Board member and volunteer skipper Tim Buckley said despite fundraising setbacks in the past six months, the unit had some ''irons in the fire'' and he was optimistic construction could start by the end of the year.
''I don't think that's unreasonable. If we can get some go-forward in the next two or three months, I hope that can happen.''
Now operating from a small storage shed at the back of a Scouts building at Frankton Marina, the unit was granted consent by the council in 2012 for a lease on a vacant neighbouring site.
The new building will house rescue equipment and serve as a training centre and operations base during search and rescue missions.
Although fully designed and consented, its construction cannot begin until its full cost has been raised.
Last September, the Otago Daily Times reported the project as costing an estimated $575,000.
Fundraising committee chairwoman Laura Harry confirmed that cost had risen, but how much would depend on the outcome of discussions between architects Warren & Mahoney and project tenderers.
Mr Buckley said about $150,000 was still needed.
''The fundraising continues, and we're always keen to hear from anyone who would be interested in helping us out.''
Major contributors are the Central Lakes Trust with $250,000, the Community Trust of Southland with $42,000, and the estate of former Lake Hayes resident Peter Wilding.
The unit has also accepted the offer of a $50,000 interest-free loan from the Queenstown Lakes District Council.
