If your Radio is 27 mhz, it shouldn't be too much of a problem.
However if it s a 72mhz I would not recommend reusing the the transmitter or reciever, as 72mhz is reserved for Aircraft only.

Proboat, and Mtroniks make some great reversable water proof ESC.

Free boat plans...

http://nwrcsm.freeyellow.com/springer.PDF

http://www.mo-na-ko.net/images8/LodPuerto.jpg

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http://www.mo-na-ko.net/images/Prist...LOMplanek1.jpg
http://www.mo-na-ko.net/images/Prist...LOMplanek2.jpg

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http://www.mo-na-ko.net/images/Prist...nek640x480.jpg
http://www.mo-na-ko.net/images/Prist...nek640x480.jpg

******
http://www.mo-na-ko.net/plans/index.html

Oh yeah, and a fast one from Powerpetes pages
http://www.rcuniverse.com/forum/fb.asp?m=1766902