X-Star Conversion

[TeamTEOR]

I have been looking around everywhere for a set of plans to build a foam boat, and have not found one. So while I was out X-Mas shopping, I found a New Bright Mastercraft X-Star at Walmart. It runs on a 19.2v (600mha) battey and has a AM 27mhz system. After carefully looking over things I am going to convert it to a FM 75mhz system with a real servo. Also, I want to put in a set of Sub-C cells into it rather than this Square (Unknown, maybe AA) battery pack.

Has anyone else do this yet? For $76 for the boat it looks like a great place to start. I have some stock sized servos and a my digital 3ch TX from my Emaxx to play with along with a spare RX. Maybe I'll put lights on it with the spare 3rd channel to switch it on and off.

I have no idea what motor is in here, but I imagine it is a drill motor of some type. Maybe I'll get the bug to change it one once I see how fast the boat goes in the water, but it looks like a pretty strong motor to be turning that nice sized prop.

[Kmot]

Don't know anything about thier boats. I have had a few of their 1/6 scale trucks. Definitely not 'hobby class' stuff. I usually get them for the bodies.

I must say though, as in their trucks, the scale detail is awesome. So is your boat. Looks awesome.

[TeamTEOR]

They all do look are nice for sure, and I have on of their larger H2 Hummers as well for my kid. It ran fine for a long time, and now it seems like a gear in the tranny of diff broke, so it doesn't roll anymore. No big deal tho, the kid likes his Power Wheels H2 a little better anyway.

The X-Star goes straight without a problem, looses half of its speed in a turn. As far as anything close to hobby speed, no way. I brought the boat in at first sign of the pack getting weak, I had maybe about 8mins or so of run time. Not to bad for a stock New Bright setup. It sure does look like the prop is not running as efficently as it could tho. I wonder why they geared the setup, maybe to save on some amps?

In any case, I hope there are a few people that could kick in about where to start for a good motor/battery/prop choice.

The info on the boat is:
32" length
9" wide
about 6" from the bottom to the top of the hull
4lbs 9.5oz with the battery pack installed.

[ropanach]

I just picked up one of these boats today, I got it at a second hand shop, I go there to find cheep r/c units and tear them apart for the motors & gear box's, I got it for a $1.99 usd.

I cant get it to run, the battery box looks like there may be a contact gone, there are three contact points in the boat, BUT ONLY TWO CONTACT POINTS ON BATTERY BOX?

Is your boat setup in this way?

[TeamTEOR]

$1.99, lucky! HEHHEHEH
I have only 2 contact points on the battery tray. The battery is supposed to be a 19.2v pack, and it kinda clips into place, and then the latch holds it down from popping out.
The motor will not spin unless the boat sences it is in the water. It has two little wires that come out to the bottom of the boat hull that tell the motor control that it is safe to power up. The rudders should still function when out of the water.

[Bobslr]

Hi Ropanach
Your boat looks identical to the boat I got my grandson for Christmas last year,Does it run on a 6 Volt sealed battery pack?
I'd have to look at the battery box the next time I go over to see him but I can check the number of contacts if you want and get back to you.
We never could get the hull and deck joint to seal completly so we just put some pieces of sponge in the hull and empty any water out when he changes the battery pack,also the rudder is either all or nothing it goes all the way over no matter how much you move the stick.
Despite that the kid loves that little boat best 30 bucks I ever spent.
Bob

[ropanach]

TeamTEOR:

After reading your post, I find that this is a 6.v battery pack, and no wires going out the bottom of the boat, so I opened the electronics box and found water damage inside, so I gess this is a rebuild project in the future, after I've got the Envoy tug & and the pt-109 in the water. my work bench never will see the light of day at this rate. thanks for the info, have fun with your rebuild/ upgrade.

[TeamTEOR]

Share your rebuild info too buddy. I am not at all versed in Boat physics, So I am just winging it. MY idea was to try to hang it on a piece of string and keep the same angle when I am done with the mods to it. Any idea what size prop that is on this boat?

[tim slocum]

How accessible is the drivetrain?? Would it be easy to upgrade it?Is there room for a 7.2 pack? I guess Ill drop by WalMart on the way home form work tomorrow to check it out. :)

[ropanach]

I will be useing the fotaba or sanyo battery, two of each for ballance on on each side, They will fit quite nicely on each side, the motor is 6v, but I can get more speed with the 12v,
or I will get alot of cavitation:rolleyes:
I think I will go with 6v first, It maybe all it needs, for the boat is quite light, to do this I need to make sure both batterys draw the same amount of power so I don't draw power from one or the other, this eats up MA fast. or run them sepretly, useing one for ballust untill I need it, switch plugs and go on, finding center of gravity before the tear down is a go idea, you can match it with the new stuff, also check water line, you want to keep it the same as well. I'll try to do this project in the spring so I can do test runs, right know the lakes are frozen over and the snow we got last night don't help, the frezzing rain to day is not helping ither :censored: . But I still have two other projects on the work bench that I need to get done. :)

[TeamTEOR]

How accessible is the drivetrain?? Would it be easy to upgrade it? Is there room for a 7.2 pack? I guess Ill drop by WalMart on the way home form work tomorrow to check it out. :)

Tim, once the stock brain is removed, you can mount maybe two to three 7.2v packs in there. The inside of the hull has pleanty of space, lucky us. I can't imagine why the boat was actually so slow at 19.2v. I wonder how much of that voltage the motor is seeing. It appears that the motor is mounted on some type of gear box or belt drive. I can't tell for sure without removing things. It looks like it could be completely dissasembled without much of a problem. The prop didn't sound like it was having any problems turning under the water, but for its size I imagined that it would have done a lot more for speed. Maybe there is a bit of cavitation (a term that I will be looking up in my quest for understanding). I truly hope that there are a few others that look into this conversion as well, this boat is capable of more speed.

Sorry to hear about the lakes by you. Here in Scottsdale, Arizona it is still in the 60s during the day, and the lake is a nice 20-25 min drive. The wife likes to go there, as opposed to the field when I go fly my planes.

[TeamTEOR]

Quoted from: http://en.wikipedia.org/wiki/Cavitation

Cavitation is the formation of pockets of vapor in a liquid. This process is caused by low pressures in the liquid. When the local ambient pressure at a point in the liquid falls below the liquid's vapor pressure, the liquid undergoes a phase change to a gas, creating "bubbles," or, more accurately, cavities, in the liquid.

Problems

Cavitation is, in many cases, an undesirable occurrence. In devices such as propellers and pumps, cavitation causes a great deal of noise, damage to components, and a loss of efficiency.

When the "bubbles" of cavitation collapse, they create large amounts of noise. The noise created by cavitation is a particular problem in submarines, as the noise destroys its stealth.

The collapse of cavities involves very high energies, and can cause major damage. Cavitation can damage almost any substance. The pitting caused by the collapse of cavities produces great wear on components and can dramatically shorten a propeller or pump's lifetime.

Additionally, the creation of and subsequent collapse of cavitation bubbles creates friction and turbulence in the liquid. This contributes to a loss of efficiency in devices that are experiencing cavitation.

Pumps and propellers

Major places where cavitation occurs are in pumps, on propellers, or at restrictions in a flowing liquid.

As an impeller's (in a pump), or propeller's (as in the case of a ship or submarine) blades move through a fluid, low pressure areas are formed as the fluid accelerates around and moves past the blades. The faster the blades move, the lower the pressure around it can become. As it reaches vapor pressure, the fluid vaporizes and forms small bubbles of gas. This is cavitation. When the bubbles collapse later, they typically cause very strong local shockwaves in the fluid, which may be audible and may even damage the blades.

Cavitation in pumps may occur in two different forms:

Suction cavitation

Suction cavitation occurs when the pump suction is under a low pressure/high vacuum condition where the liquid turns into a vapor at the eye of the pump impeller. This vapor is carried over to the discharge side of the pump where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure. This imploding action occurs violently and attacks the face of the impeller. An impeller that has been operating under a suction cavitation condition has large chunks of material removed from its face causing premature failure of the pump.

Discharge cavitation

Discharge cavitation occurs when the pump discharge is extremely high. It normally occurs in a pump that is running at less than 10% of its best efficiency point. The high discharge pressure causes the majority of the fluid to circulate inside the pump instead of being allowed to flow out the discharge. As the liquid flows around the impeller it must pass through the small clearance between the impeller and the pump cutwater at extremely high velocity. This velocity causes a vacuum to develop at the cutwater (similar to what occurs in a venturi) which turns the liquid into a vapor. A pump that has been operating under these conditions shows premature wear of the impeller vane tips and the pump cutwater. In addition due to the high pressure condition premature failure of the pump mechanical seal and bearings can be expected. Under extreme conditions this can break the impeller shaft.

Discharge cavitation is believed to be the cause of the cracking of joints.

[Roger in France]

Thanks TeamTEOR, a clear, accesible and helpful explanation. I presume you are a prof. engineer?

Roger in France.

[TeamTEOR]

Thanks TeamTEOR, a clear, accesible and helpful explanation. I presume you are a prof. engineer?

Roger in France.

Nope, just someone who took a moment to use a search engine.

[tim slocum]

With 19.2v the boat should fly!!A Traxas Villian EX is 14.4v and it flies.I believe I would set up the drive line like the Villian EX,two nice motors,two 7.2v = 14.4v and maybe a proboat esc(I like them).I bet that alot of the 19.2v is going to other stuff.Id change the prop too.bye

[TeamTEOR]

Well, I think that what I am going to do is place the hull into the tub and have a volt meter attached to the motor to see how many volts is actually making it to the motor. Also, it seems that there are 2 versions of this boat. I can't seem to locate the 19.2v version on the New Bright website, but there is a 6v version. It seems that they have another 19.2v boat listed on thier site, and they say it goes 20mph! Something must be way wrong on this boat. Maybe I should call New Bright tech support tommorow. Here is a link: http://www.newbright.com/nb-consumer/product/index.php?id=391&action=detail

I have two old Great Planes Wildcat boats. One is setup to run, but has a cracked prop from when I tested it in my pool. I set that boat up with 2 20t motors and that thing HAULS! Moves like Stank! It runs with 2 7.2v Sub-C packs and a Traxxas EVX esc (made for the EMaxx offroad truck). I'd be way happy with that if I was able to get some local help on some good props and connecting hardware from the motor to the props. Then I could get the other hull running with the same setup.

That performance is what I based my purchase of this 19.2v boat on. I thought that it would seriously have some nice speed. I thought it would be as fast as the Wildcat.

[TeamTEOR]

Well, get this. I called to complain to New Bright about the boat. How could they release a boat stating that it is POWERFUL with its 19.2v pack and it moves slower than my son can run! They were kinda shocked, but they did state that it was really rated for 7mph anyway, and it was just bad marketing on their part. To try to make things right, they made me an offer that I did not refuse! I was given a RMA number and was asked to ship the X-Star boat and TX back to them (Keep the battery and charger), and they would send me back one of the 36" Liquid Heat Racing Boats (Not released for sale in the US) which is rated for 20mph, along with 2 more battery packs and a extra charger. The boat is already off in the mail back to them.

[wingnut163]

whoray for our team
let us know how it is

[TeamTEOR]

Yeah, I will. This is still a fun boat to convert. I just wonder what possed them to make it so slow like that and then market it the other way. I'll look around the local shops, if I find another hull cheap, I will try to do some work with it. I would still like to see what you all come up with no matter what.

[spiffy_spaceguy]

With 19.2v the boat should fly!!A Traxas Villian EX is 14.4v and it flies.I believe I would set up the drive line like the Villian EX,two nice motors,two 7.2v = 14.4v and maybe a proboat esc(I like them).I bet that alot of the 19.2v is going to other stuff.Id change the prop too.bye

Unfortunately it's just not that simple. Voltage is not the only number that matters when we're talking about electric motors. Since the number we actually care about is watts (horsepower), current makes a big difference. Huge. Massive. Colossal.

I've been experimenting with a simple electromagnet-essentially the same deal as one of the poles in an electric motor. Get this: it creates a stronger magnetic field on 2 'D' cells than on a 9V battery. So for some reason, I get more power out of 3V than 9V! Why? Current. Watts=Volts*Amps. 9V alkaline batteries are actually a 6-pack of little dinky alkaline batteries, and smaller cells make less current. Therefore the massive D cells make more current, therefore more watts to the electromagnet, therefore more gauss out of my magnet.

The 12 cell hobby-quality pack is not created equal to the 19.2 volt New Bright pack. That nice pack-with sub C cells-is optimized to make current and watts for your typical e-power speed junkie. The New Bright pack is designed to make enough current to make an 8-year-old kid happy. Big difference.

[TeamTEOR]

LOL, it didn't make my 4yr old happy, he was wondering why it was so slow! LOL. I agree with you tho about the the cells and their capabilities.

I'll post up the picks of the new boat when it arrives. so we can compare the difference in the two boats.

[TeamTEOR]

Here is the new Ship.

This is a link to the ship on their site again.
http://www.newbright.com/nb-consumer/product/index.php?id=391&action=detail

[Greg_Vincent]

TeamTEOR,

I know this is an old thread, but I have a current interest in these large New Bright boats. I recently won the 32" Mastercraft X-Star in a raffle and am trying to make it more "fun" on a budget. Performance mods so far have been limited to relocating the receiver/battery holder aft to move the center of gravity, and creating a new stuffing tube/drive shaft to move the "surface drive" prop away from the hull. Everything else is still stock (including prop). The mods have probably upped speed from 7 mph to 10-12 mph and it actually gets up "on step" and turns faster as well. Still experimenting and will probably try a new prop at some point. Once I am satisfied with speed I will consider a new radio and ESC. Since I found the batteries on clearance (with 1-hour smart chargers!), I have 3 extras and would like to keep using them if possible.

Oh yeah, I also removed the wakeboard rack/tower for aesthetic reasons.

I have two questions: Is the Liquid Heat much faster than the X-Star, even though it uses the same 19.2v battery and seems to have an identical prop and rudder setup on the exterior? If it is faster, what do you think is different from the X-Star? Knowing this might help me further improve the X-Star.

I measured volts at the motor and 19.2v is actually getting delivered to the X-Star's motor. I also determined that the X-Star gears down its motor 1.5 to 1 (which is not much of a reduction).

I wonder if the X-Star receiver limits the amps to lower the RPM and the Liquid Heat receiver does not do this. Other possibilities I can think of are that the LH may be direct drive or may simply have a more powerful motor.

Thanks for any insight - Greg

[TeamTEOR]

Hey Greg, I am sorry. I have not really ran the boat much. I am kinda stuck on it as I have no real boating background or major knowledge on how to prop or mod these things with their stock parts. These boats are great subjects to be modified, and if you can then you are way ahead of the game. The new boat that replaced the X-Star was MUCH faster, but still not faster than the wildcats. Bet if I slapped some lipos in there that would change things up a bit.

I have to really try to find someone who can help me out with these boats. If you know of a good e-boat group please share the info.
Tom

[Massey]

Teor, here is a link to a Nikko Toy boat that I converted to real R/C. The process is similar to what you are going to be doing when it comes to the electronics and servo. After that is done you can check out if it helps the boat and then ask us here and we can help you with better prop and motor combinations. Just remember to post lots of pictures, the more we see the better we can help you

http://www.rcgroups.com/forums/showthread.php?t=573854

Massey

[TeamTEOR]

Massey, thanks. Pictures is easy to put up for sure.

More than anything, I need to find items to rebuild the driveline. Couplers and shafts, again, all stuff I have no idea on where to source. I took all of the last stuff my LHS had for the one Wildcat that runs. When I go to change the prop it will most likely need a new shaft as the brass one didn't appear to be in the greatest shape last time it was looked at, and also when I take it out of the lead coupler, I will need to replace that as well, they are 1 shot deals!

So if you can point me to some stainless steel couplers and drive shafts I would greatly appreciate it. It makes me happy to see this thread revived.
Tom

[Greg_Vincent]

Teor, thanks for the quick reply. If I continue with the X-Star mods I will probably focus on the radio and ESC for now. Cheap 2-channel radios are not hard to find, but the only fairly inexpensive ESC I could find to handle the 19.2v is made by Electronize in England. It's about $57 US. Other alternative is to do minimal upgrades to the X-Star and put my money into a more hobby-level RTR like the Hammer EP.

Good luck with the Wildcat. I checked it out on the GP web site (under discontinued), nice looking boat. I think you are probably already in a good e-boat group to get what you need (but not from me, I am just getting started)!

[Greg_Vincent]

I have a question regarding toy boat conversions. What is the advantage of, or reason for, replacing the steering servo on a toy-grade boat ? Do these servos not respond to proportional signals from the new receiver? Or is a new servo just quicker to respond (and if so how much quicker)?

For reference, the servo in the X-Star is a 2-wire servo.

Thanks!

[Shaun Hendricks]

compatibility. Most 'toy grade' servos are proprietary to the electronics that drive the boat. Hobby grade servos are compatible with hobby grade receivers and ESC's...

[TeamTEOR]

The toy grade servos are normally just a 3 position set up as well, Left, middle, right. Our Hobby servos are fully proportional.