They accounted for Brer, who was in receipt of five kilos, by three and a half lengths with Krase third ahead of the outsiders Old Redfeather and Marvon Downs.
Sea King has now won three times over the big fences, including the Mosstrooper Steeplechase at Bendigo last winter, as well as nine wins over the smaller jumps with an Australian Grand National Hurdles success taking pride of place on his CV.
Runner-up Brer gave a strong account of himself after he had finished fifth when sent out a hit favourite on the opening day of the meeting.
"He improved a lot with that run after plenty of long, slow work following a couple of years off," said Jamie Richards, who prepares the seven-year-old with Stephen Autridge.
Brer was side-lined by injury after he won a lower grade steeplechase at the 2014 Grand National carnival at Riccarton.
Earlier, Ready Eddie showed he was on target for one of the country's major winter prizes after upstaging a number of better-performed jumpers.
The Awapuni visitor took punters by surprise when he triumphed in the Porritt Sand Waikato Hurdles at odds of 28-1 for trainer and part-owner Laura Knight.
"It's very exciting and we didn't really know what to think with so many decent jumpers in the race," she said.
Ready Eddie had three flat runs to fit him for a return to jumps racing and a campaign focussed on the Hospitality New Zealand Grand National Hurdles on August 10.
The son of Yamanin Vital was successful over fences at the carnival last year and he also won his maiden on the flat at Riccarton when previously with Mark Oulaghan.
He prepared Ready Eddie to win his first hurdle race in 2013 before a tendon injury side-lined the gelding for a year and he subsequently transferred to Knight, who races the seven-year-old with her father and former All Black prop Gary.
With steeplechase winner Fannin aboard, Ready Eddie challenged three flights from home and led over the last two fences to beat San Pedro by a length with Nancho Lass taking third money.
