Showing posts with label portholes. Show all posts
Showing posts with label portholes. Show all posts

Monday, March 31, 2014

Wooden Ship wheel

Ship's wheel

ship's wheel is used to change its course. Together with the rest of the steering mechanism it forms part of the helm. It is typically connected to a mechanical, electric servo, or hydraulic system. In some modern ships the wheel is replaced with a simple toggle that remotely controls an electro-mechanical or electro-hydraulic drive for the rudder, with a rudder position indicator presenting feedback to the helmsman.
Helmsmen on older ships used a tiller (a horizontal bar fitted directly to the top of the rudder post) or a whipstaff (a vertical stick acting on a tiller).
Early ships' wheels (c. 1700) were operated to correspond to the motion                                          of The design of ships' wheels probably influenced that of the modern steering wheel.
the tiller, with a clockwise motion (corresponding to a right tiller motion) turning the rudder and thus the ship to the left. Eventually the control direction of the wheel was reversed to make it more consistent with the action of a motor vehicle's steering wheel.
A traditional ship's wheel is composed of eight cylindrical wooden spokes (though sometimes as few as six or as many as ten) shaped like balustersand all joined at a central wooden hub or nave (sometimes covered with a brass nave plate) which housed the axle. The square hole at the centre of the hub through which the axle ran is called a drive square and was often lined with a brass plate (and therefore called a brass boss, though this term was used more often to refer to a brass hub and nave plate) which was frequently etched with the name of the wheel's manufacturer. The outer rim is composed of four sections each made up of stacks of three felloes, the facing felloe, the middle felloe, and the after felloe. Because each group of three felloes at one time made up a quarter of the distance around the rim, the entire outer wooden wheel was sometimes called the quadrant. Each spoke ran through the middle felloe creating a series of handles on the outside of the wheel's rim. One of these handles/ spokes was frequently given extra grooves at its tip which could be felt by a helmsman steering in the dark and used by him to determine the exact position of the rudder—this was theking spoke and when it pointed straight upward the rudder was dead straight. The wood used in construction of this type of wheel was most often eitherteak or mahogany.
The steering gear of earlier ships sometimes consisted of a double wheel where each wheel was connected to the other with a wooden spindle that ran through a barrel or drum. The spindle was held up by two pedestals that rested on a wooden platform, often no more than a grate. A tiller rope or chain (sometimes called a steering rope or chain) ran around the barrel in five or six loops and then down through two tiller rope slots at the top of the platform before connecting to two sheaves just below deck (one on either side of the ship's wheel) and thence out to a pair of pulleys before coming back together at the tiller and therefore the ships rudder. Movement of the wheels (which were connected and moved simultaneously) caused the tiller rope to wind in one of two directions and shifted the tiller left or right. In a typical and intuitive arrangement, a helmsman turning the wheel counterclockwise would cause the tiller to move to starboard and therefore the rudder to swing to port causing the vessel to also turn to port.

Tuesday, March 11, 2014

Porthole - Maximus International - - nautical gift manufacturer


Maximus International -
porthole is a generally circular window used on the hull of ships to admit light and air. Though the term is of obvious maritime origin, it is also used to describe round windows on armored vehicles, aircraft, automobiles (the Ford Thunderbird a notable example) and even spacecraft.
On a ship, the function of a porthole, when open, is to permit light and fresh air to enter the dark and often damp below-deck quarters of the vessel. It also affords below-deck occupants a limited, but often much needed view to the outside world. When closed, the porthole provides a strong water-tight, weather-tight and sometimes light-tight barrier.
A porthole on a ship may also be called a sidescuttle or side scuttle (side hole), as officially termed in the International [1] It is also used in related rules and regulations for the construction of ships.[2] The use of the word "sidescuttle" instead of "porthole" is meant to be broad, including any covered or uncovered hole in the side of the vessel.
Convention for the Safety of Life at Sea. This term is used in the U.S. Code of Federal Regulations.


A porthole consists of at least two structural components and is, in its simplest form, similar to any other type of
window in design and purpose. The porthole is primarily a circular glass disk encased in a metal frame that is bolted securely into the side of a ship's hull. Sometimes the glass disk of a porthole is encased in a separate frame which is hinged onto the base frame so that it can be opened and closed. In addition, many portholes also have metal storm covers that can be securely fastened against the window when necessary. The main purpose of the storm cover is, as its name implies, to protect the window from heavy seas. It is also used to block light from entering lower berths when darkness is preferred. Storm covers are also used on Navy and merchant marine ships
to prevent interior light from escaping the ship's lower berths, and to provide protection from hostile fire. Hinged porthole windows and storm covers are accessible from inside the ship's hull, and are typically fastened to their closed positions by hand tightening several pivoting, threaded devices, commonly referred to as "dogs." Older portholes can be identified by the protruding collar of their base plate which may be up to several inches deep, thus accommodating the thickness of a wooden hull.
Portholes range in diameter from several inches to more than two feet, and weigh from several pounds to over one hundred pounds.
Much of the porthole's weight comes from its glass, which, on ships, can be as much as two inches thick. Metal components of a porthole are also typically very heavy; they are usually sand-cast and made of bronze, brass, steel, iron, or aluminium. Bronze and brass are most commonly used, favoured for their resistance to saltwater corrosion. The design of the porthole is such that it achieves its humble purposes without sacrificing the integrity of the ship's hull. The porthole's thick glass and rugged construction, tightly spaced fasteners, indeed even its round shape, all contribute to its purpose of maintaining hull strength and pressure of storm waves crashing against it.