Any idea how fast a brushless supervee would go with a 6 cell 7.2v 4200 duratrax battery

MAybe about 20mph.

That seems slow for a brushless boat Are you sure thats right?

Yes its slow with a 7.2v battery. You will really get the performance once you get some more voltage into it. 7.2 is slow for just about anything.

Supervee25, were you referring to using two 7.2v packs or just one? Cuz the sv27 is built for two 7.2v cell packs, not one.

If you're referring to one then like what twomanytoys said the thing will probably haul at about 20mph, maybe even less.
A 7.2v pack in a SV27 would be the time to call in for a high amp SAW setup lol.

Less than 20, and you'll have to mod the boat to do it. You'd have to build a loop to close the circuit where the other batt is supposed to be. You'll also be out of balance which is a pretty big issue. I say less than 20 because:

A - it may not even plane off with one pack, and
3 - running that slow you'll also be running wet (lots of hull in the water). You really need to air this boat out to get into the high 30's.

good luck is your supervee shorter than it should be? (25)

Sorry guys I meant with two of the batteries not one. So would the speed be about 35 of lower

If you are new to the boat you can probably expect about 30. There are about 8mph hiden in subtle adjustments. I've got 40+ on IB4200WC's after a year of learning. If you don't have a gps then don't worry about it becuase if you have it doing 30 you'll swear it's doing way better than that. It's still a handful on anything other than glass water. Those batts aren't bad. Read the super tune thread to learn where to squeeze the boat. Have fun.

I have the nitro supervee. Also how long will the batteries last in the electric supervee at full charge. and will the boat just stop when they run down or can you tell when they are running down

I'd say 5-7 minutes run time. Running NiMH packs you will notice a serious drop in performance as the packs discharge. Once you notice it slowing down bring it back in.

If you don't bring it back you will hit a cut-off and the boat will stop. Generally when this happens the voltage will recover after several minutes and you can idle the boat back to shore. This is not recomended because discharging the batteries this far will often get them very hot and damage cells (I have this problem more with my racing packs than my sport packs). It's best to watch for the performance drop and bring it in pronto. With Lipo it's a whole different game - use a timer or get a good LVC (or both)

What type of lipo battery would be good for the supervee27

I personally like Zippy batteries from HobbyCity.com. They are good packs for the price. Look for one that has a minimum of 60A discharge (more is better, of course). If you have the stock ESC, I'd get 2 3s 5000 mAH lipos and run them in parallel (make a jumper for one of the connectors on the ESC and parallel the batteries to the other connector). This should give you 10+ minutes of run time, but you'll have to make your own battery mounts because they're much larger than 6-7 cell NiMH packs.

What about 2 2cell lipos?

That's what I'd recomend, 2 x 3S lipos will fry your electrics, the esc isn't rated to 22V. 2s 5000mAh with a 25 or 30 C rating would be ideal.

2 3s lipos is SERIES will fry it. I recommended that he run them in PARALLEL. Series adds up voltage, parallel is for capacity. If you run 2 2s lipos in SERIES you will fry the internal BEC of the ESC unless you unhook the internal BEC and either get a Rx pack or an external BEC. Running 2 5000 mAH 3s lipos in PARALLEL should give you 10-15 minutes of run time.

Mind you I have no Lipo experience.....yet[>:]. But 3s equates to 11.1volts correct? 12 cells = 14.4v. 4s = 14.8v. Are you saying that 14.8v will fry the BEC? I'd be surprised at that as many people have run 14nimh cells w/o disconnecting the BEC. (16.8v). Can you clarify. 1 lipo cell is 3.7v right?

running 2 x 2s Lipos will not need any mods to the boat at all. the boat is already wired up to take 2 x 6 cell sub C packs, so using 2 x 2s Lipo packs is no different. Why run 3S when you drop your voltage to 11.1V instead of the recomended 14.4 - 14.8V from a 12 cell subC setup or 4 cell Lipo setup?

The BEC will not need to be dissabled with a 4S setup.

If you go pack through the SV battery thread or the supertune your SV thread, you will see that this topic has been gone through several times already.