I guess I don't understand why a person would spend the money for a marginal backup drive system when you could as easily just have another identical drive system. I can understand adding one to an existing boat. It also seems that using the gen to power it would require a much larger unit than would be otherwise neccessary, adding to the inefficiency. I haven't done the math, but am guessing that the difference in fuel economy between a single (with a ghd) and a twin powered boat would not be a big enough factor to justify the expense of the ghd, given the need for a larger gen, especially factoring in the added inefficiency. But I could be wrong. http://clk.atdmt.com/GBL/go/171222986/direct/01/

Hi Bob, I have to say I agree with this....i have not done the numbers yet either, but it will be an interesting comparison! Brian -----Original Message----- From: passagemaking-under-power-bounces@lists.samurai.com [mailto:passagemaking-under-power-bounces@lists.samurai.com] On Behalf Of bob england Sent: Monday, September 14, 2009 8:07 PM To: passagemaking-under-power@lists.samurai.com Subject: [PUP] Get home power I guess I don't understand why a person would spend the money for a marginal backup drive system when you could as easily just have another identical drive system. I can understand adding one to an existing boat. It also seems that using the gen to power it would require a much larger unit than would be otherwise neccessary, adding to the inefficiency. I haven't done the math, but am guessing that the difference in fuel economy between a single (with a ghd) and a twin powered boat would not be a big enough factor to justify the expense of the ghd, given the need for a larger gen, especially factoring in the added inefficiency. But I could be wrong. http://clk.atdmt.com/GBL/go/171222986/direct/01/ _______________________________________________ http://lists.samurai.com/mailman/listinfo/passagemaking-under-power To unsubscribe send email to passagemaking-under-power-request@lists.samurai.com with the word UNSUBSCRIBE and nothing else in the subject or body of the message. Passagemaking Under Power and PUP are trademarks of Water World Productions, formerly known as Trawler World Productions.

Twin engine trawlers, based on the empirical data I've seen with Nordhavns, get about 15% worse fuel economy than the same single. Some of that was measured very accurately when two Nordhavn 55's made the passage from the US to the Marquesas Islands run last year, departing at the same time. One was a twin and the other a single. Given that 10 to 20% is the usual fuel reserve planned, the twin was cutting it closer on fuel and had to go slower than the single-engine boat. Eventually the single was a couple of days ahead if I recall. That's two more days of weather exposure, etc. Also, whenever you have to change oil, filters, belts or do any other kind of engine maintenance, the twins double the work. Get home systems, whether they are wing engines or other drive systems, need relatively little maintenance other than to run them once in a while to make sure they are working. Initial cost is obviously a little higher. The single is just the ultimate in simplicity, cost, maintenance and overall efficiency. I've not much of a fan of get-homes that utilize the main shaft, preferring a completely separate system, but either one can do the job. But all that said, twin-engine trawlers do cross oceans and are becoming increasingly popular. But I still think its an unnecessary complication and complexity. John Marshall Nordhavn 55-20 Serendipity On Sep 14, 2009, at 4:06 PM, bob england wrote: > I guess I don't understand why a person would spend the money for a > marginal > backup drive system when you could as easily just have another > identical drive > system. I can understand adding one to an existing boat. It also > seems that > using the gen to power it would require a much larger unit than > would be > otherwise neccessary, adding to the inefficiency. I haven't done the > math, but > am guessing that the difference in fuel economy between a single > (with a ghd) > and a twin powered boat would not be a big enough factor to justify > the > expense of the ghd, given the need for a larger gen, especially > factoring in > the added inefficiency. But I could be wrong. > http://clk.atdmt.com/GBL/go/171222986/direct/01/ > _______________________________________________ > http://lists.samurai.com/mailman/listinfo/passagemaking-under-power > > To unsubscribe send email to > passagemaking-under-power-request@lists.samurai.com with the word > UNSUBSCRIBE and nothing else in the subject or body of the message. > > Passagemaking Under Power and PUP are trademarks of Water World > Productions, formerly known as Trawler World Productions.