Sand ridges for navigation

[JamesBon92007]

Good points there Sam, particularly about the "back of the ridge." Also, to state the obvious, if you swim parallel to the ridges you are swimming parallel to shore (once again, usually). Close enough in many cases anyway, especially along straight beaches. But as MaxBottomtime just pointed out things can be very different on a peninsula or irregular beach. To get to a particular reef that I frequented I would swim out until I reached a specific depth (Point A), turn right and follow the lines in the sand, keeping track of the time I spent swimming in that direction (to Point B) where I would note the depth (probably not necessary if the destination is a distinctive formation). Since Point B was the end of a rock reef it was easy to find my starting point for the return trip. I would use my compass mainly when I returned to Point A to verify my position but my depth, swimming time, and the sand ridges were usually quite adequate and my exit from the water was always spot on. I still use my compass too, especially when shore diving. At the beginning of the dive I would swim out, face the shore entry/exit point, and set the compass bezel. It seems like there's always a couple of big rocks I'd like to avoid coming back in to shore. Without the compass reading I might have to surface to verify my position and I could easily stray a bit swimming in with the surge and reduced visibility and all. Knowing the tides can also be helpful because that can change the depths a little but I'm not usually down there long enough for it to be significant.

 

[Sam Miller III]

@SteveC

"Don't remember which one? Solo, Nav, OW, AOW, probably Nav, but I remember a course where sand ridges were mentioned/in the book. I checked and it is mentioned in the SDI solo manual. "
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Good for you ! And good for SDI for including such a basic knowledge in their Solo Manual and the course that you needed on your way to become a "diver"

So what was printed in the manual ? Can you copy it and share so all can read it and be further educated on the subject ?

I suspect it would be appreciated by all who didn't take the course-- including me

Thanks in advance

SDM

 

[Steve_C]

@SteveC

"Don't remember which one? Solo, Nav, OW, AOW, probably Nav, but I remember a course where sand ridges were mentioned/in the book. I checked and it is mentioned in the SDI solo manual. "
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Good for you ! And good for SDI for including such a basic knowledge in their Solo Manual and the course that you needed on your way to become a "diver"

So what was printed in the manual ? Can you copy it and share so all can read it and be further educated on the subject ?

I suspect it would be appreciated by all who didn't take the course-- including me

Thanks in advance

SDM

It is in the section on navigation and trying not to get lost. Bottom of page 74. "with a little effort and practice , you can become proficient at under water navigation and course plotting. These skills coupled with observation of underwater "landmarks" such as unusual rock formation, wave patterns in the sand, coral outcrops, ...." This is the first quote I saw in the manual. There may be others. I have also seen (somewhere) diagrams about wave patterns relative to shore. Know in the SDI SOLO course that the instructor talked about how to interpret the wave patterns.

Have some stuff to do but will go back this weekend and see what else I have.

 

[Steve_C]

Couple other places

-PADI Adventures in Diving Manual, page 272 in the Underwater Navigation chapter, Bottom composition and formations. There is a paragraph on sand ripples, how they form and what they mean. Even a drawing of divers pointing to a ripple pattern.

-Clay Coleman's "The Certified Diver's Handbook" I found this a good read when I was starting out. In the Natural Navigational Aids section on page 235 there is a paragraph devoted to sand ripples, how they form, and how to interpret. Usually parallel to shore, steeper and closer together nearer to shore, etc.

 

[Steve_C]

Speaking of natural navigation one I have found very useful. You know you are somewhere close to the boat but do not see it. Look around and see if in some direction the water appears to be a slightly darker in the distance. It usually is the shadow under the boat which is often visible from much further away then the boat. Especially useful in places like the reefs in the keys. Also useful when deeper like 60-80 ft in the vicinity of a wreck with a fair amount of vertical. If you are off from the boat and do not see it but one direction appears somehow a bit darker it is probably the wreck.

 

[northernone]

Note of caution to add to the excellent replies already expressioned.

Sand ridges are good if you know what direction they are forming. A regular spot I dive has beautiful deep sand ridges. Some days they are parallel to the shore, some days they are perpendicular. Some dives they change directions within half an hour.

Regards,
Cameron

 

[MaxBottomtime]

Typically the ridges get larger and closer together nearshore.

 

[ScubaWithTurk]

It is in the section on navigation and trying not to get lost. Bottom of page 74. "with a little effort and practice , you can become proficient at under water navigation and course plotting. These skills coupled with observation of underwater "landmarks" such as unusual rock formation, wave patterns in the sand, coral outcrops, ...." This is the first quote I saw in the manual. There may be others. I have also seen (somewhere) diagrams about wave patterns relative to shore. Know in the SDI SOLO course that the instructor talked about how to interpret the wave patterns.

Have some stuff to do but will go back this weekend and see what else I have.

RAID has a section in the Advanced 35 course material that is all about Natural Navigation and includes sand ripples. It also discusses direction of sunlight, direction of surge or current as well as bottom depth profile and composition.

 

[Steve_C]

The point of all these posts is that natural navigation is discussed in several places in the materials of several agencies. Most have the same general content as mentioned in the RAID post. Now what people learn and pay attention to or teach is a separate question.

 

[Sam Miller III]

@Steve C
Thank you for your immediate and complete and responses -- they answer the questions
I have always gleaned a certain amount of knowledge and never been disappointed in reading your posts on the right coast

Sam Miller, III
ps inquiring minds want to know--Are you wearing a Canadian "Tilley Hat" in you avatar picture? sdm