The Tuas Port and Long Island developments may force two of Singapore's lighthouses to relocate. SINGAPORE: Every time Mr Ithnin Atan climbs to the lantern room of Sultan Shoal Lighthouse, he checks the same things: the lenses, the batteries, the glass panes that look out over the Singapore Strait. It is a routine he has repeated for years. But the lighthouse he tends may not stand where it does for much longer. When completed, Tuas Port is set to block Sultan Shoal Lighthouse from the sea. On