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Powerboat Steering Flaps

Differential Shearing
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A normal powerboat employs a steering mechanism that rotates the propeller as the wheel is turned. In this design, however, the propeller would be fixed, and steering would be accomplished by means of retractable flaps on either side of the boat. As the wheel is turned in one direction, the flap on that side of the boat is extended into the water. This creates uneven drag, which causes the boat to turn.

In addition to allowing for tighter turns (since the boat essentially is attempting to “pivot” on the flap, thus slowing forward momentum during a turn), this mechanism would also allow for a brake to be employed by extending both flaps simultaneously. The brake would not extend both flaps completely, however, to allow for some steering capability even under maximum braking.

ytk, Nov 20 2012

Trim Tabs for boats http://www.bennettt...guidetotrimtabs.php
Like this idea, but for fore-and-aft levelling. [baconbrain, Nov 21 2012]

The man... the legend... http://coopcatalyst...311_f39d210da51.jpg
the trimtab... [2 fries shy of a happy meal, Nov 21 2012]

Skid fins http://www.thunderb...ry/history0563.html
- The Load They Carry / A historical look at skid fins and how they help hydroplanes turn left. [CraigD, Nov 24 2012]

The Pterodactyl ultralight http://en.wikipedia...terodactyl_Ascender
A "tip-rudder" controlled aircraft [CraigD, Nov 24 2012]

[link]






       The sort of thing you're describing is in common usage in offshore powerboat racing, and presumably elsewhere.
Alterother, Nov 20 2012
  

       Really? I couldn't find anything. Can you provide a link? I'm genuinely curious to know if what I'm thinking of exists already.
ytk, Nov 20 2012
  

       Mount the flap vertical and you'll have a good rudder
piluso, Nov 21 2012
  

       Depending on the geometry of the flap, activation will nnot only induce the desired yaw, but also rolling- which is potentially disastrous.
8th of 7, Nov 21 2012
  

       There is something a lot like this, mounted horizontally on the back of some speedboats. They trim the boat to ride level, so they are called trim tabs.   

       I know I've thought of this exact idea before, whether I made it up or I read about it. It was for something like a Hickman Sea Sled, which is about the only boat shape this would work for, in a vertical plane. On normal speedboats, the sides of the hull are up out of the water at planing speed, and on non-speed-boats, the back end isn't square so there'd be no good place to mount.   

       If, as the description may mean, you want to mount these midships on the sides of a slow powerboat, like a tugboat, say, there would be some advantages. Except for a total lack of slow-speed steering, and a real risk of crushing the things against the dock (there's a reason the two sides of a boat are the "steer-board" side and the "port" load-and-unload side).
baconbrain, Nov 21 2012
  

       Yep, the names are the same, which confused my memory.
baconbrain, Nov 21 2012
  

       Buckminster Fuller compared himself to the aviation trimtab, which steers a mighty aircraft through minute influences, not to the powerboat trim tab, which lets fat drunk people go water-skiing.
baconbrain, Nov 21 2012
  

       Apart from the tautology of //"steer-board" side//, that's some fine cyber-pedantry, [baconbrain].
spidermother, Nov 21 2012
  

       He has been mis-quoted then [baconcrain]   

       "Something hit me very hard once, thinking about what one little man could do. Think of the Queen Mary -- the whole ship goes by and then comes the rudder. And there's a tiny thing at the edge of the rudder called a trim tab." ~Bucky Fuller~   

       Thank you, [2fries], I hadn't seen that one. You are well informed, indeed.   

       My apologies to the great man's memory.
baconbrain, Nov 21 2012
  

       Trim tabs are the powerboat racing things I was talking about in the first anno. I couldn't remember what they were called either. In offshore powerboats, they are sometimes mounted in pairs and used as secondary steering devices for fine control, as well as to combat roll when angling into heavy chop (in the same manner employed by surfaced submarines using the stern planes).   

       I came by this knowledge by watching televised offshore powerboat racing on sattelite TV in the middle of the night. Sometimes the commentators need something to talk about so viewers won't realize that they're just watching boats zooming back and forth.
Alterother, Nov 21 2012
  

       HA!
Truth be told, I am quite profoundly un-informed sir. I just stumbled across this quote the other day.
  

       One of the cool side effects of being in a state of profound un-informed-ness seems to be random pre-informed relevance...   

       <shrugs>   

       Would have liked to have met him.   

       A lot of the times when I pull some unbelievably relevant fact out of my ass, it's something I was just reading about very recently. The trick to seeming well-informed, I think, is not having a huge base of knowledge, but to be constantly informing one's self.
Alterother, Nov 21 2012
  

       True.
It seems more than that sometimes though. The whole; singing along to a song in your head and then it's playing to the exact same lyric on your car stereo when you turn it on, or remensicing about someone you haven't seen in years just instants before they call you out of the blue.
  

       God help me I like it.
Can't take credit for it... can't reproduce it at will... can't even use it... but I likes it.
  

       We'll see your Shamelessly Uninformed, and raise you a Vince Cable …
8th of 7, Nov 22 2012
  

       //The sort of thing you're describing is in common usage in offshore powerboat racing, and presumably elsewhere// //Really? I couldn't find anything. Can you provide a link? I'm genuinely curious to know if what I'm thinking of exists already.// Perhaps Alterother is referring to a “skid fin”, as they’re called in hydroplane design. See link for a decent description and history of them in the Unlimited Hydro class of racing boats (sheltered water, not offshore).   

       The purpose of skid fins is to allow a fully planning boat to turn more sharply, as they have a natural tendency for wide, skidding turns. Though they’re often changed for different race conditions, I’ve never seen a movable one used for steering as in this idea.   

       The idea reminds me of the “tip rudders” on a popular 1980s ultralight, the Pterodactyl. These control surfaces could be turned outward individually to turn, or together to act as a brake. Though tricky to learn to use, once mastered, they made the Pterodactyl one of the more precisely land-able ultralights of its era, and important feature, as folk often landed them in less-than-ideal small fields with lots of surrounding trees.   

       Prior to the development of the modern sterndrives (steerable propellers, as described in the idea), ca. 1970, nearly all boats with engines too large to be mounted outboard used non-steerable, shaft-mounted propellers and separate steering rudders. This arrangement quite maneuverable at speed, but were largely replaced by sterndrives because low speed maneuvers like docking are much easier with them. Docking a large fixed-prop boat is something of an art, largely lost to boaters my age (born 1960) and later.   

       Given how well outboards and sterndrives work, I don’t think this idea offers much if any improvement. Braking isn’t much of a problem with modern powerboats – you just reverse the prop, which on nearly all but the largest boats, is done simply by pulling the throttle past its center, neutral position.
CraigD, Nov 24 2012
  

       Yep.   

       [Marked for deletion]   

       US Patent No: 5,193,478 is for exactly this. Baked.
Kansan101, Dec 05 2012
  

       First of all, no, it's not.   

       Second of all, “baked” means widely known to exist. A single patent for a somewhat similar idea does not constitute “widely known”: “Mere existence alone is not grounds for deletion; it needs to also be widely known.”   

       Third of all, calm down dude. The belligerent types who take everything personally tend not to last very long here.
ytk, Dec 05 2012
  

       Not really good form to keep marking somone's ideas for deletion saying "yep" after they did the same to one of yours.
rcarty, Dec 06 2012
  

       Help page: “baked - a snarky way of saying "widely known to exist".”   

       Historically, “baked” was the original term used here, which was officially replaced by “widely known to exist” (this actually predates my account here, but I know this thanks to the Wayback Machine's archive of an old help page). Since then, people have used “baked” in a looser form, meaning something exists already whether or not it is widely known. However, in the context of an MFD, it /always/ means WKTE.
ytk, Dec 06 2012
  

       Again, mere existence is not a justification for an MFD.   

       My idea doesn't involve flaps that can be adjusted independently after they are deployed. The flaps in this idea extend into the water simply by turning the wheel left or right. A simple mechanical linkage is all that is required, unlike the patent which involves a complicated hydraulic system.   

       Frankly, after all the comments here, I'm convinced this is probably a bad idea, but I'm leaving it here because a) I don't delete my bad ideas, and b) I still think it's a novel enough concept that, even though it likely would be a bad idea to actually implement it, it merits some consideration.
ytk, Dec 06 2012
  

       //If it's pointed out that your idea isn't original, even though it may not be WKTE, I think authors should do the right thing and self-delete.//   

       Okay. I don't agree with that position, but you're welcome to take it. I think self-deleting because somebody somewhere filed a patent application for something vaguely similar is silly, unnecessary, and deprives others of an opportunity to comment on/mock the idea as deemed fit, but to each his own.
ytk, Dec 06 2012
  

       If I have seen farther than others, it's because I've been sitting on the face of a midget… or something like that.   

       Everything is derivative. There hasn't been any truly original invention since we tamed fire. And just because something has been patented doesn't mean much actual thought was put into it, or even that it works. See, e.g., the patents for various perpetual motion devices.
ytk, Dec 06 2012
  

       //A better example would be the wheel, or sliced bread, or the abacus, or inflatable tires, or radios, or the telephone, or fax, or the steam engine, or airplanes, or... you get my drift. Those were all derivative?//   

       No, I guess you're right. The steam engine just sprang forth fully formed from the head of the inventor, like Athena from the head of Zeus. Frankly, I can't understand why it took as long as it did for humanity to come up with that one. Why haven't we found evidence of the Great Prehistoric Railroad by now? Must be a conspiracy by archaeologists.
ytk, Dec 06 2012
  

       Actually, suppression of that paleotech was a joint Alterorder Inc. and BorgCo conspiracy project. We unearthed and tore up the tracks so that we could re-bury and subsequently 'discover' them in a more media- accessible location (after filing any relevant patents gleaned from the technology, of course).
Alterother, Dec 06 2012
  
      
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