Yeah, that seems about right. The amazing thing about. Swell with periods of 15+ seconds is the amount of energy they contain. Their wave lengths are huge comparatively as is their speed. The start feeling bottom in deep water and bend and refract based on local bathemotry. So some breaks will seem relatively small and closed out, and other that can focus swell bigger. So your 4’ swell at 17 seconds quickly becomes a 10’ breaking wave. Points are the way to go on that type of swell. Lucky for me on of the best on the east coast south of RI happens to be clos