Heck, I say he'll have a great time!
Seattle and surrounding areas- As mentioned, Fisheries Supply is a great resource, as is LFS
Marine Supply. Shilsole Marina, Elliott Bay Marina, and Bell Harbour Marina are near the downtown area.
If you have/make the time,
head north to Anacortes- it's a small town with a huge marine presence.....including the 90' Northern Marine that turned turtle recently
There are a lot of shops, chandleries, and marine related businesses in Anacortes. La Conner is just a few miles away, and is worth a visit. The
ferry system to the
San Juan Islands will take you to Friday Harbor- one of the friendliest
ports in the area.