About this Item
- Commercial-grade cable
- Most commonly used in boat lifts
- Size determined by the outer diameter
- Minimum Breaking Strength = 7,000 lbs.
- Safe Working Load = 1,750 lbs.
The 1/4″ Pre-Cut Galvanized Wire Rope Cable is a 7 x 19 strand aircraft cable. Factory cut to specific boat lift lengths. Moderate corrosion resistance & remains ductile over long periods running over sheaves. Galvanized steel cable is stronger than stainless steel cable. The most commonly used cable for boat lifts. Made by BH-USA.
Any boat heavier than 6,000 lbs. needs the boat lift cable to be compounded. We use the ASME (American Society for Mechanical Engineers) recommended safety factor and rating system. The same is used in the overhead crane industry. Never use “Breaking Strength” for rating a cable.
Aircraft cable is specified by the number of strands in the rope times the number of wires in each strand. “7 x 19” means the rope has seven (7) strands, with 19 wires in each strand. 7×19 is the most flexible aircraft cable construction.
BH-USA recommends 7 x 19 aircraft cables for boat lift applications. Always consider at least a 5:1 safety factor when figuring working loads. Use a minimum of 4 drops when using in boat lift applications. A test certificate for all cables sold by BH-USA is available upon request.
7 x 19 aircraft cable is not suitable for use in aircraft controls. Never lift humans with 7 x 19 aircraft cable.
Safe Working Load vs. Minimum Breaking Strength
It is important to use the Safe Working Load (SWL) of the cable and not the breaking strength when selecting wire rope. The breaking strength is just that… the amount of force a brand-new wire rope can hold in a perfect world where if you put one more pound on it would cause it to SNAP!
Why don’t we use the breaking strength?
The breaking strength of wire rope tested using a machine that isolates just the wire rope so that the end connections do not affect the overall strength. In the real world, the wire rope is a system of components including the wire rope itself and the end connections working together dynamically which have to bend around sheaves and cable winders and are only as strong as the weakest link. The minimum breaking strength is simply a measure of how much tension the wire rope can withstand in a perfect scenario that does not take into consideration the other factors that reduce the capacity of the wire rope system in a boat lift.
Why is the rating so low?
The Safe Working Load includes a safety factor (SF) to allow for all the things that can happen to wire rope during its useful life that will reduce the breaking strength. The safety factor is a recommendation from the American Society for Mechanical Engineers (ASME) for this type of equipment such that the lift can still safely hold the load when some or all factors working to break the wire rope are present. The safety factor gets “used up” as the wire rope deteriorates effectively lowering the breaking strength. In the next steps, we will determine the loads that each wire rope will be exposed to and then will choose a wire rope size with an SWL rating higher than the maximum loads.