The all-weather lifeboat station at Selsey will be closed to the public from July 25 until further notice.
This closure will allow the removal of sections of the walkway so construction of a new ramp and associated flood gates can begin.
A temporary stair will be erected for RNLI access and other authorised personal. The lifeboat will remain fully operational.
Selsey RNLI apologises for any inconvenience these works may cause.
The temporary inshore lifeboat station and souvenir shop at the eastern end of the lifeboat green will not be affected.