"It also came down to a lot of hard work - our middles worked extremely hard for us today.
"For us, coming from the South Island, the conditions probably suited us a bit better. We're used to playing in these slippery, wet conditions, keeping it tight and playing it up the middle."
This result is also the culmination of four years where Jacobs and colleague Tai Arona have brought the same group of players through under-15s and under-17s, struggling for wins, but building experience along the way.
"Now they understand what's required and our expectations. They understand what it takes to come to these tournaments and be successful."
South Island now find themselves up against Akarana Falcons for the second time this week, having lost 44-10 in their pool.
Falcons were always in control of their semifinal, cruising clear of Auckland Vulcans 26-4, with winger Mathew Timoko grabbing a pair of tries.
In the under-15s grade, titleholders Akarana Falcons were thoroughly tested by their Vulcans opponents, a side made up of players who missed selection for Akarana or Counties rosters.
The Vulcans led 6-4 at half-time, but conceded 12 straight points to lose their grip on the contest. Akarana eventually prevailed 16-12, with Dillon Vale crossing for two tries.
"It was very tough," reflected Falcons coach Alan Ettles. "Auckland definitely brought it to us and it went down to the wire."
"We had to change the tempo of the game, controlled the ball a bit more and played more down in their half.
"It's a big rivalry, with lots of points to prove on both teams, but they're brothers, on and off the field."
They now face arch-rivals Counties Manukau Stingrays, who made no race of their semifinal against Wai-Coa-Bay Colts, running out easy 34-6 winners.
Meanwhile Wai-Coa-Bay Colts take on the Auckland Vulcans in the under-15s grade third and fourth playoff game whilst the under-17s take on Wellington Orcas in the fifth and sixth playoff match.
NZRL National Youth Tournament
Puketawhero Park, Rotorua
Thursday results:
Under-15s
(5-8) Wellington Orcas 30 (Maui Wallace 2, Keelan Ng, Stanley Fiso Vaelei & Iiai Tuai tries; Ng 5 goals) Northern Swords 12 (Tuia Mehano-Puru, Nokisi Kaiarake & Brigham Jackson tries)
(5-8) South Island Scorpions 18 (Manaia Edwards-Aumua 2, Salio Tafaese & Caius Faatili tries; Edwards-Aumua goal) Central Vipers 16 (Zamaya Lilo, Ngarimu Waru & Jamie Lee Robertson tries; Brookly Herewini 2 goals)
(semi) Akarana Falcons 16 (Dillon Vale 2 & Christian Tuipulotu tries; Tuinamo Tepulolo & Samuel Kamu goals) Auckland Vulcans 12 (Daylen Meredith & Darius Hignett-Morgan tries; Sione Moala 2 goals)
(semi) Counties Manukau Stingrays 34 (Semisi Sikei 2, Fangupo-Paea Fotu, Brian Lealifano, Aamon Dean & Etuale tries; Fotu 3 & Te Napi Waipour 2 goals) Wai-Coa-Bay Colts 6 (Sean Field try; Rhemus Rutene goal)
Under-17s
(5-8) Wellington Orcas 24 (Isiah Tauri, Te Aorere Wanoa, Mason Lucas & Darius Patau tries; Wanoa 4 goals) Central Vipers 20 (Israel Hape-Moke 2, Jahlon Governor & Corey Lee Hadfield Robertson tries; Governor 2 goals)
(5-8) Wai-Coa-Bay Colts 34 (Aublix Tawha, John Friis, Te Ranga Kihi, Brandin Carlson, Sheldon Rogers, Taelem McGregor & Waratana Hartley tries; Liam Jones 3 goals) Northern Swords 22 (Diani Timms 2, Taine Shelford & Owen Shanks tries; Levita Levita 3 goals)
(semi) South Island Scorpions 28 (Jordan Leigh 2, Cruz Topai-Aveai 2 & Nash Forrester tries; Brad Campbell 4 goals) Counties Manukau Stingrays 8 (Sione To'a & Dylan Tavita tries)
(semi) Akarana Falcons 26 (Mathew Timoko 2, Carlos Henry, Vito Tevaga & Jonty Timoti tries; Regan McClennan 3 goals) Auckland Vulcans 4 (Nathaniel Law goal)
Tomorrow's draw:
Under-15s
10am - (5/6) Wellington Orcas v South Island Scorpions
10am - (7/8) Northern Swords v Central Vipers
11.15am - (3/4) Auckland Vulcans v Wai-Coa-Bay Colts
12.15pm - (final) Akarana Falcons v Counties Manukau Stingrays
Under-17s
10am - (5/6) Wellington Orcas v Wai-Coa-Bay Colts
10am - (7/8) Central Vipers v Northern Swords
11.15am - (3/4) Counties Manukau v Auckland Vulcans
1.30pm - (final) South Island Scorpions v Akarana Falcons