Texasdiver2:
My navigation skills are horrible. I am AOW certified and have about 50 dives, most in Cozumel where it is the custom to have an underwater guide.
I had navigation in my OW and AOW classes (both NAUI) but I don't feel comfortable with this skill.
I want to be able to swim out from the boat and be sure to return to where the boat is anchored.
Does anyone have advice or know of a good book to read re: this topic.
Well....I'm really good at this (my regular buddies call me the "homing pigeon") and I'll tell you what I do:
Orientation: First of all, you need a mental map of the site. If you don't have a mental map you're going to get get lost. So before you go in the water you need some basic information. If it's a shore dive, which way (on the compass) is the shore? How deep is it? Is the bottom regular or irregular? does the slope of the bottom follow the shore or is it flat? Are there any landmarks (small wreck, unusual features like a bow net or something) that you can "recognize" when you see them? That kind of thing. The best way to find this information is to either on the internet or better yet by talking to other divers who have been there before you.
visualize your dive: Know where you want to go and how you'll get back. Think about your turn pressure and turn time and the pattern your want to swim before you ever get in the water: For example, before I get in I know if I'm diving an out and back pattern, left, right, how long, how deep and where I want to come out at the end. It helps a lot when you're first learning how to navigate on your own to enter and exit at the same place and I'll assume for the rest of this post that this is what we're doing.
Compass: Next, once you're in the water, and this might sound funny, try not to navigate too much with the compass. What I usually do with the compass is to set it before I descend to point at either the shore (if that's relevant) or in the direction of where I want to exit. My navigation plan and the setting on my compass are linked and unless I'm running search patterns for something my compass tells me only one thing...the way home. After that, I use time and bottom features to get around and the only time I use the compass to see which way I'm going is if the bottom is totally flat. Once again, the mental map and visualizing your dive are important to how successful you are in this.
Land marks: : When you're swimming, look around and pick out some landmarks (an old tire, a bit of junk, an odd looking rock, anything that doesn't move). You only need one or two but when you have a land mark make a mental note of the depth and bottom-time when you saw it. Why? Because often times you'll see it on the way back too. Say you don't have any current and you see a good landmark after 10 min. Then you swim past it for 10 min and turn around on the way back you'd expect to see your landmark after another 10 min and you'll reach the exit 10 min after that.
In other words...... Get ready for Rob's golden rule of navigation.....
Your bottom timer is your most important navigational instrument. Not your compass.
Tempo: say for example that your tempo isn't constant. This can happen if you become distracted or you're swimming in current. In this case, a land mark close to home is your best friend. Pick one a few minutes from the exit (max 5-7 min swimming). In current you may need to search around for it on the way back (it may be closer or further than you thought it should be) but when you do find it you *know* for sure that you're only 5-7 min from the exit. After seeing that landmark you can ascend to safety-stop depth and keep swimming toward your exit having done the safety stop while swimming (easier in current) and you're guaranteed to come out close to home. Using this technique I can almost always come out within a stone's throw of where I started even in a current.
Turn pressure: Say for example you're swimming out-and-back. Say you swim out at 15 metres and turn the dive at 110 bar and swim back at 10 metres gradually working up to 5 metres for the safety stop. Your pressure isn't going to tell you when you're there because your depth fluctuated. What you need to do is note the bottom-time when you turned and use your clock to tell you when you're back again. For example, in the dive I just mentioned, you may have 110 bar when you turn but if your bottom time is 27 min then you know that at 54 min you're back again. In other words pressure can control the dive but your still need your bottom time to navigate.
Lead, don't follow: And finally Kracken is right about practice but practice isn't enough. Lead the way. Every dive you make under supervision hurts the development of your navigation skills. This also applies if your buddy is navigating. If you want to become a homing-pigeon then you need to be in charge.
Finding the anchor: Just to go into your point about finding the boat back..... if you're diving from a boat and you want to get back to the anchor then an easy way to do this is to descend to the bottom, pick the direction you want to swim in and set your compass on the reverse course and swim out and back. When you turn, then your compass points "home" .... ie .... back to where the anchor is. Even if you miss the anchor if you use the tips I outlined above then you stand an excellent chance of ending your dive within a stone's throw of the boat.
R..
