Tied another crab up the other night, this time I used white acrylic caulk from Lowe's to coat the underside and cover the dumbbells. I'm not sure if the coating will have any impact on the noise made during entry, however I also tied this on a number 6 rather than the number 2 that I tied the previous fly on, so it's much smaller. I'll tie a few more of each up using this "technique".
Quick question regarding the noise made during entry: if you were casting using more of a side-arm stroke, rather than over-head or off-shoulder, the fly would have less distance to drop to the water on the completion of the cast. Wouldn't this at least help compensate for some of the noise and spalsh created as the fly touches down on the water surface?