You Do Need power plug adapter while traveling from Ireland (Eire) to Saint Martin.

Here is Why You Need An Adapter

The outlet and plug type used in Saint Martin are C and E and in Ireland (Eire) is G. This is how they look like.

Ireland (Eire)

In Ireland (Eire), outlets of type G are in use.

Type G

Saint Martin

In Saint Martin, outlets of type C and E are in use.

Type C

Type E