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Thread: History of the planing dinghy

  1. #71
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    Default Re: History of the planing dinghy

    Re the scow V 18 footer comments earlier, sometime in the 80's or 90's an A scow came out from the US for some reason. It was all hype and a media built grudge match was set up out on the harbour. The result on that day was a fairly conclusive win or set of wins to the 18 ft skiff. I can't remember the conditions or state of the harbour. Incidentally there was a similar match set up between our top racing cat at the time , Split Enz, and Bullrush the famous Australian ocean racing trimaran. The Cat won.

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    Default Re: History of the planing dinghy

    Quote Originally Posted by John B View Post
    Re the scow V 18 footer comments earlier, sometime in the 80's or 90's an A scow came out from the US for some reason. It was all hype and a media built grudge match was set up out on the harbour. The result on that day was a fairly conclusive win or set of wins to the 18 ft skiff. I can't remember the conditions or state of the harbour. Incidentally there was a similar match set up between our top racing cat at the time , Split Enz, and Bullrush the famous Australian ocean racing trimaran. The Cat won.
    About what I would expect. The A scows have evolved only incrementally since the class was founded in 1901, and the scantlings require that they be built as heavily now as they were then. They are also restricted as to sail area, and don't allow trapezing or hiking wings.

    they are still about the same shape as the boat in post #53, but with bilge boards, better rigs and stiffer hulls.

    And you never hear of one pitchpoling.

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    Default Re: History of the planing dinghy

    I think it's great that they're reviving the historic types. But I'm still wondering, when did they start to plane?
    I'll ask!

    Rick

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    Default Re: History of the planing dinghy

    Quote Originally Posted by RFNK View Post
    I'll ask!

    Rick
    Our spies are everywhere!

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    Default Re: History of the planing dinghy

    It occurs to me that if you added hiking wings and trapezes to an A scow, you could probably carry another 500 square feet of sail. But of course, they are sailed by "sedate" Midwesterners, not Aussies. I believe Buddy Melges won the A scow championship when he was 80 years old.

    Oops, checked that, he was leading for a while in 2008 but didn't win.
    Last edited by johnw; 05-23-2013 at 08:17 PM.

  6. #76

    Default Re: History of the planing dinghy

    Quote Originally Posted by johnw View Post
    Most sailors around here don't actually know how to distribute their weight on a scow, because most junior programs don't use them.
    So you don't have Toppers then?

    http://www.youtube.com/watch?v=Hm_FturE_Z8

    sailed and abused in their thousands by kids in the UK. Definitely scow shaped and yet very easy to nosedive

    And don't forget the classic Australian scow Moth, which also needed to be sailed well heeled. As, sometimes, does the semi-scow-like Fireball

    Richard Woods

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    Default Re: History of the planing dinghy

    Quote Originally Posted by John B View Post


    That looks very much like Sunbeam to me Chips, and I've never heard of her being called a Patiki before, in fact I wouldn't. She was about 42 ft Logan bros fin keel boat of circa 1900 or so.
    I was wondering, given the quite different hull form, but Baigent included it in his post and I reckoned he knows more about the subject than I do.

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    Default Re: History of the planing dinghy

    Quote Originally Posted by Richard of Woods Designs View Post
    So you don't have Toppers then?

    http://www.youtube.com/watch?v=Hm_FturE_Z8

    sailed and abused in their thousands by kids in the UK. Definitely scow shaped and yet very easy to nosedive

    And don't forget the classic Australian scow Moth, which also needed to be sailed well heeled. As, sometimes, does the semi-scow-like Fireball

    Richard Woods
    The topper has never caught on here. Perhaps people tried it and found it as miserable as has been reported here.

    However, the Topper is a damnable version of the concept: soggy, overweight, undercanvassed, and poorly rigged.
    Our scows have been known to dip their noses, but they haven't developed a reputation for pitchpoling.

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    Default Re: History of the planing dinghy

    Interesting thead to read with this mornings pot of tea. Thanks for posting.

    With regards to Nordic pram shapes possibly planing,i dont have any doubts that may have been possible. There are a lot of pram shapes,some that would be ripe for planing given the right conditions, even if not intended.

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    Default Re: History of the planing dinghy

    Quote Originally Posted by The Bigfella View Post
    NG Herreshoff 1877

    http://www.duckworksmagazine.com/03/...aran/index.htm


    Sounds like a planing dinghy to me.
    Quote Originally Posted by johnw View Post
    Here we get into the knotty problem of what constitutes planing. I don't think the narrow hulls of the catamaran are planing, because shapes that produce little lift are as fast or faster than those that are flatter. It seems to me that the hull's lift is part of what makes it planing, and of course, the effectively longer waterline as the water breaks cleanly from the transom. By most standards, it isn't planing until the boat reaches 2.4 X the square root of the waterline length in knots, so there are plenty of designs that will exceed hull speed but not plane. I'm not sure what to call what catamarans do other than going fast. There doesn't seem to be a transition point, whereas a planing boat suddenly needs less power to keep going than it needed to get out of the hole.
    Quote Originally Posted by Richard of Woods Designs View Post
    I agree, catamaran hulls don't plane

    If you have an hour or two spare you might like to read this thread

    http://www.boatdesign.net/forums/hyd...ing-45248.html

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
    The Herreshoff cat Amaryllis which still exists, has horizontal adjustable trimming boards, whether they promoted planing or perhaps more correctly inefficient hydrofoiling, is of course debatable, but I would think it did, this of course an outlier in the argument, since as far as I know no other cat has ever used that system

  11. #81
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    Default Re: History of the planing dinghy

    Quote Originally Posted by johnw View Post
    supported more by hydrodynamic forces than by buoyancy," leaves out the fact that the express canal boats of the 1830s used hyrdrodynamic bearing to travel at 10 knots while being towed by horse.

    Some pretty good history here:


    The boats were, if I recall correctly, about 60' long, so they were traveling close to hull speed but having the power needed to push them dramatically reduced by the lift they were getting.

    .
    That is a subset of conditions, where planing is promoted in very shallow water, the water reflected downward by the bow, is in turn reflected upwards by the canal bed and promotes lift. I've done it in a Laser, on a very broad reach because the rudder and daggerboard have to be up. It's the same mechanism as skimming boards on the beach. I knew a powerboat captain who would regularly seek out shallow water while transitiing the the intracoastal, to get more speed, of course if he had dropped off the plane, he would have had a major grounding,

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    Default Re: History of the planing dinghy

    Quote Originally Posted by Hwyl View Post
    That is a subset of conditions, where planing is promoted in very shallow water, the water reflected downward by the bow, is in turn reflected upwards by the canal bed and promotes lift. I've done it in a Laser, on a very broad reach because the rudder and daggerboard have to be up. It's the same mechanism as skimming boards on the beach. I knew a powerboat captain who would regularly seek out shallow water while transitiing the the intracoastal, to get more speed, of course if he had dropped off the plane, he would have had a major grounding,
    That is not about planing per se. It is about a wave of translation creating an orbital velocity on the wave crest that is moving in the same direction as the hull. The speed of the hull through the water is the same as for deep water, but the water it sits in is also moving forward over the ground.
    As to whether a planing catamaran could be designed, if you can power it up over the hump with sail, yes. After all there are now racing cats on the motor race circuit, and water skis are long slender planing surfaces.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: History of the planing dinghy

    Cats are faster when they're kept fairly level, and they"re often barely touching the water, apart from their dagger boards and rudders. It looks a lot like planing to me!
    Rick
    ,

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    Default Re: History of the planing dinghy

    Having sailed Kittycats (with whopping great spinnakers) and Tornadoes extensively - I reckon they plane.... as does my original one design Windsurfer. We used to blast past the Manly Ferry, which does 18 knots, with tourist camera flashes popping away, quite easily. We were way over 2.4 times hull speed.
    "Travel is fatal to prejudice, bigotry and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome and charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime" Mark Twain... so... Carpe the living sh!t out of the Diem

    I'd rather look back at my life and say "I can't believe I did that" instead of being there saying "I wish I'd done that"

  15. #85

    Default Re: History of the planing dinghy

    I have sailed Toppers enough to be able to confirm ATTLG comments. But it works for kids, probably because they are much lighter than adults.

    To plane a hull needs two things. A good lifting surface, which means some of the hull has to be flat and beamy, preferably aft. It also needs an angle of attack

    So if a Tornado really did plane you would never nosedive, instead you would lift like a speedboat does. Waterskis are very inefficient planing surfaces, the aspect ratio is all wrong

    Having said that, the real problem with vehicles at speed is control, not speed per se. Put enough HP on a IOR monohull and it will plane, but it will be so uncontrollable you will never manage to go in a straight line but roll it over. Look at how uncontrollable the racing cars from the 1930's were compared to today's cars, even though they were going slower than you do when driving to work with one hand while drinking a coffee or putting on makeup with the other.

    Richard Woods of Woods Designs

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    Default Re: History of the planing dinghy

    Quote Originally Posted by John B View Post
    Re the scow V 18 footer comments earlier, sometime in the 80's or 90's an A scow came out from the US for some reason. It was all hype and a media built grudge match was set up out on the harbour. The result on that day was a fairly conclusive win or set of wins to the 18 ft skiff. I can't remember the conditions or state of the harbour. Incidentally there was a similar match set up between our top racing cat at the time , Split Enz, and Bullrush the famous Australian ocean racing trimaran. The Cat won.
    A modern 18 vs. a modern scow in the 1990's ??? I don't doubt the result, assuming it was an E scow your talking about a design, hull shape, sail configuration, total sailing weight, etc... that is little changed since the 1920's !!! VS a modern 18' skiff? a hull type with another 80+ years of form evolution and weight reduction and trapeze and hikeing wings... etc no wonder the skiff won. a 1920's E scow vs. a 1920's 18' skiff is a very different story. I don't doubt that a 1920's 18m ft skiff was the fastest 18' monohull afloat but it would never have been able to keep pace with a 28' E scow, see original post vid. those type speeds were achieved by the very early scow hulls about 1900+-

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    Default Re: History of the planing dinghy

    Here's a sharp bow scow sailed out of Manchester Massachusetts 1910, note dual rudders and bildge boards.

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    Default Re: History of the planing dinghy

    Quote Originally Posted by Daniel Noyes View Post
    Here's a sharp bow scow sailed out of Manchester Massachusetts 1910, note dual rudders and bildge boards.
    Is that a Sonder boat?

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    Default Re: History of the planing dinghy

    Quote Originally Posted by Hwyl View Post
    The Herreshoff cat Amaryllis which still exists, has horizontal adjustable trimming boards, whether they promoted planing or perhaps more correctly inefficient hydrofoiling, is of course debatable, but I would think it did, this of course an outlier in the argument, since as far as I know no other cat has ever used that system
    Can you get us a picture of that? I've seen some plans for Amaryllis, and those weren't on it, so they may have been a later addition. Could they have been to prevent the hulls from diving?

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    Default Re: History of the planing dinghy

    Quote Originally Posted by The Bigfella View Post
    Having sailed Kittycats (with whopping great spinnakers) and Tornadoes extensively - I reckon they plane.... as does my original one design Windsurfer. We used to blast past the Manly Ferry, which does 18 knots, with tourist camera flashes popping away, quite easily. We were way over 2.4 times hull speed.
    I think there is more than one way to go fast. Submarines, I understand, can be quite fast, but they definitely don't plane. I've seen pictures of an attempt to build a planing catamaran with flat bottoms. It didn't go any faster, but if it could make the bow rise rather than dive as speed increased, it might make them more seaworthy.

    Small waterline area twin hull vessels are also fast, and they certainly don't plane. In fact, they look like a couple submarines joined above the waterline.



    I'd say foilers, catamarans, submarines and SWATH vessels all exceed hull speed without planing.

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    Default Re: History of the planing dinghy

    Great thread! In all this reflecting on hull form, I think that equal importance in the development of sustained planing can be placed in the "invention" of the boom vang (kicking strap to you Brits). I know from experience in my Fourteening days that a broken vang makes planing difficult. Also the recognition that weighted centerplates were better unweighted as they only helped when heeled and the boat were better sailed flat. This weight reduction and powering up the mainsail with a vang made the boats plane more readily as much or more than hull shape evolution.
    We have a modern A scow on the Chesapeake and I think it would give most any other single hull boat a run for it's money, upwind or down. Huge asym spinnaker, bowsprit, carbon rig and 7 crew - all busy, the boat is as much fun as you can have on the water. Sailing a scow downwind is tricky. They still like some heel downwind in a breeze, as the bows will shovel in. Breaking them out is best done by heeling which sheds the water off the foredeck. Heeling the boat is about the last natural inclination you have in those conditions though!
    TP

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    Default Re: History of the planing dinghy

    Quote Originally Posted by Richard of Woods Designs View Post
    I have sailed Toppers enough to be able to confirm ATTLG comments. But it works for kids, probably because they are much lighter than adults.

    To plane a hull needs two things. A good lifting surface, which means some of the hull has to be flat and beamy, preferably aft. It also needs an angle of attack

    So if a Tornado really did plane you would never nosedive, instead you would lift like a speedboat does. Waterskis are very inefficient planing surfaces, the aspect ratio is all wrong

    Having said that, the real problem with vehicles at speed is control, not speed per se. Put enough HP on a IOR monohull and it will plane, but it will be so uncontrollable you will never manage to go in a straight line but roll it over. Look at how uncontrollable the racing cars from the 1930's were compared to today's cars, even though they were going slower than you do when driving to work with one hand while drinking a coffee or putting on makeup with the other.

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
    I'm thinking scows solve the problem of angle of attack differently than the style of dinghy Uffa Fox invented. Rather than raise the bow and sink the stern by moving crew weight aft, they rely on a flat surface farther forward to lift the bow, and leave the stern where it is. When I'm sailing a Geary 18 and the crew tries to move aft, I have to point out that if we move too far aft, the transom sucks.

    And since the transom must be kept out of the water for the boat to function properly in displacement mode going to windward, the resulting shape looks pot-bellied to Nick, but it seems to be fast on the water. The only problem is that they don't do well to windward in lumpy water.

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    Default Re: History of the planing dinghy

    Quote Originally Posted by johnw View Post
    I'm thinking scows solve the problem of angle of attack differently than the style of dinghy Uffa Fox invented. Rather than raise the bow and sink the stern by moving crew weight aft, they rely on a flat surface farther forward to lift the bow, and leave the stern where it is. When I'm sailing a Geary 18 and the crew tries to move aft, I have to point out that if we move too far aft, the transom sucks.

    And since the transom must be kept out of the water for the boat to function properly in displacement mode going to windward, the resulting shape looks pot-bellied to Nick, but it seems to be fast on the water. The only problem is that they don't do well to windward in lumpy water.
    That "Pot belly" comment about the Herreshoff sneak box really stings?
    Your table has the typical planing surface attitude. It is the most efficient form for running level on absolutely flat water.
    If you have to heel, deal with waves and slip along when there is not enough power to plane you need to change the shape. If the transom sucks you are not going fast enough to plane. If you are going at a speed where moving weight aft will cause the transom to suck, you are probably in the semi-displacement mode.
    Did we say that life was easy?
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: History of the planing dinghy

    I hope that Nick will correct me if I am mistaken in believing that the diagram in the top right hand corner of the second page of this paper http://www.westlawn.edu/ReferenceInf...gHulls1964.pdf illustrates a hefty rise in pressure near the forward end of a planing surface.I realise that it relates to a flat surface and that a hull will have a different pressure curve as the pressure tails off.My belief is that we are being shown that the bow is being lifted by the pressure created when the water can't get out of the way fast enough for displacement mode to prevail.

  25. #95

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    Quote Originally Posted by johnw View Post
    And since the transom must be kept out of the water for the boat to function properly in displacement mode going to windward.
    The big difference between the old planing boats and new ones is that the latter plane to windward. Only in very light winds do they not plane.

    Then it's all about reducing WSA. As the bows are fine if you sit forward you increase WSA, but if you sit aft the transom drags. If you heel you get a massive distortion of the hull lines, also adding drag. So in some respects sailing a modern performance dinghy fast in light winds is harder than it used to be, even though the boats are "faster" (as I said earlier when talking about the dinghy racing on the Thames)

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    Quote Originally Posted by Peerie Maa View Post
    That "Pot belly" comment about the Herreshoff sneak box really stings?
    Your table has the typical planing surface attitude. It is the most efficient form for running level on absolutely flat water.
    If you have to heel, deal with waves and slip along when there is not enough power to plane you need to change the shape. If the transom sucks you are not going fast enough to plane. If you are going at a speed where moving weight aft will cause the transom to suck, you are probably in the semi-displacement mode.
    Did we say that life was easy?
    The problem with the transom is that you are often at the edge conditions, where the boat planes in the gusts but not in the lulls. If you sit too far aft in a Geary 18, the transom will suck in the lows and prevent the boat from achieving planing speed.

    And no, the "pot belly" comment doesn't sting. I mention it to point out your bias against an unfamiliar type. How do you explain the speed of a C scow, when it has a pot belly? In the past, if memory serves, you've claimed that scows only go fast because they are sailed heeled and with a narrow waterline, which is why I started the thread with a video of a scow planing. I think scows solve the problem of planing differently than other types, but they definitely experience a reduction of immersed volume because of hydrodynamic lift, and certainly achieve the speeds associated with planing.

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    Default Re: History of the planing dinghy

    Quote Originally Posted by Hwyl View Post
    That is a subset of conditions, where planing is promoted in very shallow water, the water reflected downward by the bow, is in turn reflected upwards by the canal bed and promotes lift. I've done it in a Laser, on a very broad reach because the rudder and daggerboard have to be up. It's the same mechanism as skimming boards on the beach. I knew a powerboat captain who would regularly seek out shallow water while transitiing the the intracoastal, to get more speed, of course if he had dropped off the plane, he would have had a major grounding,

    Quote Originally Posted by Peerie Maa View Post
    That is not about planing per se. It is about a wave of translation creating an orbital velocity on the wave crest that is moving in the same direction as the hull. The speed of the hull through the water is the same as for deep water, but the water it sits in is also moving forward over the ground.
    As to whether a planing catamaran could be designed, if you can power it up over the hump with sail, yes. After all there are now racing cats on the motor race circuit, and water skis are long slender planing surfaces.
    What we have here is a failure to communicate.

    I think most sailors use the term 'planing' to indicate a condition where the vessel has experienced a reduction in immersed volume because of hydrodynamic lift and consequently becomes more easily driven.

    For you, Nick, the word seems to be a term of art indicating hydrodynamic lift not dependent on depth of water and a length/speed ratio of 2.4 or higher.

    We clearly need a term for a boat experiencing hydrodynamic lift and traveling at a speed/length ratio between 1.4 and 2.4, because often, that's what sailors are referring to, and any lexicographer will tell you that words mean what they are used to mean. Perhaps we could do what the dictionaries do when a word means more than one thing, and have definition 1, your definition, and definition 2, the definition of a guy trying to get his boat to climb over the bow wave so he can get to the mark first.

    I did think of calling this semi-planing, but that seems to refer to semi-displacement mode, in which the water is breaking cleanly from the transom, giving the effect of extra length, and the boat is not supported by hydrodynamic lift.

    So perhaps instead of correcting each other and arguing about definitions, we could specify which definition we mean. I've used the term 'exceed hull speed' to refer to the second definition, but it doesn't seem to communicate that I'm not claiming a specific speed/length ratio, only lift and reduced drag.

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    Default Re: History of the planing dinghy

    Quote Originally Posted by Daniel Noyes View Post
    A modern 18 vs. a modern scow in the 1990's ??? I don't doubt the result, assuming it was an E scow your talking about a design, hull shape, sail configuration, total sailing weight, etc... that is little changed since the 1920's !!! VS a modern 18' skiff? a hull type with another 80+ years of form evolution and weight reduction and trapeze and hikeing wings... etc no wonder the skiff won. a 1920's E scow vs. a 1920's 18' skiff is a very different story. I don't doubt that a 1920's 18m ft skiff was the fastest 18' monohull afloat but it would never have been able to keep pace with a 28' E scow, see original post vid. those type speeds were achieved by the very early scow hulls about 1900+-
    I was simply reporting an event I remembered. The scow as I recall was close to 40 ft long. maybe it was a smaller one, but the media hype of the day was all about whether the short skiff could beat the big scow.
    Last edited by John B; 05-24-2013 at 04:27 PM.

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    Default Re: History of the planing dinghy

    Quote Originally Posted by John Meachen View Post
    I hope that Nick will correct me if I am mistaken in believing that the diagram in the top right hand corner of the second page of this paper http://www.westlawn.edu/ReferenceInf...gHulls1964.pdf illustrates a hefty rise in pressure near the forward end of a planing surface.I realise that it relates to a flat surface and that a hull will have a different pressure curve as the pressure tails off.My belief is that we are being shown that the bow is being lifted by the pressure created when the water can't get out of the way fast enough for displacement mode to prevail.
    Here, from another source, is that very famous illustration:


    It shows the stagnation point fairly far forward, yet boats deeply veed forward are able to plane. I wonder how much you can bend the plate, giving it rocker, before it won't plane.

    Apparently, given enough velocity, even a barrel shape can attain some hydrodynamic lift.



    On the other hand, Ben Fuller has towed a replica of the sandbagger Comet behind a powerboat, and found he could not get it to climb out of the hole. Comet has a rather deep, veed stern, because sandbaggers were built with a flat, full-length keel, and built down to it. Sandbaggers were also deeply veed forward, so not much lift there.

    Lines for Comet:


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    Default Re: History of the planing dinghy

    Quote Originally Posted by John B View Post
    I was simply reporting an event I remembered. The scow as I recall was close to 40 ft long.
    Sounds like an A scow. Buddy Melges was still competitive in the class at 80, so it's quite a bit more genteel than sailing an 18.

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    Default Re: History of the planing dinghy

    Answering #97.
    Gareth was discussing the effect of Scott Russell's wave of translation or soliton. It was of benefit in canals for the fly boat service (where it is impossible for a 60 foot fly boat to develop any hydrodynamic lift). The UK Admiralty used to get burned by warship builders who used to run speed trials in shallow water to take advantage of the same effect.

    http://www.ma.hw.ac.uk/solitons/press.html

    The term for speeds between 1.4 and 2.4 is semi-displacement. The form usually has flatish buttocks, round bilges, a transom, and a high prismatic coefficient. The most common application was for patrol craft, fast but too heavy to get up onto the plane.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: History of the planing dinghy

    Quote Originally Posted by johnw View Post
    Here, from another source, is that very famous illustration:


    It shows the stagnation point fairly far forward, yet boats deeply veed forward are able to plane. I wonder how much you can bend the plate, giving it rocker, before it won't plane.
    Rocker aft, rather than straight buttock lines will prevent planing by causing a lessening of pressure. The planing surface puts the stagnation point on straight buttocks. "V" is less efficient as it increases wetted surface for horizontal area generating lift but it does soften the ride in lumpy water.
    Look at 111 Surfury in the later part of this vid to see how effective it is.


    Apparently, given enough velocity, even a barrel shape can attain some hydrodynamic lift.
    but only if it is spinning at a suitable RPM. Think of the extra flight that you get with spin on a golf ball.

    On the other hand, Ben Fuller has towed a replica of the sandbagger Comet behind a powerboat, and found he could not get it to climb out of the hole. Comet has a rather deep, veed stern, because sandbaggers were built with a flat, full-length keel, and built down to it. Sandbaggers were also deeply veed forward, so not much lift there.

    Lines for Comet:

    Just so, you need flat straight buttocks and a wide transom or it will just lock in to a hole and fail to climb its bow wave.
    It really is quite difficult to build an ugly wooden boat.

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  33. #103
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    Default Re: History of the planing dinghy

    Quote Originally Posted by johnw View Post
    Can you get us a picture of that? I've seen some plans for Amaryllis, and those weren't on it, so they may have been a later addition. Could they have been to prevent the hulls from diving?

    This question is in reference to my mentioning trimming boards, I can find nothing on the web about them. I definitely remember seeing them, I'll call the museum tomorrow.

  34. #104
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    Default Re: History of the planing dinghy

    Quote Originally Posted by Richard of Woods Designs View Post


    Having said that, the real problem with vehicles at speed is control, not speed per se. Put enough HP on a IOR monohull and it will plane, but it will be so uncontrollable you will never manage to go in a straight line but roll it over.
    Richard Woods of Woods Designs
    I am not sure I agree with this. I have found that they just dig a hole in the water if you go fast. King George found the same thing years earlier that the IOR, he would have his yacht Britannia towed by a RN ship (a destroyer I think)) and the boat would always bury itself at speed. The ultimate in tank testing.

  35. #105
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    Default Re: History of the planing dinghy

    Quote Originally Posted by Peerie Maa View Post
    Answering #97.
    Gareth was discussing the effect of Scott Russell's wave of translation or soliton. It was of benefit in canals for the fly boat service (where it is impossible for a 60 foot fly boat to develop any hydrodynamic lift). The UK Admiralty used to get burned by warship builders who used to run speed trials in shallow water to take advantage of the same effect.

    http://www.ma.hw.ac.uk/solitons/press.html

    The term for speeds between 1.4 and 2.4 is semi-displacement. The form usually has flatish buttocks, round bilges, a transom, and a high prismatic coefficient. The most common application was for patrol craft, fast but too heavy to get up onto the plane.
    My question is, what about a true planing hull traveling between 1.4 and 2.4? Those boats aren't shaped like that, and experience lift before they reach 2.4.

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