PS Advisor February 2009 Issue

PS Advisor: Sea Anchor Sizing

As with most anchors, size does matter.

 

 

 

I read your interesting article, "Best Tested Sea Anchors," in the Feb. 1, 2005 issue. I applied the sizing tables from each of the manufacturers you cited, and came up with very different size recommendations. My vessel is 40 feet and 26,000 pounds. Fiorentino recommends a 12-foot Para Anchor, and Para-Tech recommends an 18-foot Sea Anchor. How do I know which size is right? Do these different size
Photo courtesy of Para-Tech

Deploying a parachute-style sea anchor—like this one made by Para-Tech—off the bow stabilizes a boat’s attitude to the wind in stormy conditions.
anchors really produce the same amount of drag?

 

Stan Weed
Twin Diesel Tollycroft 40
Via e-mail

 

 

 

While most sea anchor manufacturers may use similar formulas for determining the right size sea anchor for a boat, other factors must be considered, including the weight of the material used in the anchor and a boat’s windage. Ultimately, what matters is that the anchor can displace enough water mass for your size boat.

It’s a good idea to select a sea anchor, and then use that maker’s criteria to determine what size you need for your boat. If you have questions or concerns, contact the manufacturer for clarification.

According to Don Whilldin, president of Para-Tech (maker of the Sea Anchor), the company figures Sea Anchor sizing based on a boat’s length, displacement, and type. If the result is on the line between two sizes, Para-Tech recommends going with the larger size.

"We like to see the Sea Anchor (

 

 

www.seaanchor.com) displacing about two times the boat’s displacement," explained Whilldin. "A 12-foot Sea Anchor displaces 22,400 pounds of water; 15-foot, 43,800 pounds; and 18-foot, 75,700 pounds. It is the water mass which is holding the boat."

Practical Sailor

 

 

also spoke with Zack Smith of Fiorentino Para Anchors (www.paraanchor.com

). Smith maintains that rode tension is the big secret in successfully using and sizing a parachute sea anchor.

"Rode naturally stretches under force until it becomes taut. As force is reduced, rode becomes relaxed," Smith wrote us. "What we want to avoid is too long a period of rode slack because this leaves a vessel-swinging beam to, where waves can heavily roll the boat or in rare circumstances, cause it to fall back on the rudder(s)."

One way to get and maintain more rode tension is to deploy a larger anchor; however, this also makes retrieving the anchor more difficult. In order to get more tension out of a smaller anchor, Smith suggests paying out shorter lengths of rode, adding a small length of chain next to the parachute, or flying a riding sail to increase vessel windage.

For more on storm survival gear, check out Lin and Larry Pardey’s "Storm Tactics Handbook" (

 

 

PS, January 2009), which delves deeply into sea anchors, and our
sea drogues evaluation on pages 24-30 of this issue.

 

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