Reviving the world's first submersible slalom course - is there anything cheaper ?

[swbca]

Starting with a lake and nothing else I am going on a limb to return to competitive skiing in Men9. Just bought a 2004 Master Craft Prostar TT but still need a boat lift etc.

 

Next month (January) is the ideal time for a Winter installation of a slalom course. The course has to be setup and removed for each practice session. We are on a busy lake, with a lot of residents that have zero tolerance for a course becoming an attractive nuisance. The county Sheriff who has sole jurisdiction delegated by our DNR, says we don't need a permit as long its not visible between sunset and sunrise. But realistically, it can't be up unless we are using it.

 

I have looked at cable courses and individual anchor courses with air pumps and 1000's of feet of sunken pressure lines, fittings, bladders etc but they seem too expensive, complicated and subject to technical problems.

 

So unless something better comes along soon, I think I will be going back to the course we setup in 1975. Its based on individual anchors. As far as I know, it was the world's first submersible course. (Historical Note: Mike Suyderhoud patented the cable course in 1975 and later someone made a cable course submersible)

 

When we built this course in 1975, we hard-wired a garage door remote control into our ski boat with a button on the dashboard to raise & submerge the course. We used it for 18 years with no unusual problems with the course or with other lake users. Caught a about 5 fish lures . . that was our biggest problem.

 

I wrote a how-to article for the Water Skier magazine in August 1983. The only downside was the submersible feature pulled the skier balls about 6" down course from ideal alignment. We could have fixed that but never got around to it. The submersible feature was all done with a couple of spools of AWSA water ski rope and 1/3 yard of cement for the center anchor. Total cost about $300 until I converted from a manual winch to the electric winch with remote control.

 

This only works with deep water . . our lake in 1975 had 85' depth . . our current lake 75' depth.

 

Any suggestions ? for a course that has to be setup for each practice session.

[Alberto Soares]

I do not have an answer to your question, too bad Ed Brazil is not with us anymore to help you, I just would like to say that you are my hero.

[Nando]

@SWBCA, your original submersible course was a great design- why mess with it? I only saw it once, after you had installed the garage door opener (if I recall correctly) to power submerge it. Was there significant wear to the lines from going up and down? Either you or Lance F. once explained how relatively low the force was on all the components and the simplicity of the setup is pretty appealing. (We'd consider it for our course, except we're in about 5'-8' of water.)

[swbca]

@Nando You asked if there was wear on the lines from the course going up and down. The only problem we had with "wear" . . . After 12 years of very heavy use, one of the ropes finally cut into the 3" PVC coupler on the Center Anchor. The anchor was about 85 feet down, so I dragged a replacement anchor into position using Copper pipe instead of PVC. About 20 years of use and none of the 5/16 AWSA rope needed to be replaced.

 

The 3" PVC pipe in this illustration was changed to copper after 12 years of heavy use.

 

[Nando]

Thanks, @swbca, that’s pretty good. The simplicity of this system is pretty appealing, especially when hearing about the amount of maintenance on Accusink courses or even Wallyskier ones, though Wally seems to have simplified things.

[swbca]

For the course I am installing through the ice today, I just located a 180 degree stainless steel 3" tubing for $51.00. Its a single piece to replace the PCV parts in the drawing above. The stainless steel is from a performance automotive supplier. It shorter but that isn't a problem and the rope won't wear through SS.

 

[pregom]

This is definitely an interesting way to submerge the course. So, if I understand this correctly, from the anchor there is one rope that goes to ball/gate 3 which then goes to ball/gate 2 which then goes to ball/gate 1 which then goes to the entrance gate which then goes to the 55m buoys. And another rope that goes on the other side to ball/gate 4 and then all the way to the other 55m buoys. How much do you need to pull the main rope from the center anchor before the 55m buys get submerged?

 

Also, regarding the 180 degree stainless steel tubing you have found, depending on the quality of the steel, rust and corrosion could still develop depending on the chemical composition of your lake water.

[swbca]

@pregom To answer your question, this is the illustration from my 1983 article in the Waterskier magazine.

On the original 1975 version of this course, the horizontal ropes that pull all of the anchor lines over at an angle were attached to existing sub-buoys on an existing course. On the new course that we are installing - today- I have all the connections at 44 feet above the bottom of the lake, so the horizontal rope connection varies from 11-25 feet below the surface. This keeps the lines further down from fisherman and creates a uniform horizontal "pull" distance to get all the buoys lowered the same amount. The specific value of 44 feet was governed by the shallowest water depth - 55 feet- so the connections are 11 feet below the surface on the the 55M gate buoys at one end. The geometry of a 14 foot differential in the 'altitude' of the connections only creates a trivial difference in the length of the horizontal ropes.

 

The sub-buoys are 7' below the surface with easy adjustments if the water level goes down a significant amount, the horizontal pull ropes are lower on the anchor line at 44' up from the bottom of the lake.

 

You asked how much winching to pull the course down. 18 feet pulls it down 7 feet. On this course we have switched to coated 3/32 stainless cable to the shore because its 630 feet and poly-rope has too much stretch for that distance.

 

Another revision from the original course. To prevent the network of ropes from distorting the course because of friction from 600 feet cable going through plastic tubing, there is a single sub-buoy pulling straight up from the center anchor so the buoyancy of the slalom course isn't powering the extraction of the cable from the winch as the buoys approach their final position.

 

To minimize the use of the plastic tubing, we profiled the topography of the lake bottom with our own through-the-ice depth measurements from the center of the course to my dock. Only 350 of cable needs to be in tubing because the last half is not in contact with the lake bottom. We may use more tubing length, but that won't happen til June.

 

Manual or Electric Winch This isn't my primary place to practice, so to keep it simple we are using a manual winch. Its a common boat trailer type of winch modified by using a 15" john-deer lawn tractor steering wheel. The original hand crank on all of these winches is too unbalanced and the winch unwinds at very high speed. The wheel is a better human interface for pulling in about 20 feet of cable with the very low gearing on a manual winch.

 

On the original course which had to pull in more than 20 feet, it took 3 minutes to wind the course down and 30 seconds for it to pull itself up, spinning the winch wheel 6 times faster than when I wound it down winding as fast as I could. When we added the power winch it slowed everything down, but we could let the course surface or submerge from the house, so slow didn't matter.

 

There are no inexpensive electric winches with programmable limit switches based on winding or unwinding progress. On the original winch I had a 10/32 threaded rod connected the winch hub somehow and positioned switches that would trigger when a threaded object would travel on the rod to reach the COURSE UP position and COURSE DOWN position along with some crude logic using electro-magnetic relays. It worked for decades, but I would rather be skiing than trying to do that again. Its the Men 9 perspective changing priorities.

[swbca]

@PREGOM You warned that stainless steel tubing could corrode. The pre-made 180 degree tubes are for vehicle exhaust systems. Perhaps you don't have enough info, but do you think the stainless could deteriorate enough for it to be a structural problem over 5 years in a clear freshwater lake ? My concern would be corrosion being abrasive to poly rope passing through it. With frequent use, the rope would keep the steel polished, but the course is only used 5 months of the year. Cold and 70 feet deep would have less oxygen . . right ?

 

Maybe going back to copper would be better.

[MISkier]

Cool design. I wanted to do something like this for years. But, my lake is only 6 to 8 feet depth over the entire course dimensions, so I had a modified design. I would have been doing the installation 100% alone, so I never initiated it. After a while, having a club membership was the way to go for me and I would rarely put the portable into the lake and then leave it in for a while, taking my chances with the daily removal requirement.

[pregom]

@swbca I'm far from being an expert on the subject of corrosion or rust. I've suggested you check that because I think that not all stainless steel is created equal and because I've seen rust on all the stainless steel eyelets at the end of the steel cables on the slalom course we have. This is at Webster Lake, a fresh water lake with water depths that vary from 5-6 feet to 20-30 (my wild guess). It's a busy lake with water chemistry that could be influenced by many factors. Another thought: the pipe interacting with the cement of the anchor should be similar to the rebars in reinforced cement, I imagine, or is it different? Would it be possible for you to tie an extra poly rope from the center anchor to one of the gate 3 or gate 4 lines? In this way you could pull up the anchor for inspection from time to time.

[pregom]

@MISkier to get around the problem of not enough depth, one solution could be to have an "anchor" directly under each point to be submerged, a total of 10 anchors from 55m pre-gates to 55m pre-gates at the other end. In other words, instead of pulling one rope to submerge the course as in the first drawing of this thread, you pull 10 ropes. I like the idea of mechanical means to submerge a course - @swbca is a genius. Much easier to maintain than all the air lines of a Wally Sinker or similar.

[swbca]

This is the "fix" to take any residual tension away from the horizontal ropes as the course buoys approach their final floating position with the winch unwound. It fixes a 6" longitudinal error in the final position of some skier buoys.

 

 

 

[Nando]

Brilliant!

[Bugnagn]

Can anyone provide a sketch of the retractable slalom course?  None of the links in the previous posts work.  Thanks!

[swbca]

@SkiLife The course drawings only exist in an article I wrote for a 1980's AWSA Water Skier Magazine.  I will be at our home where I have a copy of that magazine next week.    I will post the drawings next week.  (Week of September 25, 2023)  

Edited September 19, 2023 by swbca

[Horton]

sorry about the lost images. changing forum platforms was absolutely necessary and the loss of images was a very unfortunate side effect.