design and construction of a human powered/ pedalled kayak

Hi

I am currently taking a first (under graduate) degree in Mechanical Engineering and this year I will start my fourth (final) year during which I must do my thesis (final year project).

my thesis is titled: "design and construction of a human powered kayak".

my basic idea is to have a kayak where the person should be in a recumbent position and pedals to drive a propeller. steering is achieved by using a propeller.


i think that i should divide my thesis into four sections: hull, rudder, propeller and propulsion.

Hull: the length, width and shape of the bow, stern and midsection of the kayak to achieve good stability and good efficiency to have good speed

Rudder: shape and size which must give good maneuverability and small turning circle. also a mode of application which makes it easy to use together with mode of mounting to the hull

Propeller: size i.e. diameter, pitch, surface area and number of blades to achieve efficient propulsion

Propulsion: the mechanism required to move the kayak in water i.e. from pedals to propeller


throughout the thesis i will focus on mechanics and fluids.

i really would appreciate any ideas, suggestions and any information that will help me with my thesis

THANK YOU

 

Welcome, hillmaster. You've come to the right place; we're full of ideas here. Check out the other pedal-powered boat threads first, there's a lot in them. Will you be building a boat as part of your project?

 

yes i will have to both design the whole "boat" and also physically construct it to be able to perform testing!!

 

I'm not sure who's good at kayak hulls here, but Rick Willoughby is the go-to guy for all your other categories. I just don't know how many more irons he can fit in his fire, haha.

Read all the pedal-power stuff first, then use the search function for kayaks, all of Rick's posts, etc. Pedal power is very popular on this forum, and there's loads of good information and new ideas.

Dig in, good luck, and have fun.

 

Hillmaster,
Some general rules;
Hull: very narrow at waterline and as close to semicircular underwater cross sections. This though creates a boat with almost no righting moment so you need to build in a lot of flare above the waterline (it's still a balancing act) or add on a little outrigger or a tiny self adjusting foil at the end of a light crossbeam. No need to have one on each side.
Drive train must be chain or belt, forget about gears (especially bevel gears) as they soak up too much of a limited power source. Setting up an airprop actually simplifies things greatly and is just as efficient.
Prop must be one or two blades only (one is best), very large, high aspect ratio, and very carefully adjusted pitch (adjustable is ideal) and fine tuned twist.
This type of efficient boat simply will not be maneuverable. However, to make the best out of it i would suggest a miniskeg about 65% of the way aft along the hull (if water prop then this skeg can house the shaft) and a tiny high aspect ratio rudder at the extreme bow.
Tcubed

 

You know that the choice of words here begs for a definition of some kind before you can get to work. What will be the parameters of "good" is the place to start. Is there a speed over distance goal? How far does it have to remain in the "good" envelope and how much fall-off is tolerable to remain within design goals?

There are several excellent rudder mechanism strategies for a boat of this type that have proven to be reliable and effective. The correct rudder foil section and planform will be defined by the speed range of the boat and its design.

Same as last answer only substitute propeller for rudder.

Is the boat weight and performance sensitive in the extreme, or can it be regarded as a more forgiving recreational example which, instead, will lean towards the durable and less powerful side of the potential design solutions?

My suggestion... make a list as to how the boat will be used and by how many persons at once. Decide if it is about the fastest boat capable, or if it is more about a casual, recreational design study in which stability, comfort and all around utility is more important. Will it need to be capable of car-topped transport? Will the craft need to be disassembled for transport and storage? Is there a weight target? Is there a limit on the length for keeping it in a house or garage? Will it be used by the average male, or will the design needs also include women? This last bit is under the transportability and use topic and is reflected by the weight, width, length, etc. The typical solution for women is not the same as for men.

Look-up the vast amount of info on the Web dealing with human powered vessels and study the solutions that have been developed already. Look at the collection of existing commercial offerings to see what they have developed for that part of the overall human powered section of the boating market.