[PCW] fuel per horsepower

[Brian Knesal]

 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.


 





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