Preparing Your Boat for a Tropical Storm

Posted by By Darrell Nicholson at 01:01PM - Comments: (7)

Boats doubled up on dock lines in local marinas as storm surge sets in.

If you haven’t given hurricane season a thought yet, you might want to start with our July 2008 report, “Lines, Snubbers, and Other Gear for Battening Down Ahead of Storms.” Technical Editor Ralph Naranjo’s first-hand account of his storm preparations “Tropical Storm Dos and Don’ts” and “How to Help Your Boat Survive A Major Storm” should also be required reading.

One storm-related product that has been sitting on (or under, to be exact) my desk for some time is a sample from of the Eco-mooring Rode developed by Dave Merrill Merril came by our office last winter while he was pitching his product to local marinas and municipalities—and dodging the chill of his home in New England. His company recently got a contract to install moorings in Provincetown, Mass.

Eco-mooring from uses a sheathed, elastic rode.

The Eco-mooring Road is effectively a super, heavy-duty bungy cord. It operates on the same principle as others like it, including the Seaflex Mooring System and the Hazelett Mooring System. These mooring rodes incorporate an elastic rode that allows mooring fields to pack more boats into smaller spaces. The elasticity also helps reduce shock on boat hardware. Merrill also sells a stretchy mooring pendant to incorporate into conventional chain moorings.

We haven’t yet tested these systems or taken a close look at their record in the field (the Hazelett has been around for some time), but the carnage caused here by a relatively weak tropical storm has bumped this test up on the “to do” list. Our most recent discussion of mooring holding power was published in 2009.

A couple other mooring-related products on our radar are the new helix-type mooring anchors offered by the same company that sells the Spade anchor in the U.S. We should mention that similar screws installed by a professional contractor here in Sarasota, Fla., ultimately failed to meet specified pull tests, so it is important to match the bottom type.

As marine surveyor Jonathan Klopman pointed out in response to our recent discussion of elasticity in anchor rodes, the topic of how much stretch is a good thing is a “hot” topic so to speak. Heat-induced friction in nylon rode, it seems is on everybody’s mind.

New England Rope's Cyclone Mooring Pendant incorporates two types of cordage.

Because of this, we are also interested in evaluating England ropes’ approach to storm moorings. In the New England Ropes system, the cyclone mooring pendant (set between the mooring ball and the boat) is made of two components—a length of low-stretch Endura 12 to handle abrasion on the boat and a high-grade nylon mooring pendant that goes from it to the mooring ball. New England Ropes has also launched a new line of chafe protectors, which we will be pitting against the best chafe protection from our last chafe-guard test.

There’s plenty to say about this topic, but the most important thing is this: The time to plan your hurricane strategy is long before the storm hits.

Comments (7)

The non-stretch bit of line through the chocks to reduce chafe by reducing motion is well-proven by rock climbers for over 50 years. Although the ropes they use are some of the highest stretch (to absorb shock), the short runners that go to anchor points have always been non-stretch to reduce chafe. When Dyneema arrived on the scene, it took over the market withing a few years and is now used almost exclusively. For heavy duty applications, it is sometimes covered with loose fitting (so it can move) tubular webbing chafe gear.

Motion through the chocks or over the roller is very bad. Many builders locate cleats well back from the bow for convenience, but that allows a lot of motion (resulting in friction) when nylon stretches under high load. It's not something you notice on a nice day.

Posted by: Drew Frye | June 10, 2017 8:40 PM    Report this comment

This article is mixing apples and oranges, starting with photos of boats tied to a dock and then a discussion about mooring buoy anchoring systems...they are very different. As someone who has successfully moored boats (San Juan 28 and Tayana Vancouver 42) to a buoy in Puget Sound since 1995 I have learned four things: 1.) A mooring is only as strong as its weakest part which can be as simple as 25 cents worth of seizing wire; 2.) It must be immovably secured to the bottom...anything that can drag will drag eventually and that includes concrete blocks; 3.) Like everything else, it will require periodic it simple enough to do yourself; and 4.) A multiple leg mooring system design has built-in backups should one leg fail, single leg systems do not.

~ ~ _/) ~ ~ MJH

Posted by: MJH | June 9, 2017 11:32 AM    Report this comment

PS July 2016 studied dockline forces and gave some examples based upon direct measurement. There were two basic recommendations: first, add a full compliment of spring lines (fore and aft on both sides) with just enough slack to allow for storm surge. They reduce the forces by reducing the motion of the boat in the slip and by sharing the load, and they add important redundancy if something fails. Because of the nature of fatugie and chafe, reducing force by 1/2 will increase line endurance by at least 10 times. Second, dock lines should be sized about the same as the anchor rode for storm use. See ABYC H-40 table 1 (the most commonly referenced guidance). Finally, chafe is a combination of many factors, not the least of which is the presence of sharp edge and abrupt turns through the chocks or on the dock edge. Use tubular webbing or other durable chafe gear, and keep the turns as gentle and few as possible.

Posted by: Drew Frye | June 8, 2017 1:35 PM    Report this comment

I'd like for PS to comment on correct sizing of anchor rodes and dock lines from the perspective that some stretch is desirable...but not so much to build up heat across a chock. Oversized lines give no protective shock absorption.

Posted by: Wayne Richard | June 8, 2017 8:50 AM    Report this comment

I'd like for PS to comment on correct sizing of anchor rodes and dock lines from the perspective that some stretch is desirable...but not so much to build up heat across a chock. Oversized lines give no protective shock absorption.

Posted by: Wayne Richard | June 8, 2017 8:50 AM    Report this comment

All good data. The fundamental violation I see repeatedly is boats left in slips or on moorings with sails still on roller furlers. You must absolutely take all sails off.

Posted by: MARK H | July 2, 2012 9:18 PM    Report this comment

Having had a brand new 1" bridle break, and the next year losing the boat to a sustained blow with new bridles, I can claim a certain experience. Here's what I discovered after making the changes and weathering Hurricane Irene's NE quadrant with just a little chafe. USE A LONG BRIDLE. Your boat cannot stay on a mooring if it rears up, instead of pulling back. We quadrupled the length. I was advised that the minimum length is 5 times the freeboard plus the distance from the chocks to the cleats. The boat is 43 feet long. In a storm, the front end goes up in the air ALOT! The line cannot make a turn in radius so small as that going over the edge of the deck or chock. If the boat pulls back, the radius is much bigger.

Posted by: David S | June 30, 2012 8:04 PM    Report this comment

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