Putting the boat in the water?????

[Flukemeister1]

My son bought a 29 foot boat that the previous owner claimed had been out of the water for 2 years. I think it may have been longer. Anyway I do not have experience with stuffings boxes other than I know if they are too tight they burn up and too loose you are sinking. What do we have to do, replace them, adjust them, will they swell when we put the boat in? Also how well do they work if a boat is kept on a trailer vs being in a slip?

Thanks!