You Do Need power plug adapter while traveling from Thailand to Saint Vincent and the Grenadines.

Here is Why You Need An Adapter

The outlet and plug type used in Saint Vincent and the Grenadines are A, B and G and in Thailand are A, B, C and O. This is how they look like.

Thailand

In Thailand, outlets of type A, B, C and O are in use.

Type A

Type B

Type C

Type O

Saint Vincent and the Grenadines

In Saint Vincent and the Grenadines, outlets of type A, B and G are in use.

Type A

Type B

Type G