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Hi to the moderator, This is not a complaint. I sent a message today. As you can see it was repeated 3 times. Am I doing something wrong? Thanks, Brian ----- Original Message ---- From: "power-catamaran-request@lists.samurai.com" <power-catamaran-request@lists.samurai.com> To: power-catamaran@lists.samurai.com Sent: Monday, January 14, 2008 9:00:05 PM Subject: Power-Catamaran Digest, Vol 35, Issue 15 Send Power-Catamaran mailing list submissions to power-catamaran@lists.samurai.com To subscribe or unsubscribe via the World Wide Web, visit http://lists.samurai.com/mailman/listinfo/power-catamaran or, via email, send a message with subject or body 'help' to power-catamaran-request@lists.samurai.com You can reach the person managing the list at power-catamaran-owner@lists.samurai.com When replying, please edit your Subject line so it is more specific than "Re: Contents of Power-Catamaran digest..." Today's Topics: 1. Re: fuel per horsepower (Brian Knesal) 2. Re: fuel economy (Malcolm Tennant) 3. Re: fuel per horsepower (Malcolm Tennant) -----Inline Message Follows----- What a great information stream! Malcolm if I might ask, I have some follow up questions: - If a one needs say 50 hp to move a cat at say 10 knots, what are the pros and cons of choosing a 75 hp engine over a 150 hp engine. -I have read that diesel engines should be run at approximately 70% of their rated horsepower. Why is that? -I have noticed the rating (200+ hp) of the Escape model is higher than I, the neophyte, would expect in an economical catamaran design. The graph I have seen shows this boat uses 1.5 liters per engine at 10 knots. Is it alright to cruise for long times at 10 knots with engines this big? I am looking for a catamaran design which will cruise a approximately 10 knots and have the ability to "run away" from weather at 17 knots. With that in mind, what size engines would you put on a boat design like the Escape? What are the design differences between the Escape and Ragtime models? While they are approximately the same length, the performance specs and recommended engines are different. Would the hp needs at 10 knots and 17 knots be similar for each model? Thank you in advance for the support and knowledge you bring to this group. It is appreciated! Brian Arild, It is 0.238l or 238ml. The system used is immaterial. What is important is that a 400hp engine will use roughtly the same amount of fuel to produce one HP/KW for one hour as a 50hp engine. As a designer I use the metric system because it is much easier and systematic than Imperial and I use grams instead of litres because I am constantly concerned with mass [weight/displacement]. Designers generally tend to have slightly different concerns to the everyday user. I hope this helps. Regards, Malcolm Tennant. ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ What a great information stream! Malcolm if I might ask, I have some follow up questions: - If a one needs say 50 hp to move a cat at say 10 knots, what are the pros and cons of choosing a 75 hp engine over a 150 hp engine. -I have read that diesel engines should be run at approximately 70% of their rated horsepower. Why is that? -I have noticed the rating (200+ hp) of the Escape model is higher than I, the neophyte, would expect in an economical catamaran design. The graph I have seen shows this boat uses 1.5 liters per engine at 10 knots. Is it alright to cruise for long times at 10 knots with engines this big? I am looking for a catamaran design which will cruise a approximately 10 knots and have the ability to "run away" from weather at 17 knots. With that in mind, what size engines would you put on a boat design like the Escape? What are the design differences between the Escape and Ragtime models? While they are approximately the same length, the performance specs and recommended engines are different. Would the hp needs at 10 knots and 17 knots be similar for each model? Thank you in advance for the support and knowledge you bring to this group. It is appreciated! Brian Arild, It is 0.238l or 238ml. The system used is immaterial. What is important is that a 400hp engine will use roughtly the same amount of fuel to produce one HP/KW for one hour as a 50hp engine. As a designer I use the metric system because it is much easier and systematic than Imperial and I use grams instead of litres because I am constantly concerned with mass [weight/displacement]. Designers generally tend to have slightly different concerns to the everyday user. I hope this helps. Regards, Malcolm Tennant. ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ -----Inline Message Follows----- Jonah Jones. Dear Jonah, The Petersens purchased the Chrysalis as a shell and finished it off themselves. So I really do not know what it cost. It may be possible to find out the fuel used to cross the Atlantic somewhere on their web site. I believe there was a mention somewhere that they had crossed to the Azores five days faster than a group of Nordhavns and had used half the fuel. Sorry I can't be of more help. Regards, Malcolm Tennant. MALCOLM TENNANT MULTIHULL DESIGN LTD PO Box 60513, Titirangi. Waitakere 0642 NEW ZEALAND Ph: +64 9 817 1988 e-mail: malcolm@tennantdesign.co.nz www.tennantdesign.co.nz www.catdesigners.com Jonah Jones. Dear Jonah, The Petersens purchased the Chrysalis as a shell and finished it off themselves. So I really do not know what it cost. It may be possible to find out the fuel used to cross the Atlantic somewhere on their web site. I believe there was a mention somewhere that they had crossed to the Azores five days faster than a group of Nordhavns and had used half the fuel. Sorry I can't be of more help. Regards, Malcolm Tennant. MALCOLM TENNANT MULTIHULL DESIGN LTD PO Box 60513, Titirangi. Waitakere 0642 NEW ZEALAND Ph: +64 9 817 1988 e-mail: malcolm@tennantdesign.co.nz www.tennantdesign.co.nz www.catdesigners.com -----Inline Message Follows----- Brian Knesal. I am not an expert on diesel engines, I rely on the advice of those who know. However I will try to anwer your questions. Generally you would choose an engine with just a little, say 10% more horsepower than you need for whatever is your top speed. This makes allowance for wind and waves but of course you usually slow down in the rougher conditions anyway. There really is no point in chosing an engine that has 3 times as much horsepower as you need. It is not uncommon for people to get a much larger horsepower engine than they need and then run it a very reduced revs in the belief that they are prolonging the life of the engine. This is not a smart move. it may invalidate your engine warranty and probably damage your engine. If you are doing long hours, long distances etc get a commercially rated engine. All this means is that the engine will then be governed and injected to develop its maximum horsepower at lower rpms with the result that the maintenance intervals will be longer. Aside from the "hand grenade" engines of dragsters, reciprocating engines cannot be run at full throtle for ever. The engines in the Escape are the size they are because it does 25 knots top speed in full load displacement. The HP, gearbox, reduction, propeller parameters etc are generally all based on top speed in full load. 10 knots is probably the worst speed you could possibly chose for the Escape. It is right on FN.4 for the hull ie: the point of maximum hull resistance. You would use less fuel at 15 knots. The Escapes ideal cruising speed appears to be 19 knots at which speed I believe it is using a total of 2.2 litres per nautical mile. The Escape is a more recent design than the RagTime and as such has a more refined hull form[ie more efficient] and has our contemporay wing deck structure and shape. Any differences are largely attributable to the Ragtime having 4 tonnes more full load displacement. They probably have different speed/length and displacement/length ratios. I hope this helps but you will need to consult a diesel engine expert for more detailed [accurate] information. Regards, Malcolm Tennant. MALCOLM TENNANT MULTIHULL DESIGN LTD PO Box 60513, Titirangi. Waitakere 0642 NEW ZEALAND Ph: +64 9 817 1988 e-mail: malcolm@tennantdesign.co.nz www.tennantdesign.co.nz www.catdesigners.com Brian Knesal. I am not an expert on diesel engines, I rely on the advice of those who know. However I will try to anwer your questions. Generally you would choose an engine with just a little, say 10% more horsepower than you need for whatever is your top speed. This makes allowance for wind and waves but of course you usually slow down in the rougher conditions anyway. There really is no point in chosing an engine that has 3 times as much horsepower as you need. It is not uncommon for people to get a much larger horsepower engine than they need and then run it a very reduced revs in the belief that they are prolonging the life of the engine. This is not a smart move. it may invalidate your engine warranty and probably damage your engine. If you are doing long hours, long distances etc get a commercially rated engine. All this means is that the engine will then be governed and injected to develop its maximum horsepower at lower rpms with the result that the maintenance intervals will be longer. Aside from the "hand grenade" engines of dragsters, reciprocating engines cannot be run at full throtle for ever. The engines in the Escape are the size they are because it does 25 knots top speed in full load displacement. The HP, gearbox, reduction, propeller parameters etc are generally all based on top speed in full load. 10 knots is probably the worst speed you could possibly chose for the Escape. It is right on FN.4 for the hull ie: the point of maximum hull resistance. You would use less fuel at 15 knots. The Escapes ideal cruising speed appears to be 19 knots at which speed I believe it is using a total of 2.2 litres per nautical mile. The Escape is a more recent design than the RagTime and as such has a more refined hull form[ie more efficient] and has our contemporay wing deck structure and shape. Any differences are largely attributable to the Ragtime having 4 tonnes more full load displacement. They probably have different speed/length and displacement/length ratios. I hope this helps but you will need to consult a diesel engine expert for more detailed [accurate] information. Regards, Malcolm Tennant. MALCOLM TENNANT MULTIHULL DESIGN LTD PO Box 60513, Titirangi. Waitakere 0642 NEW ZEALAND Ph: +64 9 817 1988 e-mail: malcolm@tennantdesign.co.nz www.tennantdesign.co.nz www.catdesigners.com _______________________________________________ Power-Catamaran Mailing List ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs

>This is not a complaint. I sent a message today. As you can see it >was repeated 3 times. Am I doing something wrong? I don't know why your message appears that way in the digest. In the archives, it shows only once: http://lists.samurai.com/pipermail/power-catamaran/2008-January/002344.html May have been some temporary glitch somewhere. Let's see if it happens again. --Georgs -- Georgs Kolesnikovs Power Catamaran World http://www.powercatamaranworld.com