuck tho.
And i used a trigger from the drill as a speed controller. I think it would be a good power system for a retrieval boat and a small 12v lead acid battery.

[Flying Scotsman]

What a great looking boat, is that scratch built?

Douggie

[Doby]

Just get a cheepo drill for 20 bucks on ebay and you could use the chuck to go strait to the drive shaft.

I used two for my 2nd version of my old pos villian when i was 12! Didn't use the chuck tho.
And i used a trigger from the drill as a speed controller. I think it would be a good power system for a retrieval boat and a small 12v lead acid battery.

Hmmm...interesting.......never thought of that, I do have a few old drills laying around.

[Doby]

What a great looking boat, is that scratch built?

Douggie

Nope, its a kit , on order from a company called Robbe....they are in germany (I think) should be here in a few weeks.

Should make a great winter project

I have enough FE boats ,,time to get back to some scale and sail boats!

[Jacked1]

Yea the drill would not have a problem moving that prop.