Thursday, October 01, 2009

TechTip: 3 Inch Cargo Strap

Short Answer Three inch polyster cargo strap in large pieces is a very good, relatively inexpensive way to tie down a boat in a hurricane. Get yourself some now.

Long Story Before we left for Vancouver Island, DrC researched some alternatives for a stern tie line. The problem with many solutions is chafe. As the tide goes out, your line often falls on incredibly sharp oyster bed and gets chewed up. He decided to try a 3” cargo strap advertised for its strong holding properties as well as durability in the face of sharp objects.

As a stern tie, this strap worked reasonably well. If you decide to use it for that purpose, make sure you set yourself up with a roller off the stern of the boat. It’s heavy, and it likes to twist. It also doesn’t float. You’ll want to make sure you can easily roll it off and on.

When I arrived in Santa Rosalia just hours before Jimena hit, I was greeted by my fellow cruisers with the most important phrase in hurricane preparation: What line do you have? I pulled out all my dock lines, the jib sheets we’d already planned to replace this fall, our primary and secondary anchor rodes, and the strap. At 300 feet, it made sense to use it to run a line over to the far-side breakwater.


The strap doesn’t break It has a breaking point of 10,000 lbs. Frankly, unless you plan to hang the boat from the strap, whatever you tie it to is likely to break apart long before the strap snaps. After watching dock lines and anchor rodes snap like threads all over the marina, it was reassuring to have this enormously powerful material holding Don Quixote off the dock. I also used a piece to bridle the boat to a dock piling. There was no question it would hold the boat as long as neither the starboard cleat, nor the bridle attachment point gave way. Consider using the strap around extremely well founded, back plated points such as the stays or even loop it around the mast.

The strap doesn’t chafe Though god knows it tried on the pier, our strap showed no sign of wear after 12 hours of attempting to beat itself to bits on the concrete and wood of the opposite shore.

The strap is relatively cheap We purchased 300 feet for about $125 at a year ago. It looks like it’s running roughly $USD.60/foot right now for the 2 inch. I would call to see if they have the wider widths. You also get a discount at longer lengths. The pricing is considerably less than anchor or dock line.

The strap stores well Once you get roller for it, you can roll this thing up into a neat, small roll and stuff it in an protective bag for dry storage. It certainly takes up a lot less space than a comparable length and strength piece of line or rode.

The strap doesn’t stretch You need stretch in lines during a hurricane for shock absorption as your boat jounces in the waves. The stretch reduces the jerk against your cleats or other attachment points. As a result, several captains here suggested adding shock absorbers to a strap line or using the strap only as a secondary line in case your standard dock line or rode gives way. When you lose a line, you’ll use anything to keep yourself attached to a pier, breakwater, tree, or other anchor point.

The strap has high windage Do not use it for a long line as we did. A three inch strap has a great deal more windage than a standard piece of rode and will twist and flap and fly in the winds. Cut the long line into chunks and use it for much shorter ties to pilings and dock cleats. Save your dock lines and anchor rodes for any stretches that must go over about 20 feet point to point. Alternatively, I think you could attach this to an anchor as a back up to a chain rode. In addition to providing a secondary hold, the wet weight and its resistance to movement underwater would help hold you down.

The strap doesn’t like knots The stuff is slippery. It likes to come undone. When you tie knots with it, add double, triple or even quadruple hitches.

My boat was saved during Jimena primarily because there were an incredible group of people on the docks throughout most of the storm attending the boats. You are only as safe during a storm as the weakest boat around you. Having said that, I credit our bridle strap and the long line to the off side breakwater for keeping my own boat precisely where I put her -- four feet off the docks and positioned precisely mid-way between two dock pilings.


Seven C's said...

One thing that we do when we use the 3" straps as tie downs is to pre-twist the straps. Each strap we give about 1/2 twist per 10' of lenght. This helps prevent the flapping as the wind speed increases. Not sure how it will react though to the distances that you had out.

Anonymous said...

Love your blog, hope to retire to a cruising cat I am going to build myself in about 10 years after my youngest is out of school. Have you considered taking random lengths of the strap and having a saddle maker or upholstery shop sew loops in the ends? This would eliminate having to tie it to go over a cleat or such, and larger loops could easily be made by slipping the loop backwards over the strap.

Desertbound Sailor

Behan said...

We too love this stuff and use it for a pile of things... it's the dinghy lift, it's a soft tie to hold our solent stay in place, etc etc etc. strong & versatile, and lacks the usual "Marine Markup"!