Royal Caribbean could still decide to build a fourth Oasis-class cruise ship that would be ready by 2018.

Cruise Currents is reporting that UBS Investment Research says Royal Caribbean is deciding if they want to exercise the option to build a fourth Oasis-class class ship.  The decision to go ahead or not needs to be made by mid-2014.  

If Royal Caribbean picks up the option, then the ship would be deployed by 2018.

Royal Caribbean already has an active order for a third Oasis-class cruise ship that is due for delivery in mid-2016.

Royal Caribbean placed an order for its third Oasis-class cruise ship late last year and will have the steel cutting for that ship occur on September 22, 2013 at STX France.

Cruise Industry News posted an article that cites supplier reports, a fourth Oasis-class ship will be confirmed by next summer, followed by an order for a fifth Oasis-class ship.

There's been an option for Royal Caribbean to build a fourth Oasis-class ship ever since they signed their contract with STX France for the third ship last year.  If Royal Caribbean exercises their option for a fourth ship, it would be ready for delivery by mid-2018.

For a fifth Oasis-class ship, Royal Caribbean has up to four days prior to the one year anniversary date of the signing for the fourth Oasis-class ship contract.

Last December, Royal Caribbean made headlines when it ordered a third Oasis-class cruise ship and then went on to order 3 Quantum-class cruise ships.  It turns out Royal Caribbean might not be done ordering new cruise ships.

UBS Investment Research cruise industry financial analyst Robin Farley says Royal Caribbean currently has an option for a fourth Oasis-class order.  If ordered, that fourth Oasis-class ship would be delivered in mid-2018.

Royal Caribbean must decide relatively soon, as the option for the fourth Oasis-class ship expires in December.

Farley feels lower prices to build new ships, thanks to lack of new ship builds recently, are what may compel Royal Caribbean to consider yet another new cruise ship order.