Why do we get bogged down with SOG

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scottie

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I think that we all get carried away with the occasional high SOG that make our day but it would seem that many posters do not understand the difference between speed over ground and speed through water .
I also find it amusing the number of claims that such and such boat with X hp can achieve Y speed using Z amount of fuel
I was taught that for cruising purposes that one gallon of fuel gave 10hp per hour with petrol and 20 hp with diesel and I do understand that engines have got much more efficient but not 20 for petrol yet !
Rant over !
 
Horsepower per hour is a strange unit, rather like the ubiquitous Amps per hour. I'm trying to comprehend when rate of change of power would be useful. Maybe the electricity supply people need to know the rate of increasing electricity generation when everyone gets up in the morning.
 
scottie said:
I think that we all get carried away with the occasional high SOG that make our day but it would seem that many posters do not understand the difference between speed over ground and speed through water .
I also find it amusing the number of claims that such and such boat with X hp can achieve Y speed using Z amount of fuel
I was taught that for cruising purposes that one gallon of fuel gave 10hp per hour with petrol and 20 hp with diesel and I do understand that engines have got much more efficient but not 20 for petrol yet !
Rant over !
Click to expand...

What colour is the sky on your planet?
 
For most cruisers speed through the water is irrelevant. SOG is the only thing that will get you somewhere in time to creep over a sandbank, get in a half tide Marina or to the pub before it shuts. Anyway it's more fun to see 7.5 knots on the dial even if you know there's a couple of knots of tide.

Go sailing and relax.
 
MoodySabre said:
For most cruisers speed through the water is irrelevant. SOG is the only thing that will get you somewhere in time to creep over a sandbank, get in a half tide Marina or to the pub before it shuts. Anyway it's more fun to see 7.5 knots on the dial even if you know there's a couple of knots of tide.




Go sailing and relax.
Click to expand...

Just back from a week away best sailing for years now stuck at home doggie sitting for my daughters 2 collies and a cat and you ask why I am posting a rant?
 
scottie said:
...
I was taught that for cruising purposes that one gallon of fuel gave 10hp per hour with petrol and 20 hp with diesel and I do understand that engines have got much more efficient but not 20 for petrol yet !
Rant over !
Click to expand...
That'd be half a gallon of diesel an hour for a 10 hp engine - I hope not. My 8hp Farymann will run for an hour if you fart in the tank.
 
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