Re: the other comments about overseas workers –
This motu proprio Stella Maris was very clear that, if you work somewhere where you can’t get to church, you are not a bad Catholic. You are a lay part of the Church’s missionary efforts. You are on the pointy end. This applies to tourists, refugees, and everybody else, too. Wherever we find ourselves, we are automatically there to do God’s work also!
Of course, the more challenging it is to live a holy life, the more God rewards even tiny efforts to do God’s will and cooperate with Him. So don’t feel bad about your father; help him make tiny improvements. Even if your father just says one Our Father every day, or reads a snatch of the Bible occasionally, or says the Rosary sometimes, that’s all much better than nothing. Printing out a list of Stella Maris Centers, Seafarers’ Centers, and parishes with Masses at crazy times, in ports he goes to, with maps and such – that might help a lot! If he doesn’t have a Bible, or any holy pictures or medals or sacramentals or prayerbooks, you might be able to get him something small and useful.
Of course, this doesn’t mean that everybody is called to work overseas, either. You should do what you’re called to do, and help your father do what he’s called to do. God made all of us with special gifts for special purposes; that’s part of His Wisdom and Providence.
Also, the best search term to use for the Maritime Apostolate or Apostleship of the Sea or any of its other local names is “Apostolatus Maris”. There are tons of different webpages run by the Apostolates in different countries.
The general place to look for resources for all kinds of overseas workers is
the Pontifical Council for the Pastoral Care of the Migrants and Itinerant People. (Apostolatus Maris is under this organization.) Most military Catholics are under their country’s military archdiocese.
Oh, and don’t forget to pray for your father, and to ask the aid of the many many sailor saints. I am sure they would be delighted to help your father grow in the faith and in virtue, and do better at resisting temptations and helping others do the same. Don’t forget to pray for his safety, also.