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Thread: In need of run times for big/huge electric hulls

  1. #1
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    Default In need of run times for big/huge electric hulls

    Ok guys, I'm after some ideas of run times. Seems like big electric deep-vee hulls are few and far between. But I'm building one anyway so here's what I want. Give me any info you can on your boat and run times. What kv motors, c rating and mAh and number of cells for lipos and type of drive you're running.

    I'm building a 69" MHZ Hunter. Direct 760kv Scorpion motors hooked up to the Merc drives. HeiFi Swordfish 300a Pro's and looking in the 10s 10000mAh area for batteries. Undecided on props as of yet. I have no freakin idea what to expect as far as run times.

    Now equally important. What I don't want. I don't want, "your an idiot you need to run gas on a hull that big" or comments like "your run is gonna be sucky minutes per charge". I want actual experience and don't need a sermon on how many kidneys I'll have to sell on Ebay to pay for the project. Money is not a factor here. I run big electric 5th scale trucks so I already have a selection of batteries that will be used on both truck and boat. So sorry for sounding like a jerk but it seems like every forum I post on I never get any valid info. Just a lot of the above statements about how it would be better gas and blah blah.

    I'd even take some run times from you big cat guys. I'm looking for stats from hulls 55" and up. I'm not looking for going out and running for 3 days. But I honestly have not gotten any constructive responses to what to expect for times. So I'm looking for some ballpark numbers.

    Anything you guys can offer up would be appreciated!

    Thank you in advance!

    Mike

  2. #2
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    HI Mike
    A valid and important question is what sort of speeds you are after as the faster you go, the shorter the runtime. If you are looking for 60 mph plus you are only going to get 2-3 mins. If you are looking at fast scale speeds the runtime will increase but much more than 5 mins would likely be unrealistic on 10000 mah. Any info offered up will only be a ball park as the drives you are running will have much bigger energy losses over flex shafts. You may find that going to 8s will be better depending on the speed you want and the props required.
    Can we assume you are planning to run 10s 10000mah on each motor?
    Are the drives 1/4" or 3/16" shaft? This will determine what prop sizes you will have to work with, i.e. 1/4" shaft means you will need larger size props 65mm and up.
    There are a few guys with big hulls that may be able to get close to what you are wanting to know.
    My own biggest is a 45" hull (ex gasser) running a TP 56110 650 kv. On 10s 5000mah and an X455/3 speeds are around 55 + mph and use around 3000mah for a heat race (I only race it). I have a 42" Osprey with a TP4070 440kv that runs for 20 mins on a prather 245 and 12S 20000mah, which I use for offshore endurance racing.
    I know my boats are a fair bit smaller, but you do have the room to put more batteries in that hull for longer runtimes if you wanted.
    NZMPBA 2013, 2016 Open Electric Champion. NZMPBA 2016 P Offshore Champion.
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  3. #3
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    Peter,
    That's pretty much perfect as far as what I'm looking for. I know with boats there are soooooo many variables. But I'm just looking for ballpark numbers for sure.

    And I should have clarified, I will be running a 10s 10000mAh per side. One for each motor. And yes, the hull is huge with lots of room so I can add more if needed.

    The shafts for the props are 1/4".

    I'd honestly be happy with 50mph. And if I could get around 15 minutes run time? I'd be over the moon happy. I'm hoping that's not too out there but we'll see. This is my first big brushless boat so.

    I had a twin Zenoah set up to go in it with a gear box and the works. But I use a chair to get around so trying to pick up and maneuver that big heavy hull with that set up and not fall out of the wheelchair was a joke. The brushless setup just suits me for ease so much better. And it'll be nice not to end up covered in gas and oil crap! LOL!

    Thanks again Peter for the response. Looking forward to more.

  4. #4
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    One reason you don’t get a lot of responses is not because folks want to criticize you, it’s because very few boaters here have experience with what you want to do. Most here either race, or want very high speeds - not your goal. Too, because the boat exceeds the insurable length for most (60”) few run boats that size. There are a few who do, but specific experiences will, as you’ve discovered, be few. Lots of opinion though......

    But to specifics, 15 minutes of run time on 10S means an average amp draw of 30 amps per motor. That won’t get you anywhere near 50 mph.

    .
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  5. #5
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    I have built several big monos and a cat. But mine were for racing. I used a 680kv motor on 10s 10,000 and a big gas prop. I got 65 mph and 3 minutes with that set up but could have got more if I wanted to prop down. Your doing twins which helps a good amount with pushing a bigger boat. I don't know what prop your set up likes but I hope there big ones. Your going to have to build the boat and run the packs you have and see what you get. You will have to play with props too. I sell batteries and can make you some 5s 16,000 or 22,000 mah batteries for you to get some more run time if that helps.

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    Quote Originally Posted by MarkF View Post
    I have built several big monos and a cat. But mine were for racing. I used a 680kv motor on 10s 10,000 and a big gas prop. I got 65 mph and 3 minutes with that set up but could have got more if I wanted to prop down. Your doing twins which helps a good amount with pushing a bigger boat. I don't know what prop your set up likes but I hope there big ones. Your going to have to build the boat and run the packs you have and see what you get. You will have to play with props too. I sell batteries and can make you some 5s 16,000 or 22,000 mah batteries for you to get some more run time if that helps.
    Mark, so you make 5s 16,000 MAH Batteries? Would they be heavier than 2. 5s 5000 MAH revo lipos?

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    Yes they would but you got a big boat.

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    Mark,
    I’m interested in what you can do for 5s 22000mAh batteries. Mainly on price. I’d need 4 of those for 10s on each motor....and probably more like 8 so I can have more than one run. Also might have another buddy interested depending on cost. I know batteries aren’t cheap
    Last edited by 5150WS6; 08-15-2019 at 05:26 PM.

  9. #9
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    I can do $350. 00 each if you buy as many as you say. Normal retail is $425.
    Specs are 52x92x200mm 2250g

  10. #10
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    Hi there i own a sv43 outerlimit scale model made in germany by Andy
    Its a 1.80m 18 kg but light running stept big boy hull.
    Motors are 2x TP 5850. 600 rpmv
    Controllers 2x swordfish 300 a
    Drives strut ( mtc from germany)
    Running time 10s 5000 mah zippy flightmax per motor 4,5 min
    When using my normal setup off 2x 10s 5000 mah zippy flight max ( budget lipo setup) per motor this ship weight is 18 kg and runs 95 kmh for 9+ min. running 6514/3 propshops. Alternative props i use are the octura x470 same speed ,better accelleration from start but little less running time.
    Top speed with the same 1000mah per motor setup using only andy brown 7016/3 propshop props was close to 115 kmh but only for an few short speed runs because of the much higer amps
    When running a non stept hull and also z drives the amps will be higer because of the energie loss in the drive and water friktion.
    I hope this info can help you.
    https://youtu.be/dS7zVzr9SHE
    The hull corner handeling is what it is for a stept scale hull but also was not yet optimal trimmed in this video.
    Here is another one exactly the same setup run by a guy in France , nice slomo video https://youtu.be/3zpqacQQu9E
    Greatings Ramon ( from the Netherlands)
    Last edited by rscheffer; 08-23-2019 at 06:09 PM.

  11. #11
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    Ramon!
    Thank you for the post! And thanks for the video links.

    Just to clarify, you are only running 5000Ah total or doubled at 10000mAh?

    Very happy to see that some decent speeds and run times are achievable!

  12. #12
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    Normal 10000 mah per motor .9+ min running time
    4x10s in total 6kg lipo’s is my normal setup , i like the long runnig time and its not as hard on the lipo’s
    But the 5000 mah per motor is also very good 4.5 min running time

  13. #13
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    One thing that I want to know is, on the outdrives, are the props surface drive or are they submerged? With a surface drive you can run a a much bigger prop than a submerged drive, the submerged drive will draw a LOT more amps. A surface drive will be much more efficient and will offer better speeds and better runtimes.
    We call ourselves the "Q"

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    Madmike—
    That’s a good point. I know the MHZ drives run props semi-submerged. Not as much as a surface drive I’m sure but not completely submerged. So that will draw more amps out of the hole probably until get gets up on plane. Something I’m willing to deal with for the killer scale looks of the drives! :)

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    Thank you for all the posts and reply's. I know this is a tough topic because it's so situational. Water, props, throttle management, drive type.....so many variables. But this definitely gives me some hope that I'll be good to go for at least close to 10 minute run times I think. Time will tell for sure.

    I just picked up the new Futaba 7PX and will be running temp, voltage and gps sensors so I can really get a live idea of run times and be able to monitor things closely......specifically battery voltage!

  17. #17
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    Subscribing to this one, as I am working on my own large v-hull electric build (70" CRC Marine Outerlimits). I have a build thread going here. Do you? If so I'd love to follow that as well.

    I am actually hoping to get a maiden voyage done before freezing temps hit here in IL. If I succeed, I will report here what my run time was, just to chip in and possibly give you some additional info.
    WheelMan Designz - Custom RC Creations

  18. #18
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    Guys

    I can also make 5s in 8000, 10,000 and 12,000 mah as well as the larger packs.

    Mark

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    Quote Originally Posted by MarkF View Post
    Guys

    I can also make 5s in 8000, 10,000 and 12,000 mah as well as the larger packs.

    Mark
    What's the dimension and weight of the 5s 10,000 mah packs?

  20. #20
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    This is my 6s 65c version. https://www.dinogylipos.com/collecti...19079869497440
    In 5s 65c it would be 1160g and 38x103x162
    I also have a 5s 35c 11,000 mah 52x62x175mm 1125g
    Last edited by MarkF; 10-13-2019 at 12:28 PM.

  21. #21
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    Default fast large electric race boats

    Hi, I belong to a race club called OMRA (offshore model racing association). https://omra.co.uk
    we race large electric boats 1.45m (58 inches) offshore (on the sea) race duration 20 minutes, speeds over 50mph, checkout YOUTUBE,if you want any further info post me a message, Jonathan.

  22. #22
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    Mike,

    I just completed a successful maiden run with my 70" CRC Outerlimits, built with a single Lehner 3080 motor, MGM 400amp ESC, running on 15S lipo (three 8000mah 5S packs connected in series). I got right at 10 solid minutes of run time out of it. There was only one full throttle pull in that session, but I averaged around 1/2 to 2/3 throttle a good portion of the time. Just wanted to share my findings, in case it helped you with your request here.

    I do plan to double up on my packs in the future. Six 8000mah 5S packs, basically 3 pairs of packs each in parallel, but the 3 pairs in series to each other, for 16000mah worth of 15S power. That will be for next spring though. Right now I'm happy with the three packs run time.
    WheelMan Designz - Custom RC Creations

  23. #23
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    WheelMan

    I can make you single 5s 16000 packs so you don't need so many packs.

  24. #24
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    Hey Mike i to am converting a big gas boat it is 54 in long it use to be a aquacraft v24 i chose a 500kv motor and am still in build mode i look forward to reading about your build good times for sure.Mike M.

  25. #25
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    Just chiming in - I have a 57 Apache with a 11T Lehner 3080 - 477kv running a 12s 10,000 setup and I get just shy of 10 minutes of partial throttle & full throttle fun . Speed are about 50 mph . I have run it on a 14s setup also and came close to 60mph . It could definitely go faster but but the run time penalty is huge .

    I see that Lehner now makes a 30100 motor

    I want to extend a hello to Mark F & Mad Mike
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    Last edited by Punisher 67; 11-19-2019 at 01:39 PM.
    Necessity is the mother of invention.............

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