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propeller, revs. & speed |
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Pepote 
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Joined: 21 April 2015 Location: España Status: Offline Points: 37 |
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 Topic: propeller, revs. & speedPosted: 26 April 2015 at 17:43 |
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Hi All,
I recently purchased a Hanse 345 with engine Volvo D1-30, sail drive 130S and a fixed propeller, 2 blades, 16x13 a) What type of propeller you usually use on your boat?, b) the maximum rpm can get, and c) the
maximun speed, on calm conditions. |
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Jesús
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Fendant
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Joined: 03 November 2012 Location: Switzerland Status: Offline Points: 1671 |
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Posted: 27 April 2015 at 08:04 |
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Ola Jesus,
I also have the D1-30 with the factory supplied two blade folding prop: Here is the calibration curve for calm sea and no wind: RPM Speed kn 700 idle 2.5 1000 3.6 1500 5.2 2000 6.3 my "normal" most economic Speed, min specific fuel consumption 2500 7.3 3000 7.6 Have fun with the boat! |
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Pepote
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Joined: 21 April 2015 Location: España Status: Offline Points: 37 |
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Posted: 27 April 2015 at 15:00 |
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Hello Fendant, Thank you so much for your quick response and the details
you provides me. But I'd like to ask you something: As noted VOLVO, motor D1-30 has to reach a maximum of 3.200
rpm. Mine only gets to 3.000. Also yours? Kind regards. |
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Jesús
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Fendant
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Joined: 03 November 2012 Location: Switzerland Status: Offline Points: 1671 |
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Posted: 27 April 2015 at 18:13 |
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Honestly I haven't tried it with the new engine when I established the calibration curve. As the curve gets noticable asymptotic after 2500 rpm I considered the extra 10th of a knot beyond 3000 rpm as academic
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Frank
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Pepote
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Joined: 21 April 2015 Location: España Status: Offline Points: 37 |
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Posted: 12 May 2015 at 17:40 |
Hi Fendant, The curve isn't as asymptotic according to VOLVO technical data for D1-30 motor we have ... r/min 2.200 2.400 2.600 2.800 3.000 3.200 Crankshaft power (hp) 22,30 24,21 25,16 26,25 27,20 28,42 Propeller shaft power (hp) 21,41 23,24 24,15 25,20 26,11 27,29 Why give up that power in a "time of trouble"?. Regards
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Jesús
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Fendant
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Joined: 03 November 2012 Location: Switzerland Status: Offline Points: 1671 |
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Posted: 13 May 2015 at 06:48 |
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Hello Jesus,
sure the power output curve is more or less linear. The whole drive system however is dependent on the efficiency factor of the prop. This factor goes down with increasing prop speed, In addition to this the hydrodynamic resistance of the hull increases considerably when you approach hull speed. The result is that your speed/rpm diagram must be asymptotic. Edited by Fendant - 13 May 2015 at 06:50 |
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Frank
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panos
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Posted: 13 May 2015 at 13:49 |
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Things are not so easy!
The power produced by a Diesel engine is approximately linear function of rpm. The power needed to turn the propeller is quadratic - linear to the rpm squared. at some RPM the power output the engine and the power input of the propeller meet. This is a design criterion to select the propeller. Over this rpm the engine will be overpowered and the warranty void. So you don't want this RPM to be too low. Usually about 200 RPM lower than the max engine RPM is ok. Now suppose that your engine at 3000 RPM just about succeeds to turn the propeller without being overpowered. If you run the engine at a cruising speed of 2200 RPM the power output will be 2200/3200 or 69% less than the maximum while the propeller will only ( 2200/3200)**2= 47% of the maximum power. In other words the engine will be lightly loaded and possibly building up a carbon layer on the cylinders surface. This is the reason you do not want to select a small propeller. Edited by panos - 13 May 2015 at 13:51 |
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Panos
Hanse 630e - selling her - |
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CharlesP
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Joined: 23 September 2010 Location: United Kingdom Status: Offline Points: 1208 |
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Posted: 13 May 2015 at 14:13 |
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Panos said. "the engine will be lightly loaded and possibly building up a carbon layer on the cylinders surface. "
At what percentage of maximum power does the loading of the propeller on the engine change to an acceptable loading, which will not lead to carbon buil up. To my unmechanical mind, the 47% loading in the example, seems a reasonable load. Thanks Charles |
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'MERIDIAN LADY'
320 Nr 536 2010 Medway |
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Pepote
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Joined: 21 April 2015 Location: España Status: Offline Points: 37 |
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Posted: 13 May 2015 at 15:15 |
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Someone knows the speed of H345 hull design?
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Jesús
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Pepote
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Joined: 21 April 2015 Location: España Status: Offline Points: 37 |
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Posted: 13 May 2015 at 16:58 |
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Hi all, According to Volvo Penta, the D1-30 engine delivers the maximum power (hp 28.42 or 20.9 kW) at 3,200 rpm. The question is, ... Your ship, at full power, reaches those 3,200 rpm or only reaches 3,000 rpm ?. If so, obviously the propeller mounted on the H345 is not well calculated Someone knows the speed of H345 hull design . ?Regards
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Jesús
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. I would like know:
Fendant wrote: