You Do Need power plug adapter while traveling from Cape Verde 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 Cape Verde are C and F. This is how they look like.

Cape Verde

In Cape Verde, outlets of type C and F are in use.

Type C

Type F

Saint Martin

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

Type C

Type E