As long as you purchase the shipboard wifi package then you can do so. Be sure to make sure your phone is in airplane mode (if you are savy with your phone you can simply turn roaming data off), then turn wifi on, connect to the ship's wifi (not/never ship's cell tower) and then use Skype, whatsapp or messenger or any wifi based messaging app. As long as you don't answer any calls you will not be charged any additional Rogers charges. I leave my phone on, with cellular data turned off. That way I can still recieve phone calls and see who called. I DO NOT answer the calls. I simply see the number of a missed call, and then call the back using Skype. We also video call our kids every day while we're away. Hope this helps.
Came home after a 10 day cruise and discovered we were charged for 173 outgoing text messages while on the ship. We had roaming off and cellular off and only used the ship's WiFi (which we had prepaid). Maybe I'm being naive but I thought the text messages would be transmitted via WiFi as opposed to the cellular network. I used my Telus phone and my wife used the Rogers account. Was billed on Rogers but not Telus.
text messages are always (except one scenario) transmitted by the cellular network - that one scenario where they aren't transmitted is when you have a device capable of WiFi Calling, to which you are billed the roaming country's standard per-message rate.