M_Boats: Sleeping accomodations

I am currently the owner of a Sea Pearl 21 with convertible cabin, which is ok for just me, but since my two grandsons now go with me nearly every time I am out, I really need a boat that will sleep 3 comfortably. I am 5'7"; my oldest grandson, age 14, is a couple inches taller already, and my 10 yr old grandson will probably become adult size early as well. We just came back from a 5 day trip on the barrier islands near Pensacola, and the boys had to tent camp in the sand. Question: are the berths in an M-17 comfortable for three adults? Thanks, Jerry Renno