GL: Hyper Mileing

[Luther]

Another monkey wrench please, what would be the outcome if one were to figure gph rather than mpg? I never relate to mpg on the water even when the charts indicate such. For fuel consumption I find gph much safer.


Luther


--- On Tue, 6/24/08, M S <valhalla360 at yahoo.com> wrote:

> From: M S <valhalla360 at yahoo.com>
> Subject: GL: Hyper Mileing
> To: great-loop at lists.samurai.com
> Date: Tuesday, June 24, 2008, 7:16 AM
> I'll throw a monkey wrench into the discussion:
>    
>   If you are in an area with no current or a current going
> with you, slowing down will improve fuel effiecency. If you
> are fighting a strong current (which is not always possible
> to avoid), faster may be more efficent. Example:
>    
>   Two Throtle settings with no current: 
>   2000rpm: 5 mph 1 gal per hour = 5 mpg
>   3000rpm: 8 mph 2 gal per hour = 4 mpg
>    
>   3 mph current against you:
>   2000rpm: 2 mph 1 gal/hr = 2 mpg
>   3000rpm: 5 mph 2 gal/hr = 2.5mpg
>    
>   Ideally you would develop a graph showing the
> relationship between speed, RPM and Fuel Consumption. By
> checking the difference between the GPS speed and speed
> thru the water, you could determine the most efficent
> cruise speed. Realistically, I use guesstimates. Trying to
> develop the graph mentioned would take a lot of time and
> effort and then as soon as a couple of barnicles sneak on
> board, the fuel level changes or wave action changes, the
> graph losses accuracy. 
>    
>   The other question is at what speed does it just start
> getting silly? Recently, I've had situations where I am
> at around 80% throttle and make 3.5 mph gps. If I ease up,
> I'm only going to make 1-2 mph. 
>    
>   I generally set my throttle and then if the speed drops
> below 4 mph gps I start throttling up to maintain at least
> 4 mph gps. If the current is going with me, once I get up
> to around 7.5 mph, I'll start backing off on the
> throttle rather than going faster (Recently coming down the
> Savanah River I was doing 7 mph with just enough throttle to
> maintain steerage. I'm guessing a little bit, but
> estimate I was getting around 30 mpg.). This maximizes fuel
> effiecency, while ensuring we are actually making some
> headway.
>    
>   Mike & Tammy
>   Valhalla II
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