Help me build my small project

[Crystallas]

I have a small retention pond behind my house, so I bought a 20" Sea Ray from Toys r us. This is the first I have ever gotten into RC anything.

I like the boat, and im not really interested in racing or getting something else.

The boat works well, and the cheapo 49MHz transmitter does the trick from any point of the pond. So Im interested in making it a little more powerful.

I dont know what I was thinking, I ordered a Graupner Speed 600 Race 8,4V from offshoreelectronics. It spins fine fine with the stock setup, but its definately starved for power.

I want to know if I can avoid replacing the transmitter, and just install the correct shafts and the correct batteries.

I bought another cheapo nikko boat for my son, and reventually eplaced the stock motor with the slightly larger one from the sea ray w/o any problems. So I really cant go back to stock now on the sea ray.

All I really want is to get this thing running and play around with it every so often.

I would greatly appreciate any advise to get this 600 motor going for a small budget project.

[BoatDoc]

the 600 might be a little big for a 20" boat. a stock 19turn car motor bay be better. you can get them for 20-30bucks. maybe for batteries you could have a look at cheapbatterypacks.com or battlepacks.com for some GP2200's or something of similar size. a 6 or 7 cell pack would probably be suitable. they are smaller than the usual sub-c batteries that we use most of the time. they may not have the highest capacity either, but it doesn't look like you'll be straining them too hard. this is just a suggestion, so you may want to wait until you hear more from others, but, maybe just maybe it might work. and the speed control that came in the boat may not handle the 600 for too long. but again, if you're not straining anything too hard, it may be ok just as a "toy".

[Crystallas]

Thanks for your reply. Maybe I could get something smaller instead. Im still curious to how this one would hold up with the 600.

[BoatDoc]

i 'spose it wouldn't hurt to try, since you already have it. but it is probably a heavier motor than stock. plus it will most likely require a larger prop. experimentation is half the fun. i just hope it doesn't let the smoke out the speed controller the first time you pull the trigger :eek:

[Crystallas]

Yeah... Im thinking about replacing a few components in the controller because I know that it wont handle the passing amps safely(but thats okay for me, I know electronics, I dont know RC.)
The stock motor was 80grams and the new one is 195. I went to the hobby shop to look at motors for a visual idea on size, but that didnt help. Their selection was from 9 Elite motors, and the rest was about 20 feet of nitro/gas parts in a display case.
The battery pack will add another 200 grams, so Im looking at maybe 300 grams total(including the weight shaving.) I might even do some things to it to make it float better. Im not quite sure what, but there is a lot of room to work with internally.

Im not giving up yet!

Any idea that doesnt work with this project might come in handy in my sons 13" nikko.

[BoatDoc]

don't worry...we'll talk you into a race boat in no time :D if you like the little boats, you can go to a micro with an e-flite motor and a small castle controller (my next project, actually). it won't take long before you're completely addicted to speed. it is my personal mission to be a bad influence :)

[streetforcegp2]

instead of using the stock tx...maybe you could buy a better tx like futaba or other brands....it will allow you to contro it further....thats what i di to my radio shack r/c boat which i got on a thrift store for dollar 98...good deal but did come with tx so i took my extra airtonics tx n rx and hook it up in there...i also made the steering steered by a servo...and i use same stock motor and a duratrax esc n a 9.6v battery pack....works just fine....

[Crystallas]

I might upgrade other things, and just improve as I go. Its no so much about liking the sport enough to race, I'm just way to short on time to do what I really want to do, and be able to enjoy it. The way I see it. If I complete this little project, play with it, learn the ins and outs ect, I'll have a lot more knowledge to plan my next build. Once things start to slow down for me, I'll be able to join the ranks of some pretty nasty boasts and have a blast. I guess I'm going the conservative route :)

I ordered the bps and charger, so TYVM for the suggestion on what to get BoatDoc :)
The actual weight of the new battery pack will be 56g lighter than the weaker stock pack. So that was definately a great bonus. I re-enforced the boat with styrafoam in key areas to keep it ballanced and float better. But now that I see my projected weight gain will be under 100grams, I have faith that this will work out very well. :)

[BoatDoc]

he he he...already looking forward to the next one. perfect. i think we have another addict and they don't even know it yet! btw...where about's are you from? we might be able to point you towards a club where you can get some tips and look into your next build. the internet is great for gathering information, but seeing some of this gear in person is so much better. meeting up with a club is the best way to go. since i hooked up with the Madison Area Fast Electric club i've learned TONS! the first thing i learned is the fact that i was going slower than i thought, but they've helped me to get up to speed, so to say. and here's another thought for ya, and yes, it's a totally shameless plug. if you want another boat after what you have, but you don't want to do a lot of work, look into the aquacraft supervee 27. 31mph out of the box, 35mph with the right prop (it's no B.S. i've seen it go). it'll be out soon, maybe another month, i think. all you need to add is cells and appropriate charger. i started a thread about it in the FE section of this forum. and it's less than $300!!!!!!!! you can't beat that anywhere, even building it yourself. Steve V. at offshore is taking pre-orders right now.

[Crystallas]

haha yeah, I'll prolly work on something better soon. I saw that supervee 27 clip, and it looked killer.

I got the batteries, and I used to original shafts to get her going. I upgraded the caps to 200uF and it took a good 20minute run on the base before the batts died. No idea how fast it will be, the original barely went 1mph, but this 600 screams compared to the nickel diameter motor that was in her before. I also threw her in the bathtub for a float and leak check. I didnt waterproof the inside well yet just yet. I wanted to make sure she floated so I knew how to renforce her better. Sofar no issues floating. Ballance is very good and it looks like im almost a go for this weekend.

It wasnt designed for a big prop. So can I just add an extension shaft and double the prop size? I did buy a carbon prop from offshore that was 6mm in diameter larger, so maybe that will be more than enough for me to close the door on this one before I start thinking about something else.

[BoatDoc]

don't run the cells until they die. once you notice a slowdown, bring it in. you can damage them if they are over discharged.

[Crystallas]

Is it smarter to keep a low center of gravity, or is it okay for me to mount the batteries to the cap? The batteries are the heaviest part, and because they are flexible to many positions, Ive been pretty critical about mounting them to the floor. But I can see how floor mounting would provide less drift on high speed turns.

[BoatDoc]

it's best to keep the CG low. drifting through the turns isn't always a good thing...it can lead to flips. it also helps keep the sideways rotation of the hull under control during a turn.

[Crystallas]

It all went well, but I was losing control to the servos, so I went ahead and ordered an ESC, rx, tx, and new servo. Which brings the total cost for the boat to about $150.
*sigh* an expensive hobby. And Im going the super budget route LOL. Yeah, I dont think Im going to get much more interested in this, but who knows. Its just to expensive, and I allready have to many expensive hobbies.

I still want to beef up the 13" boat too :) so I might make a return at it. I think that one will just get a slightly faster motor and I'll call it a toy.

[Crystallas]

actually, are there some good sites with schematics for ESCs, tx/rxs ect?
Ive found a few, but they dont look all that great. Maybe Im looking in the wrong places?
I'm just learning RC, but Ive been building electronics from scratch for over 20 years.

[BoatDoc]

i used to have a schematic for an esc, i'll see if i can find it. i don't know the site where i got it from anymore though. it would probably have to be beefed up to run a 600 as i believe it was meant for a 400 size motor.

[BoatDoc]

as for the expense part...yeah it does get pricey sometimes. an inexpensive race boat can easily cost 600 bucks. you can build some for less, i think i have 300 into my spec class vee boat, i could've built it for less, but didn't get a handle on what i was doing right away and ruined some gear. once a person decides to start running brushless motors and all that jazz the checking account starts to suffer. that's why i don't have much of a life outside of boats...no money left over :D