Mailport: DSD; PFD Testing; Water Purification; Rewiring; Air Conditioning at Anchor


DSC for MOB rescue

Like Tom Taylor and Joseph DiMatteo (see Mailport PS August 2019), Ive stopped using inflatable PFDs and instead wear inherently buoyant foam versions. I found that ones designed for dinghy sailing are often very comfortable and have convenient pockets for knives, whistles, flashlights, and even handheld VHFs (I keep one with GPS and DSC on myself, especially when single-handing).

My main disappointment is that I cannot find foam PFDs that also have harness rings built in. When I want to clip on to jack lines, I need to swap the inherently-buoyant PFD with a harness or an inflatable harness/PFD. I presume that the USCG has not approved any foam PFDs with built-in harness rings, but I wonder if Practical Sailor or any of its readers have any suggestions.

Sam Lord
Don Miguel, Catalina 34
San Francisco, CA

PS reader Sam Lord furls the main abroad his Catalina 34 Don Miguel.


We have had more than a half dozen PFD clinics in Chicago in the last few months. The one I attended included representatives from the three major inflatable PFD manufacturers. We include more abbreviated information in our clubs Crew School. Everybody is paying better attention. The manufacturers representatives at the clinic said they do not recommend activating the CO2 self-inflation system during routine inspection, or for checking operation. (I spoke to one retired and one active Coast Guard service member about using the CO2 pull-handle for testing and they said they do it all the time.) We pulled the handle on an expired Hammar inflator as part of a demonstration in Crew School. I figured Id leave it inflated for 24 hours to check for leaks. In fact, it deflated observably in less than 24 hours. But then I re-tested, inflating orally. Inflated this way, it seemed to hold the pressure indefinitely. So either higher pressure from the CO2 cylinder over-stressed a seal in the PFD causing it to leak, or orally inflating enabled the seal to seat better. If the seals don’t seat, thats another reason to do the regular oral inflation test.

Dave Brezina
Tartan 10
Montrose, IL

Shungite Water Purification

Some multihulls require very little modification to make excellent rain catchers.

Regarding your report on rain-catching (see PS December 2012, The Raincatchers Guide), our catamaran has a rainwater collection Bimini and the water passes through a filter en route to the tank. However I suspended a mesh bag of Shungite in the tank to make sure. It is a mineral mined in Russia that Roman soldiers added to their water bags. I remove the collection hoses when not in use since loops cannot be avoided and do not connect until after an initial rain has rinsed the Bimini off. Even so, we have an RO water-maker.

Grant Nele
Amaleo, Kennex 38
St. Petersburg, FL

We have no experience with the high-carbon content mineral shungite, but we have tested a variety of filters that use activated carbon (see PS June 2012, Water Filters).

Rewiring Made Easy

I am an ABYC certified electrician and have been using 1 x 19 rigging wire for decades. It is far superior to anything I have found commercially. I crimp a small copper ferrule to each end to keep it from unwinding. Then I round the ferrule on a grinder so it slides through more easily. Also, I never used liquid soap or thick lube. These items congeal, gum up the works, and can attract and hold dirt and debris. I spray the 1 x 19 with T-9 while it is coiled and do the same thing with the cable I am pulling­-especially transducer cables. I not only fish the cable but protect and clean the chase at the same time. I have been at this for 37 years and have never had to cut a transducer cable and can count on one hand the number of RJ45 connectors I have had to cut. Beware: The color sequence of an RJ45 connector is usually reverse of what it is on the other end. These can be a real challenge.

Ed Wiser
ABYC/NMEA certified Electrician
Punta Gorda, FL

Air conditioning at Anchor

Regarding your recent article on the Velair air conditioner (see PS August 2019), any way you slice it, running an AC unit on a boat or RV using battery alone is, in a practical sense, an impossible task. The engineering numbers done properly simply do not add up. You would not even get one short night out of the average battery bank.

Gary Wiseman P. Eng,
M. Eng. Marine Engineering,
M. Eng. Naval Architecture

Thanks for your letter. We received this response from the author of the article, technical editor Drew Frye:

Yes, the Velair unit is a 120 V, not 12-volt, and we have since clarified this in the article. We also explained in the June 2019 report that a 12-volt air conditioner actually would not be of much benefit, since the 12-volt components are generally less efficient. Indeed, in theory, it would seem that running an air conditioner on battery power alone would seem improbable for many boats-and there are strict limitations. In practice, however, we and many others have been able to accomplish this in moderate climates with a well-designed charging system, BIG battery banks (lithium helps), and by working within the strict limitations of the system.

A few formulas and rough conversion factors will keep the discussion moving forward. Battery capacity varies with temperature and rate of draw down. Voltage varies with the battery state of charge and rate of draw down, and charge controller and inverter efficiency influence power conversion efficiency, but they are close enough for discussion purposes.

The focus is simplicity. In practice, add 30 percent or more battery and charging capacity to make up for approximations, battery aging, and inefficiencies in charging.

Watts (W)=volts (V) x amps (A). Since the AC voltage is about 10 times the DC voltage, but there a 5-7 percent loss in the inverter. As an approximation assume the 12-volt DC draw will be 11 times the 120V AC draw.

Amp-hours (Ah) at 12 volts is related watt-hours (using the device for an hour) by Ah = Watt-hr/12. An air conditioner rated at 1,000 watts draw will draw about 90 Ah from the batteries when running full time. It will typically run full time for during the day and for 1-2 hours cooling the boat down, but will run far less at night.

Is it practical for the average boat to run AC on batteries? Not really, and we said that. My original article (see PS June 2019) included a discussion of the inefficiencies mentioned above. Obviously, batteries age and that needs to be accounted for as well. However, what many have overlooked is that the AC runs at full load only when cooling a hot boat. Once the boat is cooled down, and specifically at night, the load can be several times less, and this is what we have experienced. The AC cycles, and it is actually off most of the time.

Thus, although it is impractical to air condition a boat during the day without a large generator, it may be practical for a boat with a good power system to use AC only in the sleeping cabin during sleeping hours. This is, in fact, proven. I often ran the AC for several hours in the morning, after leaving the dock, because the family was sleeping in. The cabin was already cool, so the load was light until the sun got high.

The 250 Ah battery bank we gave for our example is actually small for many cruising boats; my cat had that much. Many cruising boats have 2-3 times that battery capacity.

No doubt AC at anchor is impractical for many boats. It would be impractical on my F-24. It was practical, and in fact practiced, on my PDQ catamaran. If I had wanted to do it more regularly and for 8 hours, I could easily have increased my solar and added several more batteries. I probably would have, had I not sold the boat. It had a very well designed power management system.

Fin Delta

I am writing with a full endorsement of the Fin Delta Riding Sail. My schooner, a 57-foot Nigel Irens Design, has a fair amount of forward windage due to the big, unstayed, rotating carbon fiber masts relatively forward. She, Farfarer, can motor around a lot.

I purchased a Fin Delta and found it worked great. In August, 2011, we had a bit of a Southeast blow here in Maine. Winds to 50 knots, gusting. She rode fine in the harbor.

You say in the story that the riding sails should be somewhat offset from the centerline. That is not true for the Fin Delta, and, in any case, is rather problematic to me. The Fin Delta two tails are already offset.

Frank Blair
Farfarer, Nigel Irens 57
St. Georges, ME

Chafe gear Update

The Goyer Chafe gear featured in the August issue is no longer available. Practical Sailor apologizes to readers for any inconvenience. A long-standing manufacturer of chafe gear, Fjord, does make a polyurethane-coated commercial version of a chafe protection product that weve tested rigorously. Our report on chafe in this months issue (see PS October 2019 Revisiting Chafe Protection Options) has prompted a closer look at using Climb-spec webbing combined with RP-25 coating as a viable DIY option. Also see PS October 2012 for more details on this and other products-as well as DIY solutions-that will help protect against chafe.

Get More PS at PS Online
Mailport: DSD; PFD Testing; Water Purification; Rewiring; Air Conditioning at Anchor

Fall is a good time to tackle do-it-yourself projects and onboard maintenance or systems upgrades. It’s also when many of us will shop for that next “new” boat.

Do It Yourselfers

Here are a few worth DIY projects tackling in the off-season. We detail building a simple winter boat cover frame in the September 2011 issue. For those with tired-looking decks, be sure to check out our reports on nonskid options for the do-it-yourselfer (PS November 2013); these include mats and paints. Have an electronics installation or rewiring project on tap? Get some pro tips for rewiring (PS July 2016). If you’re looking for a boatyard where you can actually do the work yourself while hauled out, you can find a rundown of DIY-friendly boat yards (PS June 2009), as well as a list of reader-recommended DIY yards in the Oct. 29, 2013 Inside Practical Sailor blog post. Other good cool-weather projects worth considering: fuel tank cleaning (blog post, June 6, 2018), sail cleaning (blog post, Dec. 6, 2016), making your own chafe guards (PS July 2011), and building your own dinghy wheels (blog post, August 15, 2017).

Boat Shopping?

In the market for a new-to-you boat? We highly recommend reading our checklist for DIY boat surveys (PS June 2012 online) and our “Sailor’s Guide to Marine Insurance” (PS October 2012 online). Cruisers should also be sure to check out the April 2009 issue’s look at cruising boats over 35 feet long and under $75,000, “Affordable Cruising Sailboats.” If you’re considering a boat that’s well-weathered (or possibly storm damaged), the January 10, 2017 blog, “Buyers Beware of Post-storm Bargains,” is also useful.

PS’s Exclusive Ebooks

PS has a growing library of exclusive ebook offerings in our online bookstore ( The ebooks, compilations of many PS articles, offer comprehensive coverage of topics in a convenient-to-read package. You can immediately download the
ebooks to your computer upon purchase to have them always at your fingertips. The most popular
ebooks include our marine cleaners series (essential and specialty cleaners and gelcoat maintenance and restoration); marine sanitation systems series (toilets, holding tanks, plumbing, odor control, etc.); anchoring series (anchor test findings, chain and rode tests, and rode accessories); sails series (mainsails, headsails, specialty sails, and furling gear); and survival series (life rafts, ditch kits, first aid, electronics, etc.).

Darrell Nicholson, editor of Practical Sailor, grew up boating on Miami’s Biscayne Bay on everything from prams to Morgan ketches. Two years out of Emory University, after a brief stint as a sportswriter, he set out from Miami aboard a 60-year-old wooden William Atkin ketch named Tosca. For 10 years, he and writer-photographer Theresa Gibbons explored the Caribbean, crossed the Pacific, and cruised Southeast Asia aboard Tosca, working along the way as journalists and documenting their adventures for various travel and sailing publications, including Cruising World, Sail, Sailing, Cruising Helmsman, and Sailing World. Upon his return to land life, Darrell became the associate editor, then senior editor at Cruising World magazine, where he worked for five years. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.


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