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geo.tatum

USA
5 Posts

Posted - 10/19/2018 :  08:35:24  Show Profile  Visit geo.tatum's Homepage  Reply with Quote
It has bee a while since I have started a Wavebike build. I have four Wavebikes at the moment, and it has been a few years since I have even been out cycling the water. The old fleet needs some TLC for certain. Life has taken its twists and turns.

So 20 years later, after the last record attempt in the IHPVA worlds championship in Toranto, I looked up cycling records and found the new popular ones to be measured in endurance time efforts, I think from one hour to 24hrs, though clearly the 100 meter sprint is still a big one.

I think I would love to spend an hour or even a day on a wavebike taking one of those hour endurance records. But the Wavebike has evolved in my head over the last 20 years, and now I am disappointed with the engineering of the old wave bikes. They are now an antique human powered water bike machines, and they no longer fit the canard fin balanced water bike idea that has evolved in my head. Also I have grown much older, so it would help to unlock the potential of a few of my new speed ideas. So I shall build a new one to fit my imagination of the fastest water bike possible for hour endurance effort. Luckily I have piles of parts and pieces to draw from, as I think it would be nearly impossible to start again from scratch.

It looks as if this forum has gone rather quite over the last 18 or so years of my absence. Does the IHPVA still hold a National human powered water bike contest? Is Jake, or Warren, or Bob, or Bill still here?


Since this time I am not looking to make something marketable by size, or cost, I can really push the limits of my ideas of what it takes to make a water-bicycle as fast and sea-worthy as it can be. Though clearly I must still be able to transport it car top, lift it myself, and have it stand up to UV and salt water. Has the IHPVA of the Americas held the hour endurance event for the world record?

george walter tatum

billjoat

USA
1 Posts

Posted - 10/20/2018 :  07:00:50  Show Profile  Reply with Quote
I still feel as though the Wavebike was engineered far beyond what the standard was of the day. I think that its a viable machine even now. The only way "I" see to significantly improve on the design is to put foils under it!!??
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geo.tatum

USA
5 Posts

Posted - 10/20/2018 :  08:47:27  Show Profile  Visit geo.tatum's Homepage  Reply with Quote
I still feel as though the Wavebike was engineered far beyond what the standard was of the day. I think that its a viable machine even now. The only way "I" see to significantly improve on the design is to put foils under it!!??

Hi Bill. This is my thinking:

Theory 1: Given a perfect ogive hull shape and given a displacement, there is an optimum balance between hull waterline length and wetted surface hull area for any energy input.
Clearly the longer the water bike, the higher the waterline speed. The Wavebike’s drag curve showed drag rising dramatically after it passed its hull speed. Prior to hull speed, the drag curve was well under the normal bicycling training effort. So the Wavebike felt like a road bicycle on flat land, going about 8mph for a resulting speed around 6.0 mph. Then more effort resulted in more speed, and I think my best effort maxed out at around 14 mph on my fastest design. 14 mph took an effort close to a 38 mph sprint on my road bike.
It would be very easy for me to calculate Watt input on wavebike vs. speed, and Watt input on my road bike and calculate speed. For certain this would show the water bicycle slower in speed for any given effort of input. However, things remain pretty tight until the wavebike passed its hull speed.
So lets go backwards for a moment with the hull form, to the limits. Let us go for a speed first, then calculate the ultimate waterline length. Why not 20mph? A hull form that fits its hull wave at 20 mph is like 180 feet long. With a displacement of less than 400 pounds including, rider, cargo and, vehicle weight, this thing would be a wild looking skinny needle of a structure. If the race were a 100-meter sprint, the operator body would be well behind his competitors. Still, it might be fast as all get out, save for one problem. That would be wetted surface drag. This machine would have so much skin, all of which creates drag, that it would be substantially harder to make go 6.0 mph than the 20-foot Wavebike. Perhaps 7 times the skin, so times the wetted surface, and effort at 6 knots. The rider would max out his power input into this long needle, as the cyclist on the shorter wavebike, comfortably road away from him.
Given a rider’s power output, we can go the other direction. Unless hydrofoils are added to canard fins to lift the Waterbike and decrease wetted surface (Yes Bill I agree here. It takes one look at the America's Cup sailboats to see the power of this idea. At 9knots speed, there are enough forces to seriously consider foils to lift boat and reduce skin drag), the balance between hull length and wetted surface on ogive hull form, must be focused on the average obtainable power output from the rider for whatever distance he needs to ride. With power know, we can calculate the best spot on graph of waterline hull form drag vs. wetted surface skin drag. These two curves for any displacement and power effort, must cross at some point, and that point I shall dub, Locker Point. Now this point moves when you change power input a lot, and some when you change the vehicles displacement, but otherwise it stays the same. Having raced against sailboats up to 44 feet, rowing shells in singles (27 feet), doubles, 4s and 8s, and the single man surf-skis up to 30 feet, I am going to gamble Locker point is around 33 feet long for a single man Wavebike at an old man’s endurance cycling effort. Should be a walk in the park to get to 6mph, though harder than the 20-foot Wavebike’s effort for 6mph, due to the increased friction from skin drag. At 8.5 mph, it crosses the Locker point. At this point is much easier to pedal than a Wavebike at 8.5 mph. And because the hill starts after 8.5, but the climb is almost not even noticeable at first, 9 mph maybe sustainable. And in fact, the 33-foot hull design should have a faster sprint for same power input, than the 20-foot long Wavebike.
The 33 foot Wavebike’s design, as it is now, looks much like the old Peedobike from the 90’s. Where canard balance all started. It will be built in three 11-foot sections to the ogive perfect pattern. The bow and stern parts are quick release units. This will allow me to break the machine into something I can transport on top of a car. Also, it will be easy to lengthen or shorten the bow and stern sections, though I confess I will bastardize the perfect ogive shape when I do this. But small changes in several feet increments will probably not hurt overall efficiency of final hull shape. The idea is to test the 33-foot hull form, compare it to the 20 and 18 foot Wavebike drag curves, with drive, cycle frame and propeller, all shared, and find the Locker point within the resulting data for the best effort I can do.
There are a few more considerations, based on reflection on some of the other great IHPVA waterbike engineers, inventors and technicians, some of which used Wavebike parts for their drive trains, and long thin ogive like hulls for their hull shape. After many years of thought and reflection, and revisiting the data as well of photos of these boats in operation, I have several theories as to why there seemed to be a 8mph limit on my competitors watercraft and why the wavebike easily exceeded that speed in efforts.


george walter tatum
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Don S

USA
88 Posts

Posted - 10/21/2018 :  21:33:08  Show Profile  Reply with Quote
Bill and George, Welcome to the forums. Your posts are welcome and appreciated but regrettably this entire forum is largely inactive.

George, The IHPVA doesn't currently host a national human powered waterbike contest with the main emphasis seeming to be the World Human Powered Speed Challenge, which is an international event held in Battle Mountain, Nevada, for land speed records. Warren still hosts the Human Powered Boats forum on the Recumbents.com web site but is largely inactive here.

"it's important to understand what makes them fast. It's more important to understand what keeps them from going faster." DS
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geo.tatum

USA
5 Posts

Posted - 10/22/2018 :  11:16:56  Show Profile  Visit geo.tatum's Homepage  Reply with Quote
Hello DS. I am glad to hear Warren is still aroun. I do not mind an inactive forum. The forum is perfect and user friendly, and your organization seems well managed. I will shortly join the IHPVA as a member, as I had been years ago. The European endurance water bicycle records are no joke. The hour record sounds like a track event on the water. Needless to say, as a past world champion and US National champion of IHPVA, I need a target, a plan, a machine, a working shop, a challenge, and a little plastic trophy at end of huge effort.
So if not now, when? And if not here, where? I think a world record attempt on the 1 hour water cycle record, and perhaps the 6 hour one as well, might cause a conversation in this forum.

I will set the new benchmark for water bicycle 1 hour international record. I could probably do it now on a old restored traveller class wavebike. But I prefer to build from scratch and test out my new ideas. The idea was pretty raw in 2000 when records were set, and the Wavebike design was driven toward a product line.

I really am hungry to explore my new hull form, and just see what the original idea's limit could potentially be.

The new Wavebike will set an international human powered vehicle record that no surf-ski or rowing shell can beat. So the cycle will be the world's fastest human powered water craft, and the most sea-worthy.

Happy cycling.



george walter tatum
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fastwes

USA
2 Posts

Posted - 12/12/2018 :  21:30:04  Show Profile  Reply with Quote
It's great to see you discussing boats again! No, it's really fantastic George to have you on a forum sharing some of your Wavebike concepts again. I've been thinking about your stability and control solutions for 18 or so years also working on a SUP design with your good stuff. I kind of feel sorry for all the people putting so much energy into just creeping at a snails pace on SUPs.
I started looking for anyone who thought active stability control(by canards, etc)in boats was the way to go or anyone who even heard of you/your conclusions, for the last 6 months. Nothing but a few mentions of the Wavebike with nary a mention of its active stability concept. But back here at the IHPVA site I found you! Not too much drama but the truth. The R&D you shared on the building of WB was a great time and showed me that the web didn't have to be only a gossip connection. It can be shared original thinking, engineering, and more.
Later,
Wes
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