I can't say if this method is the best for you since I can't see the image. You could try using the magic wand tool. Uncheck contiguous in the settings on the top and select all the white portions of the boat. You may need to adjust your selection. While having the selection, adjust the levels in the adjustments panel to get the desired result. If this approach does not work for you, please post the photo that you are trying to edit here so everyone can understand what you are trying to achieve.
Better to use a Hue/Saturation adjustment layer, and target the problem colours. If those are the Blues, then use the RGB drop-down and select Blue, and desaturate it. If it leaves an area with an inapropriate tonal value (a band that is too bright or dark) also adjust the Lightness slider. Use the layer mask to keep the effect to where you want it.
I have a feeling that CS3 does not support scrubby sliders in its Hue/Saturation adjustment layers. but if there is a little pointy finger icon in the top left corner, then you can click on that, and then on the image, to target the colours causing you a problem.
Trevor, Scrubby Sliders is the term used when you get to adjust values of a field by hovering on its title, and when you get that hand surrounded with arrows, or when you CTRL+hover on a numerical field.
the term you want is Targeted Adjustment Tool, I think. (Sorry for the schooling, but as you are one of the big responders, using the correct terminology is important)
KWE, you could try to neutralize the color of the white using the eyedropper in Levels (especially if there is a shadow on the boat)
Letting us see even part of the image might be useful.
Selective color has a white option in its drop down.
Thanks for the heads up Pierre. I am not the only person using the wrong term though, but I'll know next time.
You'll be able to spread the word!