On Wed, 11 May 2005 15:01:56 -0400, Mike G
wrote:

In article ,
says...
I had a debate with a friend this morning concerning miles vs gallons
per hour.

I contend that gallons per hour is a more reliable method of
determining how far and fast a boat can/should go. Obviously, my
friend took the opposite viewpoint.

What is the collective wisdom concerning these measure of fuel
efficiency?

Actually, as stated I'd have to opine the gallons per hour was almost
right or rather only part of that side of the argument.

I'd would think gallons per hour at X rpm is much more accurate for a
boat. With all the variable forces acting on a boat in motion, hull and
upper works design, wind, or current, for example

A boat at, say, 3500 RPM isn't going to cover the same distance with a
head wind and cross current as a boat with a tail wind and following sea
or one in a dead calm and glass smooth surface. The only constant you
can really use to figure your range at any specific time is the is the
fuel consumption at that RPM rate.

Let's say your favorite fishing grounds is, under ideal conditions, a
two hour run at the boats ideal cursing speed/RPM. That makes things
easy but how often are you going to find ideal conditions that will
allow you to run at your best cruising speed/RPM with no external
variables to figure in. Once you get past the break water the whole
thing is a crap shoot till you get your RPM's up to where you are
getting the best ride. That may or may not be at your ideal cruising
speed, may or may not be covering distance over the ground at the same
speed as you would in ideal conditions. Again, the constant, RPM.

Hell you can't accurately tell what one automobile will really give you
in miles per gallon. It all depends on how much of a lead foot the
driver is, traffic and weather conditions. You take an EPA rating on a
new car and some people are going to be able to better it some not even
get close. That's why they call them estimates and your mileage may
vary.

I agree with you, but for a different reason.

My argument is that GPH is a more reliable measure of efficiency
because it covers the spectrum from sitting at the dock warming up to
running full throttle. For example, my Ranger with the 200 FICHT
averages 5 to 6 gallons per hour considering everything. At cruise,
which is about 35 mph, it's about 8 GPH and that seems to be pretty
consistent in most sea conditions. The base is 8 GPH and from there I
can figure MPG - believe this or not, I just typo'd MPH :). So the
way I look at it, GPH is essential to determining MPG and thus the
more relevant factor in determining efficiency.

We argued this for a freakin' hour this morning. :)

Of course, he's a physicist - dumbass. :)

Later,

Tom

On Wed, 11 May 2005 15:07:02 -0400, John H
wrote:

On Wed, 11 May 2005 16:50:28 GMT, Shortwave Sportfishing
wrote:

I had a debate with a friend this morning concerning miles vs gallons
per hour.

I contend that gallons per hour is a more reliable method of
determining how far and fast a boat can/should go. Obviously, my
friend took the opposite viewpoint.

What is the collective wisdom concerning these measure of fuel
efficiency?

Later,

Tom

If they're both accurate, then they're both reliable. Most of my boating is
cruising to get to the fishing area and then trolling for however long I'm going
to do it, and then cruising back. I figure 8gph cruising and 2 gph trolling.
This morning I cruised about an hour, total, and trolled for about an hour.
(Took that long to catch a 38"er and a 36"er.) So, I figured I burned about 10
gallons, or $25 worth of gas. We split the gas amount.

I'd say the most reliable way is to use a flow meter, but I haven't put mine in
yet.

I don't have one on the Ranger, but I do on the Contender. Of course,
I have no idea what the GPH figure is on the Contender BECAUSE THEY
HAVEN'T FINISHED INSTALLING THE FREAKIN' THRU-HULL AND OR PAINTED THE
BOTTOM!!!!

AARRRGGGHHHH!!!!

Later,

Tom

On 11 May 2005 12:56:41 -0700, "Camilo" wrote:

~~ snippage ~~

My only reason to have a flow meter on my boat (GPH) is to ultimately -
through a mental calculation- determine the most efficient speed, in
other words, the speed that maximizes MPG.

Nowadays, it becoming more common have the flowmeter GPH input to the
GPS's MPH measurement to give you an MPG reading on your GPS screen.
If I could afford a new unit, I would definitely get that feature -
because again, that's the only reason to measure GPH in the first place.

I mean no offense here. Don't get upset - just follow me through
this.

To do a MPG calculation you basically need to know how many miles you
have traveled. Which means that you either need to know that by
experience or stop to use a chart or take a measurement with a GPS.

Now, you already know how many gallons you are using per hour. So all
you need to do is know how much gas is in your boat and how many hours
you have been traveling.

That seems a hell of a lot easier than doing arithmetical calculations
on the fly.

And just to add a complication, let's say that your GPS is kaput for
some reason. You have no idea how many miles you have traveled, but
you have a good idea of how many gallons you have left and how much
time it takes to return. That's a GPH calculation, yes?

Later,

Tom

On Wed, 11 May 2005 21:26:39 GMT, Gene Kearns
wrote:

On Wed, 11 May 2005 16:50:28 GMT, Shortwave Sportfishing
wrote:

I had a debate with a friend this morning concerning miles vs gallons
per hour.

I contend that gallons per hour is a more reliable method of
determining how far and fast a boat can/should go. Obviously, my
friend took the opposite viewpoint.

What is the collective wisdom concerning these measure of fuel
efficiency?

Hmmm.. there seems to be some games with semantics, here, but my take
is that an engine can be expected to consume X gallons of fuel per
hour to develop Y horsepower. One may then calculate the "miles per
gallon" figure, but I fear it is of more interest to the marketing
department than the practical boater.

For example, a boat traveling into a 15 mph current at 15 mph could be
expected to get 0 miles per gallon, but would reasonably be expected
to burn Y gallons per hour developing the requisite horsepower to
maintain 15 mph....

So, Tom, I'm with you on this one, since we are traveling in a movable
liquid and at the mercy of the wind. Get a totalizer... at least
you'll know where you stand and how far off shore you are likely to
run out of fuel....

I think the GPH side has won the day.

Therefore, I RULE!!! :)

Later,

Tom

On Thu, 12 May 2005 00:08:02 GMT, otnmbrd
wrote:

Both terms can be useful, especially for planning purposes, and when
used together.
If you have an engine with known GPH at specific rpm's (+/- a small
percentage) you can easily plan ahead for consumption and reserves for a
specific distance at various speeds or for days of operation (where
mileage isn't a consideration) before needing to "watch for a gas station".
Although MPG/MPH is great for planning, it doesn't take into
consideration that it's "through the water", so that even when connected
to a GPS, the number will vary up and down.
In the end, a lot depends on type of boat, type of operation, and route
to be traveled.
To be honest, I'd use both for comparison. Most ships use B/M
(barrel/mi) with a reserve of 2-3 days .... always calculate some degree
of reserve.

Good points.

Later,

Tom

Actually it is neither in this particular case.
If I am so stupid as to head out on a lake/river that I don't know without a
chart or gps and I did not fill up my gas tank before leaving but I kept up
w/ my time at various rpms then GPH at each of these rpms would mean
something.
On the other hand, assuming I at least filled the gas tank, as long as I
have over 1/2 tank left (not what the needle says but actually 1/2 tank) I
should be able to get back as long as I don't run any harder than I did
getting to where I am.

I use MPG as an overall average but GPH as an overall average works out to
be the same thing.
MPG I know I can run for 2.5 miles per gallon of fuel on average (averaging
40 miles per hour). This of course changes if I run wide open for long
periods of time or idle along.
GPH I know I can run one hour on 16 gallons of fuel on average (averaging 40
miles per hour). This of course changes if I run wide open for long periods
of time or idle along.

Both work just as good.
--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"Shortwave Sportfishing" wrote in message
...
On 11 May 2005 12:56:41 -0700, "Camilo" wrote:

~~ snippage ~~

My only reason to have a flow meter on my boat (GPH) is to ultimately -
through a mental calculation- determine the most efficient speed, in
other words, the speed that maximizes MPG.

Nowadays, it becoming more common have the flowmeter GPH input to the
GPS's MPH measurement to give you an MPG reading on your GPS screen.
If I could afford a new unit, I would definitely get that feature -
because again, that's the only reason to measure GPH in the first place.

I mean no offense here. Don't get upset - just follow me through
this.

To do a MPG calculation you basically need to know how many miles you
have traveled. Which means that you either need to know that by
experience or stop to use a chart or take a measurement with a GPS.

Now, you already know how many gallons you are using per hour. So all
you need to do is know how much gas is in your boat and how many hours
you have been traveling.

That seems a hell of a lot easier than doing arithmetical calculations
on the fly.

And just to add a complication, let's say that your GPS is kaput for
some reason. You have no idea how many miles you have traveled, but
you have a good idea of how many gallons you have left and how much
time it takes to return. That's a GPH calculation, yes?

Later,

Tom

In article ,
says...

I had a debate with a friend this morning concerning miles vs gallons
per hour.

I contend that gallons per hour is a more reliable method of
determining how far and fast a boat can/should go. Obviously, my
friend took the opposite viewpoint.

What is the collective wisdom concerning these measure of fuel
efficiency?

Later,

Tom

Gallons per hour can determine work output only. If you rope
the boat to the dock, and burn 20 gallons per hour, what does
your numbers say about that?

I know when the gas guage stops bouncing, I need to be near a gas station.

"Shortwave Sportfishing" wrote in message
...
On 11 May 2005 12:56:41 -0700, "Camilo" wrote:

~~ snippage ~~

My only reason to have a flow meter on my boat (GPH) is to ultimately -
through a mental calculation- determine the most efficient speed, in
other words, the speed that maximizes MPG.

Nowadays, it becoming more common have the flowmeter GPH input to the
GPS's MPH measurement to give you an MPG reading on your GPS screen.
If I could afford a new unit, I would definitely get that feature -
because again, that's the only reason to measure GPH in the first place.

I mean no offense here. Don't get upset - just follow me through
this.

To do a MPG calculation you basically need to know how many miles you
have traveled. Which means that you either need to know that by
experience or stop to use a chart or take a measurement with a GPS.

Now, you already know how many gallons you are using per hour. So all
you need to do is know how much gas is in your boat and how many hours
you have been traveling.

That seems a hell of a lot easier than doing arithmetical calculations
on the fly.

And just to add a complication, let's say that your GPS is kaput for
some reason. You have no idea how many miles you have traveled, but
you have a good idea of how many gallons you have left and how much
time it takes to return. That's a GPH calculation, yes?

Later,

Tom

Around 5/11/2005 5:20 PM, Shortwave Sportfishing wrote:

On Wed, 11 May 2005 15:01:56 -0400, Mike G
wrote:

I'd would think gallons per hour at X rpm is much more accurate for a
boat. With all the variable forces acting on a boat in motion, hull and
upper works design, wind, or current, for example
snip

I agree with you, but for a different reason.

My argument is that GPH is a more reliable measure of efficiency
because it covers the spectrum from sitting at the dock warming up to
running full throttle.
snip


I like GPH just because I know that after about two hours of cruising,
it's time to switch to the other tank. MPG (as measured with a GPS)
isn't nearly as consistent.



--
~/Garth - 1966 Glastron V-142 Skiflite: "Blue-Boat"
"There is nothing - absolutely nothing - half so much worth doing
as simply messing about in boats."
-Kenneth Grahame, The Wind in the Willows

On Thu, 12 May 2005 01:15:25 GMT, "tony thomas"
wrote:

Both work just as good.

True, but one relies more on technology rather than seat of the pants
reckin' :)

Later,

Tom