Best swing class choices for overlaying instruments/marker data on map?

Question

Hi everyone. The title pretty much says it all.
I'm looking for some insight into how to draw things correctly so I don't get glitches. This is a nautical GPS application. Right now I have the following classes:
MapView extends JPanel
VectorMap (standalone class)
InstrumentOverlay extends JPanel
BoatOverlay JPanel
GPSGridOverlay (standalone class)
MapView is simply a place to consolidate the drawing of everything. VectorMap is actually the data storage object for a series of contour lines and geographic points with associated text labels. GPSGridOverlay and InstrumentOverlay are things that will overlay and possibly move around on top of the map. When I drag my InstrumentOverlay around, it smears any other overlayed data (like the BoatOverlay or GPSGridOverlay). It doesn't smear the background map. I can only fix it by manually calling repaint on MapView. I can post a screenshot if that would help.
My question is, am I doing this in a silly manner? What would be a better choice of Swing classes for this task? Is it alright to use standalone classes as I have done and pass them a Graphics object to paint into, or should they be made into Swing class objects like JPanels?
the paintComponent method of my MapView object is:
protected void paintComponent(Graphics g) {
     Graphics2D g2D = (Graphics2D) g;
// clear screen
     g2D.setColor(new Color(255,255,255));
     g2D.fillRect(0,0,getWidth(),getHeight());
// manually paint components that aren't JPanels
     vectormap.draw(g2D);
     gpsgridoverlay.draw(g2D);
// JPanel children (instrument, boat) will paint automatically after this due to
// paintChildren() call made by swing.
}

Answer 1

Here are some screenshots:
before dragging compass:
http://www.kulkarnicorp.com/coastnav1.jpg
after dragging compass to the left in an S pattern:
http://www.kulkarnicorp.com/coastnav2.jpg