Tips On Keeping Track of the Dive Boat?

[sixt3denied]

Hi all. I need some advice on something that's been bothering me since a recent dive.

I was in the Florida Keys (Key Largo) 2 weeks ago. Diving was fantastic! But.....

On one boat trip - the seas were pretty rough. We were diving on a wreck about 45 feet down. The wreck was spread out over a very big area. It has been there for about 70 years. There was a fairly strong current and a lot of surge - even on the bottom. We went into the water at a pretty good distance from the wreck. It was a good 15 minute swim against the current to get to to the wreck. Due to the current and strong surge, visibility was not good. Luckily the dive was being led by 2 divemasters. There was a total of about 10 of us. Long story short, when we reached the half way point on our air, we all headed back to the boat. The general course was a big oval to the dive site and then back. I was really worn out fighting the current and surge while trying to maintain my buoyancy to get to the wreck etc. I ended up losing track of where the boat was. Due to the poor visibility, you could not see the boat from the bottom until it was pretty much right above you. So anyway I continued following the divemasters back to wherever the boat was. My air started getting low (700psi) and my dive computer began chirping and flashing "low air". Not usually a problem because I usually have an idea where the boat is and if I'm close I dont really worry because I can predict how much air I will need to get back to it. But on this dive I had no idea how much farther away the boat was. I couldn't see it, and wasn't sure how much longer of a swim I had. Although I kept my cool - the dive computer alarm and flashing "low air" on the display was getting me a little nervous. I knew that once I was on the surface I would be fighting the rough seas and waves while awaiting my turn on the line - getting my fins off and get back on the ship. So my regulator would be staying in my mouth until I was pretty much on the boat. So in my head I was accounting for the air I would need while ascending, performing a safety stop, and also while on the surface. It was a little rough for snorkel use - unless I had no choice.

So the big question is - what can I do to not lose my bearings on where the boat is? I was thinking that I should have taken a heading with my compass when swimming to the wreck, but this still would not help me account for how much farther away the dive boat was when heading back. Due to this "oval" dive pattern, you aren't passing the same wreck or reef areas on the way there as we did on the way back. So the use of underwater landmarks was difficult.

Any suggestions? My loss of bearings as to where the boat was is really bothering me!!!!

 

[TMHeimer]

Tough situation. Difficult to keep track of where the anchor line was also. Compass navigation difficult in any current, but especially strong--complicated estimated calculations needed to have any compass success. If you were doing a straight out and back from the anchor line to the wreck a line on reel would be a pain but it would obviously get you back. Why the oval route?

 

[Jim Lapenta]

Or did it seem like an oval due to the surge and current. What site was this? Guessing either City of Washington or the Benwood?

 

[sixt3denied]

Yeah if it was a straight route then a compass heading at the start would have helped. I could have used landmarks on the way back to clue me into how much farther I had to go. I think the oval routes were used to cover more ground and allow us all to "see more". Unfortunately it was a solo dive vacation to the Keys. I didn't have a dive buddy so I was stuck with the group. Else I would have doe a straight dive there and back. No oval. But at least this ended up being a learning experience. I identified a shortcoming in my diving ability (keeping track of the boat) and will work on improving in this area on future dives.

---------- Post added April 17th, 2012 at 06:48 PM ----------

Or did it seem like an oval due to the surge and current. What site was this? Guessing either City of Washington or the Benwood?

I have to check my dive log but I think it was the City of Washington. I dove on both the City of Washington and also the Benwood - but i'm thinking it was the City of Washington...

 

[TSandM]

I don't know that site at all, but I can offer a few tips from my own experience. If there is any depth variation to the bottom at the site, knowing the precise depth of the anchor is very useful. Paying attention to exactly HOW the bottom falls off can be useful, too, because that will give you an idea of how far you need to go to get to the depth of the anchor.

If you were a 15 minute swim from the wreck when you got to the bottom of the downline, your compass would have worked, and if you'd followed it closely, you would have been able to know for sure if you swam an oval or not. (Although ON the wreck, the metal masses can completely flummox a compass, as I found out in the oil rigs off LA.) In addition, if the current is constant, using the current direction can give you cues, as well as which way any soft structures are lying.

I really hate guided dives where the guide doesn't describe the path he intends to follow. If I run my own dive, I make sure I don't stray from navigational cues I can use, but if I have to follow a guide, it can get much more complicated. I can take people through our local mudhole site in low viz, because I've done enough dives there to recognize specific pilings or logs or pieces of debris, and I would guess your guides are folks who have the same kind of familiarity with the wreck site. That doesn't help you if you lose the group, though!

 

[Doc Harry]

You navigational problem was complicated by heavy seas, strong current and poor viz. Many years ago I found myself at the bottom of the mooring line in similar conditions on the wreck of the Eagle as a novice diver. I asked myself how I would handle getting lost or blown off the wreck. I realized that I didn't have an answer and so thumbed the dive immediately.

You have to have a plan for navigation and plan to deal with getting lost or blown off the wreck.

Constant reference to your compass and a virtual map in your head is always useful.

In a worst-case scenario, if you get lost and low of gas or blown off the wreck, shoot your SMB right away and start a drifting ascent. Hope that the dive boat sees your SMB. Hope you're dressed warmly. Hope that you have signalling devices to help people find you.

 

[DivemasterDennis]

Compass skills, and other navigation skills, are kept sharp through practice, practice, practice. The impact of current can be accounted, but to do so with precision requires more calculations than you are likely to have the facility to do once the dive has begun. An approximation is about the best we can achieve. Just as a quick review for those reading this post, I have a blog post entitled Navigation for the recreational diver, which offers in pertinent part as follows:
...Navigation is second only to buoyancy control on my list of important skills to master in order to be a competent diver. Here is my short list of important navigation tips:
1. Believe the compass.
2. Navigation involves vectors which have both direction AND distance.
3. When diving on you own in conditions that require good navigation, a slate is an essential tool. Use it to note your course. Some people who do navigation skills work regularly can maintain a good mental chart, but a slate is a must for most of us.
4. Distance determination is harder to master than direction determination. All the suggested methods are useful: kick cycles, time, air consumption. Unfortunately, none are constant. Use the method that is most constant for you, which will vary with the conditions you are diving. Each of them requires lots of practice to be mastered. When possible use landmarks- they don't move.
5. However your compass is mounted, (and I'm ok with console mounts or compass only on a retractor) holding your compass level is important.
6. Make use of landmarks to confirm your location.
7. Always be thinking about how to make your navigation more precise.
I like to navigate from object to object when possible. Example: we went off shore at 80 degrees for 5 minutes to the big coral head (note on slate) The we went more or less 145 degrees to the main reef, taking 3 minutes, where the big elkhorn coral was (note on slate).Then we went on a course more or less 180 degrees for about 10 minutes, looking at the reef. Now I could try to navigate straight back to our point of origin (about 330 degrees for 14 minutes) OR... I can reverse my direction by going on three simple reciprocals: 00 degrees, then 315 degrees, then 275 degrees, using the landmarks and time for confirmation. The second way is easier.
If you want to be a good and accurate navigator, practice with your compass on every dive, even if you are being led by a divemaster. It's a little work, but it's actually nice knowing where you are and how to get home!
DivemasterDennis

 

[sixt3denied]

Divemaster Dennis - EXCELLENT INFORMATION! I will look for your blog post as well...


Thanks