Battery powered ferries are relatively new, but have recently become a hot topic in news reports due to their green-energy credentials.

Because river ferries have short, repetitive runs and spend a lot of their time at one dock or another, they are well suited to being battery powered. A common practice is to charge the batteries during the overnight shut-down period, although there are many different approaches being taken currently as this is a new and developing technology. Electric propulsion systems emit no pollution to the atmosphere, which is an important consideration when a ferry operates close to habitation.

On the Ottawa River the "Ecolos" ferry operating from Thurso to Clarence was an early implementation of battery power, hence its name. When a new vessel was built for the Quyon ferry further upstream on the Ottawa it was modelled on the battery electric system in the Ecolos.

For this type of ferry one or two cables or chains are strung between the two ferry docks, but normally kept slack enough that they sink to the river bed and allow other boats to pass over.

The ferry motor can be diesel, electric or in now rare cases hand powered (the in England is an example), and works by winching the cable up and through the boat on pulleys.

They are only suitable where the ferry crosses in a straight line, where the water currents are not too strong and where the amount and type of other boat traffic does not run a risk of collision with the cable. They also have the advantage of removing the need for any steering mechanism or any underwater propulsion (propellers). Many of the shorter Ottawa and Saint Lawrence ferries are cable operated.

An incident on the Thurso–Clarence ferry however illustrates one potential drawback. In this case a series of circumstances resulted in the cable breaking and without that the ferry had no power and steering, and was at the mercy of the current. It eventually swung into one shore of the river at the end of the unbroken part of the cable.

Car floats are a variation on the towed barge (see below), but specifically designed to ferry railway cars (wagons). They became very important as railway networks extended and faced major river crossings. There are few around now. The rail connection between Matane and Baie-Comeau across the Saint Lawrence is listed as being still served by car floats, but I think these may now have been replaced by more conventional powered railway ferries.

These are boats with multiple hulls—normally two. The name derives from the Tamil, where they were first encountered by Europeans.

Single hull boats require a deep hull or keel with ballast to make them stable enough to resist capsizing. The catamaran gets its stability by using two narrow hulls, widely spaced. The result is much less displacement of water than a conventional mono-hull, and they have much less resistance to moving through the water, especially as speed increases.

Other benefits of catamarans are that they have smaller draft, allowing them to operate in shallower water, and their width allows a wide loading deck for vehicles, avoiding the multiple levels that are sometimes needed in conventional large ferries. Against this they are more expensive to build and more complex, requiring separate propulsion in each hull.

These are large, ocean-going ferries that take cars, buses, trucks and people, but are equipped and marketed to act as cruise ships as well as ferries. Some people use them to get from point A to point B. Others go just to enjoy the onboard food and entertainment, often staying onboard when the ferry reaches its destination and returning straight away to their home port. The Baltic seems to be full of cruise-ferries, probably due to the distances being right for simple overnight crossings.

Not much to say here. Diesel powered engines have been the traditional power source in small and large commercial vessels for many years. They tend to be heavier and more reliable and efficient than petrol (gas) engines, and work well in the marine environment. They have a reputation of being bad polluters, which is one reason why electric ferries are gaining ground. Diesel engines however are easy to adapt to running bio-fuels.

Vehicle ferries can have loading ramps on one or both sides of the boat or on the bow, the stern or both ends. The configuration depends on many factors.

The docking facilities, port layout and the conditions of the river or sea may mean the boat has to dock beside the dock or end-on to the dock. The most efficient loading of vehicles is with double-end-loading when there is a ramp at both ends of the boat and vehicles can drive on one end and off the other end without any need to turn round or manœuvre

The term "floating bridge" is sometimes used for a large, cable or chain ferry over a short crossing. Several ferries in the UK are called floating bridges, for example the Cowes Floating Bridge in the Isle of Wight, England. More often the term is used for a bridge that actually floats on pontoons instead of being supported by pillars.

Hmm? Sounds a bit like a ferry designed to take just one part of your anatomy. In fact so many ferries these days are associated with taking vehicles that foot ferry is the designation for a service that only takes pedestrians—foot passengers. In most cases this extends to bikes also—or as we used to call them in England, push-bikes.

Water buses operating in cities are invariably foot ferries. The other common usage is to reach a pedestrian-only attraction, such as a castle or park.

The original and most basic of ferries. Poled or rowed ferries were once the norm, but are now a rarity. But where the circumstances allow there are still a number of hand powered cable ferries around.

Most commonly these are powered by a winding mechanism on the boat, powered by a single operator, or in rare cases the passenger him/herself. They are only feasible where the crossing distance is short. The only remaining hand ferry I know about in North America is at Los Ebanos, which can carry three cars across the Rio Grande between Texas and Mexico.

The first ferry I crossed on, Grove Ferry in Kent, England, was hand powered. It took just one car, and passengers, and was moved across the river by a ferryman simply pulling on a rope. Mind you, the river was only a few ferry-lengths wide at that point!

There are no remaining horse powered ferries that I know about, but they were important category up until the internal combustion engine started to become available. The Quyon Ferry was one such service. The horse was tethered into a treadmill which turned a waterwheel which powered the ferry.

Many people are completely unfamiliar with hovercraft, or air cushion vehicles, as they are often known. Before heading to for more details, the simple principle behind hovercraft is that air is blown under the flat surface of the craft to maintain a positive pressure that keeps the craft just above the ground—or water. A flexible skirt around the edge of the craft helps to maintain the pressure and stability, and propulsion is usually provided through a propeller (or two, or four).

I saw my first hovercraft at the 1964 Farnborough Air Show—a fact which underlines that the culture of the first generations was that of the aircraft industry. By 1966 hovercraft were in service on the Ramsgate–Calais and Southsea–Ryde ferry routes as well as in a number of other military and civil applications.

They have a number of significant advantages over boats. They operate as easily over land as over water, which makes them useful where the route includes sandbanks and shallow water such as the approach to Ryde, Isle of Wight, or the Goodwin Sands between Ramsgate and Calais. Compared to boats they are fast, as they "float" a short distance above the surface, without any contact with the water. But on the downside, being related to aircraft inevitably makes them more expensive to manufacture and operate than a conventional boat. And their ability to operating in heavy seas is generally more limited than boats. The earlier models were also somewhat noisy, making them less popular near urban areas.

is an enthusiastically run website with loads of photos. A good starting point to browse through the world of hovercraft and their history.

Hydrofoils are simply boats that "fly" on wings in the water. When at rest or slow speed the boat floats on a conventional hull. As the speed increases wings on struts under the hull start to generate lift so that the vessel rises out of the water. Eventually the hull is completely clear of the water and the whole weight of the vessel is supported by the dynamic lift generated by the wings, or foils.

The advantage is that the water resistance on the wings, especially at higher speeds, is a lot less than it is on a conventional hull. In addition the disturbance from moderate sized waves is much reduced.

Hydrofoils have therefore specialised in high-value passenger ferry services, where their speed has commanded a premium fare. However their extra complexity and need for more powerful propulsion systems has made them more expensive to operate—they are a hybrid between boats and aircraft. Because of this operating cost penalty they have been losing popularity, often being replaced by high speed catamarans which have many of the same speed advantages with less complexity and cost.

In 1985 we travelled from Guangzhou to Hong Kong down the Zhujiang (Pearl River) on a hydrofoil ferry.

I think these are my favourites, because they are "free energy" ferries. They are powered by rudders (wings, foils, sails?) under the boat that are angled such that the current of the river provides the force to move the ferry across the river. The angle of the rudder is controlled by the operator and is changed so that the ferry moves first one way across the river and then the other.

Because they are not independently powered they need a cable to prevent the ferry simply drifting downstream. Our local ferry at Île-Bizard uses tightly-strung over-head cables and the ferry pulls against those cables with pulleys.

Like cable ferries the arrangement of the restraining cable has to suit the other river traffic. The Île-Bizard cables are about 20 above the water allowing smaller pleasure craft to pass under. At Dolní Žleb larger commercial boats can pass the ferry, but only when it is stationary on the same bank the cable is attached to.

Conventionally ship-born freight is loaded by crane into a ship which is moored beside a dock. In a roll-on/roll-off ferry wheeled vehicles (normally cars, trucks and buses, but also railway stock) drive on and off the ferry on ramps. Ro-Pax is simply an acronym for a roll-on/roll-off ferry that also takes passengers, as almost all do.

The first roll-on/roll-off vessel was a train ferry over the First of Forth in Scotland in 1849. The concept is now almost ubiquitous for vehicle ferries as the speed of loading is so much faster and cheaper than loading by crane.

The only vehicle ferry service I am aware of that is NOT ro-ro is the M/V Bella Desgagnés which operates along the Lower North Shore of the Saint Lawrence. Vehicles are loaded by crane, with smaller vehicles put into containers first. This configuration is because the vessel provides a full passenger and freight service to communities which have no other connection to the outside world. The vehicle service is secondary to the freight.

A river bus is a scheduled ferry service operating along a river, connecting a number of destinations. Many large modern cities are situated on a major river and have river bus operations integrated into their public transportation systems. Originally ferries would have been the principal way of crossing the river, but now that most cities have multiple bridges the river buses tend to connect points along the river, although often making stops on both banks.

The viability of river bus services is often based on a mixture of commuter traffic and tourist sightseeing trips, and congestion of the roads can also make using river buses attractive alternatives to regular buses.

It can sometimes be difficult to decide if a river bus service is a ferry or a river cruise. Some services tend more one way, some the other. The river bus service in Budapest, Hungary is a good example and is always referred to as a ferry.

These are craft that crawl across the sea-floor or river bed, like a tractor on wheels or caterpillar tracks, but have their passenger deck raised on stilts above the level of the water.

The best known is at where it takes hotel guests from the mainland to the island when the tide covers the causeway. It looks like a fun little excursion on a pleasant summer afternoon, but there is a video on the web showing that bad weather can turned things a bit too exciting!

There is which is used to take passengers from the shore to the ferry.

And for a bizarre variation take a look at . This was an electric railway which operated (barely) across the sea-bed between Brighton and Rottingdean, Sussex in the 1890s, with the passenger carriage held way above the water surface.

Barges or lighters towed or pushed by tug boats are a traditional way of ferrying heavy equipment but these days are rarely used on regular ferry services. The only one I know about is the Oka ferry when I first used it in the 1980s.

Back then the service was provided by flat-bed, unpowered barges, each towed by a powerful, open, diesel-powered boat. These required significant skill and experience on the part of the operators who had to “toss” the barge towards the loading ramp and manœuvre the towing power boat out of the way at each docking. In 2008 these were replaced by conventional end-loading, powered ferries (which were in fact constructed by extending and adding to two of the original barges.) Two of the old barges remain moored near the Hudson dock of the ferry.

Turntable ferries combine the benefits of end-loading and side-loading ferries. They are relatively small with room for a maximum of about 6 cars. The car deck is mounted on a turntable on top of the boat. The boat stops beside the slipway and the turntable is rotated, by human muscle power, until it is angled over the slipway, and then a ramp is lowered. Vehicles can then drive straight on, and the car deck is rotated to align it with the boat for the crossing. At the other side of the crossing the car deck is rotated so that the cars can drive straight off. A big advantage of this type of ferry is that it is very adaptable to different tide conditions, an important consideration for crossings of Scottish sea-lochs.

I crossed on four of these in Scotland in the 1970s. The ones at Ballachulish, Kylesku and Kyle of Lochalsh have both since been replaced by bridges, but the one at Glenelg connecting the Isle of Skye to the mainland, remains in operation.