If you are just going to fool around, then get what you want. If you want to race eventually, then some other things should be taken into consideration.
Lots of good advice here. I would parrot the response of checking with your local clubs to see what is popular. .21 mono normally makes its class around here. But if you only have a couple in your area, and someone drops out of the hobby, then you have a boat that never makes class. So...check with the local clubs. A lot of folks around here are switching to gas. Too much wind for small nitro boats. This might also be a good reason to look at the .45 mono, if it makes class near you. It will be able to handle a little bit rougher water.
I got back into the hobby during the hay day of RTR around here. It has died off a lot, but normally still makes class (we normally have a stock RTR class, and a mod RTR class). Might be a good place to learn about nitro motors, because if you burn one up, it only costs about $100 to get a new one.
On a side note, I find that folks on forums are more willing to tell you that you are wrong, then they are to give advice in the first place (not saying everyone, just a general comment). So if you have an idea of how you are thinking of doing something, if you share that idea, it seems to me, you are more likely to get inputs.
If you are not going to run with a club, make sure you have recovery set up. Too many folks make bad decisions because they had not planned on their boat dying out in the middle of a lake/pond. Seems like every year someone dies trying to get their boat back. I am not one to say don't swim for a boat. I grew up swimming in ponds and lakes. Just saying you should be prepared for the worse case scenario. I will say to take a life jacket with you if you don't have a retrieval boat (and if you do, of course). That $10 life jacket can save your life.
Welcome aboard,
Sean
