Human Power
Humans are the engine of the Open Waterbike.
The performance of the human engine is therefore the most important input design parameter of the Open Waterbike.
This page summarizes the relevant knowledge and justifies what total power input defined as a design requirement.
First of all, human power can be delivered by various motions, but the superiority of leg cranking has been demonstrated in several studies.
The Open waterbike is a long distance watercraft, so we are particularly interested in sustained performances. Besides, she is essentially a recreational boat (even if we believe we can derive race boats from her), so we are interested in power produced by reasonably fit people for a few hours.
The maximal human power produced by foot cranking decreases over time as described in the following figure.
We can therefore set the input power of each human engine as follows:
Athlete (several hours) or amateur (one hour): 200 W
Amateur (several hours): 100 W
Specific power
Since the performance of a Human Powered watercraft is usually highly affeted by the total mass of the craft (plus the human(s)) the concept of power available per Kg could be relevant, addressing the case of less powerful but lighter riders (e.g. women). Since the mass of the boat is usually a fraction of the total mass we can set the specific power as follows:
Athlete: 2W/Kg
Amateur: 1W/Kg
As all the documents in The Open Waterbike Project this is a startup proposal; your opinion is very welcome.
Our boat is faster than mine
Sources:
Abbott, A.V. and Wilson, D.G., Human Power Transfer to Modern Vehicles, in Human-Powered Vehicles, Human Kinetics, 1995