View Full Version : Current Predictions
06-05-2007, 07:52 PM
Ok I'd appreciate any help in helping me prove my theory on rig current. I went out and dove this weekend and we had a ripping current out of Port Aransas. Looking at the tidal chart below we dove on a two tide day with big differences between high and low tides. I'm thinking that on 4 tide days with minimal differences the current is maybe not as bad. SO to test this I'd like to compare this tidal chart below with obeservations from divers out in the gulf. Looks like this weekend, if my predictions are correct, should have very little current out at the rigs.....let me know if I'm right.
06-05-2007, 08:29 PM
The loop currents have more to do with it than tidal movement. We fished 20-40 miles offshore last weekend out of POC and there was no current. We dive an area that has 5 rigs within 3 miles of each other and the current will be different from rig to rig.
06-06-2007, 12:42 AM
what time? I'm curious to find out a way to predict if there is going to be a ripping current at certain rigs.
06-06-2007, 06:58 AM
I don't think the is a way to predict the currents on platforms. I have dove two different rigs within a 1/2 miles of each other and one had no current and the other was ripping. But it does seem that right after a big rain the close to shore you are the stronger the currents will be within 20 miles. Seems like once we are about 30 miles out the seems to be less current. But that is just what I have noticed.
06-06-2007, 08:38 AM
Currents in the GOM, outside the Loop Current which is part of the North Atlantic Gyre, are mostly driven by local density gradients, local winds, and tidal flow.
Off the mouth of The River I have seen 7 different density layers all moving in different directions in the first 150' of water column.
06-06-2007, 08:44 AM
we went out of sabine last thursday and came back thru san louis pass late friday night, hitting about 20 rigs along the shelf. we didnt have much current at any of those rigs. on the way back in on friday evening, we stopped at a rig about 25 miles offshore. that rig had more current than any of us had ever seen. it was like what you'ld see going thru a jetty during a strong tide. we scrapped the dive.
06-06-2007, 12:56 PM
narc that's what this rig was like around 2 or 3pm. I had a hard time making any headway with stiff #4 Omer fins.
06-06-2007, 08:40 PM
If my d@ng dogs hadn't eaten the paddle wheel off the transducer I coulda told you how fast it was. Easy 3 knots I believe. I was smart I forgot my BC so I just watched. They did get some fish even with the sucky vis and rippn current. Way to go Ya'll. :thumps:
06-06-2007, 09:07 PM
Dave make sure you get a report from John on the Lookdown!
06-20-2007, 06:49 AM
There is no reliable way to predict subsurface currents that I've ever seen. But, if you use a product like Ocens(.com) you can download some grib files that include surface currents and predicted surface currents. Most surface currents in the Gulf are wind drive, but a wind must blow a while before it can change a surface current.
You may want to read the explanation section of the book Tidal Current Tables (it doesn't need to be the current year) for the Gulf. It has a table that relates current speed to wind speed/direction and duration.
Currents are created by differentials, temperature, density (specific gravity/salinity), etc, and friction. Thus, if there is no wind or little wind, the surface water will tend to take on the underlying current.
I dove the Tenneco Towers out of Lauderdale last year and I was amazed that the boat put us in the water in such a current. I was still a pretty new diver then so I couldn't judge the current speed, but I know hanging on the anchor line coming up was really something.
Of course, no current is a curse as well when you're on a rig - you have to have current or wind to "hang off" with your boat.
06-20-2007, 10:34 PM
Thats very interesting. I never thought about it before, but there are a lot of factors that affect currents. I agree that 0 current is bad. I have had a couple trips when we had to keep pushing away from the rig because the wind would change directions or die down to nothing. I can be a real PITA. We dove 2 weeks ago and the current was maybe 2 knots at noon and seemed to have picked up to 3 knots by 3:00pm. It could be I was getting tired after the second dive. The week before, I swear it must have been 4+ knots. I was smart. I left my BC at home so I stayed on deck. Looks like ya'll might have a decent weekend shaping up.
06-25-2007, 02:54 AM
Another thing to remember is that most people estimate current on the high side. I'm not saying you did in this case, but here's how current breaks down:
1 knot = 1.7 ft per second
2 knots = 3.4 ft per second
3 knots = 5.1 ft per second
4 knots = 6.8 ft per second
5 knots = 8.4 ft per second
You'd be hard pressed to swim against a 4 knot current for very long. I'm not sure I've ever been in a 3-4 knot current, but I'm hardly the most experience diver on the board.
To complicate matters there is little to gage that distance by. You can use the boat length as a guide, or in the rare case when you can see the bottom. On top of that, objects in glass may be smaller than they appear.
I've never found that high current makes much of a difference to spearing though. Obviously it changes the amount of work you must do, but otherwise the fish line up nicely behind structure where they are easy to find and reluctant to leave.
People always ask me what fish I spear; I tell them I go for the dumb or lazy ones.
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