The ISA claims that the barriers could severely restrict access to the slips, and even encourage dangerous behaviour for those still trying to launch boats from the slips.
ISA Chief Executive Harry Hermon said that installing overhead barriers could prevent vehicles from accessing the slipway, meaning that people try and launch boats by hand, a potentially hazardous situation.
The ISA proposed alternative measures, including increased signage and a protective lip at the edge of the slipway to prevent drivers from reversing vehicles off the edge of the slipway as they try to launch boats, or a permit system which would regulate slipway usage.
The letter pointed out that there are few public slipway options between Clontarf and Bray, and to hinder access to the Dun Laoghaire slipways would restrict the public's access to the water considerably.