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Planing

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Jetboats Plane, just like a car can water-plane on a wet road when the brakes are applied suddenly. A hydrofoil is a lifting surface/shape in the water that raises the vessel in a similar manner to an aircraft wing. A boat that "planes" rides on the surface of the water because of the force required to displace the water under the boat.kiwiinapanic 05:30 Jan 20, 2003 (UTC)

Cameron, fair enough. I thought that's what you trying to describe, but I was doing more copyediting than anything else. Revert at your own discretion Two Halves

Your criticism has improved the article - I think.kiwiinapanic 05:53 Jan 20, 2003 (UTC)

Thanks. I just want the best Wikipedia we can have. --Two Halves


Manufacturers section

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The Manufacturers section currently appears to be an advertisement for JetPac. —Preceding unsigned comment added by 222.152.8.69 (talk) 02:17, 3 December 2005


Reversed?

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"Jet boats are highly maneuverable and can often be reversed and brought to a stop within its own length from full speed in a maneuver known as a Hamilton turn."

I assume that "reversed" means not that the jet is reversed or the boat, but that the boat is rotated 180°, bring it to a stop or reversing the direction it was traveling in. -- Soupisgoodfood 13:25, 5 February 2006 (UTC)[reply]

No real Info=

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This article lacks any real true details on the marine jet. I suspect this article has been written by a person who does not know much about jet boats, or perhaps own a propeller driven boat.

125.239.223.5 12:14, 27 April 2007 (UTC)Sel Whats the comparison to an hydro foil got to do with a jet boat???? All fast boats plane, it is because they can go faster on top of the water than in it. The jet boat happens to enjoy this advantage as well! There are jet boats specifically designed not to plane, the advantage from a fully protected propeller and a safer boat is reason enough to use a jet. Jets are more efficient at planing speeds, but so are propeller boats.[reply]

125.239.223.5 12:14, 27 April 2007 (UTC)Sel Many commercial vessels, such as ferries from 10 to 50 metres, use jet propulsion, because they are more economical to run. It is about time the phrase 'jets are not as efficient as propellers' is put to rest - just look around at any harbour in the world, there will be a number of jet vessels working.[reply]

125.239.223.5 12:14, 27 April 2007 (UTC)Sel Hamilton never said he 'invented the jet' - rather he improved it. This was mainly by lifting the nozzle clear of the water, but also because he used an axial design pump improving efficiency. In fact the idea of lifting the nozzle clear of the water was not his idea, it was given to him by an engineering student visiting him. The student, after watching a prototype jet boat performing, mentioned that it was very difficult to control a fire hose, Hamilton did the rest.[reply]

125.239.223.5 12:14, 27 April 2007 (UTC)Sel Multiple impellor stages to accelerate the water is not strictly correct. Most commercial jets are single stage, that is they have only one impellor, the water is accelerated further by the slightly tappering design of the housing and nozzle. While speed of the water exciting the jet provides thrust,there are jets that move higher volumes of water for thrust, in fact it is a careful interaction of volume and speed of the water entering and exiting the jet that provides efficient thrust.[reply]

125.239.223.5 12:14, 27 April 2007 (UTC)Sel The straightening of the exiting water, i.e. removing the rotation that the impellor imparts to the water, is an advantage that the jet enjoys over the propeller. The torque reaction of a single screw vessel has to be taken into account whereas a single jet has no such issue.[reply]

While some boats, usually from 5 to 8 metres use v8 petrol engines for power, they are certainly not the most common motor. I would say the 2 or 3 cylinder two stroke motors in the jet skis are more common, but for the 5 metre range of trailer boats many very succesful jet boats use v6 motors. Generally from 8 metres and above the diesel is king.

A good rule of thumb for a high performance jet boat, 100 hp per ton is the power to weight ratio to aim for. Anything below 70hp per ton is sluggish - this also applies to any other form of propulsion.

125.239.223.5 12:14, 27 April 2007 (UTC)Sel Jet boats are often regarded as not as efficient as a propeller driven boat. This argument is flawed in many aspects, as there are numerous types of jet boats as there are propeller boats, each vessel having a particular design and performance envelope. It is therefore best to compare apples with apples. Jet boat design is more involved than just dropping a motor into a hull, it is important that the hull, motor, and jet unit are correctly chosen for the task at hand. A propeller boat is probably more tolerate of a mismatch in these areas. Over the years many jet boats have been poorly designed often by backyard builders, but sometimes by boat builders themselves. It is often theses vessels which have attracted the attention for comparison purposes. A correctly design jet boat can out perform an equivalent propellor vessel in most areas including economy, and I have never experienced any sloppy handling at slow speeds, at worse a jet will experience less economy at slower speeds.[reply]

Other Jet boat advantages: Long life: a well maintained jet unit can easily outlast the motor driving it. Maintenance: Many areas of the jet unit requires less maintenance that it's equivilent propeller vessel. A jet unit is less demanding on the motor. Though this can be dependant on the operator, but an engine in a jet boat in cruise mode will experience a steady load, no matter what the sea conditions are, whereas a propeller vessel will experience a varying load as it pushes through different sea states.

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I cleaned up some links and checked quality inserted and cleaned. —Preceding unsigned comment added by 71.204.44.49 (talk) 23:15, 29 March 2008 (UTC)[reply]

I've cleaned up the external links section per WP:EL.

The following were removed as inappropriate:

The following links may be appropriate but were dead:

- Davandron | Talk 13:44, 3 May 2007 (UTC)[reply]

I've just been bold and remove the entire manufacturers section. Only one linked to a Wikipedia article, so the section was just External links in disguise. If there is consensus that some coverage is needed, I would suggest creating List of marine jet manufacturers - with full referencing required for inclusion. dramatic (talk) 05:02, 30 March 2008 (UTC)[reply]

I have just been bold and undid your removal. These are all the most popular jetboat MANUFACTURERS not, spam forums and websites. This information is important and should be known to the public. I see no external links in disguise here. If there are they should be removed individually like the inappropriate links above. —Preceding unsigned comment added by 71.204.44.49 (talk) 09:29, 30 March 2008 (UTC)[reply]

And I see no references for anything in the list. (The manufacturers' own websites are not valid for establishing their notability as a manufacturer). dramatic (talk) 10:42, 30 March 2008 (UTC)[reply]

In the article section under the function heading there is an error statement: "It makes no difference to the amount of thrust generated whether the outlet is above or below the waterline........." In fact, it makes a large difference. With the same horsepower applied to the water pump, the thrust developed will be considerably more with the propulsion water exiting the nozzle above the water surface compared to below it. The same principle applies to jet boats as it applies to rockets. NASA says their rockets develop more thrust in the vacuum of space than in the earth's atmosphere. Why you ask? Because air slows the propulsion gasses exiting the rocket nozzle. Air must be pushed out of the way. Thrust is determined only by volume and velocity of the thrust medium, be it gas or water, and anything that slows it down reduces thrust. Another statement I see is this, "this probably meant that disturbed water was entering the jet unit and reducing its performance, and the main reason why the change to above the waterline made such a difference." This is, of course, not the main reason why performance was vastly improved as explained previously.

In the case of the jet boat, if the thrust nozzle is located under the surface of the water it is very inefficient because it has to move water out of the way as opposed to air. Rockets or jets do not rely on "pushing" against anything external for thrust development. It is action and reaction.

Rukovich71 (talk) 20:28, 20 August 2009 (UTC)[reply]

Drawbacks section

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The drawbacks section contains the following text: "In my experience, a jet boat will normally use about half the fuel that a boat of the same size does which is propelled by an outboard motor at the same speed." Does anybody know of a source that can be cited instead of this original research?173.48.160.10 (talk) 03:48, 1 April 2011 (UTC)[reply]

HANLEY HYDROJET

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The article briefly acknowledges the "Hanley Hydrojet". There is, however, regrettably no further Wiki citation.

The "Hydrojet" was patented by (James) Keenan Hanley, who commercialised various related successful innovations, starting from about 1930 well into the late -1950s. His first patented jet boat was the "Edward T Rose" fireboat design #2,276,193. Hanley Engineering Services in Prospect, Marion County, Ohio used a 30-foot steel hull designed by Sparkman & Stevens [sic - Stephens ?], with four centrifugal pumps each driven by a Chrysler engine, to propel as well as impel water through its fire-fighting monitors. During 1942-43, Hanley's delivered 103 such craft to the US Coast Guard. These were used succesfully in shallow water.

In 1948 a slightly larger Fire Float was constructed in Ohio (and then shipped from New York, to the Fremantle Harbour Trust) for use at the main Port of Western Australia, close to the State's capital Perth.

All of the preceeding summary facts are derived from the book "Without a Prop" by David S. Yetman, Dog Ear Publishing 2010, ISBN 978-160844-475-5. The book extensively discusses the modern progression from Keenan Hanley Hydrojet designs; most particularly those from the mid-1950s, in Bill (later Sir William) Hamilton's use of axial turbines for his internationally-succesful New Zealand jet boat developments.

From my personal late-1950s knowledge, the Fremantle Fire Float was only propelled rather slowly up the Harbour by its Hydrojets. Moreover, its on-station manoeuvrability became limited once the harbour sea-water was diverted primarily into its fire-fighting monitors. The WA Museum records that this Hanley Fire Float remained in service on Fremantle Harbour until about 1961. 180.200.140.215 (talk) 08:18, 25 January 2014 (UTC)[reply]

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