Hello Daniel,
Curiousity led me to sail this mission again, in a surch of the problems you have encountered.
I just got damage and sank and have no idea why, probably ran aground,
but how can I tell and how do I prevent it??
With all the precize info you've got from Marty in the controling of the ship, be advised:
The Phi Phi island scenery has places where the depth's aren't enough for a ship like the Ocean Star.
And in this particular mission coming alongside the Titanic it is important to know of / look for the AI ships.
They are on your path towards the Titanic; from the little sailingvessels to the fast moving yachts !
And there is a blue colored /marked depth hazzard between you and the Titanic. (see the MAP / RADAR)
Find your way around it and avoid the AI shipping and you'll get the result, you are looking for.
Whenever you'll hit grond or an AI ship you'll recieve some damage % to the hull, witch will add to sink your ship eventualy.
Try, try and try again if you want to know how it is / should be done ! That is the fun of this simulation-game.
vr. gr. / kind regards, Erik