Glad to hear you have crossed over to the "dark side" of R/C.....lol Well, to answer your question no, there is no such thing as "giant scale" per se. However, with that being said, there are a miriad of ship kits available that are quite large and would impress your friends. If you are looking for a tugboat type I do business with Harbor Models in California. http://www.harbormodels.com
They have some very nice kits available and some of the tugs are quite large I am a big fan of the "Invader" class tug they have for sale. Its around 51" long and powerful enough to pull the dock away from shore. Another kit that comes to mind is the Mr. Darby by Dumas. This boat is also available from Harbor Models. I have built three fo them in the past and am currently working on my fourth. Powered correctly they are very good performers.
If, on the other hand you are looking for a warship type ship, Loyalhanna Dockyard http://www.loyalhannadockyard.com/
comes to mind. They have a large selection of ships & fittings to keep you busy. A word of caution though, the larger (1/96th) warships typically are in the $1000.00's to build.
Last but certainly not least, if you are looking for a gas powered boat, Warehouse Hobbies sells some dandy ones. Tony C. is a great guy and I have bought multiple boats from him in the past. Obviously, he is not the only one. Aeromarine, Hoover Hydros are but just a couple of the companies producing fine boats.
I would suggest that you just do a Google search and see what tickles your fancy. If you need any more questions asked we are here to help!