Prism99

Regarding the extra batting under the whales, yes, this is called trapunto. You would need to quilt some of the details in the whale to keep the extra batting in place. Actually, instead of spray basting the extra batting to the top, you could use a soft fusible such as MistyFuse to fuse it to the top.

Another thing to keep in mind is that you want to keep the amount of quilting somewhat uniform across the quilt. If the background is fairly densely quilted, you don't want to leave the large whales completely unquilted (even though outlined). You need to add some quilting to the whales. It would be pretty easy with this panel to simply quilt where the white and black meet, around the fins, around the eyes, etc.

The lower the number on thread, the thicker it is. 30wt is thicker thread. Regular weight that most people use for piecing and quilting is 50wt 3-ply. I like Aurifil 50wt 2-ply for quilting. Another option would be a polyester 60wt thread. JoAnn Fabrics has a fairly good assortment of C&C 60wt polyester, although I don't remember them having any variegated. Aurifil has variegated as well as solid colors.

To be honest, if this is a special quilt I would not take a chance on an unknown brand of polyester batting from JoAnn's. I'd probably order some Quilter's Dream polydown online. Perhaps you could go back to JoAnn's and figure out what brand you have? Maybe I'm overly cautious, but years ago I used a poly batting that did not hold up well.

For quilting the background, I meant using either wavy lines across the water background in the panel, or quilting the rays of light into the water. For the coral and stones I would probably switch to a brown thread (for the top, anyway), outline quilt them, and outline quilt along any of the interior shapes.

Edit: There is a method for adding trapunto where you add a layer of batting underneath the shape and use water-dissolving thread to sew around the outline from the top. Then you turn the quilt over and, being ***very*** careful, trim the batting to just outside of the sewn outline. That way you can be sure to catch all of the whale outline in the quilting, as you will be able to see where the water-dissolvable thread is. However, this is a lot more work than the other method and you do risk accidentally cutting a hole in your panel.