Restoring missing turn buoy anchors

[Waternut]

Over the last couple weeks a friend and I have been restoring an old slalom course on a public lake. Unfortunately, some of the original anchors (T posts) seem to be gone. The occasional boat guide is less concerning to me provided they're close and in line with the rest. However, it appears that one of the turn buoys (4 ball) seems to be missing. To make matters worse, the boat guides for 4 ball are also gone. I've got the boat guides at 3 and 5 as well as the turn buoys for 3 and 5.

 

The only thing I can really think of to put 4 ball back is to make 2 ropes measured to 154 ft 6 in and stretch them from 3 and 5 ball to about where 4 ball should be. We'd then temporarily mark it and see if it lines up with 2 and 6. Does that sound reasonable? Can you think of a better way?

[Orlando76]

That's similar to what I've done recently. My .02, do it on a day with a down course wind because it's amazing how much a rope can catch a cross breeze causing it to bow (even on a calm flat morning). After my last bout, I think I'd use surveyors string rather rope. To measure the turn buoy a room e will work but a ~41' 2x4 square is easier.

[Waternut]

Was there an auto correction in that last sentence @Orlando76 ? I have no idea what that was supposed to say. I do plan to keep the ropes 3-4 feet underwater so no wind affects them...but mostly because I want to reduce the angle coming up from the original post.

[mwetskier]

you can also run low stretch nylon cord between 3 ball and 5 ball and mark the mid point then run a second cord between 2 ball and 6 ball and mark that mid point also. a cord run between the two midpoints will give you the line for your 4 ball and its boat guides and a measuring tape will tell you where the boat guides go. obviously the 4 ball itself goes on the mid point of the 2 ball to 6 ball cord.

[Waternut]

@mwetskier I did that for the boat guides at 4 ball but I feel like there could be a substantial error when doing that for a turn buoy. The problem I see lies in the fact that I don't have a tape measure that long nor do I have flat ground that long. So I do what I can and measure 25 feet at a time. I'm trying to use rope with low stretch but at over 100 feet, there is going be some flex for sure. Plus running from 2 ball to 6 ball would also require 538 feet of rope.....

 

Other opinions? Would spanning 2 ball to 6 ball be better than measuring cross course from 3 and 5 ball?

[mwetskier]

the stretch in any cord or rope can be corrected for quite easily if you will reconsider my proposed solution. Since you know that the distance between the 2 ball and the 6 ball is 538 feet (plus 3/4 inch) you can measure out two points in a a school playground near you that are 269 feet apart with one end being a stake or other solid thing to attach to. tie a hook onto one end of two pieces of cord that are each at least 269 feet long. hook those two ends onto your fixed point. now walk the other end of the cords out to your point 269 feet away and then stretch them until they're about as tight as they can easily be pulled. now use a sharpie and mark them where they pass over the 269 foot point.

 

tie another hook onto each cord at the sharpie mark and then cut off the excess. take the cords to your slalom course and hook on end of one cord onto the 6 ball anchor point and one end of the other cord onto the 2 ball anchor point. bring the two cords together in the vicinity of the 4 ball and stretch them together until you can connect the two hooks. that point where the two hook connect should be *very" close to the midpoint between 2 ball and 6 ball so if those two are accurate then your half way point will be too. so set an anchor block at the cords connection point and get your width accurate by using a spotter to sight down the 2 4 6 line.

 

also no matter how you do it spend 20 bucks on a long tape measure -you'll be real glad you did -

http://www.benmeadows.com/lufkin-100l-hi-vis-orange-linear-tape-measure-ft-10ths-and-100ths_s_158637/?searchterm=158637&ef_id=VVZZZgAAAG1Kbq%40k%3a20150913052053%3as&cid=BMPL10&gclid=Cj0KEQjwms-vBRDlsM7utpaJ47ABEiQAIpKjTDkj65Jg792iIdJ-DsTLEry9t3z7JP6YU02xsZPKhwUaAhyG8P8HAQ

[Orlando76]

@Waternut yeah my dog could've wrote a better sentence than that. I was trying to say, what I did was I recently took a 134.6' of rope ( my tape was short too so I measured in increments, attached one end of the rope to a street sign and pulled). I originally used 1/4 rope on the surface on a glassy morning but it acted like a sail so surveyors string/brick mason line should work better. That'll give you the boat guides then I made a square out of 2x4's shown in this figure: http://www.iwsf.com/slalomcourselayout/fig2.gif to come up with the turn buoy. You could use a 41' rope rather a wooden square to set the turn buoy which I did but wasn't close enough, wooden square was much better.

[Edbrazil]

The original poster doesn't say where the course is. Check the USAWaterSki website for a list

of Technical Controllers: http://www.usawaterski.org/pages/offdirectory.asp

Look at: AWS Tech Controller. Most of them should have survey gear that could make the task

a whole lot easier and more accurate. You probably don't want to deal with local surveyors, as

it will be lots of $$, plus learning on the job at your expense.