The roller ship was not an effective way to cross the high seas
hackaday.com
hackaday.com
Super fun. I'm a marine engineer and design vessels. I've seen a lot of whacky designs over the years and never encountered this one!
Apparently, from the above quote, the culprit for increased drag was skin friction (in this case, that meant water clinging to the surface of the rollers and being lifted out of the water - kind of like the reverse effect of a Tesla turbine which exploits skin friction between moving air and a stack of rigid discs on a rotor). That would certainly cause propulsive inefficiencies.
However, from my view, the primary source of drag here are the "hollows" between the rotor discs. If you were to look at a plan (top) view of the vessel as it moves through the water you would find significant water pressure gradients between (at the aft and fore end of) each wheel. When you have multiple wheels in series, you have oscilating high and low pressure zones along the length of the waterline. That's a tremendous amount of energy lost to water turbulance.
When you look plan views of hydrodynamic hullforms at the waterline (whether monohull, or multihulls like catamaran/trimarin/SWATH) or even aircraft foil shapes, you don't see "wavy" form lines for this very reason.
I will say that these inventers were encroaching on the SWATH hull shape. The author states that this roller disc hull would not be stable due to the high CG. However, SWATH hulls are known for their stability in high sea states.
How do you see this as a SWATH? This is a catamaran that combines buoyancy and propulsion. I do agree it has a high center of gravity, but that's a relative term--what counts is the ratio of height to width. And a catamaran or SWATH has a much wider base than a typical ship.
Wikipedia says SWATH ships require complex control systems--why? Yes, they're very load sensitive because the small contact at the surface means a lot of vertical movement to compensate for weight changes, but couldn't that simply be handled with some pumps and tanks? Make the ship always weigh X--take on water or pump it out as needed to maintain that X.
Dealing with known weight, simply pump the right number of gallons. If your ship can change weight rapidly you might need some fairly big pumps. (I'm thinking of a warship--VLS equipped ships can throw an awful lot of weight into the sky awfully quickly. But on the flip side you can dispense with a whole bunch of stuff meant to deal with the missile exhaust--your VLS tubes go all the way through the ship, when the missile lights it simply blows a panel open on the bottom of the cell and the exhaust slams into the ocean. And it's a safety advantage to be able to jettison a missile without having to launch it or rig a crane.)
It's not exactly a problem impossible to solve, SWATH have already been operated half a century ago, but it seems to be rarely worth the effort.
- Displaced volume wouldn’t be lower than that of a traditional ship (likely even quite a bit higher because the wheels would add mass and the hull would have to be stronger than one that rests on the water)
- Surface area would be higher than that of a single hull.
Also, looking at this as a variant on the paddle steamer (https://en.wikipedia.org/wiki/Paddle_steamer#Seagoing_paddle...), didn’t we already know in 1897 that screw propellers are a lot more efficient? SS Archimedes (https://en.wikipedia.org/wiki/SS_Archimedes) was built in 1839.
So, what was the thinking? It being easier to have low rpm in steam driven engines, and that compensating for those disadvantages?
I assume the thought was similar.
Some of the energy is lost to friction, some is lost to the motion of water.
Imagine a ship where the hull sufface has the same relative velocity as the water. It would behave the same as a frictionless ship.
You raise the question of whether Teflon-coated rotors might have improved the efficiency... but isn't the skin friction also the source of propulsion? Would eliminating the tendency to "drag a great deal of water up" also eliminate the tendency to make headway?
On his first trip, the Coast Guard intercepted him, but eventually let him continue, but then a few days later he had to be rescued.
On his second trip, they were much less lenient and forcibly removed him from the bubble.
So it sounds to me like the Coast Guard didn’t think he had planned well enough to do what he was trying to do safely, and they were probably right.
If he had instead done a series of progressively longer trips accompanied by a support ship ready to rescue him, and then planned to do the trip to Bermuda with a support ship, then he may have been able to convince the Coast Guard to authorize him to do the voyage.
There are amphibious monster trucks. Here's a Russian one.[2] No props, just ridged tires. They're not great watercraft, but if you are crossing frozen ground and break through the ice over a lake, they can grind across the water and up onto hard ground.
Damnation Alley was Plan 9 From Outer Space-level bad.
It is hard to google, but there a bunch of research papers and open source designs (from 80s, 90s) for all kinds of wacky 3, 4, 6-wheelers. The last patents related to these expired in early 00. Newer patents are all from the SHERP guys.
The older patents are from a bunch of other companies that failed before Sherp. For instance, one below was made by SMZ in ‘94, (sub)contractor for the military that produces parts for nuclear submarines and what not. https://pnevmohod.ru/forum/index.php?topic=3956.2180 (Now nicknamed Elon’s cyber truck)
This reminds me of a lot of my failed efforts to refactor code.
Are there materials that let us change that on the fly? For example, can we apply a magnet to the back of some material to change its surface to increase or decrease its coefficient of drag?