A Maine company that wants to operate ferry service between Portland and Nova Scotia says it has an agreement to lease a new $165 million vessel and could start service this summer if it is awarded a contract. Quest Navigation Inc. of Eliot is one of two companies proposing to operate the service between Portland and Yarmouth, Nova Scotia. Quest officials tell The Portland Press Herald, the vessel is 531-feet long, has 162 cabins, two restaurants and capacity for more than 1,200 passengers. The other company, Baltimore-based Maritime Applied Physics Corp., is an engineering firm that specializes in designing electro-mechanical systems for harsh environments. The Nova Scotia government is expected to decide this month whether to partner with one of the companies or issue another request for bids.