What is Boat: Definition and 364 Discussions

A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size, shape, cargo or passenger capacity, or its ability to carry boats.
Small boats are typically found on inland waterways such as rivers and lakes, or in protected coastal areas. However, some boats, such as the whaleboat, were intended for use in an offshore environment. In modern naval terms, a boat is a vessel small enough to be carried aboard a ship. Anomalous definitions exist, as lake freighters 1,000 feet (300 m) long on the Great Lakes are called "boats".
Boats vary in proportion and construction methods with their intended purpose, available materials, or local traditions. Canoes have been used since prehistoric times and remain in use throughout the world for transportation, fishing, and sport. Fishing boats vary widely in style partly to match local conditions. Pleasure craft used in recreational boating include ski boats, pontoon boats, and sailboats. House boats may be used for vacationing or long-term residence. Lighters are used to convey cargo to and from large ships unable to get close to shore. Lifeboats have rescue and safety functions.
Boats can be propelled by manpower (e.g. rowboats and paddle boats), wind (e.g. sailboats), and motor (including gasoline, diesel, and electric).

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  1. CarlPace

    Misc. DIY RC Boat with Parallel Impeller

    I'm not sure if you would call it a "Parallel Impeller," but the pics below should tell the story. I'm designing/3D printing my next RC boat from scratch, and I wanted to try something different from tried-and-true propeller and shaft system. Reasons? 1. Fun. 2. Using a "wet" brushless motor...
  2. Trikenstein

    Powerful fans on boat, blow to own sails, would this move the boat?

    A sail boat got stuck because there is absolutely no wind. The boat happens to have some powerful fans. Which are then bolted on deck and blow to the sails. Would that make the boat move? When the artificial wind direction is horizontal (0 degree) When the wind direction is 45 degrees. Would...
  3. paulimerci

    At what angle must the boat travel so that it moves in a straight line

    I'm assuming the boat is traveling north at an 8 m/s and the river is flowing east at a 2 m/s. For the boat to move in a straight line, it has to aim at an upstream angle given by #theta#. Using SOH CAH TOA, ##v_r = 2m/s##, ##v_b = 8m/s## $$\theta =\sin^{-1} \frac{v_r}{v_b}$$ $$\theta = 14...
  4. V

    Flag orientation for a boat observer Vs a ground observer

    I am confused by the question. So, the first thing I am trying to understand is whether the flag direction will be same to a boat observer as to a ground observer. I know that the flag will orient itself in the direction the wind is blowing towards, so the flag should always point in NE...
  5. DaveC426913

    Misc. Digitizing a Boat Hull: Mac26 Modeling Data

    My boat (Mac26) is not revered enough for anyone to have bothered to data model its shape. My Mac26 friends have all expressed an interest in getting their hands on it. I've been trying to think of an expedient and cost effective way of modeling it in data form. One way is to place...
  6. unoonu

    Relative Velocity Against the Water Current

    vcanoe_wrt_ground = 3 m/s + (-6) m/s = 3 m/s - 6 m/s = -3 m/s Thus, if I understand this correctly, the rower will never reach his goal 36 m away as his canoe's resultant velocity is negative (i.e., his canoe is effectively going downstream even though it is trying to go upstream). My only...
  7. G

    Find the Upward Force of a Boat with 6 People Aboard

    Apply Principle of Archimedes - upward force is equal to the weight of the volume of water displaced. Density (boat) = 120 kg/(3x1x.24)m(3) = 500/3 kg/m(3) Density of water = 1000kg/m(3). Density (water)/Density of boat = 1000 kg/m(3)/(500/3) kg/m(3) = 6. So density of water is 6 times the...
  8. J

    B Why does a stiff boat rudder produce forward thrust when pumped left to right?

    In small sailing boat like optimist is well know technique when there is no wind, rudder pumping which push boat forward.You just need push-pull rudder left to right with fast movement. 1) Rudder is stiff(not flexibile like flippers for diving),so why rudder produce forward thrust if high and...
  9. E

    I Solving the Boat Crossing a River Problem using the Calculus of Variations

    I was hoping to explore the Calculus of Variations. How do we prove by Calculus of Variations that the minimum time for boat crossing a river (perpendicular to the current for starters) with current ##v_r##, and boat velocity in still water ##v_b## that the path will be a straight line? I...
  10. H

    I Proper placement of boat on trailer

    New trailer and new self built boat. Need confirmation of my calculation for placement of boat on trailer to have the correct tongue weight. For those not familiar with trailers: The tongue of a trailer is the forward beam that has the female ball receiver at the front end. It is imperative...
  11. O

    I Can I load my boat without a winch?

    I have a boat that weighs about 100 lbs. and is 10’ long. I’d like to load it on my pickup rack in the manner shown in this (and many others) video, but without having to purchase and mount a winch. I’m fairly certain I can get the boat upright. The portion I don’t know how to calculate is...
  12. M

    Construction How do you build a self-submersible boat?

    So I've been thinking for a long time now about making a self-submersible boat out of a plastic bottle without electronics. It should resurface by itself after a few minutes. I was thinking that it might increase its volume. By slowly dropping weights down the bottle and opening flaps on the...
  13. T

    B Is this determinable? (Size of this Russian patrol boat)

    Is it possible to determine the length of the boat by using the physics of the shrapnel arcs? Can the traces of the arcs be used to determine the distance the shrapnel travels and then be send to determine the boat length. Tex
  14. H

    I What will the angle of a boat with an outboard motor be?

    I want to calculate the angle of a wooden boat at rest in salt water, with a 55 lb outboard motor mounted on the transom + 3 gallons of gasoline (18 lbs) + 2 adults weighing about 150 lbs each. So just figure a total weight at the back end of the boat being 55 + 18 + 300 = 373 lbs. The boat...
  15. Lay1

    A boat being pulled by two other boats with cables

    FAx = F cos 40 FAy = F sin 40 2FAx = Drag Drag = 6128N The answer says 6200N
  16. G

    B Maximum Force on transom of a boat under acceleration

    I'm trying to calculate the maximum Force in PSI applied to the transom of a planing boat under acceleration using F=ma. boat mass is 300kg accelerates from 0 to 10m/s in 6 seconds F=ma -> 500N = 300kg *(10m/s/6s) = 112.4045lbf the contact area between the boat transom and motor is 1000 mm2 =...
  17. F

    Boat Lift Design: Building 8'x12' Platform

    Building a 8' x 12' platform that will hold a small boat next to my dock. The platform needs to be able to be lowered below the surface of the water (launch boat) and lift above the water (store boat). Four pilings (one each corner) that each have an electric motor & reduction gearbox that has...
  18. S

    Time for boat to enter harbour

    Equation for the tide: $$y=-\cos \left(\frac{2 \pi}{6}t\right)+2$$ When ##y## = 1.5 m : $$1.5=-\cos \left(\frac{2 \pi}{6}t\right)+2$$ $$-0.5=-\cos \left(\frac{\pi}{3}t\right)$$ $$\frac{\pi}{3}=\frac{\pi}{3}t$$ $$t=1$$ But the answer key is t = 2. Where is my mistake? Thanks
  19. Tapias5000

    How to solve this balancing exercise? (towing a boat with two ropes)

    This is the image of the problem I tried to solve it and I got the following is it correct?
  20. T

    River Boat Problem: Minimizing Travel Time

    From equation (3.7) , we know t = d/v_y = d / v_ABcosθ = d/ v_Asinβ Now for time to be minimum , denominator must be maximum this implies θ=0 and β=90, but this doesn't make sense as when we try to row the boat at 0 degree with y-axis due to stream it will have a some net velocity which will...
  21. H

    I How to weigh a car topped boat?

    I'm planning to build a 12 foot jon boat that will be car topped on our van. The rated loading on the roof racks is 165 lbs. To weigh the finished boat, I plan to do the following: Position the boat upside down in our carport. Stand on a bathroom scale and lift the front of the boat. Write...
  22. sciencebum

    Maximizing Boat Speed: Exploring Human Power Ratios

    In competitive rowing, the more people in a boat, the faster it goes, but what is the ratio of additional human to speed, and what is the theoretical limit? If I could fabricate a boat where each additional person added 100kilos, 100watts of power, and 1 meter of length to the wetted surface...
  23. H

    Car top boat loader: What is the lifting weight?

    BACKGROUND: I'm thinking of building a flat bottom Jon boat. We don't have room for a boat trailer so I want to load the boat on top of our 2019 Honda Odyssey van. Without a trailer, the boat can be stored on a side against our hollow tile wall. The dimensions of the boat will be: 12 feet...
  24. A

    Boat is going across a river

    v upstream = 5 - 3 =2 v of the water = 3 arccos = (2/3) = 48.19 v across the river = c^2 - a^2 = b^2 √3^2 - 2^2 = 6m/s t = 80/6 = 13.3 can someone please point out my mistakes? am I even supposed to solve for angle like this or "perpendicular to the shores" just means that the angle is supposed...
  25. brotherbobby

    Sinking a toy boat with lead pellets

    Attempt : I begin by plotting the graph of depth x against mass of pellets m as shown alongside. Using ##m_B = \Delta m_L\Rightarrow m_B = \rho_L A_B\, x(B)## where ##\rho_L## is the density of the liquid, ##A_B## is the cross-sectional area of the boat and ##x(B)## is the depth to which the...
  26. lucas pentland

    Net forces on a boat (propulsion, water and air resistance)

    2500 N [south] + 3200 N [south] = 5700 N [south] 5700 N [south] - 6000 N [north] = 300[north]
  27. W

    Simple Vector Boat Problem, Conceptual Misunderstanding

    Hi there, I have attached the problem I'm working with. I believe I must have the wrong idea of how to approach this question. My issue is with the stated width and calculating how long the boat will take to cross the river. It's using width; 110m and the boats velocity to determine how long...
  28. Adesh

    Oscillation of a boat in still water (Metacenter and Center of Mass)

    Let’s say we have a boat whose longitudinal axis is the y-axis (which goes into the screen in the figure below) standing upright in a still water . ##S## is the Center of Mass of the boat and ##C## is the Center of Mass of the displaced water.On ##S## lies the force ##\mathbf W##...
  29. Athenian

    Rowing a Boat Across a River - FODE Physics Problem

    First off, to solve for this problem, I relied largely on my below drawn diagram. Forgive the poor work as this was done on a laptop. Using the above image as reference, I came up with the below equations. $$\frac{dy}{dx} = \frac{sin \, \theta}{1- cos \, \theta}$$ where ##cos \, \theta =...
  30. G

    Find the velocity of the wind relative to the boat

    Could someone please help me see where I am going wrong here? During a race between two boats A and B there is a wind of 18 km/h blowing from due north. The resultant velocity if A is 12 km/h on a bearing of 060. Find the direction of the wind relative to A. My reasoning: (Relative to the...
  31. R

    Personal Jet Boat Water Craft Thrust Question

    Assume a jet boat or personal water craft (JetSki, etc) has a movable propulsion nozzle. This nozzle can be moved vertically so that the water jet driving the boat forward can be either above the surface or below the surface of the water. Further clarification. You are speeding along on your...
  32. G

    MHB Calculating Boat Costs: Splitting 60/40 & Time Usage

    Hi, I am struggling with a calculation. A boat costs x to maintain and I and a friend decide to split the costs 60/40, where I put in 60% of the cost. However, I will have the boat less than my friend, he will have it 3/8 of the time and I will have it 5/8 of the time. So what is my actual...
  33. A

    Uniform Motion Review - Boat travelling

    displacement (x) = 750 m [E] distance = 1100 m I drew a diagram. Now what??
  34. P

    How to estimate a constant drag coefficient of a boat?

    Hi there, I have modeled with MAXSURF a few variations of a prehistoric logboat in order to test a few theories. Now, I am trying to look at resistance-performance over a range of speed. To do so, I need to include a constant drag coefficient without knowing the drag force and velocity (both...
  35. pslarsen

    Boat autopilot remote (question about transister choice)

    Hi, I'm about to build an autopilot remote for my boat, manual found here: http://www3.sympatico.ca/ericn/Files/Other/DIY Autohelm ST4000.pdf In the scheme I need to use two transisters, a 2N4402 (PNP) and a 2N4400 (NPN) as illustrated here: As I don't have these transisters can I use a...
  36. V

    What is the momentum of a girl jumping into a boat?

    Momentum of a girl: $$p_{1} = m_{1}v_{1} = 50 * 5 = 250$$ Momentum of an idle boat: $$p_{2} = m_{2}v_{2} = 150 * 0 = 0$$ So if the girl jumps into the boat, the two "systems" connect with each other. The momentum is passed onto the boat (?): $$p_{1} = p_{2}$$ $$m_{1}v_{1} = m_{2}v_{2}$$...
  37. fartguy46

    Unlocking the Mystery of the "Man on a Boat" Problem with Easy Tips

    Hey guys, So with some help from classmates I have seen the way I am supposed to approach this problem starting from number 3, which is to use the above equation. But the problem is I have never seen this equation before in class! I don't know what the purpose of the equation is, where it was...
  38. Q

    Boat with Friction: CoM / Minimum Time Problem

    Homework Statement A person of mass ##m## stands at the left end of a boat of mass ##M## and length ##L##. Both the person and the boat are initially at rest. The coefficient of kinetic friction between the boat and the water is ##\mu##. If the person starts moving to the right, what is the...
  39. Mohammed Sayanvala

    What do wave crests indicate about a boat's speed?

    Homework Statement *I cannot place the original image due to copyright reasons, but the image above is a good alternative. "Wave crests spread out behind a boat as shown above. What do the wave crests indicate about the boat's speed?" It is increasing. It is less than the speed of the water...
  40. Nate1

    MHB Trigonometry lighthouse boat problem

    A boat is some distance away from a small lighthouse. The angle of elevation from the boat is 9 degrees. If the boat moves forward 20m, the angle is now 12. Assume the lighthouse is at a rightangle to the boat. Calculate the distance from the boat to the top of the lighthouse before and after...
  41. A

    A ferry boat is crossing a river that is 8.5 x 10^2 m wide.

    Homework Statement A ferry boat is crossing a river that is 8.5 x 10^2 m wide. The average velocity of the water relative to the shore is 3.8 m/s E and the average velocity of the boat relative to the water is 4.9 m/s S. How long does it take for the boat to get across? Homework EquationsThe...
  42. Ripcord96

    How to approach the design for a boat step by step?

    Two pontoon boat design approach and how to find center of gravity, center of buoyancy, buoyancy, volume of displacement, meta center, meta centric height. I need to know is there a different approach to designing dual hulled boat than a single hulled boat and all the formulas and examples I...
  43. alexi_b

    River question (looking for angles and headings)

    Homework Statement A child in danger of drowning in a river is being carried downstream by a current that has a speed of 2.35km/h. The child is 0.505km from shore and 0.780km upstream of a boat landing when a rescue boat sets out. If the boat proceeds at its maximum speed of 18.8km/h relative...
  44. S

    Velocity Vectors of a Boat Relative to the Shore and River

    Homework Statement The water in the river moves southwest (45 degrees south of west) at 4 mi/h. If a motorboat is traveling due east at 15 mi/h relative to the shore, determine the speed of the boat and its heading relative to the moving water. Homework Equations Vector summation The Attempt...
  45. E

    Jumping on a boat that is moving

    Hello PF, I am a junior in high school who has yet to take physics and is currently in Honors Chem. I recently saw a video on social media, where a group of guys is on a big boat and this one guy was standing relatively close to the bow. And they hit a big wave and he jumps in the air and lands...
  46. Ofir12

    Kinematics question using vectors

    A child is in danger of drowning in the river. The river has a current of 2.5 km/hr . The child is 0.6 km from the shore. A rescue boat with speed 20.0 km/hr (with respect to the water) ,located 0.8km downstream, sets off from the shore. What would be the optimum angle (shore -> boat ) to reach...
  47. L

    What is the speed of the boat relative to the water?

    Homework Statement A 0.14-km wide river flows with a uniform speed of 4.0 m/s toward the east. It takes 20 s for a boat to cross the river to a point directly north of its departure point on the south bank. What is the speed of the boat relative to the water? I'm mostly concerned about the...
  48. L

    Speed of a decelerating boat

    Homework Statement A boat, moving at the velocity of 9,9m/s turns off its engine and starts decelerating at the rate of a=-kv^2. What is the velocity of the boat after 4,9 seconds if the constant k is k=5,5m Homework EquationsThe Attempt at a Solution I tried to integrate deceleration to get...
  49. H

    Calculating Your Boat Winch's Pulling Capacity: A Guide for Non-Mathematicians

    I am trying to determine what weight my boat ramp drum winch can pull. it has an electric 1HP motor that drives the drum via a chain and sprocket through a gearbox. what info is required to work out its capability. sorry as I am no mathematician but I do know there is a lot of variables...