Plaining or Planeing?
Printed From: CorrectCraftFan.com
Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=1750
Printed Date: May-20-2024 at 12:10am
Topic: Plaining or Planeing?
Posted By: Jim_In_Houston
Subject: Plaining or Planeing?
Date Posted: May-28-2005 at 3:23pm
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An earlier post got me to thinking about hull drag. The more I think about it the more I realize I know nothing about it.
First of all, does a boat plane or plain? And this is sounds like a simple minded question, why does a boat plain? Is hull drag a lot less after it plains? What is the force that holds the boat up on the water after it plains? How much of the hull sits in the water after it plains? What effects the speed at which a boat plains? Do you ever have to pull a tow at below plaining speed? Just curious. I'm sure someone here is knowledgable about this. I do know that at the speed at which my CC plains (when it is standing up) the riders are uncomfortable. (It stands up pretty high when I have riders in the backseat.) ------------- Happy owner of a '66 and a '68 Mustang |
Replies:
Posted By: GottaSki
Date Posted: May-28-2005 at 11:10pm
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Thats a lot of questions...but I'll take a stab at some..
Plane i'm almost certain.. Water has mass, and must be accelerated out of the way of the boat. Force = Mass Acceleration, so more acceleration of the water (or more water moved) , is potentially more lifting force. but The boat when planing displaces enough water so that the boat's weight equals the total forces created accelerating the water downward. Take the summation of downward water acceleration vectors, all functions of the angles and masses of water involved, equals lift; then the water that has lateral acceleration vectors atributed to them is, waste drag and do not produce lift. Whew... Have your seen. It is well know that Women = Time X Money as well as Time = Money So substituting for Time, Women = Money x Money = Money^2 It is well documented that: Money = Root of all evil Square both sides, so so Money ^2 = Evil Therefore it verifies Women = Evil ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: climbhigh
Date Posted: May-28-2005 at 11:49pm
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Gottaski,
I think maybe you spent too much time in the sun and water today. Or maybe I did, because you lost me with that little equation. ------------- S. A. Meade |
Posted By: Jim_In_Houston
Date Posted: May-29-2005 at 12:45am
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I knew it and that equation proves it. Men do everything, including go to war, because of women. Heck, if it wern't for women, I wouldn't even wax my boat. That alone is poof 'cause I hate waxing my boat.
Beware of the evil that lurks on the lakes and waterways and in the backs of CCs (like mine when I'm lucky).  ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 64 Skier
Date Posted: May-29-2005 at 11:32am
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Jim...lot of literature out there on these subjects. Old CC's are semi-displacement hulls...WITH...a boat tail rear end (a taper that narrows to the rear). They don't plane, but actually settle themselves almost on plane and nose up in order to track well with a professional slalom skiier trying to pull it off-course. A skiier going for the buoy's in a competition would walk a "Planing" boat all over the lake (reducing speed also).
Semi-displacement since some of the hull is lifted out of the water at 32-36 mph, but never all of it. So they don't plane at the designed speeds. My 2 cents on the subject... ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: JEFF KOSTIS
Date Posted: May-30-2005 at 12:33am
I guess it depends on how much of the hull needs to be out of the water to consider it to be planed out>?!?? ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: jameski
Date Posted: May-30-2005 at 1:35pm
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With the outboard boats that I have owned, their was a distinct difference when the boat would reach plane. But, with my inboard Correct Craft, I don't ever really notice any dramatic difference. ...Just as 64 Skier expained it.
I love my inboard! ------------- current boat http://www.correctcraftfan.com/diaries/details.asp?ID=1977 - 94 Sport Nautique previous boat http://www.correctcraftfan.com/diaries/details.asp?ID=601 - 78 Martinique |
Posted By: Bhedbloom
Date Posted: May-30-2005 at 2:12pm
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The definition of a planing hull is one that crests and rides in front of its own bow wake unlike large yachts or ships with a full displacement hulls that push their own bow wake.
Good call by 64 Skier on the semi-displacement hull....How do you tell your hull type? The bottom of a planing hull viewed from the side will have striaght lines or grow as it approaches the stern while a semi-displacement (semi-planing) hull will incline slightly as it approaches the stern. With the semi-displacement hull you get the best of both worlds. Speed and great tracking ------------- Barry, South Carolina |
Posted By: Tim D
Date Posted: May-31-2005 at 10:50am
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My Mustang planes at 18 mph. I understand it as the position or height/angle the boat gets out of the water and it doesn't change with an increase in speed. I can tell with mine, because the exhaust comes out of the water and with the certain rpms there's a certain tone I'm used to. I've also heard its when the boat becomes easier to push or has less drag. ------------- Tim D |
Posted By: Guests
Date Posted: June-02-2005 at 4:42pm
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Here you go guys. The speed at which a boat begins to Plane, is when the boat begins to exceed the maximum hull speed. The reason a boat begins to plane is because it begins to "climb" out of the hole that the boat makes in the water. the maximum hull speed is the maximum wavelenght that the boat can produce with its length. Here is the equasion. Hull Speed = 1.34 * (LWL)1/2
LWL - Length at Waterline. Mustang 17 LWL = about 15.5 [(15.5).5]*1.34 = 10.38 A Mustang 17 begins to plane at 10.38 mph. This also explains why your boat planes later if you have a bunch of weight, or have people up in the bow....your LWL increases. The formula obviously gets more complicated but this is a quick easy version we use in the sailing community to determine how fast a full displacement hull will go. |
Posted By: Guests
Date Posted: June-02-2005 at 4:51pm
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I am sorry I got the formula wrong. Glad I checked myself..it is
the square root of the LWL x 1.34 = Hull speed in Knots. 1 knots = 1.15077945 mph Mustang 17 begins to plane at 5.95 mph |