Blue Space once bubbled...
I have a brain fart question here....
Is there anyway you can find you start point with out tracking your route from the start point...
Example: I start at point a and swim around for awhile. How do I get back to the place I started with out counting swim kicks and exact direction.....
I know I know I need to take a navigation course....But I've dove with some pretty experienced divers and we've been off course several times.....
Fire away I can take it.......
And Brian no word from you...
Time. Count minutes and swim at a more or less constant speed (ie slow). I use this technique all the time and I can often come out just metres away from where I started after an hour under water (and with avg 3 metres viz). It may take a little practice to get a feeling for "more or less constant speed" but you can do it. The nicest part about this technique is that the longer the time, the more accurate this method becomes.
Perfect for long dives.
I also use bottom features extensively. Know in your mind what what shorline looks like above water because that's what the slope of the bottom will look like under water. For example if the shoreline has a point on it above water you can probably bet your testacles that you'll see it under water too. The trick is to realise what you're seeing. Look along the shore and see, for example, where it looks like a lot of rocks may have slid into the water. If you see a lot of rocks on the bottom during your dive then you'll have an idea where you are. Be creative but don't get extreme about it or you'll waste a lot of time looking for needles in haystacks.
Pick landmarks as you swim. NOt a lot. A few and remember them. Look back over your shoulder or between your legs at your landmark after you've passed it to see what it's going to look like on the way back. Where I dive we have a lot of bow-nets in the water. I make a mental note of where I see the buoys/anchors before I get in the water and when I get to the net I know where I am.
Current. Tidal waters usually have some current and you can use this to know your compass direction. For example, if you're diving in a tidal inlet and the tide is going out then the direction of the current shows you which way the mouth of the inlet is. This, like many of the other techniques requires to you have a mental map of the site before you start. Where I live the current usally runs parallel to the shore too so it makes orientation easy. Next time you dive look at which way the current runs.
Depth. If you know how deep various parts of a divesite are then you can problaby locate yourself on a mental map using depth. Deeper is often away from shore and shallower is often in the direction of shore.
Sand. Sometimes sand will ripple on the bottom. It usually does this parallel to shore.
Look ahead. Swim from object to object under water (like rocks, or even from one starfish to the next), don't just put your head down and go. Most people will swim in circles with their eyes closed (or head down) and after a short time you won't know which way you're swimming any more. Swimming from object to object keeps you going in a much straighter line.
mmmmmmmm. Can't think of any more that use a lot.
oh yeah. ...
the compass. When in doubt use a compass. I recently had an experience of getting flushed into a shipping lane on a deep dive. We swam mid-water for 25 min on a compass with no references and in heavy current to get back to the shore and we ended up only about 50 meters away from the entry point. It takes practice and it takes "trust". You must trust your compass even if you think it's wrong.
Most of these techniques are covered in a decent navigation course.
R..
