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Author Topic: 7009 / DASH II Double Horse RC Speed boat!  (Read 17600 times)

rado-steve

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7009 / DASH II Double Horse RC Speed boat!
« on: April 13, 2012, 11:19:04 PM »

Hi All,

just got one of these boats as a bit of a toy:

http://www.red5.co.uk/remote-control-toys/the-dash-high-speed-rc-boat.aspx

Problem is, its just not quick, the video on the website and subsequent ones I've seen on youtube show it to zip along quite rapidly.......mine just seem to produce a huge rooster tail, its faster on 1/2 throttle then on full  <:(

Anyone else got one or heard of any issues??

To me it looks like the prop is a surface drive????? and 30mm in Diameter, that seems pretty large for a boat thats only 350mm long!




I've had it in the bath and at rest the prop is fully submerged, but as soon as you apply power it seems to bring it out of the water, is it meant to do this?? If i hold the back end deeper in the water you can really feel the prop bite and the boat pulls hard  {:-{ Or could I maybe put some weights in the rear to lower the prop further into the water?

Would changing the prop to a smaller one help?? It seems a weird thread too, it looks like M2.5????....can only find M2 & M4 on the net...do they even make props in M2.5?

Sorry for all the questions on a 1st post, its just quite a cool little boat, just maybe wondering if mines Duff  >:-o

Any help much appreciated

Cheers

Steve
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #1 on: April 13, 2012, 11:41:17 PM »

the prop is fine, its a surface peircing drive. When the boat gets up 2 full speed on a plane only one blade of the prop is in the water, this is how they work. Due the fact that only half the prop is in the water and any one time surface props are larger in diameter to their fully submerged counterparts. Ive not seen this boat before have you got a link to some footage of one running?

actually just found some:
http://www.youtube.com/watch?v=XNkaR7SF8uw
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rado-steve

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #2 on: April 13, 2012, 11:47:26 PM »

the prop is fine, its a surface peircing drive. When the boat gets up 2 full speed on a plane only one blade of the prop is in the water, this is how they work. Due the fact that only half the prop is in the water and any one time surface props are larger in diameter to their fully submerged counterparts. Ive not seen this boat before have you got a link to some footage of one running?

actually just found some:
http://www.youtube.com/watch?v=XNkaR7SF8uw

Yeah....mine ain't anyway near as fast as that, its quicker at 1/2 throttle then full  >:-o

It just seems to pull harder when its full submerged..

I'll try and get some video of mine running, see what you think!
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #3 on: April 13, 2012, 11:48:04 PM »

if you look at the reviews at the bottom of the page youl will find your not the only one disapointed with the speed of your boat:

http://www.red5.co.uk/remote-control-toys/the-dash-high-speed-rc-boat.aspx
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rado-steve

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #4 on: April 14, 2012, 12:01:48 AM »

if you look at the reviews at the bottom of the page youl will find your not the only one disapointed with the speed of your boat:

http://www.red5.co.uk/remote-control-toys/the-dash-high-speed-rc-boat.aspx

Yeah I'd seen that, thats my comment on the website BTW (Yellow car), I'd seen someone else had complained :(

Do you think a smaller prop would help, as it does pull so much harder fully submerged........

Also M2.5????? Bit of a weird thread isn't it?

Cheers

Steve
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #5 on: April 14, 2012, 12:14:32 AM »

The push/pull force of the boat it what is called by the tug lads bollard pull. Its measured in grams or tons whatever and basically measured by fixing a scale to somewhere solid tying a boat to it and giving it some welly. Fast boats with surface peircing props have very little bollard pull but lots of top end speed. Same way a ducati wont pull a plough like a tractor can. The propeller will produce more bollard pull fully submerged, but at speed a submerged prop will cause excessive drag and slow the boat down.  have a look at this too show their operation, read the bottom bit:

http://www.originalpropshop.com.au/resources.php
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rado-steve

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #6 on: April 14, 2012, 12:24:20 AM »

The push/pull force of the boat it what is called by the tug lads bollard pull. Its measured in grams or tons whatever and basically measured by fixing a scale to somewhere solid tying a boat to it and giving it some welly. Fast boats with surface peircing props have very little bollard pull but lots of top end speed. Same way a ducati wont pull a plough like a tractor can. The propeller will produce more bollard pull fully submerged, but at speed a submerged prop will cause excessive drag and slow the boat down.  have a look at this too show their operation, read the bottom bit:

http://www.originalpropshop.com.au/resources.php

Cheers for that....

I'll post some pics of mine running, when at full throttle the revs rise buy no increase in forward momentum...
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #7 on: April 14, 2012, 12:44:41 AM »

when the boat is going full tilt and the prop starts too surface drive, the props rotational speed increases dramatically because there is less load on it. Usually such behaviour your describing would possibly call for either the increase in diameter or pitch of the propeller. Its hard to say what would be suitable because its one of those trial and error things. Changing the propeller design changes the affects and load on the motor. A wrong propeller can overwork the motor, cause a massive increase in current and heat through the electricals of the boat and basically fry it. just need to get some idea of whats in the boat:

1) what battery voltage does it run at? and what is the mah?
2) does the boat have a digitally proportional radio in it?

what i mean by that is, is it a hard right hard left steering on it with all stop all go speed controlling or can you accuartly adjust the steering to a desired postion and control the motor speed accordingly?

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rado-steve

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #8 on: April 15, 2012, 05:43:09 PM »

when the boat is going full tilt and the prop starts too surface drive, the props rotational speed increases dramatically because there is less load on it. Usually such behaviour your describing would possibly call for either the increase in diameter or pitch of the propeller. Its hard to say what would be suitable because its one of those trial and error things. Changing the propeller design changes the affects and load on the motor. A wrong propeller can overwork the motor, cause a massive increase in current and heat through the electricals of the boat and basically fry it. just need to get some idea of whats in the boat:

1) what battery voltage does it run at? and what is the mah?
2) does the boat have a digitally proportional radio in it?

what i mean by that is, is it a hard right hard left steering on it with all stop all go speed controlling or can you accuartly adjust the steering to a desired postion and control the motor speed accordingly?



It comes with fully proportional controls which I was quite imprssed buy, the battery is 7.2V 650mah. No idea what the speedo/rx combo is rated at though, can be that high! the motor is a 370 type.
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #9 on: April 15, 2012, 07:37:36 PM »

is the propeller dog drive or screw on. the nut on the end suggests a dog drive. im having a browse for the props that would possibly fit, as you say m2.5 is an odd size
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #10 on: April 15, 2012, 09:05:30 PM »

people are allways asking aboat how to speed up their boats usually those nqd things, but it MAYBE possible with your boat because it has an esc in it.

If you take this advice on your head be it, as doing this may fry your boat, may do nothing or may go like stink

IF your prop shaft has the dog drive you might be able to fit one of these larger spare props on from the nqd range:

http://www.ebay.co.uk/itm/110575171817?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2648

there is 2 in the set and one LH one RH, theyre 3mm but with some fine fiddling and a bit of craftsmanship you should be able to get the nut to screw the prop against the male dog teeth.

dont blame me if you see smoke %)

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pompebled

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #11 on: April 26, 2012, 08:24:50 PM »

Hi Steve,

What strikes me as odd is the prop; if I see it correctly it spins clockwise (seen from the rear), while most single prop boats have a counterclockwise spinning prop.
Reason for this is the motor; most brushed motors have a preferred direction in which they run faster than the other way, this is called timing.

Unless the manufacturer has a shipload of clockwise timed motors he needs to shift, my guess is that the motor will spin faster in the other direction.
The problem at hand is the odd size of the shaft, which makes finding a counterclockwise spinning prop very hard to impossible...

Also, the pitch seems to be small, which isn't a bad thing, it'll keep the motor from overheating, but the speeds won't be very high (as you've noticed).

Another thing is the hull; with strakes that have the wrong shape; maybe this works best for such a small hull, but my small boats most definitely have strakes that look 'normal', aka have vertical sides and run perpendicular to the waterline.

Regarding a bigger prop, as Mike already suggested, be careful, specially if the motor doesn't have watercooling, it may overheat very quick.
If you can alter the shaft by converting it to M4 thread, you'll have the entire M4 threaded props of the world at your disposal; most likely in the 2318.XX series you'll find a 29 and 31 mm prop with a slightly higher pitch, which should result in more speed.

Having watched the video a couple of times, it looks as if parts have been speeded up, the actual speed is hard to see due to the erratic driving...

Regards, Jan.
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Defairmans

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #12 on: June 23, 2012, 11:56:07 AM »

Hi I think the problem maybe cavitation? I found this video which seems to show the exact problem.   http://www.youtube.com/watch?v=DADgUzGGw_U&feature=related   He seems to reduce the throttle to get it up on plane and then increases the power.  I also baught one with the view to mod it with brushless and water jacket... never done it before so advice would be great...
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #13 on: June 23, 2012, 01:41:52 PM »

do as jan suggested and upgrade the propshaft to 4mm. Display your general wareabouts and people can then suggest some options.
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Defairmans

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #14 on: June 23, 2012, 05:48:58 PM »

Thanks... I really am a complete noob.  could you give me some advice as to which brushless motor you would recomend for a boat of this size to give more speed? I am going to water cool it. would I need to upgrade the speed controler too?  This is just a cheap rtr toy and I am guessing has low quality components.
Thanks
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #15 on: June 23, 2012, 06:46:57 PM »

I do not own this boat so i cannt really give good advice but i will where i can. Ill have a look around see what can be done.
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #16 on: June 23, 2012, 09:13:37 PM »

brushless motors need a brushless speed controller which this boat does not have. you have to plug the brushless speed controller into the receiver. If on your boat their is no option to plug the speed controller in and the standard speed controller is built into the circuit of the receiver then your entire radio is useless. You need to open it up without damaging anything and see. Also i might add that the standard batteries that come with your boat will be useless for brushless and you will need to upgrade to lithium polymer with a balance charger to boot. This convertion could cost you in excess of 100 pounds to complete.

It may not be necessary to go brushless which i beleive may be possible. I think the motor has the boot but the prop is the weak link. If you were to keep the standard motor. do you have the skills and tools to:

a) reverse the wires on the motor so that it spins the other way
b) possibly use the same standard coupling and drill a hole in the propshaft end to take the slightly fatter 4mm prop shaft
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Defairmans

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #17 on: June 23, 2012, 10:18:14 PM »

Hi Mike, thanks for the reply.  I have a good friend who is an electrician and is really good at making stuff, so he can help me with the project.  I am disabled and have poor dexterity.  Have a look at the Joysway Magic Vee, the hull is virtually identical, but different manufacturer.  I noticed the prop shaft is slightly longer and has off-set rudder. Also it is water cooled and is faster.   http://www.youtube.com/watch?v=9Uf9zqzjlQo Do you think that making the prop shaft longer would give it more bite in the water?

Thanks again for your help...
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Defairmans

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #18 on: June 23, 2012, 10:25:21 PM »

Just another question....  Do you think water cooling is good idea?  At the moment there is a cooling rotor fan on the prop shaft.  This obviousely takes some power from the motor.

Thanks
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #19 on: June 23, 2012, 11:16:25 PM »

judging by the photographs at the top of this page i thought this boat did have an offset rudder. your boat is larger too, the specs say that the joysway is 27cm where the dash is 32cm. as a general rule of thumb for surface peircing propellers the back of the prop needs to be between 11% and 13% the length of hull away from the transom. I have no idea what ive just written so to put into english for both us measure the hull pointy end of the bow to the flat end of the stern. Dont include the prop, rudder and the other gubbins in that measurement. for eg:

32cm or 320mm

12% of 320mm is 38.4mm

therefor the back of the prop needs to 38mm away for the transom. The transom is the back panel of hull if you didnt know.

you will need to measure it on your boat.

an offset rudder would help a lot as inline one on surface peircing prop interferes with the propwash and causes unstabilty in turns and a prop thats in the right place would defintaly help.

water cooling is a good idea if it is necessary. Its better than fan cooling as like you said a fan draws power.

I think the motor should be allright but needs to spin the other way so that the new prop wont unscrew itself. But an jan mentioned earlier that brushed motors spin faster one way than they do the other. lets just hope that when the direction of the motor on your boat is reversed its going the faster direction. Like i said you will need your mate to unsolder the wires on the motor and swap em over. But as of the minute its hard to say whats needed at this point until we know

a) if the props in the right place
b) the length of the standard propshaft. that includes 2 measurements, the tube and the innershaft

you will need a ruler.
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Defairmans

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #20 on: June 24, 2012, 11:49:29 AM »

Hi Mike, Thanks for all your help.

The hull is 29cm long, The distance from the transom to the end of the nut on the end of the prop is 2.5cm. To the end of the actual prop is 2.2cm. By my calculations the distance should be 3.19cm - 3.77cm going by the rule of thumb. I believe the nut on the end of the prop is a 4mm nut.  How do I measure the prop shaft?

Thanks
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #21 on: June 24, 2012, 08:06:12 PM »

something doesnt seem right in the calculations. Its the distance between the end of the prop and the prop. its only 3mm, that sound like the nut width. A picture here shows which bit needs to be the 11 to 13 percent length of the hull.



so far as we can tell then the prop is too close the transom as standard no doubt the reason its doesnt drive properly!

It was mentioned earlier in the thread that the propshafts diameter was 2.5mm. When nuts and bolts are measured the size go by the bolt diameter on most outer part of the thread. For example an 6mm bolt with have a 10mm nut. BUT the bolt is called an m6 bolt and the nut is called an M6 nut. M is the thread type.

What we need to do is change the too short standard propshaft for a longer one which also has the m4 screw fitting on the end. You need to get the entire length of the old propshaft, you then need to work out how much longer the new one needs to be for the prop to be in the right place. More maths
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Defairmans

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #22 on: June 24, 2012, 08:46:27 PM »

Hi Mike,

The actual measurement from the transom to the prop is 18mm (just the exposed prop shaft).  Far shorter than it should be. I may have to find a way to increase the distance between the rudder and the transom to accommodate the longer prop shaft.

Thanks Mike.  I'll try to get more info to you soon.  I really appreciate your help.
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #23 on: June 24, 2012, 10:01:32 PM »

ideally the the rudder on these types of boats should not be in line with the prop but offset to one side of the propeller. The rudder should actually be along side the prop to counteract whats called prop walk google it :-)).

if the standard rudder can be unscrewed maybe it can be moved.

If you have use of camera that would help an awful lot theres seems to be very little about this boat on the web and im only going by theory at the minute. You have to bare in mind that what your doing is experimenting and it might not work
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Mad_Mike

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Re: Red5 7009 RTR The Dash speedboat issues....
« Reply #24 on: June 24, 2012, 10:37:21 PM »

have you tried this boat on the water yet the performance doesnt seem that bad {:-{

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