Does the dive case diminish the SatCom performance?

One of the use cases is for scuba diving.  I open the dive case and then send the preset messages at the surface.  It could also be the SOS feature.  While waiting for the message(s) to transmit, I put the device back in the dive case and keep the whole thing out of the water.   The antenna is pointing at the sky.   Does the dive case decrease the SatCom operations?  I appreciate any help you can provide.