Flat Pool-Floor Distance Markers

Context and requirements

Distance markers were needed at key locations on the bottom of a swimming pool.

They needed to be:

• reliably negatively buoyant;
• stable when exposed to passing swimmers and kicks;
• flat or rectangular so they could not roll;
• visible underwater and easy to label;
• safe for pool tiles;
• resistant to chlorinated water; and
• portable and cheap enough to use in multiples.

Options considered

The discussion considered standard hockey pucks, rubber-coated diving weights, soft diving-weight pouches, underwater-hockey pucks, flat metal bars, and coated lead strips. Flat metal bars emerged as the most suitable form because their low, rectangular profile prevents rolling.

Implemented design and outcome

Black flat bars with pre-drilled holes were found and used as underwater distance markers. Their flat profile prevented rolling, they stayed on the pool floor, and they worked well in practice.

The bar material, dimensions, weight, surface coating, purpose of the drilled holes, and any additional labels or high-visibility markings were not reported and are not inferred.

Editorial notes

• A standard hockey puck has much less effective weight underwater than its dry weight and may be moved relatively easily.
• Flatness prevents rolling but does not by itself prevent sliding; sufficient submerged weight and surface grip still matter.
• Stainless steel is not automatically immune to pool-water corrosion; alloy grade, chlorine exposure, surface condition, and rinsing matter.
• Exposed or home-coated lead was not retained as a preferred pool-marker design.