Juddering boat

[Guest]

I have a 'flat bottomed' 1/4 ton racing boat which 'judders' in steep chop or waves. It is especially noticeable when on the mooring when the boat is stern to oncoming waves from inconsiderate powerboats! The judder never happens when the boat is sailing. Any ideas on how to overcome it (apart from moving the boat to somewhere with no powerboats!)

Thanks in advance

 

[Twister_Ken]

Could it be the rig shaking? Th erig is not under real tension when parked, but is when sailing, so does putting on some backstay tension cure it? Or maybe a turn on the shroud bottle screws?

 

[tony_brighton]

Or possibly the rudder - getting slap from the power boat chop directly onto it from astern?