heres my proposed setup (whats already installed)

180a turnigy marine esc
feiga 8XL
3/16th strudder setup
50mm prop ?? (still dialing in for right prop size)

i have 2x 3s, 3800mah, 20C batts (30C burst) would i fry these batts in that setup ???

Prop is waaay too big. Hurt the cells and esc most likely. Maybe start with 40mm prop .

Thats a 4S motor and in what boat??

U running 3S 2P or 6S1P ??

its in my admiral cat, running 2x 3s in series, don't quite understand all the 3s2p etc stuff, i originally had it on 4s but was slow, i think it was down to wrong prop and batts not charged fully

for starters you don't want to run 6s on that motor specially with a 50mm prop! [:-]
I don't think the system will last 30sec
and the batteries will not keep up, you could try 3s in parallel that would give you 144amps cont
but the rpm would be very slow of only about 23,000rpm
4s would work and with a 42mm and possibly bigger prop, but not to much bigger depending on the size of the hull
2p is two packs 1p is a single pack
so 3s in parallel is 3s2p

thanks srt

as you all pretty much agree on your suggestions, i'll stick with 2x 2s in series starting with a 42mm prop, i'll stick my watt meter into measure peak amps

thanks guys for helping me make up my mind