Hydraulic rowing machines have two major benefits - the low price, and they are smaller quieter than flywheel rowers. Otherwise they're considered the poor relation in the rowing machine world.

To get any benefit from a workout you need to work against some form of resistance - either low resistance for fast aerobic sessions, or high for anaerobic sessions to work your muscles.

Hydraulic rowers do this with pistons but unfortunately many rowers claim these type of machines don't give the smooth, flowing feel of a flywheel machine. They will however give you a decent enough workout but perhaps not such a comfortable one. 

Resistance is achieved by pistons attached to the handles. You pull against the air or fluid inside the cylinder and adjustments to the level of resistance is made by levels or clamps.

Advantages of Hydraulic Rowers

• Low cost compared to many rowers
  
• Smaller size, many are folding models
• Quieter than other types of rowing machines
  

Disadvantages of Hydraulic Rowing Machines

• Most models do not provide smooth rowing action
  
• Require regular maintenance
  

Hydraulic rowing machines can be a good choice if your budget is limited and / or you don't have much room at home to use it. Many hydraulic models are foldable and can therefore be stored out of the way when not in use. The most popular models of this type are made by Kettler, Stamina and HCI Fitness.

For information on other types of resistance see air rowing machines, magnetic rowers and water rowing machines.