We are experimenting with the attached, still jigging the buoyancy to get it right, the flags are really useful, has anyone else come up with a similar system, and if so, how do you manage the buoyancy ? 

We currently have a small amount of ballast in the bottom, a few holes to let some water in to achieve negative buoyancy, and a child's noodle in the top

My concern for these marks being very tall is that they may tilt over in the wind. That creates a challenge to determine the actual location of the start line - at the water line or at the top. Also a tall mark may catch the rig as a boat sails by.

As start marks are usually close to the control area that are easily visible, so a short fat cylinder may be better - wide enough that a heeled boat will not snag its fin on the ground tackle.

John

7 minutes ago, John Ball said:

My concern for these marks being very tall is that they may tilt over in the wind. That creates a challenge to determine the actual location of the start line - at the water line or at the top. Also a tall mark may catch the rig as a boat sails by.

As start marks are usually close to the control area that are easily visible, so a short fat cylinder may be better - wide enough that a heeled boat will not snag its fin on the ground tackle.

John

I hear what you say John, but we have the opposite problem, too little is showing above the waterline 

The other sat average wind the marks didn’t tip at all and much easier to see, but clearly want to get to ultimate mark!

We use a similar design for all our marks . This is mainly in attempt to be fishing friendly as their lines run round the mark . Also if you minimise floatation and ballast the mark will tilt allowing release of fishing line. Our marks are longer than yours appear to be so mooring tackle is well underwater. The other benefit of this design is that if you do catch the mark with your fin you normally float off the mark. In very light air you may need a push backwards from another yacht. Cannot remember last time we needed rescue boat.

Our marks are permanent as the lake is between 10 & 15 m deep. So we do what we can to minimise interference with fishing. When we are sailing the area used is off limits for fishing. 

As far as the floatation is concerned we use a pop bottle filled with expanding foam, We use a fitting at the top of the mark and then put a spacer in to push the float down the tube till the mark floats at the correct level. You can fine trim with ballast if required. You do need a vent hole on the top of the mark to allow trapped air to escape.

Eric

12 hours ago, Eric Finley said:

We use a similar design for all our marks . This is mainly in attempt to be fishing friendly as their lines run round the mark . Also if you minimise floatation and ballast the mark will tilt allowing release of fishing line. Our marks are longer than yours appear to be so mooring tackle is well underwater. The other benefit of this design is that if you do catch the mark with your fin you normally float off the mark. In very light air you may need a push backwards from another yacht. Cannot remember last time we needed rescue boat.

Our marks are permanent as the lake is between 10 & 15 m deep. So we do what we can to minimise interference with fishing. When we are sailing the area used is off limits for fishing. 

As far as the floatation is concerned we use a pop bottle filled with expanding foam, We use a fitting at the top of the mark and then put a spacer in to push the float down the tube till the mark floats at the correct level. You can fine trim with ballast if required. You do need a vent hole on the top of the mark to allow trapped air to escape.

Eric

Cheers Eric, we may give your floatation idea a try out 

Stability issue sorted, our training officer came up with a great solution, and these have now been tested in a blow

They stand upright, and I mean bolt upright 

The buoyancy wheel keeps the boats away from the mark(less chance of a snag)

Some dense foam was also added in the top of the mark