Help me spec out my power system

[T-Man]

Hi, gents; new member here.

I have some RC experience (nitro boats and planes), but I'm new to FE boats. I currently have a PB Shockwave 26, and it's been enjoyable to run, but the fun doesn't last very long, and I wish it was much faster. I estimate its top speed at somewhere in the neighborhood of 20 mph and run time is only about 5 min. I'm running a 6 cell 5000 mah NiMH batt, not Lipo on this boat. The X435 prop is the only part of the boat that isn't stock.

Anyway, I just bought an Aeromarine Popeye's .21 cat hull (29" L X 11" beam) and I have a Graupner GTX820 outboard without motor I'm mounting to it...
http://www.offshoreelectrics.com/pro...od=grp-2380-11
This outboard has the flex shaft in teflon tube drive system, not a gear driven lower, which should improve reliability and reduce resistance for better speed. Even though I could probably get more speed from an inboard setup, I just like the scale appearance and bolt-on simplicity of the outboard, without the need for a stuffing box and additional running hardware.

Anyway, to my questions...

If you were me, what motor, ESC, battery pack(s), and prop would you pick for this hull and outboard combination? Of course, I want to run Lipo batts in this boat. Obviously I want more speed than the Shockwave 26 delivers, but my priorities are the following (in this order):

1. Dependability/ longevity. I don't want any cheap parts or unreliable components I will have to replace anytime soon.
2. Reasonably good speed with reasonably good run time. By that, I mean I would be happy with at least 35 - 40 mph, and more than 5 min run time, preferably 10 min. I want impressive speed, but I'm not necessarily looking to get as much speed as possible at all cost. More speed is great as long as it doesn't come at a huge penalty in cost and run time. I would much rather have 10 min run time with a top speed of 40 mph than 5 min run time and 50 mph, for instance. I don't plan to race, just have fun.
3. HIGH QUALITY brushless motor and ESC. I'm willing to spend more if doing so buys quality, and I want to avoid as many parts made in China as possible for philosophical reasons (though I know I may have a hard time avoiding China - made parts in my radio, receiver, servo, and batts). At minimum, I don't want a motor made in China.
4. Cost. I don't want to go nuts, but I'm willing to spend more to get more of the above.

The motor mount screw spacing on the outboard appears to be 25mm, and the flex shaft coupler adapts to motors with 5mm shafts. Although the prop shaft is threaded for 4mm props, I have a 4mm to 3/16" prop shaft adapter, so I can use any prop for 3/16" shaft diameter.

Any explanations for your choices is much appreciated, as I don't know what to look for in the motor KV ratings, which motors are compatible with which ESCs and battery packs, amp ratings, etc. Like I said, I'm new to FE boat setups.

Thanks in advance for your help!

Ted

[BakedMopar]

To run 10 minutes at full tilt at one time will put a beating on any electronics. Even top notch equipment has it's limits.

[Fluid]

Ted, where in Texas are you located? These is an active FE club in the Houston area, we may be able to assist.



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[Flying Scotsman]

I understand your love of a scale outboard but for a cat...HMMMM....I would look at a conventional propulsion system...way more options....you are not going to have much luck, if any, in finding a motor that does not use some Chinese components. Fluid is one of the most knowledgeable cat guys on the planet.

Douggie

[forescott]

How about the electronics from the new supervee 27r? 1800kv motor on 4s? Is there room under the cowl for a water jacket?

[T-Man]

Ted, where in Texas are you located? These is an active FE club in the Houston area, we may be able to assist.



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I live in McKinney, NE of Dallas.

[T-Man]

I understand your love of a scale outboard but for a cat...HMMMM....I would look at a conventional propulsion system...way more options....you are not going to have much luck, if any, in finding a motor that does not use some Chinese components. Fluid is one of the most knowledgeable cat guys on the planet.

Douggie

I already have the outboard lower unit with cowl, minus motor, and yes, even though most catamarans use inboard propulsion, it's not at all uncommon for full scale cats to be powered by outboards. Usually the larger cats use 2 or even 3 outboards, but some of the smaller cats are powered by a single outboard. I've run a nitro outboard on a 40" cat before, so I know it will work just fine. I can move the radio box and batts further forward to balance out the weight of the o/b on back. I'm not necessarily going for 100% scale accuracy here; just "plausible scale-like" appearance.

[T-Man]

How about the electronics from the new supervee 27r? 1800kv motor on 4s? Is there room under the cowl for a water jacket?

Yes, there's plenty of room under the o/b motor cowl for a water jacket. I was thinking about maybe the Neu 1515 w/ 6s lipo. It will fit. Do you think this is too much motor?

[Fluid]

We have several club members in that area. Send a PM to Richard (txboatpilot) or Gilbert (alphadog). You can hook up with them locally - both are great guys with a lot of FE knowledge. Or PM me and I'll be glad to answer questions.



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[T-Man]

To run 10 minutes at full tilt at one time will put a beating on any electronics. Even top notch equipment has it's limits.

I don't necessarily expect to run wide open, full tilt for the entire 10 min, but I sure wish I could get more than the 5 min run time I'm getting with the Shockwave 26. That has been the main disappointment I've had with FE so far. I just can't stay on the water as long as I can with my nitro boats unless I invest in a whole truckload of spare battery packs.

[T-Man]

We have several club members in that area. Send a PM to Richard (txboatpilot) or Gilbert (alphadog). You can hook up with them locally - both are great guys with a lot of FE knowledge. Or PM me and I'll be glad to answer questions.



.

Thanks! I may do that when I get closer to completion. Right now, I'm nowhere near ready to get this boat wet anytime within the next couple months. I have a large scale nitro airboat project that I'm working on ahead of this one. I'm just accumulating parts one at a time for the cat at this stage.

[T-Man]

Bringing this back to the top. Any and all advice is greatly appreciated. Would like to see as many different ideas as possible before I make my selections.

1515 / 6s?

1512 / 4s?

KV?

Starting props?

FYI, the outboard has the same motor mounting pattern as inboard mounts (25mm mount screw spacing, adapts to 5mm motor shafts) and has enough room under the cowl for a motor that's about 2" dia X 2.7" L max, including cooling jacket. The cavitation plate on the lower end will clear props with a max dia of about 42mm (1.65").

Thanks!

[v-spec]

No offense but i don't think you are going to be running your boat with NEU motor and 6s for 5 minutes let alone 10 minutes. If you do get 5 minutes out of it I don't think it's going to last very long no matter what country the parts are made in.

Everyone who gets into FE boating comes in wanting 10 minutes run time but it's just not going to happen. And if you think you will just put around partial throttle going slower to get more runtime you'll just burn it down quicker. Most of us run 2-3 minutes max and things can still heat up in a hurry in that short time.

I'd probably pick up the proboat bj26 motor and esc and maybe you will get 5 minutes out of that setup though I'd still cut it short and be safe.

[johnf]

Ted, where in Texas are you located? These is an active FE club in the Houston area, we may be able to assist.



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Are you in the Houston area? I'd love to come out and watch some racing if so. I'm only about 2 hours from Houston.

[T-Man]

No offense but i don't think you are going to be running your boat with NEU motor and 6s for 5 minutes let alone 10 minutes. If you do get 5 minutes out of it I don't think it's going to last very long no matter what country the parts are made in.

Everyone who gets into FE boating comes in wanting 10 minutes run time but it's just not going to happen. And if you think you will just put around partial throttle going slower to get more runtime you'll just burn it down quicker. Most of us run 2-3 minutes max and things can still heat up in a hurry in that short time.

I'd probably pick up the proboat bj26 motor and esc and maybe you will get 5 minutes out of that setup though I'd still cut it short and be safe.

No offense taken, and thanks. Like I said, I'm new to FE, so I don't know what to expect for run time. Maybe my expectations are unrealistic, but damn, it's pretty disappointing to drive all the way to the nearest body of water only to run for 3 min! Is that really the way it is? Can I keep running if I take multiple batt packs, or does everything heat up to the point that I have to wait another hour before running again?