Make a small sample using the same backing you plan on using for the quilt. The "front" doesn't have to be a pieced block - just sketch out a boat and the water - it doesn't even have to be the same size. Then hand quilt it with the colors you want in the design you want. Flip it over and see how it looks on the back.

If you are using a busy backing you may not even see the quilting stitches.
If you use a solid, light color, or large print backing you probably will see the stitches.

I'm just finishing up my first handquilted quilt. Used three different colors of thread. No, my stitches aren't perfect or totally uniform. But you know what?.... I'm learning and it was fun.

Your quilt is beautiful. If it were mine, I sure wouldn't do stitch-in-the-ditch.
Be sure to post a picture when you're done.

I think different colored threads would look fine, front and back. Or... you might use white or light blue thread to create some waves in the blue water, and the same thread to create some architectural lines across the ship, and some clouds in the sky...

Your quilt is lovely. I agree with the different colours opportunities as you're hand quilting. Have fun.
Annie

It looks fine to me - I hate doing points! We're always much more critical of our own work. If it were someone else's you would be full of praise (as we all are, lol). Throw any 'rules' out the window. I think coloured, but it's your quilt and you'll know when you see it. DogHouseMom gave good advice.

What about a silk thread in a light or dark grey? I love the silk for hand and sometimes machine sewing it tends to blend in better than cotton. Also don't forget only 18 inches of thread or you will end up knotting ,twisting and just breaking not all at the same time. .what are you ashamed. Of the picture is fantastic a friend who made this boat did e ho quilting around the boat and waves in the blue.

Your piecing is beautiful!! I like your idea of using different color threads, too. Instead of looking at an off-white, look at a light gray. While there isn't a big difference in what one strand looks like, there really is a difference when it gets in the fabric. Gutterman has a light gray that is nice.

Oh my goodness! I wasn't even going to read this post since I don't really feel like I can give advice, but I'm so glad I did! I love, love, love that quilt! It's precious and I want to copy your idea. I'm sure my version won't look as nice, but it's just cute!

I think off white would work well. You could even use it to make "waves" in the blue water.

Thank you everyone! Now I have several ideas to try. I am going to step away from my norm and try a few new ideas. Of course, I will make up a small practice block (great idea-thank you), and see how it goes. I am going to play with a few things and see what I like. This is for my Grand son (who is still a bun in the oven). I know it may not be done when he is born, but hopefully before he graduates :0)

As a 95% handquilter I would use different colored thread for each color in the design or varigated thread. I would also never stitch in the Ditch when handquilting. Your quilt top is delightful. You did a great job. I have been quilitng for more than 40 years and my piecing isn't nearly that good. My favorite thing to do is white on white or preprinted "cheaters" cloth so I don't have to worry about my seams and corners etc.