Currents on Lakes ??? Safety Question

[JBreeze]

Over the weekend a professional football player died in a boating accident on Lake Ponchartrain, LA....one of the causes cited is he was caught in a strong current.

"Hill's agent, Albert Elias, told reporters the lake had a strong current, and that while the woman was able to make it to relative safety, Hill was unable to grab onto the pylon himself and was instead pulled downstream by the current"

http://www.postchronicle.com/news/original/article_21283310.shtml

Over the past couple of years, I've learned the hard way about winds/current while in my rowboat....so bad that that I've had to wade along the ocean shorefront back to the landing. Hence, the boat is named Row v. Wade.

I have a safety question....I suppose I could anticipate a current if a river entered or exited a lake, but are currents on lakes to be expected? Is the situation on Lake Ponchartrain unusual?

[Pete Dorr]

From the article

"Neither Hill nor the woman wore a life preserver."


Always wear your life vests folks. Buy a good one that is comfortable and wear it.

Pete

[S/V Laura Ellen]

The current in Lake Huron, 3 miles from the mouth of the St. Clair river, is still too strong for an average swimmer to easily swim against.

[Wild Wassa]

Wind when it blows from the same direction for an extended period of time can cause massive amounts of water to be displaced on lakes that normally have little to no current. When the wind stops or changes direction the water flows back causing a noticable current depending on how much water was displaced.

I watched an easterly wind on Lake Williams in the Gippsland Lakes Victoria, blow for over a day and a half about 6 weeks back. That night when the wind changed direction during the Marlay Classic, we rode the current through the McLennen Straits passing 29 boats who were also racing but they were tacking with the wind. We stopped sailing and rode in the current until we reached lake Victoria. Not one boat passed us in the McLennen Straits.

Last week in South Australia in the Goolwa Channel, the wind was fiercely blowing the water further up the channel and lowered the low water level by another 15 cm in the photo below.


http://www.imagestation.com/picture/sraid225/pdb059b0ffd7c8755997ee5d6ec6772fa/e96cbc21.jpg


In the afternoon the wind fell right away and the water was flowing back, so we dropped the sails and sailed back to the marina just on the rig, helped by the force of the flow. The Goolwa Channel has little flow being closed to the sea.

I sail mostly on a man made lake that is dammed and has little to no flow. When the wind is light and we are not picking up geographic wind or land effect close to the shore we go for the old water course. The old water course which is somewhat deeper than the rest of the lake, is from 20 - 60 ft in places, if we sail over the old stream bed we can pick up 0.2 of a knot, that's when the water isn't visibly flowing nor the prevailing wind blowing. So if there is a lake which is flowing, over the old stream beds, the water could be moving a lot faster.

Warren.

[JBreeze]

Life preserver.....if a young, professional athlete couldn't deal with the conditions, I certainly couldn't either.

St. Clair River...I never would have anticipated the long-range effect of this current.

Windage....I've experienced the direct effect of wind, but would not have predicted the displacement of the water.

You've given me some important things to consider!

[geeman]

Our local lake ,
It depends on the wind some days.I've seen the lake current go one way some days when the wind was blowing from one direction and the other way on others days depending on the wind.
I have also seen the wind whip that lake up in front of a storm so badly that we couldnt make the marina ,the bow was digging into the chop too badly to make it back.
It was a friends boat and he didnt have any experience in rough water.He was trying to make the marina which meant we had to sail INTO the storm.We would have never made it.My grandson and my daughter was in the boat . I mutinied and "ordered" him to make for the closest cove where I grabbed a tree root and hung on until the storm was over.

[Rancocas]

Lake Ponchartrain is actually a salt water estuary. The upper end of it is more fresh water due to the steams that enter there, while lower down the salt increases. The "lake" is tidal, which I am sure contributes to various currents during the ebb and flow.
Except for the dredged out shipping channels, Lake Ponchartrain is relatively shallow, averaging about 12 to 14 feet. Winds have a greater effect on shallow bodies of water, pushing the water in one direction or another, easily making choppy conditions, and in some large lakes, such as the relatively shallow Lake Erie of the Great Lakes, a strong wind can rapidly push up sizable waves.

[Bruce Hooke]

As Rancocas noted, Lake Ponchartrain is a very special case since it is basically a tidal inlet rather than what most of us would call a lake.

As a general rule, I'd think that the bigger the lake, the more potential there would be for wind driven current and similar issues. Long, narrow lakes are also going to be more prone to issues than round lakes. I mostly canoe on smaller lakes. Away from the immediate vicinity of river mouths I can't ever remember encountering noticeable currents. I do know from ice skating to watch out for thin ice at narrow spots in the lake -- if there is current in the lake this is where it will be strongest and therefore where the ice is most likely to be thin.

[John E Hardiman]

Life preserver.....if a young, professional athlete couldn't deal with the conditions, I certainly couldn't either.



It is important to note that muscle mass is denser than fat. And that most people drown by panic or hypothermia keeping them from keeping their heads above water, not that they don't float. I have found it far easier to survival float now that I'm older than when I was lean and 17 and could swim 3 miles at a stretch. (My mother was a Red Cross WSI, and most often ran the pool on the base we were at during the summer, so I grew up in the water and had all the swimming/lifesaving/SCUBA certs early.)

[carioca1232001]

Lake Ponchartrain is actually a salt water estuary. The upper end of it is more fresh water due to the steams that enter there, while lower down the salt increases. The "lake" is tidal, which I am sure contributes to various currents during the ebb and flow.
Except for the dredged out shipping channels, Lake Ponchartrain is relatively shallow, averaging about 12 to 14 feet. Winds have a greater effect on shallow bodies of water, pushing the water in one direction or another, easily making choppy conditions, and in some large lakes, such as the relatively shallow Lake Erie of the Great Lakes, a strong wind can rapidly push up sizable waves.

There was a thread some weks ago in Misc.Boat Related about ore-carrying ships making a passage through stormy oceans, with photos of masses of water breaking over the low hull-sides.

As the thread progressed, it surfaced that one of the major inland lakes - Lake Erie ? - had swallowed up an ore-carrier or two, in similar conditions, within the last 20 years or so.

[Bruce Hooke]

The "Great Lakes" of North America, and the handful of other similar size lakes around the world should probably be treated pretty much like the Baltic Sea and other salt water bodies of a similar size. From the perspective of weather and sea conditions to expect, I'd guess that there are a lot more similarities between, say Lake Huron and the Baltic than there are between Lake Huron and the local lake that most people (who do not live on the shores of a great lake) have in mind when the talk generically about lake boating.

If there is an underlying lesson here, it is that when it comes to lake boating there is a huge range out there, from places that would challenge the best bluewater sailor to places that would be safe to navigate on a large plank!

[S/V Laura Ellen]

As the thread progressed, it surfaced that one of the major inland lakes - Lake Erie ? - had swallowed up an ore-carrier or two, in similar conditions, within the last 20 years or so.

The most famous of the recent sinking was the Edmund Fitzgerald in 1975 in Lake Superior.

Here is a good Great Lakes shipwreck database.
http://www.baillod.com/shipwreck/swayze/swayzedbresults.asp

[High C]

I live on the edge of Lake Pontchartrain, with a mile or so of marsh between here and the lake.

Pontchartrain, being tidal as mentioned by others, is always moving either in or out at a knot or two through its narrow neck (the Rigolets). Boat guests often want to go for a swim while enjoying the HEAT, so I have developed a set of procedures that I always follow whenever anyone goes over the side swimming.

Swimmers ALWAYS wear a vest. Then I float the rescue horseshoe on 100' of floating line and instruct swimmers to stay very close to either the line or the horshoe itself. I also make sure someone who can operate the boat (usually me) stays on board in case a swimmer loses contact with the horseshoe and the boat has to be moved to perform a pickup.

It always surprises newbies how fast they are swept away from the boat. :eek:

[Keith Wilson]

As Bruce said, "lake" covers a lot of territory. Some "lakes" are actually reservoirs, some are wide spots in rivers where river current is a factor (Lake Pepin on the Mississippi), some have both river and tidal currents like Lake Ponchartrain, and some are just lakes with no current at all. The Great Lakes are in a different category altogether - inland seas, actually.

Superior has the added disadvantage that it's COLD - even in late summer the water is rarely over 40 degrees F, and colder offshore. Sailing there always scares me a bit. One doesn't live long in water that cold.

[High C]

... some have both river and tidal currents like Lake Ponchartrain....

Because of those rivers that feed the upper end of Pontchartrain, lake level is typically about a foot above sea level, caused by her narrow opening ot the Gulf.

Her mouth (the Rigolets) is less than a mile wide and usually has strong currents.

[carioca1232001]

While on business in New Orleans in´96, we drove our cars on one of the longest self-supporting bridges on the planet , stretching between the shores of an enormous Lake.

Wasn´t deep though, one could see the bottom, which also suggests it was clean !

Pontchartrain ?

[High C]

While on business in New Orleans in´96, we drove our cars on one of the longest self-supporting bridges on the planet , stretching between the shores of an enormous Lake.

Wasn´t deep though, one could see the bottom, which also suggests it was clean !

Pontchartrain ?

Musta been. The Lake Pontchartrain Causeway is the bridge you described, 24 miles long! There are two others on the eastern end each 5 miles in length.

The water is about 14' deep along the bridge, and you can see several feet into it under bridges when the light is right. It is pretty clean, and has been getting clearer with every passing year since shell dredging was halted in the late 80s, IIRC.

[WillW]

Then there's the phenomenon of the seiche, which occurs on the Great Lakes. It's sudden variation in water height, caused by wind and weather. They're very rare, but the lake height can alter dramatically:


Lake seiches can occur very quickly: on July 13 (http://en.wikipedia.org/wiki/July_13), 1995 (http://en.wikipedia.org/wiki/1995), a big seiche on Lake Superior (http://en.wikipedia.org/wiki/Lake_Superior) caused the water level to fall and then rise again by three feet (one meter) within fifteen minutes, leaving some boats hanging from the docks on their mooring lines when the water retreated. On Lake Michigan (http://en.wikipedia.org/wiki/Lake_Michigan), eight fishermen were swept away and drowned when a 10-foot seiche hit the Chicago (http://en.wikipedia.org/wiki/Chicago) waterfront on June 26 (http://en.wikipedia.org/wiki/June_26), 1954 (http://en.wikipedia.org/wiki/1954).

[S/V Laura Ellen]

Then there's the phenomenon of the seiche, which occurs on the Great Lakes.

I've only seen one seiche. The water in the yacht club basin rose by a few feet and then dropped by about 10 feet. half an hour later the water started to fill back in. Everything was over in about a half hour after that. My boat was lying in the mud with no water around it a the height (or low) of the seiche event. In this case the seiche event was caused by a very large very strong storm cell that passed over Lake Huron. If I hadn't seen it for myself I would not have believed it.

Some interesting information:
http://www.glerl.noaa.gov/seagrant/glwlphotos/Seiche/13July1995/13July1995Storm.html