Roll characteristics in planing hulls

[msc]

I am a recreational boater who's current boat is a 57' McKinna Piliothouse motor yacht. The vessel has a particular characteristic that I would like to understand so that I can avoid this problem in my next boat. When in a quarter following sea, in other words, coming to my port or starboard aft corner, the vessel will roll quite a bit. In sea conditions of 4-5 foot seas from this direction, we can take rolls that feel like they are 30 - 40 degrees and it sends things flying around the cabin, as you might imagine. Certainly the vessel can be fitted with stabilizers to mitigate this, but what I would like to know is: what are the characteristics or measurements of a hull or vessel that can be examined to predict how the vessel might roll under these or other conditions. Or, more simply, what are the hull characteristics that I should look for to predict a stabile ride. This is a planing hull and these issues are while the boat is on plane. Thank you for any help or insight you can provide.

[tom28571]

To clarify what is happening to you, how does an aft quarterting wave reach a 57' powerboat on plane? Can you describe what happens a bit more?

[msc]

Thanks for responding to this thread. Waves that are coming at roughly 45 deg to the forward motion of the vessel have, of course, two vector components. The component of the wave that is perpendicular to the vessel direction will cause the wave eventually to reach the boat. In a completely beam sea we can sit in the trough, or on the crest, but in a quartering following sea, we'll continue to encounter crests and troughs. Does that make sense?

Michael

[SamSam]

Originally Posted by msc

Thanks for responding to this thread. Waves that are coming at roughly 45 deg to the forward motion of the vessel have, of course, two vector components. The component of the wave that is perpendicular to the vessel direction will cause the wave eventually to reach the boat. In a completely beam sea we can sit in the trough, or on the crest, but in a quartering following sea, we'll continue to encounter crests and troughs. Does that make sense?
Michael

Does the wave overtake the boat or the boat overtake the wave? How fast is your boat going when it is 'on plane'?

[msc]

It isn't a matter of one overtaking the other, they are going in different directions and so must intersect at some point, but it's the wave reaching the vessel that initiates the roll.

On plane we'll be at 17-20 knots. This significant roll is typically in 4-6' seas which represents 15-20 kts of wind in my bay (Buzzards Bay, MA).