Ireland's sonar sailors suffered a disappointing start of to their Rio campaign at the Marina de Gloria.
The trio of opening ceremony flagbearer John Twomey, Ian Costelloe and Austin O'Carroll finished 10th and 14th in the first of their ten races to lie 12th overall.
Things started well for the trio as they were as high as fifth overall at the halfway point of Race 1, but they were pegged back by a number of boats on the final run to the finish.
Race 2 was more of a struggled from the start as the decision to take to the middle of the course saw them take the first mark 12th of the 14 boats.
A difficult turn saw them distanced by the rest of the field and they finished Race 2 at the back of the field.
All is not lost, however, as Ireland will certainly discard that score and will hope for improved results in Races 3 and 4 on Tuesday.
Elsewhere, Helen Kearney was unhappy with her result in the Team Test of the equestrian event.
The Wicklow rider recorded 68.000% on her test, placing her 20th of 26 competitors.
"I'm pretty disappointed with the score, I really thought I did everything I could," London 2012 medallist Kearney told RTÉ Sport.
"The horse went really well, there were a few things I could have improved upon, but overall, for day one, I was really pleased with the horse and with the test."
Kearney is back in action in the Championship test on Wednesday.
