Misplaced Pages

#927072

61-601: The 25 ft (8 m) Transportable Port Security Boat (TPSB): (AKA The Guardian) is a twin outboard motor , open deck, all weather, high performance, moderately-armed platform capable of operating in inner harbor/near shore environments in light sea conditions. It was first built in FY97 by Boston Whaler in Edgewater, Florida , for the US Coast Guard , Maintenance and Logistic Command. The 25 ft (8 m) TPSB

122-404: A change in its coupled magnetic flux, d Φ B d t {\displaystyle {\frac {d\Phi _{B}}{dt}}} . Therefore, an electromotive force is set up in the second loop called the induced emf or transformer emf. If the two ends of this loop are connected through an electrical load, current will flow. A current clamp is a type of transformer with

183-647: A choice, these factors should be noted: Large outboards are affixed to the transom using clamps and are either tiller steered or controlled from the helm. Generally motors of 100 hp plus are linked to controls at the helm. These range from 2-, 3-, and 4-cylinder models generating 15 to 135 horsepower (11 to 101 kW) suitable for hulls up to 17 feet (5.2 m) in length to powerful V6 and V8 cylinder blocks rated up to 627 hp (468 kW)., with sufficient power to be used on boats of 37 feet (11 m) or longer. Small outboard motors, up to 15 horsepower (11 kW) or so, are easily portable. They are affixed to

244-409: A circuit and a magnetic field is the phenomenon underlying electrical generators . When a permanent magnet is moved relative to a conductor, or vice versa, an electromotive force is created. If the wire is connected through an electrical load , current will flow, and thus electrical energy is generated, converting the mechanical energy of motion to electrical energy. For example, the drum generator

305-455: A closed-loop cooling system with a heat exchanger. This means saltwater is not pumped through the engine block, as is the case with most outboard motors, but instead engine coolant and outside water are pumped through (opposite sides of) the heat exchanger. An outboard engine may stall if it does not have the correct inputs. Common problems that lead to stalling are electrical issues, low quality gas or clogged fuel filer. Other issues may include

366-473: A concept he called lines of force . However, scientists at the time widely rejected his theoretical ideas, mainly because they were not formulated mathematically. An exception was James Clerk Maxwell , who used Faraday's ideas as the basis of his quantitative electromagnetic theory. In Maxwell's model, the time varying aspect of electromagnetic induction is expressed as a differential equation, which Oliver Heaviside referred to as Faraday's law even though it

427-435: A conventional propeller. The frame that holds the motor has a short, swiveling steel pin/tube approximately 15 cm long underneath, to be inserted into a corresponding hole on the transom, or a solid block or wood purposely built-in thereof. This drop-in arrangement enables extremely quick transfer of the motor to another boat or for storage – all that is needed is to lift it out. The pivoting design allows

488-489: A damaged carburetor oil switch. In Vietnam and other parts of southeast Asia long-tail boats use outboard motors altered to extend their propellers far from the rest of the motor. In Vietnam these outboards are called máy đuôi tôm ( shrimp tail motor ), which are smallish air-cooled or water-cooled gasoline, diesel or even modified automotive engines bolted to a welded steel tube frame, with another long steel tube up to 3 m long to hold an extended drive shaft driving

549-689: A different method of DI. Fuel economy on both direct-injected and four-stroke outboards measures from a 10 percent to 80 percent improvement compared with conventional two-strokes. However, the gap between two-stroke and four-stroke outboard fuel economy is beginning to narrow. Two-stroke outboard motor manufacturers have recently introduced technologies that help to improve two-stroke fuel economy. In 2012, Lehr inc. introduced some small (<5 hp) outboards based on modified Chinese petrol engines to run on propane gas. Tohatsu currently also produces propane powered models, all rated 5 hp. Conversion of larger outboards to run on Liquified petroleum gas

610-429: A pin called a topper tilt lock. Ventilation is a phenomenon that occurs when surface air or exhaust gas (in the case of motors equipped with through-hub exhaust) is drawn into the spinning propeller blades. With the propeller pushing mostly air instead of water, the load on the engine is greatly reduced, causing the engine to race and the propeller to spin fast enough to result in cavitation , at which point little thrust

671-420: A rotor approximately 20 mm in diameter from a DC motor used in a CD player. Note the laminations of the electromagnet pole pieces, used to limit parasitic inductive losses. In this illustration, a solid copper bar conductor on a rotating armature is just passing under the tip of the pole piece N of the field magnet. Note the uneven distribution of the lines of force across the copper bar. The magnetic field

SECTION 10

#1732780657928

732-473: A solid metallic mass is rotated in a magnetic field, because the outer portion of the metal cuts more magnetic lines of force than the inner portion; hence the induced electromotive force is not uniform; this tends to cause electric currents between the points of greatest and least potential. Eddy currents consume a considerable amount of energy and often cause a harmful rise in temperature. Only five laminations or plates are shown in this example, so as to show

793-485: A specific ship or boat of the United States Armed Forces is a stub . You can help Misplaced Pages by expanding it . Outboard motor In order to eliminate the chances of hitting bottom with an outboard motor, the motor can be tilted up to an elevated position either electronically or manually. This helps when traveling through shallow waters where there may be debris that could potentially damage

854-483: A split core which can be spread apart and clipped onto a wire or coil to either measure the current in it or, in reverse, to induce a voltage. Unlike conventional instruments the clamp does not make electrical contact with the conductor or require it to be disconnected during attachment of the clamp. Faraday's law is used for measuring the flow of electrically conductive liquids and slurries. Such instruments are called magnetic flow meters. The induced voltage ε generated in

915-811: Is an element of contour of the surface Σ, combining this with the definition of flux Φ B = ∫ Σ B ⋅ d A , {\displaystyle \Phi _{\mathrm {B} }=\int _{\Sigma }\mathbf {B} \cdot d\mathbf {A} \,,} we can write the integral form of the Maxwell–Faraday equation ∮ ∂ Σ E ⋅ d ℓ = − d d t ∫ Σ B ⋅ d A {\displaystyle \oint _{\partial \Sigma }\mathbf {E} \cdot d{\boldsymbol {\ell }}=-{\frac {d}{dt}}{\int _{\Sigma }\mathbf {B} \cdot d\mathbf {A} }} It

976-467: Is available as an option on most outboard motors. Although less efficient than an open propeller, they are particularly useful in applications where the ability to operate in very shallow water is important. They also eliminate the laceration dangers of an open propeller. Propane outboard motors are available from several manufacturers. These products have several advantages such as lower emissions, absence of ethanol-related issues, and no need for choke once

1037-584: Is based upon the figure to the bottom-right. A different implementation of this idea is the Faraday's disc , shown in simplified form on the right. In the Faraday's disc example, the disc is rotated in a uniform magnetic field perpendicular to the disc, causing a current to flow in the radial arm due to the Lorentz force. Mechanical work is necessary to drive this current. When the generated current flows through

1098-485: Is considered unusual and exotic although some hobbyists continue to experiment. It is important to select a motor that is a good match for the hull in terms of power and shaft length. Whether using a displacement or planing vessel, one should select an appropriate power level; too much power is wasteful (adding unnecessary weight), and may often be dangerous. Boats built in the US have Coast Guard Rating Plates , which specify

1159-417: Is designed and configured to support Port Security Units as an inshore/harbor surface interdiction response asset in accordance with Required Operational Capabilities (ROC) and Projected Operational Environment (POE) for Coast Guard Port Security Units (PSU), COMDTINST 3501.49 (series). The basic design is based on the standard Boston Whaler 25 ft (8 m) Guardian hull , customized to functionally suit

1220-438: Is generated at all. The condition continues until the prop slows enough for the air bubbles to rise to the surface. The primary causes of ventilation are: motor mounted too high, motor trimmed out excessively, damage to the antiventilation plate, damage to propeller, foreign object lodged in the diffuser ring. If the helmsman goes overboard, the boat may continue under power but uncontrolled, risking serious or fatal injuries to

1281-444: Is more concentrated and thus stronger on the left edge of the copper bar (a,b) while the field is weaker on the right edge (c,d). Since the two edges of the bar move with the same velocity, this difference in field strength across the bar creates whorls or current eddies within the copper bar. High current power-frequency devices, such as electric motors, generators and transformers, use multiple small conductors in parallel to break up

SECTION 20

#1732780657928

1342-528: Is one of the four Maxwell's equations , and therefore plays a fundamental role in the theory of classical electromagnetism . Faraday's law describes two different phenomena: the motional emf generated by a magnetic force on a moving wire (see Lorentz force ), and the transformer emf that is generated by an electric force due to a changing magnetic field (due to the differential form of the Maxwell–Faraday equation ). James Clerk Maxwell drew attention to

1403-492: Is slightly different from Faraday's original formulation and does not describe motional emf. Heaviside's version (see Maxwell–Faraday equation below ) is the form recognized today in the group of equations known as Maxwell's equations . In 1834 Heinrich Lenz formulated the law named after him to describe the "flux through the circuit". Lenz's law gives the direction of the induced emf and current resulting from electromagnetic induction. Faraday's law of induction makes use of

1464-508: Is that if the impeller is run dry for a length of time (such as leaving the engine running when pulling the boat out of the water or in some cases tilting the engine out of the water while running), the impeller is likely to be ruined in the process. Air-cooled outboard engines are currently produced by some manufacturers. These tend to be small engines of less than 5 horsepower (3.7 kW). Outboard engines made by Briggs & Stratton are air-cooled. Outboards manufactured by Seven Marine use

1525-516: Is the angle of the motor in relation to the hull, as illustrated below. The ideal trim angle is the one in which the boat rides level, with most of the hull on the surface instead of plowing through the water. [REDACTED] [REDACTED] [REDACTED] If the motor is trimmed out too far, the bow will ride too high in the water. With too little trim, the bow rides too low. The optimal trim setting will vary depending on many factors including speed, hull design, weight and balance, and conditions on

1586-447: Is the emf and Φ B is the magnetic flux . The direction of the electromotive force is given by Lenz's law which states that an induced current will flow in the direction that will oppose the change which produced it. This is due to the negative sign in the previous equation. To increase the generated emf, a common approach is to exploit flux linkage by creating a tightly wound coil of wire , composed of N identical turns, each with

1647-501: Is typically used: Electric outboard motors are self-contained propulsory units for boats , first invented in 1973 by Morton Ray of Ray Electric Outboards. These are not to be confused with trolling motors , which are not designed as a primary source of power. Most electric outboard motors have 0.5- to 4- kilowatt direct-current (DC) electric motors , operated at 12 to 60 volts DC. Recently developed outboard motors are powered with an alternating current (AC) or DC electric motor in

1708-409: The magnetic flux Φ B through a region of space enclosed by a wire loop. The magnetic flux is defined by a surface integral : Φ B = ∫ Σ B ⋅ d A , {\displaystyle \Phi _{\mathrm {B} }=\int _{\Sigma }\mathbf {B} \cdot d\mathbf {A} \,,} where d A is an element of the surface Σ enclosed by

1769-407: The transom is an important factor in achieving optimal performance. The motor should be as high as possible without ventilating or loss of water pressure. This minimizes the effect of hydrodynamic drag while underway, allowing for greater speed. Generally, the antiventilation plate should be about the same height as, or up to two inches higher than, the keel , with the motor in neutral trim. Trim

1830-482: The TPSB mission requirements. The basic craft arrangements consist of a centrally positioned control console and leaning post with an open work deck and low non-obstructive gunwales. The TPSB is outfitted as a military gunboat with three (3) hardened weapon positions: (1) forward .50 caliber (12.7 mm) tri-pod, (2) gunwale - mounted 7.62 mm M240B Machine Gun pipe pedestals, port and starboard. This article about

1891-420: The applied B-field, tending to decrease the flux through that side of the circuit, opposing the increase in flux due to rotation. On the near side of the figure, the return current flows from the rotating arm through the near side of the rim to the bottom brush. The induced B-field increases the flux on this side of the circuit, opposing the decrease in flux due to r the rotation. The energy required to keep

25-foot Transportable Port Security Boat - Misplaced Pages Continue

1952-426: The boat via clamps and thus easily moved from boat to boat. These motors typically use a manual start system , with throttle and gearshift controls mounted on the body of the motor, and a tiller for steering. The smallest of these weigh as little as 12 kilograms (26 lb), have integral fuel tanks, and provide sufficient power to move a small dinghy at around 8 knots (15 km/h; 9.2 mph) This type of motor

2013-470: The cheap cast aluminum propellers on the often debris-prone inland waterways. Electromagnetic induction Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field . Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction . Lenz's law describes

2074-422: The conducting rim, a magnetic field is generated by this current through Ampère's circuital law (labelled "induced B" in the figure). The rim thus becomes an electromagnet that resists rotation of the disc (an example of Lenz's law ). On the far side of the figure, the return current flows from the rotating arm through the far side of the rim to the bottom brush. The B-field induced by this return current opposes

2135-458: The direction of the induced field. Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism . Electromagnetic induction has found many applications, including electrical components such as inductors and transformers , and devices such as electric motors and generators . Electromagnetic induction was discovered by Michael Faraday , published in 1831. It

2196-481: The disc moving, despite this reactive force, is exactly equal to the electrical energy generated (plus energy wasted due to friction , Joule heating , and other inefficiencies). This behavior is common to all generators converting mechanical energy to electrical energy. When the electric current in a loop of wire changes, the changing current creates a changing magnetic field. A second wire in reach of this magnetic field will experience this change in magnetic field as

2257-511: The first gasoline-powered outboard offered for sale in significant numbers. It was developed from 1903 in Grosse Ile, Michigan, with a patent application filed in 1905 Starting in 1906, the company went on to make thousands of his "Porto-Motor" units, claiming 25,000 sales by 1914. The inboard boat motor firm of Caille Motor Company of Detroit were instrumental in making the cylinder and engines. The most successful early outboard motor,

2318-439: The helmsman and others in the water. A safety measure is a " kill cord " attached to the boat and helmsman, which cuts the motor if the helmsman falls overboard. The most common type of cooling used on outboards of all eras use a rubber impeller to pump water from below the waterline up into the engine. This design has remained the standard due mainly to the efficiency and simplicity of its design. One disadvantage to this system

2379-393: The induced electromotive force in any closed circuit is equal to the rate of change of the magnetic flux enclosed by the circuit: E = − d Φ B d t , {\displaystyle {\mathcal {E}}=-{\frac {d\Phi _{\mathrm {B} }}{dt}}\,,} where E {\displaystyle {\mathcal {E}}}

2440-646: The late 1920s, such as the Roness and Sharland. In 1962 Homelite introduced a four-stroke outboard a 55-horsepower (41 kW) motor, based on the four-cylinder Crosley automobile engine. This outboard was called the Bearcat and was later purchased by Fischer-Pierce, the makers of Boston Whaler, for use in their boats because of their advantages over two-stroke engines. In 1964, Honda Motor Co. introduced its first four-stroke powerhead. In 1984, Yamaha introduced their first four-stroke outboards, which were only available in

2501-616: The low-power range. In 1990 Honda released 35 hp and 45 hp four-stroke models. They continued to lead in the development of four-stroke engines throughout the 1990s as US and European exhaust emissions regulations such as CARB ( California Air Resources Board ) led to the proliferation of four-stroke outboards. At first, North American manufacturers such as Mercury and OMC used engine technology from Japanese manufacturers such as Yamaha and Suzuki until they were able to develop their own four-stroke engine. The inherent advantages of four-stroke motors included: lower pollution (especially oil in

25-foot Transportable Port Security Boat - Misplaced Pages Continue

2562-435: The magnetic field B due to a conductive liquid moving at velocity v is thus given by: where ℓ is the distance between electrodes in the magnetic flow meter. Electrical conductors moving through a steady magnetic field, or stationary conductors within a changing magnetic field, will have circular currents induced within them by induction, called eddy currents . Eddy currents flow in closed loops in planes perpendicular to

2623-422: The magnetic field. They have useful applications in eddy current brakes and induction heating systems. However eddy currents induced in the metal magnetic cores of transformers and AC motors and generators are undesirable since they dissipate energy (called core losses ) as heat in the resistance of the metal. Cores for these devices use a number of methods to reduce eddy currents: Eddy currents occur when

2684-477: The manufacturer, newer engines benefit from advanced technology such as multiple valves per cylinder, variable camshaft timing (Honda's VTEC), boosted low end torque (Honda's BLAST), 3-way cooling systems, and closed loop fuel injection. Mercury Verado four-strokes are unique in that they are supercharged . Mercury Marine, Mercury Racing, Tohatsu, Yamaha Marine, Nissan and Evinrude each developed computer-controlled direct-injected two-stroke engines. Each brand boasts

2745-401: The maximum recommended engine powers for the hulls. In the united kingdom, boats have CE plates on the transoms which specify maximum engine power, shaft length, maximum engine weight and maximum number of persons or maximum load. Outboard motor shaft lengths are standardized to fit 15-, 20- and 25-inch (38-, 51- and 64-centimeter) transoms . If the shaft is too long it will extend farther into

2806-464: The motor as well as the propeller . If the electric motor required to move the pistons which raise or lower the engine is malfunctioning, every outboard motor is equipped with a manual piston release which will allow the operator to drop the motor down to its lowest setting. Large ships, boats and yachts will inevitably have inboard engines. Medium size vessels may have either inboards or outboards, and small vessels rarely have inboard motors. If one has

2867-402: The outboard motor to be swiveled by the operator in almost all directions: Sideways for direction, up and down to change the thrust line according to speed or bow lift, elevate completely out of water for easy starting, placing the drive shaft and the propeller forward along the side of the boat for reverse, or put them inside the boat for propeller replacement, which can be a regular occurrence to

2928-462: The power head like a conventional petrol engine . With this setup, a motor can produce 10 kW output or more and is able to replace a petrol engine of 15 HP or more. The advantage of the induction or asynchronous motor is the power transfer to the rotor by means of electromagnetic induction . As these engines do not use permanent magnets , they require less maintenance and develop more torque at lower propeller speeds. Pump-jet propulsion

2989-430: The relation between the emf E {\displaystyle {\mathcal {E}}} in a wire loop encircling a surface Σ, and the electric field E in the wire is given by E = ∮ ∂ Σ E ⋅ d ℓ {\displaystyle {\mathcal {E}}=\oint _{\partial \Sigma }\mathbf {E} \cdot d{\boldsymbol {\ell }}} where d ℓ

3050-402: The ring and cause some electrical effect on the opposite side. He plugged one wire into a galvanometer , and watched it as he connected the other wire to a battery. He saw a transient current, which he called a "wave of electricity", when he connected the wire to the battery and another when he disconnected it. This induction was due to the change in magnetic flux that occurred when the battery

3111-436: The same magnetic flux going through them. The resulting emf is then N times that of one single wire. E = − N d Φ B d t {\displaystyle {\mathcal {E}}=-N{\frac {d\Phi _{\mathrm {B} }}{dt}}} Generating an emf through a variation of the magnetic flux through the surface of a wire loop can be achieved in several ways: In general,

SECTION 50

#1732780657928

3172-620: The separate physical phenomena in 1861. This is believed to be a unique example in physics of where such a fundamental law is invoked to explain two such different phenomena. Albert Einstein noticed that the two situations both corresponded to a relative movement between a conductor and a magnet, and the outcome was unaffected by which one was moving. This was one of the principal paths that led him to develop special relativity . The principles of electromagnetic induction are applied in many devices and systems, including: The emf generated by Faraday's law of induction due to relative movement of

3233-401: The subdivision of the eddy currents. In practical use, the number of laminations or punchings ranges from 40 to 66 per inch (16 to 26 per centimetre), and brings the eddy current loss down to about one percent. While the plates can be separated by insulation, the voltage is so low that the natural rust/oxide coating of the plates is enough to prevent current flow across the laminations. This is

3294-625: The system is pressurized. Lehr is regarded as the first manufacturer to have brought a propane-powered outboard motor to market by Popular Mechanics and other boating publications. The first known outboard motor was a small 11 pound (5 kg) electric unit designed around 1870 by Gustave Trouvé , and patented in May 1880 (Patent N° 136,560). Later about 25 petrol powered outboards may have been produced in 1896 by American Motors Co —but neither of these two pioneering efforts appear to have had much impact. The Waterman outboard engine appears to be

3355-575: The water (wind and waves). Many large outboards are equipped with power trim , an electric motor on the mounting bracket, with a switch at the helm that enables the operator to adjust the trim angle on the fly. In this case, the motor should be trimmed fully in to start, and trimmed out (with an eye on the tachometer ) as the boat gains momentum, until it reaches the point just before ventilation begins or further trim adjustment results in an increase in engine speed with no increase in travel speed. Motors not equipped with power trim are manually adjustable using

3416-445: The water than necessary creating drag , which will impair performance and fuel economy. If the shaft is too short, the motor will be prone to ventilation. Even worse, if the water intake ports on the lower unit are not sufficiently submerged, engine overheating is likely, which can result in severe damage. Different outboard engine brands require different transom dimensions and sizes. This affects performance and trim. Motor height on

3477-401: The water), noise reduction, increased fuel economy, and increased torque at low engine speeds. Honda Marine Group , Mercury Marine , Mercury Racing, Nissan Marine, Suzuki Marine, Tohatsu Outboards, Yamaha Marine, and China Oshen-Hyfong marine have all developed new four-stroke engines. Some are carburetted, usually the smaller engines. The balance are electronically fuel-injected. Depending on

3538-465: The wire loop, B is the magnetic field. The dot product B · d A corresponds to an infinitesimal amount of magnetic flux. In more visual terms, the magnetic flux through the wire loop is proportional to the number of magnetic field lines that pass through the loop. When the flux through the surface changes, Faraday's law of induction says that the wire loop acquires an electromotive force (emf). The most widespread version of this law states that

3599-421: Was connected and disconnected. Within two months, Faraday found several other manifestations of electromagnetic induction. For example, he saw transient currents when he quickly slid a bar magnet in and out of a coil of wires, and he generated a steady ( DC ) current by rotating a copper disk near the bar magnet with a sliding electrical lead (" Faraday's disk "). Faraday explained electromagnetic induction using

3660-419: Was created by Norwegian-American inventor Ole Evinrude in 1909. Historically, a majority of outboards have been two-stroke powerheads fitted with a carburetor due to the design's inherent simplicity, reliability, low cost and light weight. Drawbacks include increased pollution, due to the high volume of unburned gasoline and oil in their exhaust, and louder noise. Four-stroke outboards have been sold since

3721-400: Was discovered independently by Joseph Henry in 1832. In Faraday's first experimental demonstration (August 29, 1831), he wrapped two wires around opposite sides of an iron ring or " torus " (an arrangement similar to a modern toroidal transformer ). Based on his understanding of electromagnets, he expected that, when current started to flow in one wire, a sort of wave would travel through

SECTION 60

#1732780657928
#927072