She said the theft would have involved at least two or three people because of the water heater's location. She believes it had been removed by people "who knew what they were doing".
There was no damage to the roof and the water and gas had also been turned off by the thieves.
Mrs Hammond said the property was insured and the equipment will be replaced but the theft was just another hurdle the fundraisers at the club would have to tackle.
There are two heating units on the roof, one to heat the showers and the other servicing the kitchen. Both are clearly visible from the street above.
As well as the theft, the building had been targeted with graffiti in recent days.
"This is just another problem for us. Since the floods the ground in front of the clubrooms has been further eroded and now our building has developed a slight tilt," she said.
The October floods brought the river level almost level with the first floor and did more damage to the riverbank.
"We had to float boats out of the ground-level storage area, and one of the coaches stayed the night because we had to leave all the doors wide open.
"Horizons Regional Council planted flax along the riverbank, but that's been washed away. We've told the Wanganui District Council that something has to be done to stabilise the bank with either retaining wall or rocks. But they're talking about costs of $70,000, and that's money we don't have," she said.
"We're struggling with our fundraising already because of the floods, which cost between $4000-$5000 to clean up after. Then there was some damage to the electrics in the building. We had to fix that and also had to replace security camera sensors around the building that got water-damaged.
"We've been struggling since October, so here we go again."
The club had been working to fundraise for equipment, and its efforts were starting to bear fruit. "Our under-23 rowers competed at Lake Karapiro earlier this month and made 21 A finals. That's the first time the club's ever done that well," she said.