Underwater Navigation??

[moneysavr]

Did a dive last weekend with a Divemaster for a tour of a new dive site,as part of our diveplan he set me to lead the dive to a steel wreck at a depth of less than 40' not far from our entrance point.We both set our compass on surface at a heading to the dive bouy-and both had the same heading prior to submerge and do a underwater dive to the small steel wreck. well all was to our dive plan as we headed of to the wrecks location with vis less than 7'-10' I kept compass dead on my heading with the dive master close to my side looking on his compass.
As I thought we would be on the site my compass started to spin,I stopped and thought I may be off level or holding or swimming wrong,but I was allmost level-made no turns,no current,well we missed the wreck did a thumbs up,safety stop,and talked about what I did wrong.
We were close and swam right past wreck like by several feet.the compass spin was the steel boat screwing up true north of the compass.
I know on training they go over this but what could or should you do on a dive that this happens,seems like most wrecks I dive on the great lakes are older wood schooners-mostly wood wrecks,or boats that boilers may have been salvaged.
I just felt that I screwed up and would not like to have this happen again!
Help,Brad

 

[ScubaFreak]

Doesn't sound to me like u did anything wrong to be honest. Have to say I've never really had the first hand experience of this happening on a dive, but once the needle settles down, u can re-take your bearing and continue on.

Although it does remind me of all the times when people walk into my LDS(which is located on an old ship) they pick up the compass and say- HEY! This aint workin!! then we remind them they're surrounded my metal and they realise what went wrong

 

[MikeFerrara]

A small target can be hard to hit dead on. The initial heading you take may not even be accurate enough to hit it even if you swim it perfectly. Sometimes it's best to not even try. You can use intentional error. For instance you could shoot to the left, go out an adequate distance and then swim a search pattern to the right...or shoot streight at it and if you miss go far enough to know you've passed it and swim a search pattern back. This of course requires that you estimate distance as well as direction.

If there is a natural landmark or some other kind of structure you can use that in conjunction with intentional error also. As an example, if the wreck was on a drop off or ridge you could shoot off to one side (so you know which way to turn when you hit the ridge) and follow the structure to the target.

 

[cdiver2]

Did a dive last weekend with a Divemaster for a tour of a new dive site,as part of our diveplan he set me to lead the dive to a steel wreck at a depth of less than 40' not far from our entrance point.We both set our compass on surface at a heading to the dive bouy-and both had the same heading prior to submerge and do a underwater dive to the small steel wreck. well all was to our dive plan as we headed of to the wrecks location with vis less than 7'-10' I kept compass dead on my heading with the dive master close to my side looking on his compass.
As I thought we would be on the site my compass started to spin,I stopped and thought I may be off level or holding or swimming wrong,but I was allmost level-made no turns,no current,well we missed the wreck did a thumbs up,safety stop,and talked about what I did wrong.
We were close and swam right past wreck like by several feet.the compass spin was the steel boat screwing up true north of the compass.
I know on training they go over this but what could or should you do on a dive that this happens,seems like most wrecks I dive on the great lakes are older wood schooners-mostly wood wrecks,or boats that boilers may have been salvaged.
I just felt that I screwed up and would not like to have this happen again!
Help,Brad

I used to dive a wreck in about 75', 10' viz at the best of times and about 200 yds from the shore. The same thing happend on this dive, every time and everyone that did it....there is nothing you can do about the compass as soon as it comes NEAR a large metal mass it will spin and not stop until you leave the vicinity.
We used to take a small metal steak and a fifty foot line once the compass started to spin push the steak into the seabed and do a circular search with the line....got it every time

 

[moneysavr]

Hey Thanks!! Well some great info from you guys!!! Thanks ,Thought I could navigate a bit from years back "boyscouts!" One thing I do Know is how important it is to know how to navigate under water for safety of you and your buddys!
Thanks ,Brad