rye stay away from johnson motors they are cheap and nasty and eat amps they will crash and burn trust me my mate bought two and they lasted all of 5 minuites in his 4 ft RTTL which is the vosper hard chined hull used for most pt boats.these johnsons rev very high but they dont like turning boat props they just blow everything the esc the motors themselves ,they are junk trust me .far better to go with a good make of motor like graupners or similar that way you know the full specs of the motors unlike most of these johnsons.better to get a motor designed to run in a boat than buy one designed for a drill or anything else.by the way the johnsons he got were off ebay and rated at between 6 and 12 volts,he was running two 8.4 nicad packs.i also know of several other guys who had the same opinions on the johnsons having had the same happen to them,heres a link to them are these the ones you were looking at?.[link]http://cgi.ebay.co.uk/Johnson-6-12v-Motor-New_W0QQitemZ250044186424QQihZ015QQcategoryZ2564QQ ssPageNameZWDVWQQrdZ1QQcmdZViewItem[/link]