Olympic silver medalist Bouwmeester went one better in Santander on Thursday, defending her title in the women's Laser Radial class.
Bouwmeester sealed top spot with a third-place finish in the medal race, which was enough to see off Sweden's Josefin Olsson and Belgium's Evi Van Acker, who won silver three years ago in Perth.
"I am really happy to come away with a win," said the champion.
"I had a good start with a good back swell. It was kind of tricky on the first upwind. I wanted to go right but didn't quite make it. I was happy with my second upwind.
"I tried to defend a little watching the girls on the left but it was tricky. The back swell was awesome."
In the men's Laser, Bouwmeester's compatriot Heiner took the spoils, while Australian Tom Burton claimed silver and 2011 silver medalist Nick Thompson of Great Britain completed the podium.
"Going out to the race I knew it was going to be a battle so I just wanted to give it everything I could and do my best," said Heiner.
"I wasn't nervous. I was really keen to get racing. The start was difficult. I had a lane but it was really a case of who got the first wave off the break water.
"It took me a little time to find my rhythm and I struggled a bit on some chop but half way up the first beat I found it. Pretty much after that I got going.
"When I went round the downwind mark I look around and pretty sure the next shift was coming from the right. I found a nice set of waves on the right with some pressure and then pretty much planed up wind for half of the beat. It was awesome."
In the women's RS:X, Charline Picon has already sealed her triumph, before the medal race on Friday.
The Frenchwoman has an unassailable lead while Poland's Zofia Klepacka went from second overnight to 10th overall and is now out of medal contention.
Picon's compatriot Julien Bontemps looks to be in a strong position heading into Friday's finale of the men's RS:X, holding a 14-point lead over nearest challenger Piotr Myszka, who won silver in 2011.
In the 470, Australian Mathew Belcher looks set to defend his crown with new team-mate William Ryan as they lead the way while in the women's class, Jo Aleh and Polly Powrie are the front-runners.
Their fellow New Zealanders Peter Burling and Blair Tuke hold the advantage in the men's 49er, and Danish pair Ida Marie Baad Nielsen and Marie Thusgaard Olsen head the field in the 49erFX women's class.
In the men's Finn, defending champion Giles Scott further extended his lead, and the Brit now holds a 13-point advantage over Frenchman Jonathan Lobert.
After five races of the Nacra17, the French team of Billy Besson and Marie Riou are first overall.