The Waxholmsbolaget has published their Stavsnäs timetable for the heart of the summer, June 14-August 16. They publish three other timetables, not surprisingly, Fall, Winter and Spring.
Weekday boats to Aspö leave at 06:50 and 15:10, returning at 12:05 and 20:10. There are a few adjustments to times on Friday/ Saturday/Sunday to help facilitate spending long weekends on the islands. The journey is 25 minutes.
The private boat-taxi people don't have their full summer schedule yet, but they generally fill in a few of the gaps on the Waxholm schedule. An advantage of the scheduled båttaxi is their smaller boats which can go to the private dock much closer to our house. The cost is a bit more; I think 85 kronor as compared to the 75 of the Waxholms.
Another thing to do is rent a whole boat for a big group and/or a big load of stuff. We did this once last year and will do it again on June 17 when we show up with Sooz's car filled to the roof. A boat used to cost about 700 kronor, which was an OK deal with 4 or 5 people and a bunch of stuff. In fact, it's the only game in town for moving bigger loads, as the Waxholm boats limit you to 30 kilos, and the scheduled taxis typically less. 30kg is fine if you're bringing food or incidentals, but not furnishing a new house.
However, Margaret told me the other day that a private boat is now 1000kr! The good news is that most of our house-building is over, so this should be the last private boat we hire.