Thing with waves is there's a lot to use for a guestimate:
Rib example, but it illustrates the point.....
Stirling Jubilee cruise, 3 ribs , Myself (5m), an SR4, and a 6 (6.5?)m all headed downriver together and met a monstrous wind vs tide scenario at the Kincardine bridge. The troughs were big enough to loose an entire rib into visually, so big.
As the river widened past the bridge, the water speed slowed down, and so the wavelength of the chop changed. We went into it pretty much line abreast. Looking left & right I noticed that at any one moment one of the boats was always looking calm & collected, the other two were slamming like a dentist would love!
Now, the calm one was either straddling 2 waves or rolling nicely into the trough back up the other side.
Where I'm going with this is it's not just the size but the wavelength. You can alter the wavelength to suit you by "tacking" through the waves so you aren't slamming / submarining, thus making any swell "modifiable" .