Having something extending above the surface would help with visibility for small ships as well - cargo vessels will track this automatically and most modestly

Having something extending above the surface would help with visibility for small ships as well - cargo vessels will track this automatically and most modestly sized sailboats do either have a built in unit for tracking nearby ships or folks just use their smartphones - but for really small water craft (like rowboats/dingies and personal sail-craft (sunfishes)) I'm concerned that collisions would be extremely easy.