public class Tabuleiro01 extends javax.swing.JFrame {

public Tabuleiro01() {
    initComponents();
    setSize(680, 710);
    tabuleiro02.setVisible(true);

}
Tabuleiro02 tabuleiro02 = new Tabuleiro02();

 private void Navio4ActionPerformed(java.awt.event.ActionEvent evt) {
    tabuleiro02.Ponto4.setIcon(new javax.swing.ImageIcon(getClass().getResource("/br/ucsal/bes20181/poo/batalhanaval/navioMorto.png")));
    tabuleiro02.Navio4.setIcon(new javax.swing.ImageIcon(getClass().getResource("/br/ucsal/bes20181/poo/batalhanaval/navioFogo.gif")));
}

public class Tabuleiro02 extends javax.swing.JFrame {

public Tabuleiro02() {
    initComponents();
    setSize(680, 710);
}

   Tabuleiro01 tabuleiro01 = new Tabuleiro01();

  private void Navio4ActionPerformed(java.awt.event.ActionEvent evt) {
    tabuleiro01.Ponto4.setIcon(new javax.swing.ImageIcon(getClass().getResource("/br/ucsal/bes20181/poo/batalhanaval/navioMorto.png")));
    tabuleiro01.Navio4.setIcon(new javax.swing.ImageIcon(getClass().getResource("/br/ucsal/bes20181/poo/batalhanaval/navioFogo.gif")));
}