Ski Buoy Specifications

[dwfrech]

Hello BOS Members: Does anyone know the correct diameter for slalom buoys? All buoys in our course are deflated after a long Pacific NW winter. We are trying to bring it back to regulation, as close as possible. We have a template for 23 cm diameter and a bike pump. Just wanted to make sure we are going for the right size. Thank you!

[klindy]

@dwfrech - http://www.usawaterski.org/pages/divisions/3event/AWSARuleBook.pdf

 

8.09 Buoys

A. Buoys must have provisions for attaching anchor lines, and must be fastened by means of a tensioning device.

 

B. Boat guide buoys may be spherical, cylindrical, or bullet-shaped. Spherical buoys shall be 22 - 28 cm (8.75" to 11") in diameter (23 cm (9") recommended), and fastened so that they have 11 - 17 cm (4.375" to 6.75") of height out of the water (11.5 cm (4.5") recommended). Non-spherical types may have a cross-sectional area of 75 - 450 square cm (12 - 70 square inches); cylindrical buoys may have a diameter of 9.78 – 23cm(3.8 - 9 inches) (recommend 6 – 8 inches); all shall appear vertical, and shall be 15 - 30 cm (6 - 12") exposed above the water.

 

Boat path alignment gates where required in Slalom, shall consist of cylindrical buoys of a color contrasting to the official course buoys (green recommended) and shall be placed outside the official course at either end, at a distance of 55 meters beyond the entrance gates, and at the 1.15-meter width of the interior boat guide buoys.

 

C. Skier and Gate buoys shall be generally spherical in shape and 20 - 28 cm (7.8” to 11") in diameter (20 cm (7.8”) recommended), and fastened so that they have 10 - 17 cm (3.9” to 6.75") of height out of the water (10 cm (3.9”) recommended). They shall be of lightweight, pliable material with a smooth, exposed surface.

 

D. End gates and Skier Buoys in the slalom course shall be provided with an elastic device or equivalent (non-compressed buoy/ counter-weight system, recommend minimum length 16" for elastic). This will allow the Gate buoys to rise and fall under tension with the passage of the wakes and allow the skier buoys to move if a skier hits a buoy.

 

E. For colors and placements of buoys see Rules 9.16.D, 10.16.A and the diagrams in the Appendix.

[klindy]

23cm is in tolerance but bigger than the 20cm recommendation.

[Jody_Seal]

Do milk jugs fall in that criteria??

[Than_Bogan]

Be aware that some buoys expand significantly after initial inflation. So be sure to check size after a few hours in the sun -- not just when first inflating.

 

That doesn't apply to Walley Buoys,though, which is another reason to buy those!

[jimmyjamesbrown]

Aren't empty Tide jugs good enough?!?! ?

[lpskier]

As @klindy said: Just about that ? ? big.

[LeonL]

Tide jugs have a nice color, but I'm not sure how well they'll retain that color. Then again after an ankle collision you won't be using them for awhile anyway. Wally buoys are pricey but best.

[klindy]

On the post above there I simply copy/pasted the text from the 2018 rule book. I had forgotten that there were some changes for skier/gate buoys for 2019 with regard to the height out of the water. The current text is below. I added it here instead of correcting the post above to people can see the changes made —-

 

 

C. Gate buoys shall be generally spherical in shape and 20 - 28 cm (7.8” to 11") in diameter (20 cm (7.8”) recommended), and fastened so that they have 10 - 17 cm (3.9” to 6.75") of height out of the water (10 cm (3.9”) recommended). They shall be of lightweight, pliable material with a smooth, exposed surface.

 

D. Skier buoys shall be generally spherical in shape and 20 - 28 cm (7.8” to 11") in diameter (20 cm [7.8”] recommended), and fastened so that they have 8 - 17 cm (3.15” to 6.75") of height out of the water (8.5 to 9 cm [3.35 to 3.9”] recommended). They shall be of lightweight, pliable material with a smooth, exposed surface. It is recommended that a line or mark be made on the buoy at the 8 cm limit so that it can be easily determined that the buoy height is in tolerance.

 

 

 

[dwfrech]

Wow this is excellent information. To @kindly, you have all the details and we suspected, but didn't know, that there is supplementary guidance on HEIGHT. That makes sense. @Than_bogan, we will observe the laws of Charles and Gay-Lussac w.r.t. temp/gas pressure/buoy size. There you go @horton, more science sorry about that. @jody_seal, milk jugs are underrated and are fine especially for boat guides. Thanks everyone! I'm going for somewhere between 20 and 23 cm diameter and at least mid buoy = waterline or lower. May use an interferometer to be sure its accurate.

[Deanoski]

Small and low is the way to go

[MichaelGoodman]

@Jody_Seal depends on whose milk jugs they are.

[aupatking]

Maybe we can convince the wallyskier guys to put an 8 cm line on them from the factory. How does one accurately measure the buoy height anyway? Aside from the interferometer, of course, that thing is beyond my magical powers

[Than_Bogan]

Any thread gets better with some interferometer references!

[Rednucleus]

Wonder if you can use interferometer and orthoganol in the same conversation?

[DavidN]

Wally buoys have a noticeable line all around (from the mold) so it’s super easy to get them all adjusted at the same height.

[Drago]

@aupatking Build a 7 13/16” x 7 13/16” box, cut a hole in the bottom for the loop (and to keep the buoy basically plumb). Cut the sides @ 3 9/16” tall ( 7 13/16 minus 3 1/4). Inflate the buoy to just touching the sides of the box (when warm!), mark the water line. Install. Ski. ?

[klindy]

@Cooper_Trelawney not sure what the “off-topic” click was for on my post above. The OP was asking if their 23cm template was in tolerance.

[Cooper_Trelawney]

@klindy fat fingers I guess :o

[dwfrech]

@drago, thanks I will try to build the ski buoy sizing box. Good instructions! Seems like many have done course maintenance - thanks for your info everyone. We may try the Wally Buoys. It's just a matter now of recovering from winter. This will help.

[jetpilotg4]

Be careful not to over inflate they will not return to their original size

[Bruce_Butterfield]

@Rednucleus of course everyone knows that an interferometer simply measures the changes from a plane wave reflecting orthogonally from the interferometer’s reference plane.

[klindy]

@aupatking most of the buoys have a mold "seam" at the equator of the buoy. Adjusting it to be the proper depth below the waterline isn't too difficult.

[aupatking]

Yeah, it’s not like I’m going to be holding any record tournaments, just curious, really. The mold seam has always been my guide and been good enough.

[Drago]

Should go lower than the middle line: safer and now legal