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  1. #1

    Question Long Period Swells & Lulls

    I am not the best at predicting when waves will come until I see with my own eyes that there are waves that is a reason I use this site. I am even worse at the number game. It seems that longer period swells are more sought after then the shorter period (wind swells).

    My question is with a longer period swell...does this mean the waves travel faster to our beach? If so how are lulls incorporated into this? If not disregard the next paragraphs because I am a kook when it comes to this stuff.

    Say for instance we have a 12second swell. This swell would travel faster then a 8 second swell. Would this mean that Lulls in between sets would be less frequent with a 12 second swell? Which would make the paddle out a ***** in making 8-10ft 12second beachbrake swell? This is something I always wondered because I never really pay attention to numbers once the swell starts because I am to busy surfing!!

    I hope this question even makes sense sometimes it is hard typing crap out on the internet.

  2. #2
    Join Date
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    good question.

    Yes, the longer period swells travel faster than shorter period swells.

    In general there is a greater time in between sets with the longer period swells. Since, the swell are generated much further away, the wave trains becomes more dispersed over time where the faster waves outrun the slower waves.

    Also, with tropical swells there can be a lot of variation in consitency, since the wind fetch in the storm is changing quite a bit through time.

  3. #3
    Quote Originally Posted by Swellinfo View Post
    good question.

    Yes, the longer period swells travel faster than shorter period swells.

    In general there is a greater time in between sets with the longer period swells. Since, the swell are generated much further away, the wave trains becomes more dispersed over time where the faster waves outrun the slower waves.

    Also, with tropical swells there can be a lot of variation in consitency, since the wind fetch in the storm is changing quite a bit through time.

    Thanks for the reply. That makes sense now!

    It still seems like there still so many small variables that come into play still. I guess it is on a case by case basis. (wind fetch)

  4. #4
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    swells

    long period swells are more sought after if there are point breaks or reefs because the waves are broader and will hold more energy through the break but since we don't really have any structures like that here take long period waves with a grain of salt because they tend to close out most beach breaks especially when they are bigger

  5. #5
    Pull out your spreadsheet, calculator or abacus for this one, if you want to have some fun (or agony) making swell arrival predictions:
    http://www.rodndtube.com/surf/info/SwellSpeed.shtml

  6. #6
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    The period length is the distance in time between waves. So the longer the period the more time that is between the waves.

    For example a 5ft swell with a 14 second period will produce about the same size rideable wave as a 10ft swell with a 6 second period. Why? The speed the swell is moving. When the 10ft swell reaches the shore where it would begin to break, there isn't much "push" behind the wave. This will result in a more mushy wave that just kind of crumbles as it breaks. The top of the wave will never really develope because there is no strength to the wave. When the 5ft swell reaches the shore, the power behind the wave will make the wave stronger. The period length will shorten when it reaches the shore because swells travel faster through deep waters. When the water is shallow, the front of the wave slows down and the back is still travelling at the same speed, which will cause the wave to build and the lip will jack up producing a wave with a better form and possibly a hollow section.

  7. #7
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    Quote Originally Posted by tbing View Post
    The period length is the distance in time between waves. So the longer the period the more time that is between the waves.

    For example a 5ft swell with a 14 second period will produce about the same size rideable wave as a 10ft swell with a 6 second period. Why? The speed the swell is moving. When the 10ft swell reaches the shore where it would begin to break, there isn't much "push" behind the wave. This will result in a more mushy wave that just kind of crumbles as it breaks. The top of the wave will never really develope because there is no strength to the wave. When the 5ft swell reaches the shore, the power behind the wave will make the wave stronger. The period length will shorten when it reaches the shore because swells travel faster through deep waters. When the water is shallow, the front of the wave slows down and the back is still travelling at the same speed, which will cause the wave to build and the lip will jack up producing a wave with a better form and possibly a hollow section.

    Very well said.