58" Cat power plant recommendations

[Neogenesis]

Hey all,

New to these forums...so here we go.

I'm building a 58" cat, and have been toying with the idea of electrifying it. I'm not into the high end motors that cost $500+, however I was thinking of trying a different route and was wondering if anyone has done the same.

I have not been able to find any affordable inrunners to power a boat this size, however Hobby City had some very large outrunners that have great power and are proven in the giant scale 3D plane scene. They are the equivalent of up to 85cc engines. That coupled with one of their HV ESC's would provide enough power but other problems come to mind.

#1 would be coupling it to the rest of the driveline.

#2 would be cooling a motor of that size, whether it's water cooled, air cooled, or a combination of both.

#4 is the problem of a affordable water cooled ESC. If that can't be obtained I would most likely put some active air cooling on a ESC designed for a plane.

Let me know what you think, as I'm always open to constructive criticism. Is it feasible or should I scrap the idea and stick to the stock 26cc'er I have sitting on the shelf waiting for this project.


Thanks,

Scott

[Flying Scotsman]

What is your budget and anticipated speed. Big FE boats are very expensive to power. A boat of that size $1,800 minimum and the motor will be way over $500

Douggie

[Neogenesis]

Well....not sure if you read my entire post or not, but I'm exploring the outrunner possibility in boats. I can't say I've seen it any forums where it's been done, but I can't read everything lol.

Specifically, here is what I was looking at component wise. Again, these are starting to get popular in giant scale applications, and have been proven to be reliable. There are larger motors available, but I thought a 80cc equivalent
might be a bit much.

HXT 63-64-B 230Kv Outrunner
http://www.hobbycity.com/hobbycity/s.../18_or_5330/24)

Depending on what cell count I decide to run,

Turnigy Marine 180A Brushless Boat ESC

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8937&Product_Name=Turnigy_Marine_180A_Brushless_Boat_ESC

TURNIGY Sentilon100A HV 5-12S BESC (Ver4)
http://www.hobbycity.com/hobbycity/s...12S_BESC_(Ver4)

Again, this could be done very affordably if a outrunner can be used, and that is where my question lies. Does anyone here know if it's been done or those with more experience than I think it's feasible?

Oh...and about budget and anticipated speed, with these components running 20C 10s2P lipo with the above components, it could be done in the $600 ballpark. But what I'm willing to spend is the whole point of this thread. I want to know if it's feasible before I get to serious. Speed al long as it gets 30-40ish from the start I would be happy. I can tweak and play from there.


Thanks,

Scott

[Bill-SOCAL]

Most larger FE boats run on 10S, or even 12S for sport running, and 2P is the norm. The motor you noted is only 230 KV and most large FE motors are between 700 and 1000 Kv. We target between 28,000 to 35,000 rpm. The motor you note would give only 8500 rpm. That would likely not even move a boat that size.

Batteries alone, if you buy quality, will easily run $1,500 or more. Sure, you can do them cheaper, but a big boat is no place to cut corners. And a 20C would be the minimum. Most of us are going to 30C or higher if we can get them.

Cooling is another issue not to be taken lightly. The boat is a closed system (isolated from the outside) so cooling fans would do little more than circulate hot air. Water cooling is the norm.

Then, would this be your first high performance (or any) FE boat?? If so, then a big boat like this is NOT the place to start in FE.

Lastly, boats are a world different from airplanes in most every manner. What works for electric powered planes has little relevance to boats, and vice versa.

[Ub Hauled]

I large outrunner or two would work, keep in mind a couple of things:

1- buy a big outrunner w/ enough Kv to spin at least 25,000 RPM.
2- For a boat this size you'll need a lot of cells, I'd try to stay very close or above to 10,000mAh w/ at least 20-25c cells.
3- the outrunner mentioned above will not have enough kv for your application.

Speeds? I believe if you chose your parts right, in the mid 40's out of the gate and with some more fine tuning maybe in the low 50's. This is more of a guess since I don't know what motor you have selected and how you are going to prop her... I suggest a dual drive system, this is a big cat...
I have a 51" cat on a single 3060 that is under construction, I am planning for her to be in the high 40's out of the gates and after getting a feel for her, mid 50's.

[Doby]

Hey all,

or should I scrap the idea and stick to the stock 26cc'er I have sitting on the shelf waiting for this project.


Thanks,

Scott

Thats probably the best advice you gave yourself.

[Flying Scotsman]

One of the high costs,will also be the ESC none that you mention will cut it on a single drive. as the amp and voltage requirements will be high. Boats are amp hogs.

Douggie

[Neogenesis]

Thats probably the best advice you gave yourself.

lol...blunt but to the point!!

Thanks for the replies, like I said, was just exploring the options. I see the number one biggest problem with the large outrunners is the low Kv as they are designed to swing 20"+ props. Didn't think that one through enough before I posted

On the battery side of things, lipo's can be had cheaper than the Evo, TP, or MaxAmp route. They Rhino line of batts are very good and stand up well against everyday wear and tear. I've been using them in all my conversions and can't be happier. And at $110 FOR A 6S1P 5000mah pack, wow...it's a helluv a lot chaper than those name brand packs whose performance I've seen drop off fairly steeply after 50 or so cycles.

I've been bitten by the eletric bug lately on the fixed wing side of things, and with the LHS going belly up, I've been converting everything to electric. That is including my 35% fixed wings. I admit I have very little knowledge with boats, but do have a 45"ish gas mono that I play with currently. I've shelved the cat for the moment, but plan to get back to it once everything is converted over. I'm just not ready to drop 2K into a power system for a boat I don't really use that often.

I'm sure I'll be lurking around here though...lot of great information!!

Thanks for all the replies guys!!!

Scott

[Flying Scotsman]

Do not give up, start with a UL-1 and you will be have the FE pandemic.

http://www.offshoreelectrics.com/products.php?cat=115

Douggie

[Neogenesis]

Don't count me down and out....there is enough work in the cat that I don't think I could get it all done in time to run this fall anyway. It's only framed up, and with 3 kids, make it 4 if you count the Great Dane, it's tough to get much hobby time. I was just going to sell the engine and cnc clutch I have for it, and start gathering the required electric parts. However, I think I'll stick to gas with that project. I've got this addiction for large scale projects.

As far as the UL-1, I think my wife would kill me if I brought home yet another project. I've been thinning the fleet as is.


Scott

[Bill-SOCAL]

As I noted above, the universe of what works well n planes is larger than what works in big boats. Certainly there are inexpensive lipos out there, but the environment of a large boat is severe to say the least. While those packs may be perfectly acceptable in even a large plane, I would be reluctant to use them in a bigger boat.

Take Douggie's advice, get the UL-1 or maybe even an SV27. Great places to learn the FE ropes.

[Flying Scotsman]

Scott, there are devious means to bring in the next project. Just post an inquiry...you will have many replies. We look forward to your next project

Douggie

[theShark]

Scott, this guys setup might be of interest

http://www.rcgroups.com/forums/showthread.php?t=1043673

[red6]

Scott, this guys setup might be of interest

http://www.rcgroups.com/forums/showthread.php?t=1043673

I was just about to post the same link.

I was curious to see if anyone else has tried any of the outrunners in a larger boat.

I already have a titan 29 with a neu 1515/1y but the chop on my lake keeps me from going full throttle most of the time. I only get to run the snot out of it on calmer days. I have a razor 45 that flies over the same chop that the titan likes to wipe out on.

[Neogenesis]

You've made my ears perk up here again!!!! lol

I'm glad to know that it can be done.....I'm amazed at how much smaller of a outrunner he's using to get the job done through. I would have thought a larger unit would be in order. More Kv with a smaller motor...guess that's the ticket!!

Very Very interesting.

And thanks for the link!!!!!

Scott