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 specifies the total power input defined in this context 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 performance. Since she is a recreational boat as well as a racing boat, 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 categorize the input power to be expected of a human engine as follows:
Athlete (several hours) or amateur (one hour): 200 W
Amateur (several hours): 100 W
Since the performance of a human powered watercraft is usually highly affected 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:
As all the documents in The Open Waterbike Project, this is a working assumption; your opinion is very welcome.
Abbott, A.V. and Wilson, D.G., Human Power Transfer to Modern Vehicles, in Human-Powered Vehicles, Human Kinetics, 1995
Our boat is better than mine.