The duo will be competing as a pair, treating the ultra marathon as a relay - one cycling for three hours and one resting for three hours.
The Race Around Ireland is part of the Ultra Marathon Cycling Association and is considered one of the toughest cycling challenges in the world.
Beginning at Trim Castle in Co Meath the course takes in Newgrange, Malin Head, The Cliffs of Moher, The Ring of Kerry, Mizen Head and finishes back in Meath at Moynalty.
The two athletes will aim to complete the 2,150km challenge in 132 hours - or five and half days of straight cycling.
Jacob and Dorey will travel with a crew of 6-8 people including a support vehicle, camper van, medical support and bike maintenance.
Both women are aiming to raise money for mental health charity Suicide or Survive and are hoping to fundraise €100,000.
A prevalent aspect of raising money for mental health is the association between mental health and LGBT equality. Being in a long-term relationship both women have a personal understanding of the mental health issues associated with the LGBT community.
Despite 139 caps for the Irish hockey team and a year under her belt as an Irish Rugby 7s player, Jacob, who hails from Wexford, said the Race Around Ireland is a scary prospect.
"It scared me, which meant I should probably do it. I guess mostly it’s a self-exploration."
"Why I'm doing it? I suppose is two-fold. It's a curiosity around how far I can push myself, how much physically I'm able to cope with. How much mentally I can deal with as well.
"How will I react when things are hard? What will I learn about myself and others that will serve me well for the rest of my life? Where will this amazing journey take me? What difference can I make to people along the way?"
Partner Nikki Dorey, originally from Southampton, also boasted an impressive sporting career before becoming an Aer Lingus pilot. She played for Southampton until she was 18 and played for Shamrock Rovers during the 2011/12 season before taking up triathlon in 2012.
Dorey said she's want to fundraise through a challenge like Race Around Ireland for a while.
"I have wanted to complete a challenge in conjunction with fundraising for charity for a long time, but was adamant that I would choose a challenge that was slightly outside of the ordinary and was on that fine line between not completely unachievable, but where completion was by no means a given.
"I fully expect to find myself in the depths of pain and despair, but I also fully expect to have some of the most amazing experiences doing this too. In a strange way, I’m looking forward to both, although I might regret saying that when August comes around!"
Dorey also highlighted that her skills as a pilot and the positive mental health planning thought by their chosen charity will help with the race.
"As a pilot, I am always prepared and that's how I intend to go into this race. Unfortunately, I am very aware that aspects of the race will bring about situations that I can't prepare for or control, and it will be a significant challenge to see how my mind will be able to cope with this.
"The positive mental health strategies that our chosen charity, Suicide or Survive, teach will most definitely be put to good use over the five and a half days of this event."
CEO of Suicide or Survive, Caroline McGuigan, said the pair are "truly inspirational."
"What they are now embarking on is a true testimony to their incredible generosity and determination to make Ireland a better place. They have inspired us enormously with their courage and I know they will inspire countless others.
"The funds they are raising are so important as we continue to work together to address the tremendous pain and suffering associated with mental health and suicide in Ireland. We encourage everyone to get behind these heroes."
You can follow the girls progress on social media by following them on Facebook and Twitter. The challenge begins on Sunday 28th of August 2016 and members of the public being urged to cheer them on. You can donate to their campaign.