Please Help with Surf Evaluation

[Banana]

My favorite spot for surfing is almost an hour away, so I like to get a feeling for whether the waves will work for me before I go.

This is what I do: Every time I go surfing, I take a screenshot of Magic Seaweed's forecast. Then, when I return, I make note of how good the waves were (Rated from 1 to 10). I end up with a lot of screenshots like this:

Then, to evaluate whether a day will be good, I compare the forecast to a similar screeshot.

For example, before going yesterday (Nov 23), I compared the surf forecast with that of Nov 7 (specifically the time between 3 PM and 6 PM, when I surfed). You'll see that there isn't perfect agreement. The swell direction is slightly different, and MSW's estimate of surf height is different (although the swell height is about the same):

In this case, the waves weren't as good as on Nov 7 (I rated them a 7.5/10).

Can you suggest which parameters to pay attention to and which to ignore? For example, I ignore MSW's star ratings, because they aren't relevant to my surfing. I also think the swell height (second column) is more relevant than the surf height (first column).

Any better ways of estimating the quality of the waves? What do you do?

Thanks!

[Naeco78]

It's kind of a loaded subject, but to summarize some of the surf forecast criteria..

Short-period wind swells (11 seconds or less) are usually choppy and weaker because they are always generated by local winds and dont interact with the ocean floor until shortly before they break.

Long-period ground swells (generally 12 seconds or more) are usually more powerful and grow larger before breaking, because they interact with the ocean floor in deeper water. The longer the swell period, the deeper the wave will interact with the ocean floor.

Surfers usually like long-period waves (ground swell) because their height grows a lot more before they crest and break. Basically they have more potential energy that's accumulated under the water from traveling over longer distances.

[ConcreteVitamin]

There's an app for that https://lazysurfer.app/. I don't use it because I hesitate to give away knowledge to the developer (imagine the app has gathered even more accurate forecasts than surfline/MSW).

Personally, I do a similar thing as OP. I pay attention to swell combos and their angles/periods as well as tides.

[Naeco78]

There was an interesting post on Magic Seaweed that talked about how the Primary and Secondary swell periods can actually have a significant affect on the number of waves in each set. Basically, Primary & Secondary swell periods that are closer together typically create a higher number of waves in each set (ie 14s & 15s) and when the periods are farther apart (ie 9s & 16s), it creates less waves in each set. That's because the swell periods that are further apart tend to cancel each other out when the peaks and troughs overlap.

But ground swells typically travel long distances, so there's more than one secondary swell period that would influence it, but there still should be some affect of the local swell periods at a specific location. So theoretically, we should see fewer set waves and longer lulls when the swell periods are spaced further apart and vice versa.. especially as the secondary wave height increases.. and effectively combines or cancels the waves in the primary swell period. Might be an interesting indicator to watch for regarding set wave consistency.

https://magicseaweed.com/news/how-are-s ... med/11568/

[krustyburger]

Can you suggest which parameters to pay attention to and which to ignore? For example, I ignore MSW's star ratings, because they aren't relevant to my surfing. I also think the swell height (second column) is more relevant than the surf height (first column).

My thoughts on MSW... I like how the data is visualized and it is good for seeing swells coming, peaking, and going for the next 5-7 days. It is also helpful to get a quick glance at wind forecasts for the upcoming week. However, the swell height and "star" rating is not very useful, imo, other than to show trends in building or falling swell. I also find that they take the buoy readings and adjust the swell for each different spot/ break based on some proprietary adjustment... that isn't very accurate at all for my local breaks. However, they are generally accurate about which spots will be bigger/ smaller in relation to other nearby spots.

I like https://17ft.com/slo. It shows you all the North America buoy readings from the Gulf of Alaska down to Mexico. You can see the swells hitting each of the buoys as they travel down the coast. I use the Diablo Canyon buoy as an indicator for my local area and monitor that daily. I also like Surfline.. I don't pay for it so it only gives me a day or two of accurate forecasting... but I think their forecasters do a pretty good job of painting a picture of what the day's conditions will be.

[jaffa1949]

Your charting the forecast and then matching your experiences is great to know what makes your beach work.
My information consider = swell direction, size and period, then add wind direction on shore , offshore side shore. Get to personally know your banks and reefs at various tides .

So take you beach you will know what swell,get in at a good angle, period tells you power, take into accounts cross or opposing swells can enhance or hinder. ( This is the secret information that will,tell,you to go when fully forecast dependent don’t)

An hour from your beach this will be invaluable in the end!

[krustyburger]

Your charting the forecast and then matching your experiences is great to know what makes your beach work.

It really is about calibrating your internal surfometer based on repeated observation. Kind of like sighting a rifle... not that I know much about that.

[BoMan]

we should see fewer set waves and longer lulls when the swell periods are spaced further apart and vice versa.. especially as the secondary wave height increases.. and effectively combines or cancels the waves in the primary swell period. Might be an interesting indicator to watch for regarding set wave consistency.

You are on to something! I've noticed long lulls between sets on days where the secondary swell wave height is high. Depending on the swell angle it can also create a choppy sea.

[nickuwo]

There's an app for that https://lazysurfer.app/. I don't use it because I hesitate to give away knowledge to the developer (imagine the app has gathered even more accurate forecasts than surfline/MSW).

Personally, I do a similar thing as OP. I pay attention to swell combos and their angles/periods as well as tides.

Awesome to see my app mentioned here! I understand the apprehension around giving your surfing info to another person - there is an option in the lazy surfer settings to turn off all sharing of your information. That'll keep it out of my hands (although I swear you can trust me!).

Either way I can echo the sentiment expressed here - the best way to understand how conditions effect your local breaks is to keep track of them and how they translate into actual waves.

As for which metrics to pay attention to - it really depends on the break. Some breaks are sensitive to wave direction or height, some are more sensitive to period, some are sensitive to wind and some are sensitive to all of the above (and tide!). It can get quite complicated.

If you only have the mental bandwidth to pay attention to one or two and you don't want to use a tool like lazy surfer then I'd go with wave height and tide level (not tide direction) - there are plenty of exceptions but I think those two will give you the best bang for your buck. All breaks need at least some wave height and most breaks are at least a little tide-sensitive. Just my two cents!


Cheers!

[jaffa1949]

That is really refreshing, an App designer suggesting , real life observations and matching them to what is forecast and also explaining some of his ethics and use of settings.
When I look in Shoredump and serval the would be App designers who,whack a poorly thought out survey asking what often is an end of term project or assignment, or a marketing tool straight up I am delighted Nickuwo. Thank you

[nickuwo]

My pleasure!

Just to plug some other resources - if you're really into surf condition metrics get one of Tony Butt's books. "Surf Science" is a favorite of mine. Goes into wave formation, how bathymetry (the ocean bottom) affects waves and all sorts of other stuff.

[jaffa1949]

Tony Butts books are really a master class

[nickuwo]

They really are. I might be in the minority here but I just wish they had some math in them.

[Banana]

Awesome to see my app mentioned here!

I'm playing with it now—very neat! (https://lazysurfer.app/)

Al

PS Here's another idea for the app (I sent you some): What about a graphic comparison of a particular day's info with that the most similar saved session? Something like this (that I posted above):



I can grok that at a glance.

[Banana]

Yesterday was great, due in large part to the exceptionally high tide. The waves were big but manageable. I had to cut the session short because it was too damn cold!

Here's my last ride of the session (Captured by my car's security camera): https://youtu.be/5UCNceNxavI

I'm putting this chart up in my kitchen, so I won't miss future big tides:

[nickuwo]

Awesome to see my app mentioned here!

I'm playing with it now—very neat! (https://lazysurfer.app/)

Al

PS Here's another idea for the app (I sent you some): What about a graphic comparison of a particular day's info with that the most similar saved session? Something like this (that I posted above):



I can grok that at a glance.

That's exactly what Lazy Surfer does! If you have entered a few sessions you can go to the session list and sort by similarity (that's the default). That'll look at all your saved session date and order them by how similar the current conditions are to the saved conditions. It turns out to be really reliable (go figure)! Trouble is getting a bunch of sessions in there so that you always have a session close to current conditions. Just have to surf more I guess