r4e
Contributor
Like AfterDark, I disagree as well. That's the point of learning to use the compass (not just to read it), you also have to learn to measure distance and combine use of landmarks. The most common ways are counting finstrokes and counting time. In both you have to compensate for possible current drift. Calculating finstrokes might be more accurate if you plan to stop many times on your way, but, you have to be careful not to lose your count. Counting time is easier if you have a good average speed that is not much affected by depth and your varying eagerness/tiredness/etc. If you stop for a longer period, you have to take that in account.
For example, a simple open water exploratory dive for me in a new place would be:
1) 2+10 minutes in compass direction directly out. During the first minutes memorize the depth and landmarks for your return (or use lights as breadcrumbs). If depth becomes excessive too soon, stop earlier and lengthen legs 2 and 4.
2) Turn right/clockwise 90 degrees to follow again compass direction for 10 minutes plus possible lengthening from step 1. You should now be following the coastline. If necessary, limit the depth and follow depth line. This means you will be moving closer to shore than the rectangular path would take you.
3) Turn right/clockwise 90 degrees towards the shore and follow this direction about 10 minutes. If your course was fully rectangular, you are now at a shallow depth corresponding to the initial 2 minutes outbound. You might encounter too shallow water earlier, just stop and make a mental note of this.
4) Turn again right/clockwise 90 degrees and follow the shallow water towards your entry point. This again would be 10 minutes plus the possible lengthening from step 1. In the shallow you are more likely to be blocked by shallow obsructions that you have to circumvent. This takes additional time, so add about half of this to your navigation time. E.g. if circumventing a large rock takes you 2 minutes, add one minute to your return time.
5) You should now be close to the landmarks you memorized in the beginning. If you still cannot see them, continue perhaps an additional minute or two, but, not much further.
6) Finally, turn now LEFT/anticlockwise and in a minute or two you should be where you got your toes wet.
Unless I make a really big mistake, I surface within 30m/100 ft of my initial entry point. On a rectangular route, possible skewing out of the exact direction tends to even out over all.
The typical visibility on my dives is 2-5m/6-15ft and consequently night diving does not differ very much from "day" diving. I rarely dive in visibility with less than 1m/3ft visibility, but, then you really have to trust your compass and your skills to use it. My best navigation sofar was a one-way navigation 600m/2000ft across a lake to an island 10m/30ft wide. The visibility was far worse, less than 1m/3ft, than I initially expected, otherwise I would not have bothered to take a big camera with me (sic). The biggest concern in such a long(ish) navigation was to maintain an accurate direction irrespective of the asymmetric drag profile (stage tank on one side and camera in other hand) and how I might unintentionally try to compensate this by different left/right fin strokes. My solution was to alternate the stage tank and camera from side to side at regular intervals. I was also concerned of the distance because I could not check it except by hitting the island, or, I might overshoot it a lot. Well, luckily I hit it spot on (big grin). But, blunders do happen occasionally as well;-)
The only places where I view compass directions as informational only, are large (metallic) wrecks and areas with ferrous minerals.
