The Great Travis Traverse

[LVX]

Yeah, they are more pricey. They would run anywhere from $10-14 a piece. archaeologists are poor so we would always beg for a donation. You could always start up a non-profit - Friend of Lake Travis - and ask for donations of tie down anchors and Trimix....

But over time, the pvc will come out or fall over (we have used these as well) as the bottom changes and depending on the length of the tie down anchor, they will stay for a long while.

 

[LVX]

I never "tested" the thickenss of the silt on the bottom, would these tie down anchors work in the super soft stuff? I assume they would have to be really long to work in the soft stuff.

Talk about killing the vis setting one of these things

Depend on the length of the anchor. The one in the picture, NO. Longer ones would do much better.

As far as the vis, these actually work great. you screw these in. You don't pound them in....

 

[tlessard]

Agreed. I think we should keep the main traverse line just a single straight shot, like the gold line in Florida caves. I also want a double arrow at 2500' (or whatever the survey says 1/2 way is), just for giggles. We should mark 100' or maybe 500' intervals also.

We will have to find some way to anchor down lines for the mid lake boat sections also. Obviously, tying them off to a mud stake isn't going to work. Anything heavy dropped will destroy vis in the short term, so I'm not sure. I like the idea of having them say 5' off the main line so there is less chance of confusion (all though, even in 0 vis, it is going to be hard to mistake any line going straight up as a line staying at depth!).

A 10lb mushroom anchor carried by one team member should work nicely for an up line/marker bouy in the silty bottom to plot GPS points, but the uplines would have to be temporary as mid-lake traffic will remove them quite quickly...

 

[mkiiisupra89]

A 10lb mushroom anchor carried by one team member should work nicely for an up line/marker bouy in the silty bottom to plot GPS points, but the uplines would have to be temporary as mid-lake traffic will remove them quite quickly...

Correct. I want something that the first team (on scooters) can drop in and launch a bag, and then, time/gas/deco permitting lay more line. The last team out would be responsible for ascending with it, or perhaps, the boat crew would just haul it up by the rope at the end of the day.

 

[tlessard]

And yes, the silt is very soft...next diver down will find arm holes where we penetrated the silt easily. I think the best bet will be temp markers on the surface of the silt. According to old lake plots, the bottom of the river bed is at 180ffw...do the math. That's a layer of silt 5-10 feet thick. 6 foot PVC is certainly not overkill considering that only about 5 feet of it will be in the muck...

 

[mkiiisupra89]

Yeah, they are more pricey. They would run anywhere from $10-14 a piece. archaeologists are poor so we would always beg for a donation. You could always start up a non-profit - Friend of Lake Travis - and ask for donations of tie down anchors and Trimix....

But over time, the pvc will come out or fall over (we have used these as well) as the bottom changes and depending on the length of the tie down anchor, they will stay for a long while.

There is another possibility! I've got a welder (as I'm sure many people here do). With some rebar (cheap) and some scrap 1" or 2" flat plat (also cheap) and an afternoon we could make something as good or better. Maybe just use them every other or every 4th spot. In any case, that would be simple. And even if the cost 2 or 3 bucks, that is reasonable.

So, who in Houston has a welder? I've got to borrow my dads (3 hours away)? I've got a chop saw if you don't (although, if you have a welder, I'm guessing you have a chop saw).

 

[tlessard]

Correct. I want something that the first team (on scooters) can drop in and launch a bag, and then, time/gas/deco permitting lay more line. The last team out would be responsible for ascending with it, or perhaps, the boat crew would just haul it up by the rope at the end of the day.

Small bags would be good, but small high-viz non-implosive plastic marker bouys with minimal lift would be better. Line team could also pop several styro cups to get the boat crew on point...

 

[tlessard]

Here's some good archival photos of the area in 1938...

http://outdoors.webshots.com/album/551766468DEIeWR

 

[mkiiisupra89]

Phases:
1) Line Team - will just run the line maintaining course, putting in 4' PVC stakes at ~ 100' intervals. The reason for PVC for this phase is that it is light and easy. The stakes can be bungied to a 40cuft bottle nicely.

2) Stake Team - will come back and install long metal tie downs at shorter regular intervals. This will be MUCH more labor intense. We will probably need 2 or 3 Stake dives to ever line dive.

3) Marking/Survey Team - will come in and accurately install arrows to the nearest shore at 100' intervals, and also survey as required (TBD).

Equipment:
1) Primary Real with #18 braided line, knots every 100' for reference.
500' of #18 line fits perfectly on a primary reel. The knots are not for measurement purposes since the line will stretch, but will provide a guide to the line team as to where the first set of stakes should be installed.

2) 1" Schedule 80 PVC Pipe, 4' sections, notch 1" from top. For a 500' section of line, 5 stakes will be required.

3) Metal mud anchors (4' or 6' rebar, with screw in wings) for permenant anchoring. These will be heavy so we the team installing them will need some practice!


Am I missing anything?

 

[FIXXERVI6]

Phases:
3) Marking/Survey Team - will come in and accurately install arrows to the nearest shore at 100' intervals, and also survey as required (TBD).
so we the team installing them will need some practice!

If survey data is accurate as far as heading/depth I can easily create a 3D map of the line from the data.