I will now begin the process of clarifying prices.
Submerge Ship:
Since there are all variety of people on the ship that may in theory e needed to activate the item, I don't imagine you want any discounts on it (only good, only human). Would you want ranks in sailor to be a requirement for a 10% discount?
There is a 2,500gc item cost that cannot be discounted; as its a focus item for the spell. This item would have to be on the ship and you have to note what it is.
For once per day without discount for 13 hours, the cost is: 36,400gc