I forgot how I did in Blender 2.49b (Today I run at Blender 2.5.8) when I with 3 +1 vertices and Ctrl + P conect/parent object to each other on the ocean surface, before I add Wave modefier.

Yesterday I try with everything. I select the boat and with Shift key select the watersurface and press Ctrl + P and that work , but the boat do not tilt on the wave. This one
I know I did somthing with wertex, but dont remember how.

Kan you help me.
Thanks in advance

You want vertex parenting. Select the boat, shift-select the watersurface and then tab into edit mode, select either 1 or 3 vertices and then press Ctrl P.

Your advice worked perfectly
Thank you AlanK.