score:8
You have chosen two of the islands I know best. Sal is more touristy, with more activities, bars and restaurants. Maio is lovely quiet, peaceful island. Both have lovely beaches, but those on Maio are almost deserted.
There is no direct flight between Sal and Maio, you would have to fly to Praia and then from Praia to Maio.
Very recently, they have introduced a ferry between Sal and Maio, but it doesnβt appear to operate every day. As you say, the ferry operators do not publish timetables in advance unfortunately. Itβs quite a long journey.
At the moment, because of Covid-19, there is some disruption to services, which have been halted completely, but are due to recommence on 15 July 2020. However, there may be a restricted timetable initially. It is only the flight schedules that are published in advance. I would recommend the flight rather than the ferry. There is more information on travel within Cape Verde here
If you want more information about Sal or Maio, or any of the other islands, you can find that on the same site.
I hope this helps, I know you will love CV if you go & especially Maio
Philip
Upvote:2
currently no 'direct' connections to Maio from Sal or Boavista. CV Inter-Ilhas have created a new ferry route from Santiago to Sal via Maio, but due to COVID-19 I don't know when the route will commence. TICV only fly from Santiago to Maio. The only way to fly is from Sal to Santiago and then a flight, or ferry, to Maio. Therefore, access to Maio is via Santiago only at present. The best website that I've found for Maio is www.MaioCapeVerde.com
Good luck.