Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: LOCURA on October 16, 2009, 08:58:23 pm
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Hi
I am newto RC boating and need some advice before further investment. I have already purchased a 120 watt ESC but am being told that a large racing hull needs a Zenoah. I understand the world water speed record is held by electric, so why does a large Lipo brushless setup not compete in something like a Prestwich Sigma???
Any advice would help guide me, thanks
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120 watt at what voltage?
IC is fast alright but many waters won't allow them
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120 watt esc is only 10 amps at 12 volts good for a 18"- 24" at the very most, a 120 amp esc at 24 volts would be barely closer to the mark for a Zenoah which can output the equivalent of over 3000 watts even in stock form.
The limiting factor with electric, particularly fast electric is running time, 120 amps will suck a 5000 mAH battery in a matter of 2-3 minutes at full throttle.
Big FE can be done, just $$$$$ required :}
The world speed record is held by a rigger style boat designed for 2 passes only before either batteries flat or components are fried, think top fuel dragster ;)
Nick
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Hi Richard
Are you coming to the lake tomorrow found the book for the charger you wanted that ESC you have is rated at 80amp at 22.2 volts or have you bought a 120amp one? also got a power supply if you still need one.
Alan
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Thanks for the replies,
Yes Alan, see you tomorrow, but could be months before I understand the "Black Art" of electrics.
Oops again, I should learn more before I spend! Good info coming in, my bad judgement on what is required.
The ESC is the Castle Creations 120 amp Hydra Water Cooled ESC. The ad says "Up to 120 or 240A continuous current. 6S lipo".
Max Volts: 25V. Not sure if I can use top end of this info i.e. 240 amps at 25 volts.
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That is a nice ESC, :-)) their MAX voltage is a "do not exceed" rating, I once asked them about running 24 volt gels (28v fully charged) no will damage. They do a 240 amp ESC in the same series hence the ad's different specifications.
Now you wont be able to get Zenoah speeds but a respectable speed maybe 30 + Kph can be achieved on the sigma hull, go for a smaller hull and 100 kph is achievable.
Data logger an almost essential piece of kit to keep an eye on things
Nick
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With a tuned Zen and a 1 liter fuel tank the boat will run for 25/40 Min's, Try running that long and fast with a elecy boat. Even Lipo cells which are real cool bits of kit it will run out so quick you will be disappointed very soon after you set of.
The other thing is a small amount of weed will stop a elecy boat, but a Zen will just chop it up and spit it out the back.
OK so I'm bias for the petrol boats, but I have played around with some electric boats myself and I know what given the choice i would pick every time.
Anyway what ever you go for JUST ENJOY IT cause thats what it's all about. Good Luck.
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Its a toss up, fuel has limited places to run and leccy has limited running time. If you live close(or willing to travel) to a IC allowed lake or the ocean go for IC. Dont know bout the weed Ive got a leccy setup that ripped the blades off a brass prop with out even hesitating, HP is HP no matter the source. :D
Nick
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***topic title modified***
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This reminds me to post more on my slomo
I used to run a 5070 kv motor on 14.8 before i did one run and fried the ESC (100Amp)
reason why it was drawing 90 Amps before it got to the water
three thing you need to ponder and balance out in an electric motor Motor, esc, and the Battery in a fast electric
this is the basis of my slomoshun build
I will use Brushless as an example to simplify things
firstly figure out what voltage you want to run on and the budget you are willing to pay
Motor
Most motors have a chart available either on line or when you get them as to the current draw 90% of the time this is no load current I ended up getting a 2887 KV motor as it draws only 55 Amps under no load and chain that to a 14.8 V Battery and you have 42727.6 RPM (KVof motor times Battery Voltage).
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Esc
Castle Creations do a wonderful Esc But they are expensive
ETTI do a very comparable ESC 150 opto which handles 6-30V 150AConstant currant and 300 Burst Current fully watercooled and water proof and I have not read about many that have gone bust for no reason.
Battery
I use a LIPO in my Slo-Mo only due to the high currant draw basically a Flightmax 30C 5000mah battery at 14.8 Volts now all this jargon means this 30*5 = 150 so my battery can handle a constant 150Amp current draw ("C" rating of battery* Ah rating of battery) as most batteries are measured in mah just divide the mah rating by 1000 to give you the Ah rating and times by the C rating or current rating of the battery.
all of this adds up in my Slo-Mo-Shun to a heck of a lot of speed a new video is coming soon so watch for it
and to top it all off you need to get a propeller to match your boat type and drive line
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I have watched my friend The Doc slowly achieve a fast petrol boat and after reading nick 75au´s info I have sold both my electrics and bought a Prestwich Sigma 51 with the race Zenoah. I now feel I can tackle most types of inland water with decent running time.
Perhaps it is a cop-out but electrics seem to be tooooo technical
Thanks for all the help.
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If it were a choice between owning electric boats or IC only, the electrics wouldn't get a second glance from me. Enjoy your lovely smelly, dirty, oily, noisy Sigma :-)) :-)) :-))
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Just for prosperity's sake here is the info I fudged together on an electric setup fo LOCURA over a couple of e-mails (Hope you don't mind)
I've got a 60 inch hull that I'm running electric in, It has 4 700s in it, the fastest its been so far is 16 KPH (working on that just changed from Lead to Li-po batteries) so I think the motor you have is too small, (just ran it on the weekend except for an Receiver failure I know it was over 25 Kph now)
BL3 Brushless Watercooled Motor 3650. 3300 rpm per volt.( High rpm) For 8.4 to 12 volts. 3S to 4S lipo or 7 to 16 Nicad or NIMH packs. Mounting hole spacing of 19mm or 25mm. Diameter 43mm, length 63mm., shaft diameter 4mm. Replacement for 700 size motors but MUCH more powerful. I have been assured this will take 18.5 volts!! I also have 2 packs of 18.5 volt 4000ma lipos and the ESC mentioned. I wonder if I have any of the recipe?
Now I'm by know means an expert but I think I can get you in the ball park.
If you can, get 6s lipo, the maximum the ESC can handle 4s means higher amp draw and a higher KV motor. A Zenoah spins around 15-17'000 rpm but 30 Kph can be had by a stock brush cutter motor that barely makes 10'000 Rpm, so a motor with a Kv that matches up to that figure at intended voltage should give similar performance. 10'000/ 18.5 gives a KV of 540, bump to 600-650Kv to give a loaded rpm. At 22.5 volt (6s) 440Kv, a kv of 500 including fudge factor will do the job. A large 55-50 or similar size outrunner (cheap from HobbyKing.com) with the above Kv ratings will work using 55+ mm props. You could go with a Neu inrunner (very expensive) with similar Kv as well.
I would expect an amp draw of around 40-50 amps with a 500 Kv motor and 6s Lipo, a bit more with the lower voltage
Regards Nick
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To get anywhere near the speed of an IC boat with an electric, you need to spend twice as much money...
That motor would be absolutely nowhere near big enough for a Sigma, its only an inch round...
This is what the Sigma does:
http://www.youtube.com/watch?v=9_JdHMxfgpQ
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Andyn
try Diameter 43mm, length 63mm., shaft diameter 4mm if you read the post screw spacing is 25mm.
http://www.youtube.com/watch?v=IMoLFdmECHw
and they start when you want them to Oh and what holds the model boat speed record er electric
Peter
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Now then before WW3 breaks out. If you like electrics then so be it. If you like Nitro good, If like me I run Petrol boats which suites me. 1 cheap to run. 1 gal of petrol will last me for weeks. 2 they are easy to start. Bit of choke, pull on the starter cord and your away. I have not yet meet a electric boat that can stay up with me for run time yet, However over a short time i have seen one which can keep up with me speed wise. While he was changing /charging battery's i had packed up for the morning. Yes battery's have come on a very long way but so has the 26cc water petrol engine. Oh yes before anyone says about the Ex noise mine is under the limit set by OMRA & our local council. I have heard some very noise elcy boats when they are going flat out.
As I said before what ever you go for ENJOY IT !!
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I am still at the basic learning stage and do not want to get into HOT water {-), but the thing that finally changed my mind is length of running time. the 84 mph run was over something like 16 seconds (?), I am sure the Sigma with a Zenoah would continue for 15 mins on a tank full (please advise).
Drag racing or Le Mans 24 hours springs to mind, its horses for courses.
I like the idea of OMRA, are there many electric boats that go offshore racing, there seems to be quite a few Zenoah engined boats?
Thanks for feedback, I learn with every reply
Any phone numbers for the girls in your boat Bill D203? <*<
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I am still at the basic learning stage and do not want to get into HOT water {-), but the thing that finally changed my mind is length of running time. the 84 mph run was over something like 16 seconds (?), I am sure the Sigma with a Zenoah would continue for 15 mins on a tank full (please advise).
Drag racing or Le Mans 24 hours springs to mind, its horses for courses.
I like the idea of OMRA, are there many electric boats that go offshore racing, there seems to be quite a few Zenoah engined boats?
Thanks for feedback, I learn with every reply
I stand to be corrected but OMRA dose not have an elcy class boat. They start with the Z class with is the 12 size nitro and all the way up to 50cc petrol.
The Zen dose offer good value for money. Loads of spare parts can be got at affordable prices, which is maybe why they are popular in OMRA. As I said also fairly cheap to run. Tesco unleaded and a short of 2 stoke oil.
As for running time 40 mins per liter if you don't go to mad. Most boats have 1 to 2 liters tanks. Nitro fuel is over £20.00 per gal for the normal stuff and alot more as the nitro % gose up.
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Thanks for reply Bill
Does anyone use Castrol R or its equivalent, or just 2 stroke oil on a race tuned Zenoah.
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Thanks for reply Bill
Does anyone use Castrol R or its equivalent, or just 2 stroke oil on a race tuned Zenoah.
I don't think i have seen anyone using Castrol R. Just plan old 2 stroke oil. Some recomend a Honda oil which I am going to try out very soon.
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As Bill says - each have their merits and downfalls.
At the Torquay Chase boat event a few weeks ago (where you control your model from a full sized speedboat) one person did run an electric boat. He completed the 4 mile + course in just over 18 minutes! As there is no electric class in OMRA, he didn't qualify for championship points, but his time was a very respectable effort given that its run in open seas.
Its a bit like cars - if you want to deliver milk for 4 hours, don't use a Maclaren F1 {-) %%
Danny
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I am still at the basic learning stage and do not want to get into HOT water {-), but the thing that finally changed my mind is length of running time. the 84 mph run was over something like 16 seconds (?), I am sure the Sigma with a Zenoah would continue for 15 mins on a tank full (please advise).
Drag racing or Le Mans 24 hours springs to mind, its horses for courses.
I like the idea of OMRA, are there many electric boats that go offshore racing, there seems to be quite a few Zenoah engined boats?
Thanks for feedback, I learn with every reply
Any phone numbers for the girls in your boat Bill D203? <*<
Just spoted the last bit. The bloke in the middle is Tarqiun. Tracy (dark hair) Sharon (Blond).
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Could have sworn I posted here earlier, where'd it go?
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Sorry, should have mentioned aiming for 30 Kph or so (A nice sport setup) Utilising the ESC he had purchased, about the same as a basic Whipper Snipper motor I guess, Moot point as Locura is going to use I.C. which for a big boat like this makes sense.
http://hpr06.speedtoy.com/setup.htm, check some of the speeds %% these guys are getting hows 181 Kph on 32 Nimh
http://www.swissmodelpowerboatteam.ch/index.html
are running 2.33 meter class 1 cats on electric at 120 KPH for 1/2 our races, the catch is I believe it takes a couple of days to charge the 1 million Lipos in them and I would hate to think of how much it cost.
Nick
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How about this then?
http://www.youtube.com/watch?v=U5tAq531Es0
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There does seem to be an obsession with KPH/MPH among powerboat enthusiasts. While speed is important, I won a lot of trophies when didn't have the fastest boat in the race. Reliability does help. If sheer speed floats your boat try tethered hydros. It saves the cost of R/C equipment as well!
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I have to admit it.
I have not yet run the Zenoah engine and the boat is on a shelf never having touched the water after a YEAR! Tried to sell it (cheap) but to no avail!!!!
Our club lost its water and I am thinking of running in a lake or in a harbour and I would prefer to go electric. Oh Dear!!
Back to the "Black Art" drawing board.
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LOL, My 60 inch boat hasn't seen water for close a year either.
Nick
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I have to admit it.
I have not yet run the Zenoah engine and the boat is on a shelf never having touched the water after a YEAR! Tried to sell it (cheap) but to no avail!!!!
Our club lost its water and I am thinking of running in a lake or in a harbour and I would prefer to go electric. Oh Dear!!
Back to the "Black Art" drawing board.
Try contacting the Townsville club, N.A. I'm sure they run IC's and I think a few of them are looking at running Offshore style I.C. powerboats :-))
Regards
Scoop
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Good after noon friends..i am willing to post one of my experience here...i also was in a struggle, to make a faster craft..so tried many motors and batteries, some even without any ESC.making an esc is not a matter today,as you can simply make an ESC with IC NE555,as PWM oscillator, and its output can fed to BUZ type, or IRFZ type mosfets, can handle ample of currents as you increases the number of mosfets in your circuits.almost one power mosfet can handle 30 amps almost, so a bridged 6 mosfets can do the job nicely.but any how you will lost your battery instantly...
So i turned to an alternate..i purchased a small chainsaw, equipped with a small 35 CC petrol two stroke engine, forced air cooled,pull starter, and it totally weight only 245 grams,include all CDI and Ignition coil.and its size was only just larger than a cycle dynamo.it pumps out around 2.3 bhp, at 16000 rpm,and we won the gold medal last year, as our intern competition was held up...it was based on pure petrol, and a little 2T oil...tidy...exhaust was concealed within the ABS cover...it works even now, and theres no any trouble. speed radar, in our institute shows it simply cruises more than 76 kmph on salt water. at first the prop was the problem to me as the craft speeds up, the cavitation destroys the prop..so i contacted a naval engineering firm and they made a prop for me, a three bladed stainless steel one..so you can try with some engine like that, or can go for engines found in agriculture sprayers..its so cheap to run and extremely reliable..cool
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i've just read a reply to this thread and it made me laugh at some people ignorance, it stated that ''Perhaps it is a cop-out but electrics seem to be tooooo technical'', simple fact is once you have your motor in got the right esc for the job plugged a lipo in you never have to do any work apart from check the prop, grease up the shaft and tighten a few nuts and bolts, any 8 year old can do that! (although mom and pop will have to pay)
Ic if vastly more complex.
first off there's the challenge of setting up the engine (tuning) which in its self is hard work at time's and anyone will tell you, you have to diagnose issues when they crop up, if the high speed mix to lean or to rich, low speed the same idle speeds, checking if the glow plugs are the right temp for the engine condition, constant cleaning on the intake valves (carb) and this is if you run a single Ic, and this is just 2 stroke!
i run twin 2 stroke and twin 4 strokes regularly (offshore) getting both motors tuned the same is even more complex!
other issues you have is when an Electric boat fails to respond 'generally' you can make it stop using a fail safe since a lot of the decent esc have fails safes built in, IC don't, you have to add a fail safe to control the throttle servo which if your little 6v pack fails nothing works engines max out and poff bye bye boatie , then there's the added fact of the linkages (attatched to the throttle arm) although you have to be a total donut not to check them but its been known for a linkage to break or the servo yanks it off and yet again bye bye boatie!
Need we go on about fuel? balancing the boat while the tanks emptying, fire risk?
To much can go wrong if you are misinformed, sloppy or ignorant that its 'easy'. i have been Ic boating for more years then i would like to count and even i managed to crash and burn my IC into the sea wall recently with no chance of retrieval! (i think it was a rudder failure but was to late to power down) ...$1500 gone bye bye!
sure i have made my point here that IC is vastly more complex then an electric boat, i could go on with other things that you have to watch for but i think i covered the basics.
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Hai 50mm..it was a great information.. it must be complex..but if one can fix an electric motor to his craft, he can simply fix a petrol engine to his craft, if that engine came from a reputed company, as i used, indented for a chain saw..my craft clocked around 2500 kms, as my diary readings, but actual may be more..even then i haven't removed any part, inc carburettor, or exhaust silencer. the only thing i changed is the air filter element.it still pumps out lots of power and my main head ache is slipage of propeller from shaft, as i do not have any sophisticated lathe works around me...if one have a good quality stuff to workwith its not a matter about using an IC engine to ones own craft..but yes sure, we have to think many criteria , of safety compared to electrics..when compared to electrics ,IC engines will not compromise to a great extent...its designed for raw power without any remorse...so we must take care about it..i think so..its only my experience...as i lack any modern equipments and people to help here..so if i am wrong..apologize..
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I don't dispute that swapping out a electric system for an IC is complicated its just a bit of common sense and using the right parts such as a decent engine mount with the rubber shock absorbers, you honestly why bother swapping out electrics for an ic system in one boat, it would be prudent to just have a new hull for your ic.
Apart from that its all relative to your knowledge if you know what your doing its straight forward (not easy) if you don't at least your in the right place to ask how!
As i said before i laughed at the ignorance of some who think ic is easy.
Thing is Rath........
that yes IC is pure untamed raw power but you forget that rpm is rpm regardless of its source, many electric motors can keep up with Ic if your prepared to spend the money that will buy you units that can keep up, but even then electrics can be very fast in the right hands, its just personal choice as to which system you wish to run.
if your having slippage of the prop to the shaft surely you would loose the prop, or its the wrong thread size? maybe try a larger shaft or re-cut the threads. if i misunderstood would you mean slippage of the shaft to the flywheel/coupling? if thats the case, i would suggest a solid coupling made of steel or aluminium tube, no need for a lathe if you can get some solid rods, as long as you have a drill with the right bits, and a tap and dia set you can cut the threads and secure with locktight.
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Hai 50 mm, you are true..all we know electric motors are much powerful than a IC engine in to a same size..i got some diagrams of a traction motor, one used in WDM railroad engines in my country..its a small 30 inch dia around, open wounded motor , is atually drives the entire train, while the diesel engine is driving only its generator.so no dispute...but a positive side i felt with IC engine is the running time..for a mere 300 ml of gasoline it runs more than an hour at speed...and yes i loss my prop if i push the throttle stick too far...because it as actually made out of a wheel spoke of a motor bike.when load reaches to a great level,the nipple starts to slips from its base..if it happend, it will be a lost for ever...so by coming months i have to go to a lathe and will clear it...thanks for the great advices...
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if figured out your issues with the prop loss, with the rpm of the prop the shaft is spining faster then the prop, as the prop is under loa, litrally its undo its self of the shaft.
not sure what your using in the way of props and shafts but the way to not loose your prop is a simple washer and nut.
Take the washer and push on the end of the shaft, this reduce water intake up the shaft
take the nut and loosely thread it up to the washer
take the prop and wind it on shaft thread as far as it will go with out being tight.
now hold the prop and take a small spanner or pliers and now tighten the nut ( so unscrewing it basically) to the prop as tight as you dare with out destroying your threads, now what should happen at full speed the prop is unable to move on the thread in fact its turning is aiding in keeping it on the thread, now you won't loose a prop, to get it off again just hold the prop and undo the nut, and now unscrew the prop, easy and it only took a washer and a nut!
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Thank you 50 mm...and i have ordered to a lathe work,to make a prop shaft for me with BSF threads, clockwise, as my gear box turns in anticlockwise..so i hope it works...thanks for the valuable advice...