John:
I sailed to Napa about 10 years ago and didn't run aground once - a record for me, as I love to gunk-hole. There are maintained channel markers all the way up.
I'm looking at a chart rigor now that is about 8 years old, and it shows good deep water. The thing is, you really can't get all the way into town, you can get as near as a little housing settlement on the south outskirts of Napa.
There is a harbor and boat yard almost to Napa called Napa Valley Marina (707 252-8011). They would be good to call regarding this trip, especially in regards to the phone number for the draw bridge at Mare Island (town of Vallejo), as you have to call first and it probably only will raise during certain hours.
You definitely need a chart, and a good one to have is the "Bay and Delta Yachtsman Chart Book" (510 865-7500). It is good for SF bay and all the adjoining navagatable rivers and sloughs. it even goes as far south as Monterey!
The Napa River is kind of a cool trip, but the Petaluma River may be more interesting. There is a funky Greek restaurant part way up the river, and the tie-up is right downtown. Again, the same chart is important.
For both rivers, skills for sailing long narrow channels with a cross currents is accessory, as well as getting unstuck from accidental grounding on mud. And using the tide is good to, especially while going up, as its much faster and if you do go aground, the tide will soon set you free.
That's my advice - from a guy that has lived in all of those towns just mentioned for many, many years.
Question: How is it that you want to do the Napa River (Wine Country?) and how are your "aground on mud" skills?
Rich Seals