Topic: large boat motors (Read 16476 times)

nick_75au · « **Reply #25 on:** July 04, 2011, 01:12:40 pm »

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16366

That one is no good, the reverse program is to reverse the motor once its in a plane, doesn't give fwd/ reverse.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=15132

I haven't seen this one before, but one of the options is to have either 25% reverse or 50% reverse so I assume it has forward reverse functionality, they might find their way into my cart as well when they are available.

Higher amps are good, (those Chinese amps are not as big as the rest of the worlds

)

See what I mean by the prices

Cheers
Nick

Going to bed now and awaiting return fire

More Coffee · « **Reply #26 on:** July 04, 2011, 03:10:00 pm »

This has been a good thread..I never really looked at brushless as a few years ago the prices were retarded compared to brushed.

Im interested to see what reduction gear sytems are used, you guys recommend,
Im planning a tug that's about 56" (1.42m)(1/18 scale) in lenght running a 90mm ,Type A, 3 blade prop,on a M5 shaft. This may grow to 63"(1.60m)

This conversation on brushless has been most helpful, and best of all cheap!

CF-FZG · « **Reply #27 on:** July 04, 2011, 11:34:39 pm »

Quote from: andyn on July 03, 2011, 04:45:18 pm

You find me a brushless motor then Mark that on 24v will swing a 55mm plastic prop and draw less than 6 amps continuous then?

Okay, lets see 24v x 6A = 144W and approx 13k rpm

How fast do you want it turning?

Mark

nick_75au · « **Reply #28 on:** July 06, 2011, 12:10:15 am »

Quote from: More Coffee on July 04, 2011, 03:10:00 pm

Im interested to see what reduction gear sytems are used, you guys recommend,
Im planning a tug that's about 56" (1.42m)(1/18 scale) in lenght running a 90mm ,Type A, 3 blade prop,on a M5 shaft. This may grow to 63"(1.60m)

This is the great thing about brush-less - there are lots of motors available with a low enough Kv for direct drive though when you get into your size prop, gearing makes sense if only to use a smaller motor, While brushed motors with low KV are around ( I have a motor that's only 180 Kv) they are not pushed as hobby motors, you can use any reduction you would use on a brushed setup

For your boat you want about 2000 RPM at the prop , so a 160 Kv at 12 volts or a 350 Kv at 6 volts, The motors are going to have specs. that look ridiculous at these Kv,s like max amps of 50 or more, but... they are not going to pull anything like that. It might draw 10 amps at full throttle. Otherwise any reduction you would use on a brushed motor will work for brush-less.

A 2:1 belt drive will allow a much smaller motor to be used, double the Kv.
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=2101
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8492

So apparently I was slagging Andy-MMB's motor, I actually PM'ed the OP saying the MMB motor would work in his application, what I'm replying to is Andy's challenge and his claim that the motor draws 6 amps at 24 volts with a 55mm prop, Mark replied to me in this thread
http://www.modelboatmayhem.co.uk/forum/index.php?topic=31140.0
after I queried Stavros on the Amp draw of his Perkassa, His reply satisfied me enough as its average draw not full throttle and I was quite prepared to let it pass.

Andy comes on this thread spouting off so I asked him to back up the claim with some measurements because there is no way that full throttle 55 mm prop will draw 6 amps at 13000 RPM. What If someone thought OK I only need a 10 amp ESC, for my 900 powered 49 inch Perkassa, they are going to blow that ESC, net result one unhappy customer.

I always quote full throttle amps as that is what the ESC and other components needs to be sized to, quoting a motors average current is like saying I can get get 50 MPg out of my Ferrari without saying I drive at 25 Mph to the corner shop and back.

cheers
Nick

Martin (Admin) · « **Reply #29 on:** July 06, 2011, 10:04:02 am »

I hate gearboxes, toothed belt drives, reductions systems et-al in model boats (mainly because of noise they make) but in this case
where "it seems" most Brushless ESC don't have very good low speed, a reduction drive would give better slow speed control....

OK, I'm gonna ask the question... who on this forum has actually fitted a Brushless Motor in their boat?

philk · « **Reply #30 on:** July 06, 2011, 10:33:30 am »

Quote

OK, I'm gonna ask the question... who on this forum has actually fitted a Brushless Motor in their boat?

have to say martin the best i have met is alan of debbsall

has fitted lots of brushless setups all worked perfectly all still are including the hms daring now but i think he chooses not to get involved in this sort of discussion.
no matter what you know someone will always know better and make sure you know it.

phil

andyn · « **Reply #31 on:** July 06, 2011, 11:00:51 am »

Quote from: philk on July 06, 2011, 10:33:30 am

no matter what you know someone will always know better and make sure you know it.

How true...

nick_75au · « **Reply #32 on:** July 06, 2011, 11:30:03 am »

Glynn Guest Miami Crashboat hull, 3200 Kv with a 3:1 gear drive and 1000 Kv from the springer (first test hull)
850 MM Skiboat, 36-42 1350 Kv direct drive, 40 mm prop
Springer Tug 22-20 1000 Kv Legal specs
Axe Bow 1320 mm two DT 750Kv, 40 mm 5 blade props.

Cheers
Nick

nick_75au · « **Reply #33 on:** July 07, 2011, 08:28:28 am »

Ive been mucking about with the calculator and come up with a few figures to find the motor that was asked for
20 cells Nimh 55 mm racing prop,

The MMB 900
max amps 17.0, Watts in 395, out 308, RPM 10,837, 78.% efficient,,,,, Ok my 25 amps max was a little out

Plugging in a 55 mm Raboecsh prop gets this motor to its maximum efficiency and 11,000 rpm and 16 amps, Nice.

A 540 Kv brushless 42 mm motor equivalent Kv to the MMB 900
Max amps 21, watts in 487, out 465, rpm 12,105, 89.2% Efficient

a 440 Kv motor
Max amps 13.8, watts in 311.3, out 265, rpm 10,266, 85% efficient

A 330 Kv motor
max amps 5.9, watts in 145, watts out 115, RPM 8,026 79% efficient

Conclusion
A 440 Kv motor will give you about the same speed with lower amps
A 540 Kv motor will give you more speed at the expense of higher current draw
a 330 Kv motor will give the amps Andy asked for, slower but that is the maximum amps it will draw not the average amps.

Cheers
Nick

barriew · « **Reply #34 on:** July 07, 2011, 12:57:43 pm »

Quote from: Martin - admin. on July 06, 2011, 10:04:02 am

I hate gearboxes, toothed belt drives, reductions systems et-al in model boats (mainly because of noise they make) but in this case
where "it seems" most Brushless ESC don't have very good low speed, a reduction drive would give better slow speed control....

OK, I'm gonna ask the question... who on this forum has actually fitted a Brushless Motor in their boat?

I have fitted three of them but only to sort of fast boats - a Deans Fireboat and a Dave Milbourn Swordsman. Both of these I consider a success. I also fitted one to a smaller Ricky Web Huntsman 31, and that is not too successful - possible because owing to poor access I am not too happy with the motor mount and alignment.

Barrie

HS93 (RIP) · « **Reply #35 on:** July 07, 2011, 01:19:00 pm »

Martin as you now I have, and they do everything better than brushed, Oh and I like belt drives as well. no problem with slow speed or reverse if you get the right controllers

Peter

Dekan · « **Reply #36 on:** July 07, 2011, 07:30:38 pm »

Quote from: barriew on July 07, 2011, 12:57:43 pm

I have fitted three of them but only to sort of fast boats - a Deans Fireboat and a Dave Milbourn Swordsman. Both of these I consider a success. I also fitted one to a smaller Ricky Web Huntsman 31, and that is not too successful - possible because owing to poor access I am not too happy with the motor mount and alignment.

Barrie

What motor did you use in the Fireboat Barrie?

barriew · « **Reply #37 on:** July 07, 2011, 09:19:11 pm »

Dekan,

Its the one in this thread http://www.modelboatmayhem.co.uk/forum/index.php?topic=25907.0

Barrie

HawkEye · « **Reply #38 on:** July 07, 2011, 09:26:53 pm »

Quote from: Martin - admin. on July 06, 2011, 10:04:02 am

I hate gearboxes, toothed belt drives, reductions systems et-al in model boats (mainly because of noise they make) but in this case
where "it seems" most Brushless ESC don't have very good low speed, a reduction drive would give better slow speed control....

OK, I'm gonna ask the question... who on this forum has actually fitted a Brushless Motor in their boat?

I've been running brushless, direct drive in a large(ish) boat for quite a while now, details in this post - http://www.modelboatmayhem.co.uk/forum/index.php?topic=20570.msg199078#msg199078

best decision i ever made

, the only issue I encountered was getting the two seaking esc's to behave exactly the same but eventually got that sorted.

HawkEye

red181 · « **Reply #39 on:** July 08, 2011, 12:00:24 am »

Quote

OK, I'm gonna ask the question... who on this forum has actually fitted a Brushless Motor in their boat?

Im suprised nobody has answered, maybe this would be a good stand alone topic, as more and more boats are using brushless motors.

Quote

I hate gearboxes, toothed belt drives, reductions systems et-al in model boats (mainly because of noise they make) but in this case
where "it seems" most Brushless ESC don't have very good low speed, a reduction drive would give better slow speed control....

got to disagree there Martin, not all gearbox's are for slow boats!

The 900 motors mentioned are very large, and heavy, my boat lights draw more than 5 amps

, I just cant see that really, would love to see some actual recorded evidence of such a low amp draw, its riduculously low.

Brushless, with reversing esc, that will operate forward or reverse at tickover speed, with a gearbox, and a lovely sound, amp draw.... well lets just say I bet I could boil the water in the lake

http://www.youtube.com/watch?v=z1R4XXeUWC8

different motor fitted this week, an 880kv outrunner from hobbyking, gps speed today was 25.55mph, I doubt any brushed setup would match this performance for a 6.5kg ply single screw scale 42" boat

andyn · « **Reply #40 on:** July 08, 2011, 12:44:21 am »

Quote from: Red181 on July 08, 2011, 12:00:24 am

The 900 motors mentioned are very large, and heavy, my boat lights draw more than 5 amps , I just cant see that really, would love to see some actual recorded evidence of such a low amp draw, its riduculously low.

Obviously fighting a losing battle here, so here are the facts. Make of them what you will.

This boat: http://www.youtube.com/watch?v=fp3RNTVk1z4 is running a single MMB 900 motor, with a 55mm prop. It is using two 4300 stick packs in series to give 24 volts. After 40 minutes of continuous full throttle running the batteries started to drop off. Works out at just over 5 and a half amps.

As another well known trader on here is fond of saying, Suit yourself.

ACTion · « **Reply #41 on:** July 08, 2011, 09:05:45 am »

Er.................'scuse me. Wasn't the original posting about a Star Perseus tug and Robbe motors? 25.55mph and the like seems almost off-topic.

For myself I'm getting fed up with this 'p***ing contest' about brushed vs brushless. It serves about as much purpose as asking what 'the best car' is. It isn't an issue of one's manhood or personal integrity, and it's well past time that the proponents of one side or the other stopped winding each other up with inflammatory statements. It frequently results - as in this case - in a question going unanswered.

There are circumstances where I would point customers at using brushless motors rather than something like a 900 (and thereby lose a sale), and others where a brushless motor would be a waste of time and money c/w a brushed motor. In this particular instance I think that the Robbe Power motors would suit the task but the 900 motors would be more cost-effective, and either type would offer better low-speed control than an ungeared brushless set-up.

Dave M

HS93 (RIP) · « **Reply #42 on:** July 08, 2011, 10:39:57 am »

Quote from: Andy - MMB on July 08, 2011, 12:44:21 am

Obviously fighting a losing battle here, so here are the facts. Make of them what you will.

This boat: http://www.youtube.com/watch?v=fp3RNTVk1z4 is running a single MMB 900 motor, with a 55mm prop. It is using two 4300 stick packs in series to give 24 volts. After 40 minutes of continuous full throttle running the batteries started to drop off. Works out at just over 5 and a half amps.

As another well known trader on here is fond of saying, Suit yourself.

Re: Brushless motor and esc confirmation for Sea Queen 34 inch
« Reply #26 on: June 27, 2011, 10:25:24 AM »

--------------------------------------------------------------------------------
Quote
Stavros, I'm surprised by your quoted amp draw, how did you test the current draw? A 55 mm prop will pull more than 5 amps if its spinning at more than about 2500 RPM regardless of the motor used.

Well we did a rough estimate on the current draw..... (didn't work it out too accurately, couldn't be bothered!!!) 4300Mah NIMH batteries on 24v driving a 55mm 2 blade plastic prop run time 40 to 45 minutes. We estimated just under 6 amps draw under normal operating load....

Mark.

is that what you call testing for current draw etc,

Re: 3x MFA 850's
« Reply #9 on: June 28, 2011, 10:58:27 AM »

--------------------------------------------------------------------------------
MMB/ ACTion motors are a million times better than an 850, as Dave has said.

a million times better than an 850,

I thought traders had to quote facts as there is a trades description act

Peter

ACTion · « **Reply #43 on:** July 08, 2011, 11:25:45 am »

Quote from: HS93 on July 08, 2011, 10:39:57 am

MMB/ ACTion motors are a million times better than an 850, as Dave has said.
a million times better than an 850,
I thought traders had to quote facts as there is a trades description act
Peter

MMB no longer supply these motors.
We do.
We have made no such claim for them. In absolute terms it is both meaningless and a touch juvenile (no offence, Andy). However, if you are unable to differentiate between a set of technical data and the enthusiastic exaggerations of youth then I feel sorry for you, but should I feel the need to be reminded of the finer details of Trades Description Act then I will consult the proper authority, not an Internet model boat forum.
DM

Martin (Admin) · « **Reply #44 on:** July 08, 2011, 12:34:26 pm »

Well I think we'll leave the subject there then shall we .......

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Author Topic: large boat motors (Read 16476 times)

nick_75au

More Coffee

CF-FZG

nick_75au

andyn

nick_75au

nick_75au

Dekan

HawkEye

andyn

ACTion

ACTion