Newbie Building a fast electric and needing help.

[mscrampton]

Thanks Harry!! Your the best. I was actually planning on taking your advice on the battery setup and charger. So am I right?? I want (4) 4s1p packs to "in line" two side by side?? I will have the drive hardware laid out with clear picks of the planned positioning for you review in the next few days. Already laid out the (2) large water outlets, turn fins and stinger. Should receive the rudder and trim tabs tomorrow. Then on to the moter and shaft construction. If you don't mind I will keep in touch as I progress (it's good to have a mentor).

Thanks Mike

[Old Sloppy]

Yes, get (4) 4s 5,000 mah packs, a x457 prop to start. this will get you 53.1 mph, 23,843 rpm, 156.2 amps, 3.84 minutes run time, 4,996 watts.
Steve's web sight shows 5,000 watts with 6,000 burst, So I am sure this combo will work great on 8s2p.

later you may want a y557 prop,but only If Steven tells you the motor will run O.K. on 5,324 watts. This is a lot of watts, so check with Steven first. That would produce 58 mph, 23,679 rpm, 167.1 amps, 3.59 run time.

Please notice the run time reduces as your speed goes higher.
Normaly you don't run at full throttle all the time, so actual run time on the water will be greatly increased.

Harry

[mscrampton]

THANK YOU SIR!! I feel like I'm actually learning something sitting at the foot of the master :)

[mscrampton]

Hey Sir! Once more a question for my Guru. The 4s1p packs come as 20c or 25c which should I get and can you explain the constant vs Burst discharge thing. Also can you remommend which charger/discharger??

Thanks,

Mike

[Old Sloppy]

40c batteries,
http://www.hobbyking.com/hobbyking/s...dProduct=16790

get some connectors too
http://www.hobbyking.com/hobbyking/s...irs_20pc_.html

red shrink wrap
http://www.hobbyking.com/hobbyking/s...D_b_1mtr_.html

black shrink wrap
http://www.hobbyking.com/hobbyking/s...ACK_1mtr_.html

your motor will draw far over 150 amps. lower "C" rated cells are not up to the task.

Constant means the maximum amps that you can use, 40c times 5,000 mah = 200 amps.
Burst is the point where instant perminent damage happens (puffs up) 50c times 5,000 mah = 250 amps.
this applies ONLY if cell tempature is optimum (120 degrees F ) if cell tempature is lower, so is the "C" rating also lower.

[mscrampton]

Okay!! Not quite as promised because I just couldn't wait, what can I say. The pictures should show fairly clearly that all of my drive hardware has been installed (waiting on the delivery of my water line connections for the pickup lines. I went so far on my own as to mounting my stuff tube and support bar ready for the shaft length measurement. All hardware was mounted sealing with silicon as well as all joints inside the hull. I then sprayed the transome with the rustoleum black rubberized watersealer. I felt it provided a more even seal rather than smearing everything with silicon or epoxying everything PERMENANTLY in place. I think I did a pretty good job so far?? Waiting to order my battery packs in the next week or so (the boss is starting to look at me funny for the expenses :) then I can mount the motor and packs in the most balanced potitions. If you can see the black marks on the stringers that is the point of balance about 16 1/2" forward from the transome. I figured to pack a couple of "pool noodles" forward for added flotation. I am going to go with Old Sloppy's recommendation of 4- 4s packs in the 45c configuration using an Octura x457 prop. I was a bit dismayed after reading an article about finishing berilium/copper and how toxic the dust is. So I'm looking for a source for already balanced and polished props. The size (even in the ballpark equivalent on al sites seem to be sold out). I was a bit bummed out today to find out that the planned OSE offered Gunert whip antenna are no longer available, any other suggestions?? Pictures attached.

[mscrampton]

Opps!! Thought I'd also pass on a link that I have found VERY helpfull along with one more pic.

http://fastelectrics.net/monohulls.php

[Old Sloppy]

the gap between the collet and the stuffing tube is too large, I would increase the length of the stuffing tube to leave a 1/4" gap.
If possible move the aluminum support bar closer to the motor.
How are you setting your C/G without batteries or ESC ?
a single peice of black foam pipe insulation 54" long is all that is needed to float your boat.( don't ask me how I know this )
a pool noodle is over kill and adds unwanted weight unless it is very short.
speaking of weight, I set my C/G with everything loosely installed in the hull, including floatation and hatch, batteries, battery shelves, esc, motor,tape,wires, graphics, etc.
if it then ballances, I hard mount the motor, stuffing tube, etc. if not move things untill it does ballance.
set the C/G no higher than 16" (29%) down to 15.5" (28%) 16.5" is too much (33%) you want the nose light, to be free running and reduce amp draw.
at the speeds you will be running, you will not need to fear a blow over crash.
WARNING : a wet running hull will increase amps, this is bad.

[mscrampton]

Dear Harry,

Guess I wasn't clear enough I took a rough (pretty dang close) estimate of the gap based on the POB of the beginning hull. The motor has not yet been actually mounted because I want the rest of the weight first (batterries etc.) One I have everything THEN I will actually mount the motor. Advice on the noodles so noted. I will of course also be adding the bow hook. I always wondered how you would retrieve the boat if you didn't have a boat to get it :). I was more interested in the critique of my hardware placement?? Did I do good?? My gap between collet and stuffing tube will probably be more in the 2" range but by the info I had obtained this was more then acceptable. It is almost a straight shot from the the transome. I actually had the support bar farther down but I felt it put to much bend in the stuffing tube. Now even without grease it spins smoothly.

[iridebikes247]

Hey bud, boat is looking good! The gap between the stuffing tube and collet is super important as others have said. You can run into problems with the shaft flexing between the collet and stuffing tube putting an awesome amount of load on the bearings/stuffing tube. If possible you'll want to reduce it it will really help man. If not you can install a flex shaft saver thats only a few bucks and it will help clamp the flex in one area reducing the wacking/whipping of a flex thats too long. Good luck and keep us updated!

[mscrampton]

Thanks and noted. If the final gap is to much then I will mount a new stuffing tube no big deal. Working on the motor mount so it will fit properly between the stringers. Electronics box fits perfectly (or will after I shelf the stringers).

[Old Sloppy]

The motor has not yet been actually mounted because I want the rest of the weight first (batterries etc.)

This I like a lot .......you might not change the stuffing tube, just slide the motor rearward to with in 1/4" of the stuffing tube.

as for retrieval (i am ashamed of myself because I belive I can't spell well enough)
I use a "wal-Mart" one man inflatable boat, cost $10 ,
I simply paddle with my hands ( cold water makes them sting, ouch ! )

as for your hardware, looks good, i think the trim tabs could be closer to the chines, away from the prop and I think the turn fins are only needed for racing applications, not really required for sport running.

having said that, I use 4 trim tabs on my 50" Apache (aeromarine laminates of course) 2 are near the chines for turning, 2 are somewhat closer to the prop, for strait running "angle of attack"
if they are too close to the prop, the prop will slip more than desired, so watch out for that potential issue.

[mscrampton]

BEC or not to BEC??? That is yet another question.

First - I have ordered 4 of these

http://www.hobbyking.com/hobbyking/s...arehouse_.html

I will get my order in for the Swordfish 300 Pro ESC within the week. Steve has also recommended

http://www.offshoreelectrics.com/pro...d=hef-Cap8mm-2 CURRENTLY OUT OF STOCK

now given the perloined diagram from Castle Creations that I have attached do I need a BEC ??? And exactly how do I wire this bad boy given Old Sloppy's (Harry the Master) to acheive the 8s2p set up with two running serial and two parellel ?? Don't want to fry my eyebrows :) And my Guru you said you had a recommendation for the charger system....care to share???

Anyway finished the motor mount and fits like a glove. Batteries arrive this week so I'll get a better idea on the weight distrubution. Working on the servo try et all now as well as my carbon fiber lid. Always looking to upgrade and improve and so far I have been lucky. Anyway should have the next phase ready to photo and pass on. "like a Phoenix the Sea Raven begins to rise" . By the way the avatar is the topside decal of the boat and cover the entire forward deck.

Mikeccbec_multi-pack-large.jpg

[mscrampton]

Okay! Got my head chewed for ordering the wrong batteries so I have corrected once again. 4 5s1p 5000Mah 45c packs with the Castle Pro High output BEC and a Hefei high voltage capacitor bank for parrellel packs

[mscrampton]

Okay Guys!

Everything has really set up nicely so far but the wiring is throwing me. I have attached a diagram of how I think the packs setup but I can't figure out the addition of the capacitor board that Steve recommended. I have ordered four 5s1p 5000Mah 45c packs as again Steve recommended. Any light you can shed would as always be much appreciated. by the way my gap from collet to stuff tube end is 1/4" as you advised.

As Always,

Mike
Untitled.jpghef-Cap8mm-2_medium.jpg