Hi Partlyferal. I feel your pain. I've worked in the marine industry for soon-to-be 10 years and my wife and I just had our first child last month. I was absent for the second and third trimesters so at the moment when my wife was at her most delicate/vulnerable I was not around to help. That was tough, I won't lie to you. However I was able to rejig my sailing rotation slightly in advance so that I was able to do a regular contract and then return home just before the due date.
Is this an option for you? Are you worried you might miss the birth?
What I will say in defence of our way of life is this: Yes you spend half of the year at sea... But that means you also spend half of the year at home right? What a fantastic opportunity for you and your partner to be the best parents ever! The early weeks are tough! Believe me I am living through them right now! But the main thing is that we are tackling this together as a team. Since I am the sole breadwinner at the moment my wife can continue to concentrate on the little one when I have to leave again in October but the benefit of our long home stays is there's no 9-5 to worry about and believe me one less thing to worry about is welcome relief.
Skype was a big deal for us. I would call home every lunch time if the Internet was working on board. I also have a network of family around my wife that were and still are close at hand and very supportive of little things like grocery shopping etc (my mum would take her is the car to tesco for example).
There are definitely BIG positives to this lifestyle the important thing is accepting that there are some things you will miss (I'm going to miss little one's 1st Christmas) but think of all the other things that you won't miss because you will be there the rest of the time to see it first hand!