Legarth won't be lacking confidence after his last international event last month.
He combined with Dylan Neal-Hill of Christchurch to win the M18 K2 1000 at the Australian Canoe Sprint Grand Prix in Penrith.
They won by more than a second with a time of 3m28.3s.
They were competing against Aussie paddlers hoping to make their junior world championship team and this was the biggest win of Legarth's kayaking career.
Legarth, a younger brother of Waikato-based Elise Legarth, 19, who will also be travelling to Romania to represent New Zealand in under-23 events, was also a winner in the non-Olympic K4 500m distance where his Kiwi team outclassed their opponents by 2.7s.
The same K4 finished second in their 1000m race, just over a second behind the winners.
Neal-Hill and Legarth were third in their K2 200m final.
Legarth and Napier Boys' High School's Ed Parsons won gold in the K2 1000m at Lake Karapiro. Three silvers and a bronze completed his medal haul.
Legarth's Hawke's Bay Kayaking Club K4 crew, which also included Parsons, Te Aute College's Tirau Wihongi and pick-up paddler Sean McCarthy of Karapiro were second by 0.05 of a second in the 200m and also won silver in their 1000m final.
Parsons and Legarth captured silver in their K2 200m final and Legarth collected bronze in his K1 1000m final. He just missed a sixth medal with a fourth in the K1 200m final.
"I was hoping to win the K1 1000 but things didn't go to plan. It was still good to win a medal though. In the K1 200 I was hoping for a third or fourth because I'm more of a long distance paddler."
His Romanian trip will be his fourth overseas for kayaking.
Before then he will attend several training camps in Christchurch where his coach Paul Fido and two of his Kiwi K4 teammates are based.
To keep in shape for these Legarth will train twice a day, six days each week with sessions on and off the water. His club coach Ben Bennett will keep him honest on the water and prominent Hawke's Bay boxing coach Craig McDougall will monitor his strength training.
Legarth is considering an engineering career when he leaves school. He is adamant he will continue with his kayaking and no doubt more national team selections will follow his latest.