Hex grid help needed

I am trying to use a hex grid where pieces (which have 3 hexes joined togethere) have to snap at vertices instead of hex centers.

But whatever I try then end up shifted somewhat along an edge of the hexes, instead, see image attached.

[attachment=1]weirdsnaps.png[/attachment]

This is with the following hex grid settings:

[attachment=0]hexgridsettings.jpg[/attachment]
Any hex grid expert out there that can help?
Thanks.

The problem is that the center of your 3-hex images is not actually the middle vertex–you need to add some transparent space below (for piece #1) or above (for piece #7) to shift the center point.

Right, that’s it, thanks!

I’m guessing that VASSAL sees the three hex block as a bounding rectangle, and calculates the center as the center of that bounding rectangle. So to get the center of the bounding rectangle to converge with the center of area of the three hex block, the bounding rectangle needs to be expanded with transparent area.