My newest boat

[tsenecal]

Okay, so, i stopped by the LHS yesterday, and saw a nice "Hydro & Marine" 24" 12 cell hydro sitting in the display case with a "for sale"/consignment sign on it, and a very reasonable (low) price. I had the clerk take it out of the case and show it to me. It has a Hacker brushless 36mm inrunner motor, and a hacker 77amp opto ESC in it, as well as a standard size futaba servo. I told him "who do i hand my credit card to?"


then the clerk says "You get this too". he hands me a sack containing a 3 channel futaba transmitter, in the original box, and a second smaller box. inside this second box are 4 complete sets of Nicads (2 8 cell sets, 2 12 cell sets), and 3 or 4 octura props.... and a second 70amp hacker ESC (with BEC).

its like christmas in frickin June here.

so my questions here are simple. I have never owned a hydro before, and i need to know some fundamental things here. biggest concern is where should the balance point be on this thing? second question is how should i treat the flex cable, how often will it need greasing?

i am sure when i get it in the water, i will have more questions, but the center of balance is the big one right now.


thanks for any help

Tim

[Alexgar]

how much was it??

[tsenecal]

$225 out the door for everything.

[Rumdog]

Start off by getting the cg close to the trailing edge of the turn fin. It will be a good starting point. Grease the cable every other run, or if it will be put up for a few days.

[srislash]

That is a sweet deal.So do you know what KV or any #'s on the motor.I have a 2630 B50 6XL here for my hydro project.

Generally right behind the sponsons is a good CG

[tsenecal]

thanks for the info guys, i can see from the motor can that it is a B50, but the cooling coil is covering the rest of the label, so i will need to remove the coil to see all the details on the motor. I plan on taking it to the pond with a couple hyperion 3s 2200 lipos when it cools down a bit later today, to get a feel for what it can do. I will have my eagle tree data logger on board to get an idea of the draw.

[Alexgar]

great deal

[Alexgar]

you gonna run it 3s2p cause the 12 cells are more like 4s i guess the 8 cell packs are alittle below 3s but your 3s should be right in between

[ron1950]

got a feeling the nicads will be no good if they have sat for years but u never know....sounds like a great deal any pics ?

[Alexgar]

Id watch you lipos if i remember correct no cutiff on those escs

[tsenecal]

so here's the day's status...

ran the boat for about 5 laps at the local pond, and it is currently my fastest boat. I didn't bring my GPS with me, but since that pond is where i run my tunnel hull, i know this new boat is running faster than it... the tunnel hull has been clocked at 36mph, so the H&M must be somewhere between 35mph and 40mph.

the eagle tree data log indicates max amp draws during acceleration for short bursts with an average of only 20 amps, but a max of 89...

I put the two packs in parallel, so i was running somewhere between the 8 cell and 12 cell setup, as a 3s2p lipo setup. motor was a little warm after the run, but not overly warm, especially considering that the ambient temp was around 97 degrees. I would like to get the max amps down a little however, since the speed control choices are 70 amp or 77 amp. I have owned one of the 77 amp escs before, and i know they are capable of running outside their zone for the maximum bursts, but they won't live long that way. the boat is currently running an octura x442 beryllium prop. the boat came with two aluminum x442s and a beryllium y536 as well. I have run the numbers for an example boat in FECalc, with the motor set as a B50-6XL to get into the 80 amp range i was seeing with the eagle tree data. changing that to the y536, it drops to 51 amps, but the speed actually stays the same (45mph). I think i will swap props for the next run.

by the way, i put 700 ma back into one of the 3s packs, and 670 into the other one.

eagle tree data says the logger was collecting run data for 3.5 minutes with voltage dropping from 12.5 volts to 10.6 under load. maximum watts was 880...



and yeah, i really don't like the nicads... anybody want to buy a used futaba 3p and 5 pounds of nicad/nimh cells? i have no idea what type of cells they are, they are hand built, with generic white shrink wrap covering them. I will probably take them to next month's club meeting and give them to some one less fortunate. I hate that ancient battery technology. lipos are so much nicer.


thanks guys for all your help on this.


one thing i really need to do with this setup is see exactly where the center of balance was, i simply stuffed the two packs in on either side of the motor shoved as far forward as i could get them. they were basically centered at the rear edge of the sponsons, so i might have been a little nose heavy. I didn't want to move them back, there was a pretty gusty wind going on as well, and i didn't want to flip the boat on its first outing.

the boat, by the way performed flawlessly. flat as a rock, with the only bobbles when it was running over its own wake, nice rooster, not a drop of water inside.

i will post pics and video as soon as i make some, i will be going to the pond with the boat club next saturday. its kind of hard to steer, throttle, and shoot with only two hands.

[tsenecal]

you gonna run it 3s2p cause the 12 cells are more like 4s i guess the 8 cell packs are alittle below 3s but your 3s should be right in between

alexgar,

the way it was originally setup, it was either 2 6 cell packs on either side of the motor, in series, or 2 4 cell packs in series. I had the cable, so i set mine up as a 3s2p lipo (in parallel), with the lipos sitting on either side of the motor, so yeah, i should be between the 8 cell and 12 cell setup, with 4400mah capacity and 150 amp max draw before damaging batteries.

having said that, i could always buy a couple 4000 mah 2s packs and run them in series to see how fast i can make the ESC melt...

fecalc indicates going from 3s to 4s would give me a 24% boost in speed and 60% higher amp draw.

time to buy a turnigy 120 amp esc :)

[Fluid]

There were several H&M 24" hydros, it will be fun to see which one you have. 3S is a good choice for that hull and motor, a 6XL is really too much for 4S. Generic NiCds seldom delivered much over 1 volt per cell under a typical FE boat load - I've seen top-end cells drop to only .7 volts per cell. So the nominal 11 volts is pretty close to what it ran with NiCds.



.

[tsenecal]

i was wondering what anyone thought about getting a grim racer lifting prop? what kind of difference would say something like a "GrimRacer L38 x 55 Lifter Prop" make?

[tsenecal]

saturday 6/30

so, i took the bud boat out again today, with friends, so i was able to get pictures and a movie. I did find out that the motor is a hacker b50 10L, so it has a kvm of ~ 2400. I had both my eagletree, and my GPS, so here are the numbers on the 3 cell 2 parallel packs, with the y536 prop on it.. 77amps max, 28amps average. I feel much happier with those numbers than the 89 amps before. i was much more comfortable with the boat this time, so it spent less time at the lower throttle, which is why the average is higher (28 vs 20). the GPS on the y536/3 cell was max 38.5mph. knowing now that it is a 10L, i think i will try it just once with a 4s setup, just to see how fast it COULD be. i will edit or add a post of the movie when vimeo gets done with it.