We at Glacier Bay would like to comment on some of the points in your recent article on electric propulsion (September 2008).
Regarding safety, the choice to design Glacier Bay’s system around a 240-volt DC buss was made for reasons of both safety and practicality. Increasing voltage reduces current and, with it, the risk of fire from overheated electrical connections. As for shock hazard, AC voltages above 50 and DC voltages above 80 are potentially dangerous. Unfortunately, the article leaves the impression that DC voltage is more dangerous than AC voltage. In fact, the U.S. Navy has found that DC voltage is five to six times less likely to cause fatality than the same AC voltage. Our system is based on the best practices of numerous standards for DC systems in other industries. We have been at the forefront in attempting to develop American Boat and Yacht Council (ABYC) guidelines for installations in yachts.
Regarding fuel efficiency, the similar fuel burns seen by the Maine Cat 41 with diesel-electric propulsion and the Maine Cat 45 with a 160-horsepower conventional diesel propulsion are exactly what would be expected. It is only under rougher sea conditions that the diesel-electric system will be more efficient than the conventional diesel system. (See our website, www.ossapowerlite.com, for more on this.) What was not clear in the article is that Maine Cat significantly modified the hull of the boat to improve performance between testing the Glacier Bay system and the Volvo diesels. We believe that the efficiency improvement with the Volvos is a result of the hull changes, not the engines.
Your article suggested that electric boats may be difficult to insure. Four insurance companies we recently spoke with all quoted rates for a 45-foot diesel electric catamaran in the same price category as a conventional diesel powered boat. They see diesel and diesel-electric as essentially equivalent power systems.
Obviously, Glacier Bay is a committed believer in the future of electric marine propulsion. In our view, electric technology will transform the boating experience every bit as much as the advent of the steam engine.
Chief Technology Officer,
Electric Propulsion II
I think your September 2008 articles on electric drives presented a excellent snapshot of this emerging diesel electric/hybrid/plug-in/regenerative market. There are a myriad of options now, and they need to be explored by the likes of Practical Sailor, so honest, objective facts can be put forward for the consideration of the sailing industry.
The state of the regulations will shortly change. The ABYC has been following these developments very closely, and the beginnings of standards for this industry are on the table right now.
I do disagree on one item in the article, and that is the relative safety between AC and DC current. They will both kill you when not handled properly and will do it very quickly. Also, in both cases, safe handling is just a matter of education and awareness. In the commercial world, high-voltage DC has been used extensively, and there are exhaustive procedures and regulations for them. I merely adopted those standards to my own system’s design. The ABYC will have the appropriate standards very soon.
In conclusion, cleaning up our waterways and reducing fuel consumption had to start somewhere, and I applaud those that have made the commitment.
Electric Marine Propulsion
Practical Sailorstill extends its open invitation to monitor a head-to-head comparison of system efficiencies with any maker of hybrid electric, diesel-electric, or other variation of electric propulsion. In our view, peak efficiency, ideally, should be achieved during those times a sailor is most likely to be motoring. Since our article, a few new products have come to our attention. California-based SolidNav (www.solidnav.com) recently introduced an electric motor replacement for a 24-horsepower diesel and a long-shaft electric outboard, both operating at 48 volts.
Austrian company Steyr Motors recently introduced a 7-kilowatt integrated hybrid motor with a built-in 48-volt motor/generator. Bolted in line with a conventional diesel, the motor couples and de-couples the engine to permit low-speed electric maneuvering at the dock, pure diesel propulsion, or "boost mode" diesel-electric cruising at moderate speeds. According to the company, the motor can also serve as a starter and generator,
I want to put jacklines on our IF41. Can I use the 1-inch nylon webbing sold at the fabric stores for about $1 per yard? I have heard about buying tube webbing at the local chandlery. What’s your advice?
Penny and Tom Dalgliesh
Both polypropylene and 1-inch tubular nylon webbing should be avoided for jackline use. Polypropylene is not nearly as strong as polyester and suffers greatly from UV degradation. One-inch tubular nylon webbing—breaking strength 3,600 pounds—is very elastic and does not meet International Sailing Federation (ISAF) minimum strength requirements. InPS tests ("Hooked Up: A Guide to Jacklines," April 2007), a 190-pound crew member was dragged astern from 25-foot jacklines made of 1-inch, 3,600-pound tubular nylon webbing, and 1-inch, 6,000-pound West Marine polyester webbing. The nylon webbing stretched 6 percent when dry and 7 percent when wet, while the polyester webbing stretched less than 1 percent, wet and dry.
Bit For a Winch
I am interested in pursuing using a heavy-duty cordless drill to help raise the mainsail. I would appreciate what help you could give me finding a source for a driver bit to fit in a drill chuck that would mimic the business end of the winch handle.
David H. Brown
Reader Paul Carlson helped us locate a couple of bits that will fit a heavy-duty, cordless right-angle drill—the Milwaukee 0721-20 is suggested—and be used to power a manual winch. There is the WinchBit ($45,www.winchbit.com) and the Cranker at ($20, www.thecranker.com).
Scott Karlin, president of Windswept Marine, which markets the drill-powered Rotowinch (www.rotowinch.com), warned that if the drill is suddenly reversed to shift gears on a two-speed winch, the locking pin on the chuck might break, causing the chuck to loosen and spin off.
PSdoes not usually endorse using a product for something it wasn’t intended, and cautions readers against using a drill-driver to hoist someone aloft. PS has noted two potential problems with these and similar devices: a sail rips because the person at the winch is monitoring the drill instead of sail trim, or a halyard used to hoist someone aloft jumps from the grip of a self-tailing winch.
FireHose for Chafe Gear
We went to our local marina’s hurricane preparedness seminar last summer. It was an outstanding seminar. One of the things they recommended was the use of old firehose as chafe protection. I know from past articles that you folks don’t recommend PVC hose, as it tends to trap the heat in and prevent rainwater from cooling the lines. What is your thought on firehose? The hose in question looks like it’s probably a 2-inch inside diameter—certainly several times larger (in volume) than my 3/4-inch dockline.
San Antonio, Texas
Firehose does resist abrasion and is commonly used as chafing gear. It does, however, have the same drawback as PVC hose: It can trap heat. Ideally, chafe gear should be permeable to water, which will help reduce friction heat, both external to the rope and between fibers. Water, particular salt water, can be detrimental to rope performance, but in our view, its cooling ability offsets any drawbacks. Stitched leather and denim are good, inexpensive choices.
I purchased a Newmar PT-25 charger for about $300, and it failed about one month ago, less than three years after purchase. The unit was kept inside, away from any weather, without salt. When I contacted Newmar, they wanted $250 to repair and ship the unit. This is too expensive a service for a unit of that age and price range.
1976 Paceship 26
Cocoa Beach, Fla.
We spoke with Newmar, and they requested that you ship them the unit for inspection. Technicians there traced the problem to a fuse/breaker within the unit that is not user-serviceable. Although your charger was out of warranty, Newmar agreed to replace the unit (except for the existing stainless-steel case) free of charge. Newmar encourages all owners to follow the guidelines in the owner’s manual to ensure proper installation and protection from power surges, common at some marinas.
At Burning Man
Let me report that the performance of the 5MileWiFi (www.5milewifi.com) wireless networking (Wi-Fi) antenna lived up to its expectations at the 2008 Burning Man Festival (www.burningman.com) in Black Rock City, Nev.
The antenna was mounted on a 2-by-2 some 14 feet above the hot desert floor. Before connecting it, I was able to see only a single Wi-Fi hotspot. After hooking it up, I pulled in a full nine of them. Half were secured, but the rest were not. Signal strength ranged from a single bar to a full five bars.
Getting into a router took more time due to the many "Burners" interested in the same thing I was—getting out. Once linked out, I had very good performance over the 5MileWiFi antenna. Skype performed quite well, although at times there was notable lag in transmit and receive times due the weaker links in the system beyond the antenna. Gerlach, Nev., the closest "town" (population about 35) is not exactly Cyber-City. I am a satisfied customer. Next, the antenna goes onto the mast of Futhark, up some 8,000 feet on Lake Granby in the Colorado Rockies. You can expect another report once I’ve run it up the stick.
Futhark, Nor’Sea 27
Thank you for your report. This was the first time, that we are aware of, that the Burning Man Festival has been a test venue for sailing equipment. While the editor continues his so far fruitless bid to get funding for a followup test at next year’s festival,Practical Sailor’s upcoming evaluation of the 5MileWiFi takes place in a more typical marine environment.
Whale Inlet Valves
I have two Henderson (now Whale) MkV discharge pumps on board, each in need of new inlet and outlet valves. Suppliers offer rebuild kits that include everything but the housing and the pump handle, costing around $60 each. I now own multiples of Henderson/Whale MkV parts that I’ll never use because I’ve replaced the $3 rubber check valves several times, having to buy the whole kit on each occasion.
38 Nauticat Seattle, Wash.
We agree that $60 is too much to pay for a simple inlet valve. Unfortunately, bundling similar parts into kits is common practice, particularly among parts for pumps and heads. Whale explained that during normal use, the parts in the valve kit should wear slowly and at the same rate, so if one part needs replacement, the others are probably due to be changed, as well. If, however, the pump is used with a Lavac toilet (www.lavac.com), as is common, the valves will wear out faster than usual. The pump is not recommended for this use. Valves for Edson manual pumps (www.edsonnpumps.com) are sold separately for about $25.
Anchor Holding Power
I much appreciated your anchor article in the recent issue ("Rock and Roll," November 2008). I do not, however, understand the logic behind your decision not to test holding ability. Just because you have a boat large enough to carry a 100-pound anchor does not mean you can ignore holding ability. On the contrary, the required holding force goes up as the square of the boat size increases.
In the U.S. Sailing tests of which Practical Sailor was a participant, both in Puget Sound and San Francisco Bay, the Bruce showed itself to have superior setting ability but poorer than average holding ability. Now that Bruce is gone, it would be great to learn that one of the clones wins on both setting and holding ability.
As mentioned in the article, this was a rare opportunity to focus on setting ability in extreme bottoms. The logistics of carrying out holding-power tests in that location proved problematic. We will be testing holding ability again in a more practical environment. Past testing of the Bruce leads us to believe that the pound-for-pound holding power of the Manson Ray may not match that of leading plow-style anchors in sand bottoms. The testers also questioned the scalability of the design, meaning that although large Bruce-style (claw) anchors may have excellent holding power among anchors of similar size, smaller anchors (less than 44 pounds) may not.