A quick ( 3 weeks) rough 35" balsa MaiamI powered by Turrnigy 28/30 outrunner , 3cell LiPo and 30A ESC made for my son who wasn't that interested so I am adding a bit more to it and 'playing' with it myself .
Vic Smeed plan Thornycroft took about 20yrs (on and off) to complete and has an Electronize 43HX 24v 15A controller, 2x 400 sized 6-12v brushed motors 4cell 3000MAh LiPo for main power with seperate 3 cell LiPo running a computer fan for cooling (fan is linear and sucks air through the boat from the front hatches and blows it out through the rear hatches) There are also seperate 3 and 4 cell AA NmH packs for nav and interior lighting.
Boat runs 28mm 3 blade props and runs at a realistic scale speed and attitude. Radio gear is 2.4 and I have modified one TX for twin throttles and at present am running both these boats simultaniously on the one TX.
Have bought twin car ESCs, batts, RXs and BECs for the PT and the (36") British Power Boat 64ft HSL I am building (modelled on the RNZAFs 64ft HSL- the only one sold in the southern hemisphere - in 1940) Went on board as a teenager before she was ruined by being turned into a pleasure launch so it was a help with the building. Still remember the wonderful alloy 'Power Boat' stair treads down to the ward room. Will get some pics up of the HSL as well.

Lesro Sportsman kit, wood sports fishing boat 33'' in length, weight about 8lb. MFA 850 on 12v (10 NiMHcells 3.5ah) MTroniks 40amp esc, X50 prop. Built by Ian Gardner.
March 2010. I am now using 12 cells and a Graupner speed controller. I added watercooling too and the boat goes noticeably faster- but melted a fuse holder on first outing so I need to upgrade some of the wiring. There was also a bit of prop aerating on turns so might reduce the prop size.
The last photo is with increased voltage.

MY VERSIONS OF AEROKIT BOATS .SEA SCOUT &SEA HORNET. BULT USING DI MENTIONS FROM AN OLD KK CATALOG AND THE MATCHING PICTURES.THE SEA SCOUT
HAS A DC MERLIN FOR POWER .THE HORNET HAS A DC SABRE.BOTH OF THE BOATS HAVE A SINGLE SERVO FOR
RUDDER ONLY CONTROL.THE OTHER BOAT IS MY OWN
DESIGNER PATROL LAUNCH POWERED BY A PAW 1.5 CONVERTED TO WATER COOLING.I TURNED A FLY WHEEL AND MADE A WATER JACKET.
ANY QUESTIONS LET ME KNOW .TONY