October 29, 2006
Plans for the prototype human powered ocean boat
Steve Schleicher from Nimbus Kayaks in B.C. has kindly offered to donate a slightly damaged Hyak tandem kayak that I plan on modifying to build a prototype human powered ocean boat. I plan on using this boat to gain much needed experience in ocean conditions, and to learn more about exactly what the final trans-Atlantic version of the boat should be like.
The Nimbus Hyak kayak is 19' 3" long, 28" beam, 15.5" depth and weighs 79 lbs. The plan is to cut off the Hyak top and fabricate the ocean boat canopy as illustrated in the rendering at the top. I will probably use the Styrofoam section male-plug method that I used to build both the Rocket HPV fairing and a Critical Power streamliner canopy top.
Basically, I will take the computer model of the curved canopy top, slice it up into 2" thick sections and project and trace each section into 2" thick Styrofoam. I glue the Styrofoam sections together and sand down the stair-step edges. Then I cover the foam plug with a combination of fiberglass, carbon, Kevlar and some type of sandwich core material like nomex to make it all stiff and strong. Then I will build the walls and floors for the compartments, install the drive leg, rudder (not shown), hatches to access the front and rear compartment, seat, etc. Then finally I will bond the one-piece top onto the Hyak hull and then cut-out the retractable canopy mid section hatch. Then I cut out the windows and fill-in with Lexan. And finally, add hardware, paint and other details.
The prototype boat is based on a design from Rick Willoughby with help from Stevie Smith from the human powered circumnavigation expedition Expedition360 and Leven Brown from his trans Atlantic solo rowing expedition Columbus Run. The drive will be a standard bike cranks/chain ring / bottom bracket to a twisted chain that turns a small gear mounted to another bottom bracket which turns the prop. Warren Beuchamp has a fairly simple and tested drive that I plan to base my design on:
A faired fin made from carbon or fiberglass will cover the drive leg steel tube and extend to 3 feet below the boat bottom. The prop will be only about 1 foot below the boat bottom and the bottom of the fin will hold 20 pounds of lead ballast. I calculated where the center of weight was including the 20 pounds of ballast and my own weight, and positioned the seat / drive leg unit exactly in the middle of the boat, 115.5" from the stern. I assume that the front half and back half of the boat weight approximately the same. If my center of weight is slightly off, or if I want more weight in the stern, then I can install movable ballast weights under the floor boards in both the front and rear compartments to balance the boat as required.
Stability is maintained from both my weight being fairly low in the boat, as well as the 20 pound ballast 3 feet below the boat and some additional ballast weights under the floor boards of the bow and stern compartments. The weight of the ballast keel should allow me to stand up and lean slightly over the side of the boat without tipping over.
Capsizes are prevented by:
If the boat capsizes, it should roll upright even if the cockpit hatch is open and the center cockpit compartment fills with water.
The rear and front compartments are both water-tight with accessible hatches in the bulk heads. There are two sealed compartments filled with expandable foam in the bow and stern. These should prevent sinking if the hull is damaged and all three compartments fill with water.
The rear compartment could be used to store supplies, or used as a resting or sleeping cabin. The front compartment is for storage of supplies. I'm not quite sure exactly how to gain access to the forward compartment because the drive leg is in the way. It might be possible to add hatches to the top, but I don't like the idea of having to crawl up on the nose to get something from down in the front compartment.
I also have not yet figured out how to store and deploy the sea parachute (sea anchor). It needs to be fastened to the bow, and again, I do not like the idea of crawling across the nose to attach the sea anchor every time it is required. The sea anchor is very important because it prevents the boat from being pushed backward when travelling into strong head winds and rough seas. I could stow the anchor in the cockpit area with cables running outside the boat to the nose, but I don't like the idea of cables running outside the boat. I really want to keep the outside shell aerodynamically clean.
The efficient aerodynamic shape of this boat is not so much for speed, but to minimize the effect of strong headwinds which are a big problem with an ocean crossing. Most human powered boats are not designed with aerodynamics in mind because of the slow average speeds of the boats which might be as high as only 10 kph. However, when pushing through a 50 kph headwind, the 'air speed' of the boat is 50 kph, and a smooth, aerodynamic shape will absolutely help stop the boat from being pushed backward.
I have shown the canopy hatch as hinged to the rear and to the front. I am not sure which configuration is better. If the hatch flips backward, then it allows access to the top of the bow, but won't allow access to the top of the stern. Perhaps there is a way to fasten the canopy hatch with 4 hinged clamps (any such thing??). When all 4 clamps are closed, the hatch is secure. Buy un-clamping 3 of them, the 4th will act as a hinge allowing the canopy hatch to rotate away to the front, the back or either side. Or it could be removed completely and tied down to the rear deck. I like the hinged clamp approach, as it is the most flexible, but I am not sure if any such hinged clamp exists. When the canopy hatch is open, it is held in place with two lockable, removable struts.
The seat will rotate forward to allow access to the rear hatch. Although, I can see now that I could not access the rear compartment with the canopy hatch closed, as there would be no way of rotating the seat out of the way unless I could stand up - even then, it will be tricky. I can figure that out later after I have build the boat and can experience exactly how much room I have in there to move around, and how that seat could be moved out of the way.
Since this boat is designed to be operated with the canopy hatch closed, Adequate ventilation is very important. If ocean conditions allow, the canopy top could be opened slightly to allow some air flow into the cockpit. Aside from that, I will install a fan with fresh air intake and exit vents for the cockpit compartment (and the sleeping compartment if it is going to be used for that). The fans will be powered by lithium polymer batteries wired to solar panels on the top of the bow and stern. The small window cut into the canopy hatch is purposely small to avoid solar heating.
I'm not sure how to calculate the solar panel power production / battery storage / power consumption for the electronic equipment. I'm also not sure exactly how much electronics will be required on the test boat - although, I would like to run everything I plan on taking to the Atlantic to make sure that it all works exactly the way it's supposed to. Maybe someone out there in AOG land can help?
Electronics for the test boat:
For typical day trip uses of the test boat, the Iridium sat phone and the PDA with GPS could probably be powered by replaceable AA batteries and therefore probably don't require power from the on-board rechargable batteries and solar panels. I would think the items that need constant power would be the bilge pump, the auto steering system, the vent fan and the amp/speakers. How much power? How many batteries? How many solar panels? Can anyone offer advice with this?
If the rear compartment is to be used to sleep or rest in, then I should install 2 port holes to allow for lookouts and to let in some natural light.
The drive leg is inserted and can be pulled out of a slot cut into the hull for transportation and beaching. Since the drive leg includes a 20 pound ballast (maybe more), I am not sure how to pull it out while on the water. The ballast required to keep me stable when standing up is the same ballast that I would be pulling out of the water. I'm not sure how to deal with this. Perhaps the drive leg could be designed to rotate forward into a bay in the bow compartment. Then a paddle could be used to row ashore or to a shallow dock. A long slot cut into the hull would disrupt the smooth surface of the hull bottom though - I don't like that. Maybe a worm gear with a hand crank to raise it up would work. Once it has been fully raised, it could be stowed in the forward compartment or laid down flat on the deck beside the cockpit seat.
Advice, comments, suggestions, feedback ??