I have an older style shuttleworth
with the more pronounced flare. Wave slap at sea or at anchor
is never really an issue. The bump out is gradual and fair enough that the water never slaps but just keeps moving.
I have sailed on a Wharram
Tiki36 , which has a hard chime just above the waterline and it could get annoying. Mainly at anchor or more gentle sea, the noise
would run down the length of the hulls as the waves passed. The owner eventually added some fairing and the problem went away.