What is a pad eye?
A pad eye is a device that a line runs through to provide an attachment point, they are often found on boats, and often welded or bolted to the deck or the hull of the boat.
They are made typically of steel and consist of an opening for the line, usually a round opening, that is either attached to a steel plate or, in the case of removable pad eyes, are screw-in versions.
Where pad eyes are used
Pad eyes are extremely useful pieces of rigging hardware and also have a myriad of other uses, they can be used as running eyes, as anchor points for anywhere a line need to be secured, and they are used to complement the other hardware in load-lifting operations.
Typical industry sectors.
- Nautical pad eyes – pad eyes are used on sailboats for attaching a number of parts, they are good for mounting blocks and reefing blocks, attachment points for staysails, and they can be used for securing dock lines. Pad eyes used on sailboats are often the fold-away type where the loop, when not in use, folds down safely into its mounting. These have the advantage of keeping passageways and decks clear but being readily accessible when a line needs to be attached temporarily.
- Kayaks – these small light boats have are built with many pad eyes all of which are used for securing elasticized lines which are used as flexible paddle leashes and as tie-down systems on the kayak’s deck. The pad eyes used for the tie down systems can be used, among other things, as anchoring points for a kayak seat or for securing a spray deck.
Pad Eye Folding
Pad eyes for lifting – numerous industries utilize pad eyes as part of their lifting systems, for example heavy containers, such as those carrying cargos, have specially designed pad eyes on each corner, they can then be lifted by cranes by the use of the lines attached to the pad eyes.
- Pad eyes for anchoring – one example of the use of heavy-duty pad eyes is the anchoring of aircraft on the flight deck of an aircraft carrier, these pad eyes are folding ones so there are no protuberances on the flight deck when the plane is not there, and they are large enough to have lines made of chains to be threaded through them. Another example is shipping companies that export yachts, the yachts are lifted onto the ship’s deck and secured by chains attached to large pad eyes which have been welded into the ship’s deck.
Sizing and typical range of sizes
As with most pieces of hardware there are a vast number of sizes and designs of pad eyes, all designed with specific applications in mind. In addition to different sizes and shapes of the loop to carry the line, there are also different designs of the base plate to which the loop is attached. When calculating the required size of a pad eye different stress factors have to be considered, i.e. the bearing stress, the shear stress and the tensile stress. Similarly stress factors of the base must also be taken into account, the shear stress, the tensile stress, the bending stress and the bending and tensile stresses combined.
Pad eye base plates are made in many different shapes, oblong, diamond shape, circular, square or oblong. Some are made with the loop capable of swiveling on the base. The shape chosen to be used for any particular use may, to some extent, be preference, however the factors given above must always be taken into consideration when determining the size. Also, to be considered is the angle at which the line will enter the pad eye and whether the pad eye should be folding, rigid or swiveling.
Most manufacturers will supply a full range of pad eyes to fit any marine, industrial or architectural need.