How Many Cable Clamps Does a Boat Lift Cable Need, and How Tight Should They Be?

On 3/16 to 3/8 in wire rope, the clip maker's table says a minimum of 2 forged U-bolt clips per eye, torqued to 7.5 ft-lb at 3/16 in, 15 ft-lb at 1/4 in, 30 ft-lb at 5/16 in and 45 ft-lb at 3/8 in. The saddle goes on the live (loaded) side, the U-bolt on the short dead end, and every nut is retorqued after the first full load. Those figures come from Crosby's application sheet for its G-450 clip, and they are what the cable replacement procedure means by "follow the clip maker's table."

The table carries a condition almost nobody repeats. Crosby bases its clip counts on 6x19 and 6x36 class rope and, for other classes, tells users to contact its engineers. The 7x19 galvanized or stainless "aircraft cable" on most residential lifts is not a listed class. So 2 clips is the published floor for the rope the table was written for, not a rating for your lift cable.

The clip table for lift-sized cable

Crosby publishes two application sheets that cover lift-sized rope: one for the G-450 U-bolt clip and its SS-450 316 stainless version, and one for the Fist Grip clip. These rows are copied from both for the sizes a residential lift carries.

Crosby minimum clips, turnback, and torque by rope size (torque on clean, dry, unlubricated threads)

Rope size	G-450: clips	G-450: turnback	G-450: torque	Fist Grip: clips	Fist Grip: turnback	Fist Grip: torque
1/8 in	2	3-1/4 in	4.5 ft-lb (54 in-lb)	not listed	not listed	not listed
3/16 in	2	3-3/4 in	7.5 ft-lb (90 in-lb)	2	4 in	30 ft-lb
1/4 in	2	4-3/4 in	15 ft-lb (180 in-lb)	2	4 in	30 ft-lb
5/16 in	2	5-1/4 in	30 ft-lb	2	5 in	30 ft-lb
3/8 in	2	6-1/2 in	45 ft-lb	2	5-1/4 in	45 ft-lb
7/16 in	2	7 in	65 ft-lb	2	6-1/2 in	65 ft-lb

Turnback is the length of rope folded back from the thimble to form the eye. At 1/2 in both sheets step up to 3 clips, which matters only on the heaviest lifts. Both sheets also say to match the clip size to the rope size exactly; if you are unsure of yours, measure across the crowns with calipers as described in boat lift cables explained.

Torque belongs to the clip, not the rope

Read across the 1/4 in row: the G-450 calls for 15 ft-lb, the Fist Grip 30 ft-lb on the same rope. At 3/16 in the gap is fourfold. Neither is wrong; each is the figure set for that clip design. The error is quoting "the torque for 1/4 in cable" without saying which clip, and then applying it to the other style. Use the sheet for the clip in your hand.

All values assume clean, dry, unlubricated threads, so a nut run down on greased threads at the same wrench reading is not the joint the table describes. The small sizes also sit below many ft-lb click wrenches: 7.5 ft-lb is 90 in-lb and 15 ft-lb is 180 in-lb (ft-lb times 12), which suits an inch-pound wrench.

Why you hear both "two clips" and "three clips"

Forums say three, always. The clip maker's table says two. Both numbers come from real documents:

• Two is Crosby's minimum for its forged U-bolt and Fist Grip clips on rope up to 7/16 in, in the classes the sheet covers.
• Three is where Crosby starts at 1/2 in, and where OSHA's construction rule for U-bolt clips (29 CFR 1926.251, Table H-2) starts too: its smallest listed rope is 1/2 in, at 3 drop-forged clips. Rules learned on bigger rope get carried down to small cable.
• One more is required in some cases. Crosby adds a clip whenever the rope turns back around a sheave instead of a thimble. OSHA requires one more clip of "other material" than of drop-forged steel at every size it lists: 4 instead of 3 at 1/2 in, 5 instead of 4 at 3/4 in.

So for a forged clip on rope its table covers, the answer is the table's number: two at lift sizes. "Always three" is a habit, not a rating. Three clips of unknown material on a cable class nobody tested is still an untested joint.

Where the table stops applying to boat lifts

7x19 aircraft cable is not in it

Crosby's counts are "based upon using RRL or RLL wire rope, 6 x 19 or 6 x 36 Class, FC or IWRC; IPS or XIP, XXIP," plus two rotation-resistant classes. For anything else it recommends contacting Crosby Engineering "to ensure the desired efficiency rating." Residential lifts mostly use 7x19 cable, which is not listed, so this sheet establishes neither the 80% efficiency nor the 2-clip minimum for most lift cable. A clipped eye on 7x19 is unrated unless the clip maker or lift maker says otherwise.

Plastic-coated cable

Both sheets say: do not use with plastic-coated wire rope. If your lift cable is vinyl-jacketed, clips are out; use the termination the cable or lift maker specifies.

Clips with no table

The G-450 sheet covers Crosby's own clips, and the Fist Grip sheet warns against mixing them with another maker's. An unbranded hardware-store clip comes with no count, turnback, torque, or efficiency. OSHA's extra clip for non-forged material shows how much material matters at the sizes it covers; below 1/2 in nobody publishes the adjustment, so an unmarked clip cannot be made correct by counting. Buy clips whose maker publishes a table and keep the sheet with the lift manual.

Clips are not a repair

Crosby's sheet describes splicing two ropes with clips, but on a lift a damaged section retires the cable. The criteria are in boat lift cable problems.

Installing clips the way the sheet describes

These steps follow the Crosby sheet for a two-clip thimble eye, the usual dead end on a lift with 2:1 reeving, where the cable runs down around a cradle sheave and back up to the top beam.

1. Fit a thimble. If the rope instead turns back around a sheave, add one clip (sheave condition is covered in pulleys and sheaves).
2. Turn back the table length, for example 4-3/4 in for 1/4 in rope with G-450 clips.
3. First clip one base width from the dead end. U-bolt over the dead end, live end in the saddle ("never saddle a dead horse"). Tighten the nuts evenly, alternating, to the table torque.
4. Second clip as near the thimble as possible, torqued the same way. With two clips, the eye is done.
5. Three or more clips: set the second clip at the thimble with nuts firm but not tightened, space the rest equally between the first two, take up slack, then torque all of them.
6. Load, then retorque. Apply a first load at least equal to the loads expected in use, then retighten every nut to the table torque. On a lift, raise the boat it will carry, lower it, and go back with the wrench before normal service.

A finished two-clip eye has one clip at the tail and one hard against the thimble, every U-bolt on the dead side, and the thimble seated tight. Two clips crowded into the middle of the turnback mean it was cut short. OSHA's spacing of six rope diameters applies only from 1/2 in up, so do not borrow it for small cable.

Retorque and inspection

The sheet's firm schedule is one retorque after the first load, then periodic inspection "for wear, abuse, and general adequacy." On a lift, fold the clips into the yearly cable inspection in the maintenance checklist and check them again after any storm or shock load. At each eye, look for:

• Nuts that turn at the table torque. Retighten and recheck after the next load cycle.
• Broken wires near the clips or thimble. Damage at a termination retires the cable; do not re-clip it.
• Rust bleeding from under a saddle. Water sits in the joint. On stainless cable, that wet, oxygen-starved space is where crevice corrosion starts.
• An opened or deformed thimble, which lets the rope bend sharply around the pin.

In brackish and salt water, match clip metal to cable: Crosby's SS-450 is a 316 stainless clip under the same sheet as the G-450, so stainless cable can take a rated stainless clip. Stainless and zinc in wet contact form a galvanic pair in which the zinc gives way; see corrosion protection and tidal and saltwater installations.

Frequently asked questions

How many cable clamps do I need on 1/4 inch boat lift cable?

Crosby's tables for forged G-450 U-bolt clips and Fist Grip clips give a minimum of 2 per eye on 1/4 in rope, with 4-3/4 in of turnback for the G-450 and 4 in for the Fist Grip. Add one if the rope turns around a sheave instead of a thimble. The tables are written for 6x19 class rope, not the 7x19 cable most lifts use.

How tight should wire rope clips be on a boat lift?

Use the torque in the maker's table for that clip. For Crosby G-450 clips it is 7.5 ft-lb at 3/16 in, 15 ft-lb at 1/4 in, 30 ft-lb at 5/16 in and 45 ft-lb at 3/8 in, on clean, dry threads. Fist Grip clips use 30 ft-lb from 3/16 to 5/16 in. Retorque after the first full load.

Which way does the U-bolt go on a cable clamp?

The U-bolt goes over the dead end, the short tail folded back from the thimble. The saddle sits on the live end, the part that carries the boat. Riggers remember it as "never saddle a dead horse." Every clip on the eye should face the same way, with all U-bolts on the tail side.

Are swaged ends better than cable clamps on a boat lift?

Where the lift maker sells cables with a swaged eye, use them. That is the termination the maker specified, and it avoids a clipped eye on 7x19 aircraft cable, a rope class Crosby's clip tables do not cover. Clips remain acceptable where the original design uses them, if they are rated clips installed to their maker's table.

Sources and further reading

• The Crosby Group, Crosby Clips Warnings and Application Instructions, G-450 and SS-450, rev. 2 (https://www.thecrosbygroup.com/wp-content/uploads/2013/12/56.pdf)
• The Crosby Group, Crosby Fist Grip Clips Warnings and Application Instructions, rev. 2 (https://www.thecrosbygroup.com/wp-content/uploads/2013/12/57.pdf)
• U.S. Occupational Safety and Health Administration, 29 CFR 1926.251, Rigging equipment for material handling, paragraph (c) and Table H-2, Number and Spacing of U-Bolt Wire Rope Clips (https://www.ecfr.gov/current/title-29/subtitle-B/chapter-XVII/part-1926/subpart-H/section-1926.251)