WXTide32 and svHorizon forum

Good Day,

I live on St. Thomas in the US Virgin Islands and have been using WXtide32 for years. Thank you so much for the wonderful, easy to use program. I am new to the forum and I have a general question about the tides in this area. We have diurnal tides on the south side of the island and semi-diurnal tides on the north side of the island.

Why is that? Is this a common occurrence?

The islands are small - about 10 or 15 miles long and only a few miles wide. The orientation is generally east to west.

St. Croix is about 40 miles south of St. Thomas and both islands have diurnal tides on the south side of the island and semi-diurnal tides on the north side of the island.

I find this odd since the north side of St. Croix is semi-diurnal and just 40 miles away the south side of St. Thomas is diurnal.

WXtide32 does not have predictions for Tortola or St. John. Would the north side of St. John have semi-diurnal tides while the south side of Tortola has diurnal tides? They are just a mile or so apart.

Thank you,
Russ