Narrowboats are notoriously difficult to manouver due to their length, poor hydrodynamic qualities, and propulsion design - a fixed prop and a large rudder mounted behind it.

A rotatable ducted prop would have considerable advantages.

The proposal would be to remove the existing prop and shaft (closing off the stern gland) and the rudder. This is replaced with a ducted prop with a set of vanes, mounted directly below the rudder pintle.

The prop is powered by a hydraulic motor; the working fluid is plain water. The shaft bearings are water-lubricated ceramic and some leakage is anticipated. Flow and return connections run through the downshaft which passes through the aperture for the former rudder shaft. A conventional tiller bar is fitted to the top of the shaft.

Clean water is pressurised by an engine-driven pump. It passes down the shaft to operate the motor. Most of the water, now at much reduced pressure, returns to the feed tank through a filter.

As the water is admitted and retrieved via banjo couplings, the tiller can be rotated through 360 degrees while under full power. It is as efficient in full reverse as full forward.

Water can be diverted to operate a reversible hydraulic bow thruster if desired.

There are no lubricants to leak and contaminate the canal water. The below-water componenents are fabricated from stainless steel and phosphor bronze, both corrosion-resistant.

The propulsion unit can be removed for maintainance without drydocking the boat.

A tank of clean "prop water" is needed to ensure the level in the hydraulic system is maintained.
-- 8th of 7, Aug 26 2013

How does the hegemonizing work on a canal?
-- MaxwellBuchanan, Aug 26 2013


One lock at a time.
-- 8th of 7, Aug 26 2013


Excellent. Are the Borg carbon neutral, GM-free and organic?
-- MaxwellBuchanan, Aug 26 2013


That's what we claim in the sales literature (E&OE).

The reality is, of course, slightly different.
-- 8th of 7, Aug 26 2013


There's a reality?
-- MaxwellBuchanan, Aug 26 2013


Two alternatives to consider are a jet boat (ducted prop inside the hull, thrust-vectoring exit nozzle) or an external ducted prop driven by an electric motor.

A third idea is to experience greater utility-function fulfillment by defining an endless hierarchy of techno-communist governments and repeatedly assimilating oneself.
-- sninctown, Aug 27 2013


// a jet boat (ducted prop inside the hull, thrust-vectoring exit nozzle) //

Massive modifications to the hull needed.

// or an external ducted prop driven by an electric motor. //

Thermodynamically very inefficient, and the motor will be bulky, plus has to be watertight.

// experience greater utility-function fulfillment by defining an endless hierarchy of techno-communist governments and repeatedly assimilating oneself. //

Sounds like fun ...
-- 8th of 7, Aug 27 2013


Having driven a narrowboat (or possibly a canal boat or a houseboat - I suspect the definitions are meaningless), it occurs to me that it is never actually necessary to steer. Indeed, steering is just showing off.

The boat is generally longer than the canal (or lock) is wide, meaning that one can simply leave the engine running and relax in the knowledge that the "boat" (and I use the term quite wrongly) can only go in one net direction, and that any collisions with the banks will only serve to usefully widen the canal, and will do no serious damage to anything important.

This approach leaves plenty of time for serious drinking, and for pondering such questions as "why has my life come to this?".
-- MaxwellBuchanan, Aug 27 2013



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