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	Bulbous bow - Wikipedia, the free encyclopedia
		The bulbous bow of the U.S. Navy carrier USS Ronald Reagan is clearly visible in this photograph.
		Bulbous bows are rare on recreational boats as these vessels have wide speed ranges and are often designed to plane over the water at high speed.
		Experimentation and refinement slowly improved the geometry of bulbous bows, but they were not widely exploited until computer modelling techniques enabled researchers at the University of British Columbia to increase their performance to a practical level in the 1980s.
	en.wikipedia.org /wiki/Bulbous_bow (862 words)

	Bow wave - Wikipedia, the free encyclopedia
		A bow wave is the wave that forms at the bow of a boat when it moves through the water.
		The size of the bow wave is a function of the speed of the boat, ocean waves, and the shape of the bow.
		Reducing the size of the bow wave is a major goal of naval architecture, as bow waves sap energy from the boat and reduce fuel economy; as well, large bow waves can damage shore facilities such as docks if a large boat sails past at high speed.
	en.wikipedia.org /wiki/Bow_wave (186 words)

	Nordhavn - Power That Is Oceans Apart
		The bulbous bows have been used for years on most tankers, freighters and large fishing vessels because the bulb reduces hydrodynamic drag at the speeds ships travel resulting in a considerable fuel savings.
		By affecting the bow wave, tank testing has shown that a bulbous bow reduces resistance in the range of 3 to 15 percent depending on the model and speed.
		While the primary benefit of bulbous bows was to increase efficiency, it was noted that that they also contributed to decreases in pitch motion on some models.
	www.nordhavn.com /constr_con/bulbous.php4 (314 words)

	Development of a Bow for a Naval Surface Combatant which Combines a Hydrodynamic Bulb and a Sonar Dome (Site not responding. Last check: 2007-10-20)
		The purpose of this design effort was to develop a hydrodynamic bulbous bow, which would provide for a reduction in resistance of a Naval surface combatant, and integrate it into an existing bow which houses a sonar dome.
		The reduction in drag is derived primarily by the lowering of wavemaking resistance through attenuation of the bow wave system of the ship, and to a lesser extent by the reduction of viscous resistance due to a smoothing of the flow around the forebody.
		Thirteen different bow designs were examined including: four integrated sonar dome / bulbs; three bulbous bows optimized for 20 knots ship speed; and four bulbous bows optimized for 30 knots; as well as the two baseline hullforms with/without the sonar dome..
	www.dt.navy.mil /hyd/tec-rep/dev-bow-nav (3995 words)

	Bill's Site (Site not responding. Last check: 2007-10-20)
		The bulbous bow has been known to naval architects for many years and is used with good effect on relatively short fast ships, where its main function is to reduce the wave-making resistance.
		A conventional bulbous bow showed no improvernent, but we continued with our experiments and eventually a ram type bow was developed which, although giving no advantage in the loaded condition, showed an improvement of nearly 7 % in the ballast condition, the equivalent of nearly five tons of fuel oil a day.
		The basic principles behind the improvement obtained with this ram bow are the increased waterline length and finer angle of entrance obtained in the ballast condition.
	www.portglasgow.com /yards/page15.htm (1184 words)

	TSB Reports - Marine 1994 - M94L0031
		When the vessel entered the approach basin, the bow was angled to port toward the approach lock wall, and then various engine and helm manoeuvres were carried out to set the bow against the tie-up wall and to slow down the progress of the vessel.
		The hull plating on the starboard side of the bulbous bow was ruptured and, consequently, the forepeak was flooded.
		Under the effect of the momentum of the swing of the bow to starboard and of the headway, the stern was subjected to bank suction from the tie-up wall, further reducing manoeuvrability.
	www.bst.gc.ca /en/reports/marine/1994/m94l0031/m94l0031.asp?print_view=1 (1039 words)

	Bray Yacht Design and Research Ltd. - New Life for Amnesia
		Bulbous bows are not normally associated with deep V, hard chine, wide spray-flat, two lift strakes per side kind of boats.
		In Amnesia's case the goal was to reduce the bow wave, which at top speed came up to the sheer, and add buoyancy forward to correct a bow down attitude (she also had a trim problem).
		As you see in the photos, the bulbous bow is 3'-6" in diameter protruding 5'-2" forward from the stem at the waterline.
	www.brayyachtdesign.bc.ca /article_amnesia.html (1205 words)

	Learning about bulbous bows (Site not responding. Last check: 2007-10-20)
		With model testing and advanced knowledge of hydrodynamics, the bulbous bow was formulated typically giving a 5% reduction in fuel consumption over a narrow range of speed and draft.
		The second reason being that while there will be a contribution of the bulbous bow to the viscous damping and added mass of the motion of the vessel, the literature suggests that this is negligible.
		Firstly, since the bow is immersed in the fluid, it should experience only a net positive buoyancy force from the hydrostatic aspect of the water.
	www.dieselduck.ca /library/articles/bulbous_bows.htm (1703 words)

	Nordhavn (Site not responding. Last check: 2007-10-20)
		Resistance and Seakeeping tests were performed on a hull with a conventional bow and a bulbous bow.
		The bulbous bow appears to perform well in head sea conditions, seldom broaching the wave surface and re-entering cleanly on those occasions when it does.
		The bulbous bow did not appreciably reduce resistance when measured during the irregular sea state head seas tests.
	www.nordhavn.com /72/video.htm (191 words)

	Encyclopedia Titanica Message Board: Archive through 19 January, 2003
		At a ship's designed service speed the bulbous bow generates a wave ahead of that of the main ship body, the trough of the former coinciding with the crest of the latter — in other words they cancel each other out.
		Another benefit of the bulbous bow is to lengthen the effective buoyant mass of the vessel and this tends to suppress the tendency to pitch and slam in heavy weather.
		There is also some evidence that the bulbous bow reduces apparent frictional resistance, probably by replacing it with less-taxing eddy-making resistance.
	www.encyclopedia-titanica.org /discus/messages/6937/51108.html (4704 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		The bulbous bow of Costa Crociere's new flagship Costa Concordia, due to enter into service by the end of spring in 2006, has been delivered today to Fincantieri's Genoa Sestri Ponente shipyard.
		The bulbous bow, which left Fincantieri's Ancona yard where it was built on February 16, weighs 406 tons, and is 32 m long and 11.5 m high.
		The bulbous bow, which is intended to remain under water at all times, is designed to lower wave-making resistance by channelling water in front of the vessel, creating a crest astern and thereby increasing the ship's speed.
	www.marinelink.com /members/fullstory.asp?ID=16111 (134 words)

	Powerboats
		Hullform: The hull is a heavy displacement type with a bulbous bow and cruiser stern.
		First, the stern was assembled with the no-bulb bow and towed in the tank from 6.5 knots to 11.5 knots at half-knot increments to determine the baseline resistance of the basic hull form.
		Then, the first bow was replaced by the bow with the bulb, and the tests repeated, to determine the net resistance reduction effect of the bulb.
	www.sponbergyachtdesign.com /Molokai65.htm (2075 words)

	NAUTICALweb - The round bottom
		Usually at low speeds the effect of the bulbous bottom is negative, while as the Froude number (FN) increases it becomes positive and increases up to a maximum value, from this point on, for FN, which tends to the infinite, the bulbous effect tends to zero.
		Thus the decision for or against the adoption of a bulbous bow depends on an analysis of costs and benefits.
		However, it can be affirmed that the good hydrodynamic shape of a bottom with moderate wave formation does not usually need a bulbous bow, while this is necessary in the presence of a considerable wave formation due to the poor "starting" of the bottom shapes.
	www.nautica.it /superyacht/490/tecnica/bottom.htm (1350 words)

	Ship Modeling FAQ, Research Note Ramming at Lissa --- Revised: December 18, 2004 (Site not responding. Last check: 2007-10-20)
		Eventually the marginal utility of the ram bow was outweighed by the increased resistance, and they stopped using them -- really starting about 1890 -- 25 years after Lissa.
		One interesting curiosity that I was told of when I was in college, learning to be a naval architect, was that the ram bow contributed to the development of the bulbous bow.
		The story I hear is that this took place in the 1920s, and the grad students did not have enough pull to convince people of the contra-intuitive performance of putting a big bulge on the bow of your hull form.
	home.att.net /~ShipModelFAQ/ResearchNotes/smf-RN-LissaRams.html (500 words)

	Northrop Grumman Corporation - Defining the Future
		The 700-ton lower bow unit was joined to the other keel sections in the dry dock and completes the length of the carrier, which is as long as the Empire State Building is tall.
		The lower bow unit is the 98th of 161 super-lifts used to build the carrier.
		The George H. Bush is the second carrier to have the new bulbous bow design that provides more buoyancy to the forward end of the ship and improves hull efficiency.
	www.irconnect.com /noc/press/pages/news_releases.mhtml?d=74042 (532 words)

	New Page 1
		The hull is a heavy displacement type with a bulbous bow and cruiser stern.
		A bulbous bow is designed primarily to reduce the wave-making resistance of the hullform which means you can reach the design speed with less horsepower.
		The fore peak houses twin anchor lockers, and the 16” diameter Naiad bow thruster is installed in the bulb.
	www.sponbergyachtdesign.com /Molokai72.htm (2194 words)

	Boats for Beginners
		The first attempt by naval architects to reduce wave resistance was the bulbous bow, which is widely used on cruise ships, ocean tankers and cargo vessels.
		The bulbous bow lowers the height and increases the period of the transverse wave created by the ship.
		While the bulbous bow reduces the energy of the Kelvin wake by about 10 percent, this reduction occurs only at the design speed of the ship.
	www.globalsecurity.org /military/systems/ship/beginner.htm (1568 words)

	Nat' Academies Press, Proceedings of the Sixth International Conference on Numerical Ship Hydrodynamics (1994)
		For the same vessel in ballast condition the top of the bulbous bow is at 1.2 m above the still waterline (which is 15 % of the stagnation height).
		The same is true if the top of the bulbous bow is extremely close to the undisturbed waterplane [16].
		The only precaution needed is to start with an increased draught to make the bow fully submerged, and to gradually reduce this draught in the course of the iteration until the equilibrium position is reached.
	www.nap.edu /books/NI000061/html/111.html (790 words)

	Understanding the Prismatic Coefficient
		Thus a bulbous bow benefits at higher speeds and is a liability at low speeds.
		You'll note that modern tankers have very large bulbous bows - this is because they have very high prismatic coefficients and the bulbous bow tricks the water into thinking that the hull is less bluff than is the case.
		They will dig their bows into the water in heavy weather and generally be very wet and unpleasant.
	www.navweaps.com /index_tech/tech-004.htm (1007 words)

	Visor on the bottom
		In this picture the bottom at the bow is at 85 metres depth, but the bottom at the stern is at 80 metres depth, thus a 7 meters difference at the stern compared with picture no 1.
		The depth at the bow is 85 metres and at the stern 72 metres.
		The flare at the bow (on picture 13) seems excessive (but it is of course a sketch added on the picture) and the bow superstructure is not correctly sketched in.
	heiwaco.tripod.com /visoronbottom.htm (5942 words)

	USS ARIZONA MEMORIAL: Submerged Cultural Resources Study (Chapter 3)
		The stem at the hull bottom (forefoot) extends forward of the deck line, creating a bulbous bow form that is covered by silt and not visible to divers.
		The extension is not for ramming, but for additional bow buoyancy and control of the bow wave for efficiency at high speed.
		The extensive bow damage is the obvious result of a massive explosion that blew outward and upward.
	www.nps.gov /usar/scrs/scrs3e.htm (935 words)

	CVN 76, Ronald Reagan: Bulbous Bow (Site not responding. Last check: 2007-10-20)
		Ronald Reagan (CVN 76) is the first Nimitz-class aircraft carrier to have the new bulbous bow design.
		Weighing in at approximately 722 tons, Reagan's bow is larger than the bows of its predecessors.
		The new bulbous bow design will be incorporated into the final Nimitz-class carrier design, CVN 77, and may even be considered as a retrofit design change for all Nimitz carriers during refueling and overhaul.
	www.nn.northropgrumman.com /Reagan/About_the_ship/Bow.htm (84 words)

	MV ESTONIA - final report CHAPTER 3 THE VESSEL (Site not responding. Last check: 2007-10-20)
		Related differences in the main hull were an increased length of the bulbous bow by 0.83 m and a related increase of the length of the forward ramp by 0.725 m.
		It was designed with a slender forebody extending into a bulbous bow and a “pram type” afterbody with two propellers and two rudders.
		Because of the retracted position of the navigation bridge, the bow of the vessel was not visible from the conning station, as Figure 3.4 indicates.
	www.webandwire.com /chapt03_1.html (4116 words)

	Bray Yacht Design & Research Ltd - Bulbous Bows
		The bulbous bow has created a growing interest among the cruising fraternity.
		The benefit of a modern-day bulbous bow will reduce your fuel consumption 12% to 15%, give you the equivalent greater range, or higher speed, whichever you choose to use.
		Factors that can complicate the installation are bow thrusters that occur within the outline of the bulb and transducers and thru- hulls that have to be moved or extended to reach the new vessel skin.
	www.brayyachtdesign.bc.ca /article_bbows.html (1807 words)

	bulb bows
		The Great Lakes boats usually have plum bows with lots of freeboard (short choppy conditions) and the gulf shrimper bow were all designed to provide the pitch needed in unique conditions.
		Just a few words on bulbous bows in yachts; The hull form with a bulbous bow is a must in today's merchant and other such ships that spoil a remarkable share of the propulsion power for wave resistance (the other main resistance component being friction resistance).
		The bulbous bow is expensive to build due to fine lined but robust (steel) structure.
	www.georgebuehler.com /bulbbow.html (1009 words)

	Past issues - archived article excerpts & cover photos - National Fisherman (Site not responding. Last check: 2007-10-20)
		She has a bulbous bow and her skeg was opened up for about 5 feet in front of the prop.
		Part of the reason for adding the bulbous bow is to provide additional flotation for other work that is being done to the boat, says Mike Lee, the yard’s general manager.
		The bulbous bow is being plumbed to hold freshwater, though when she’s crabbing and has her holds flooded, the bow will be empty of water.
	www.nationalfisherman.com /magazine-content/pastissues/jun2005.asp (6708 words)

	White Heaven III
		This is all combined with a bulbous bow.
		The effects of the bulbous bow were tested in the towing tank of the Technical University in Delft, the Netherlands, and the results exceeded all expectations.
		Another consequence of the bulbous bow is a surprisingly low fuel consumption.
	www.superyachtsociety.com /whiteheaveniii (1315 words)

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