His wife Emma McEwen posted on Facebook about her husband being "set upon" after the couple held staff drinks for their new purchase of Blue Water Marine Services.
The couple had only just moved to the coastal community.
"We were so excited to move here and felt so utterly welcomed," she wrote on the WhitiCitiChat Facebook page.
"Last night when my husband went to return home by himself he was set upon and beaten so badly that he has been flown to Auckland hospital...I am now driving up to Auckland with our 11 month old daughter to see him. Terrified of what I will find when I get there."
Mrs McEwen said her husband was the "nicest, most gentle guy you would ever meet" and the incident "breaks her heart".
She appealed for whoever had beaten her husband to come forward to police.
"To whom ever did this I have no words, only sorrow. If you know anything please come forward so that there may be justice for Alastair."
A GiveaLittle fundraising page has been set up in the McEwen family's name, in response to the heartfelt social media plea, and donations are flooding in.
Members of the Whitianga community are rushing to donate - with $1480 being donated so far - and have been leaving messages for the family to read.
"I hope Emma and Alistair come through this ordeal ok and Whitianga shows them what a great town we are. The people that did this are not part of our community they have no place in a town like ours," Derek Collier said.
A guest donor said: "Please know the community is behind you 100% We are hoping and praying for a fast recovery for Alistair xo".
Just last week, Mr McEwen had posted a message on Facebook in awe of Whitianga.
"So we now live in a town where I can, and just did, catch flounder and whitebait within 200m of our house. Winning!!" Mr McEwen wrote.
An investigation has been launched into the assault.
Detective Senior Sergeant Graham Pikethley said a thorough scene examination will be undertaken and police have cordoned off an area of Cook Drive, between Campbell and Dundas streets.
Anyone with any information is being asked to contact Whitianga Police on 07 866 4000.