Gas springs give mooring system the gentle touch

Edited by the Engineeringtalk editorial team Jun 14, 2005

Custom-engineered stainless steel gas springs are at the heart of a revolutionary new system for mooring boats without risking scuffing their hulls on the jetty.

Custom-engineered stainless steel gas springs from IGS have been specified at the heart of a revolutionary new system for mooring boats without risking unsightly, or expensive, scuffing of their hulls on the jetty.

Described as "the opposite of a rope", the system has - not surprisingly - been called "epor" by its inventor, Richard Meredith of Silverpin .

Instead of holding the vessel in tension against the quayside using conventional fenders as buffers, the new device employs the action of the gas spring to maintain a safe gap between the pontoon and the boat, avoiding the problem of wear to the moored vessel's gel coat or paintwork caused by the fenders rubbing against the hull.

The system is designed for boats up to 12m long and consists of a horizontal IGS gas spring connected to a vertical, pivoted arm which is mounted on the pontoon.

The gas spring arm attaches to the boat hull by a sliding plug connector, and a pair of universal joints accommodates the vertical and horizontal movements of the vessel relative to the mooring.

The length of the system's arm can also be easily adjusted to suit different craft.

The device's special purpose IGS gas spring incorporates an integral oil reservoir - for prolonged horizontal use - and is fully suitable for marine use, with maintenance-free seals and stainless steel end fittings.

In operation, the gas spring provides the axial force to ensure the required standoff, as well as an extra long 520mm stroke to accommodate boat movement, even in gale or storm force conditions.

"During particularly strong surges, the spring's maximum force may be overcome, resulting in very occasional use of the conventional fenders", says Meredith.

"This feature of the design avoids excessive stresses on the boat's hull".

"Even so, for 99.99% of the time, the craft's fenders will simply not come into play".

Further features of the system include automatic disconnection of the unit if the craft loses its mooring lines, or its skipper forgets to disconnect the system before setting off.

According to Industrial Gas Springs' Field Sales Manager, James Godbold, several innovative features are incorporated into the gas spring developed for the application.

"These include a larger diameter body than standard, in order to provide a near constant spring rate over its full stroke", he notes.

"In addition, the sealed-for-life unit is required to be undamped and has been specified with a 316 stainless steel rod for maximum corrosion resistance".

Unlike many other suppliers, IGS designs, develops and manufactures all its products in-house.

According to Godbold, this provides customers with two distinct benefits.

"Not only does it enable us to offer probably the largest standard range of gas springs on the market today, but through our comprehensive applications and design service, we can also develop products with characteristics tailored precisely to customers' needs", he maintains.

"We can normally supply prototypes and one-offs in around ten days".

"So, as in this case, we can offer customers the chance to fine tune their product designs quickly and effectively, with only minimal financial outlay".