The Acid in most silicone sealants corrodes copper and destroys PCBs, you have to use electronic grade acid free silicone sealant not the stuff you use for your bathroom or fishtank, this is the stuff I use to waterproof the RXs and ESCs I use in my boats.
Hot Bodies Lightning 2 Pro carbon, Mega 22/30/2, MMM, 4s3-5Ah.
Tamiya F201 carbon, Mamba 7700, MM, 2s A123 2.3ah.
Xray XT8, 1518, MMM, 4s5Ah.
Lots of boats. fastelectrics.net