This is one of a range of DIY rowing machines that cost about $100 in materials - and compare well with machines that cost $1500.
This design shows the main frame with the components drawn out on a sheet of 18mm plywood 2440mm x 1220mm (8' x 4').
Other designs are made in solid timber or angle iron. The impeller can be easily make using a bike wheel.
This is an Opensource Project. All of the drawings and instructions on how to make the different models is freely available.
Contact me, Jim Flood at email@example.com or visit the website below.