a little confused about trimming

[kyle f]

Re: a little confused about trimming

Its almost laughable to hear someone talking about a fuel flow meter and GPS on a run about. Really? Are you freaking serious?

Look boats burn gas, and a lto of it. ITs simple engineering to know that an engine's peak efficiency is where it makes peak torque. If you want to conserve fuel, you want to converto the most of what is going into the engine into usable power.

Look up the power curve on your motor... probably difficule on some older modles, but was pretty easy on my 06 Sea ray with a 4.3..... gewt it on plane, throttle back to those RPMs, trim out until the boat picks up speed... and then throttle back to the RPMs.

Speed means nothing to the engine, only the RPMs. At peak Torque, the engine is filling the cylinders with air as best it can, and there for burning the most of the fuel going in. Horsepower is just the ability of an engine to make torque at a higher RPM and take advantage of gearing.

In the end, what you will find is if you are sweating Fuel Flow/MPH or whatever you will waste all that enjoyable time on the water worring about saving a few bucks.

In the true reality of a recreational run about... you should trim you motor to the appropriate position for the situation... and its best done by feel, listenting, and feeling the ride at a give time.

Whatch the fuel flow meter if you want, but I would rather you operate the switch by feel and keep your eyes on the water and other boats around.

 

[bruceb58]

Re: a little confused about trimming

Its almost laughable to hear someone talking about a fuel flow meter and GPS on a run about. Really? Are you freaking serious?

Actually, I am serious. When I go to Lake Powel I drive my boat 80 miles up the lake. That is around 27 gallons of fuel. By trimming my boat, I can get between 5 and 10% fuel economy differences by my flow meter. For a week long trip, I might burn over 200 gallons of fuel. if I can cut 20 gallons off my usage I am saving $80. For each run, I trim once and set it. It literally takes less than 30 secondes to dial it in for a given throttle setting.

Lets say someone runs their boat 50 hours a year with an average 20Mph. getting 3MPG. That is 7 gallons an hour +/-. If that person can save 30 gallons of fuel over a year is it not worth it?

Running an engine at its peak torque RPM is not necessarily the best RPM to rin for mileage. Too many other factors involved with the hull and friction and wind resistance to make a blanket stement like that. For example, you could run your boat at the RPM that creates peak torque and if you weren't on plane, you would be getting horrible mileage.

Too add my flow meter to my existing Lowrance GPS was less than $100. Figuring that I added it back when gas was near $5/gallon, it has paid back itself over and over again.

I agree, trimming by feel is probably the best way for 90% of the people. For me I do both but use the flow meter as a tool as well. Just as you watch your tach to get the proper RPM, I am adding one more element and it is gives me just one more number.

 

[greenwell001]

Re: a little confused about trimming

kyle f. W.T.F who doesnt want to save fuel, i bet you litter to and cut down trees and leave you faucet on when you brushing your teeth......ha ha
how did you find the power curve for you v6

 

[trendsetter240]

Re: a little confused about trimming

Its almost laughable to hear someone talking about a fuel flow meter and GPS on a run about. Really? Are you freaking serious?

Whatch the fuel flow meter if you want, but I would rather you operate the switch by feel and keep your eyes on the water and other boats around.

Last season I burned over $1500 in fuel with a 50hp on my runabout. This season I have a 70hp and I will be looking for ways to save; a fuel flow meter is on the list.

$$ saved means more days on the water fishing for salmon in the fall

EDIT: oh yeah, and this weekend I am adding a power trim unit so trimming properly is something I will be considering.

 

[kyle f]

Re: a little confused about trimming

Actually, I am serious. When I go to Lake Powel I drive my boat 80 miles up the lake. That is around 27 gallons of fuel. By trimming my boat, I can get between 5 and 10% fuel economy differences by my flow meter. For a week long trip, I might burn over 200 gallons of fuel. if I can cut 20 gallons off my usage I am saving $80. For each run, I trim once and set it. It literally takes less than 30 secondes to dial it in for a given throttle setting.

Lets say someone runs their boat 50 hours a year with an average 20Mph. getting 3MPG. That is 7 gallons an hour +/-. If that person can save 30 gallons of fuel over a year is it not worth it?

Running an engine at its peak torque RPM is not necessarily the best RPM to rin for mileage. Too many other factors involved with the hull and friction and wind resistance to make a blanket stement like that. For example, you could run your boat at the RPM that creates peak torque and if you weren't on plane, you would be getting horrible mileage.

Too add my flow meter to my existing Lowrance GPS was less than $100. Figuring that I added it back when gas was near $5/gallon, it has paid back itself over and over again.

I agree, trimming by feel is probably the best way for 90% of the people. For me I do both but use the flow meter as a tool as well. Just as you watch your tach to get the proper RPM, I am adding one more element and it is gives me just one more number.

I will admit your situation is unique for most runabouts. You drive yours more liek a cruiser. However, most runabouts are ran from A to B in very short distances, usually at almost tops speed, or they are just always pulling a tube, or skier... etc. Where trying to use a fuel flowmeter would jsut be tedious if at all possible.

My boating definately would nto lend itself to doing such things... as I am usually more concerned with the quality of the pull and constant speed more than how much fuel I am using... oh did I mention I also carry around about 2750lbs of water in the boat at the same time. Even at that, I have an inboard now, so trim is a thing of the past for me.

When I had my runabout, I think the longest I ever drove it was about an hour or so without stopping... and as I said above.. I trimmed out to where everythign was smooth and quiet, set RPMS at max torque and cruised.

If you really want to save fuel, go to a higher pitch prop as well.

Oh and I found my peak HP and TQ numbers @ what RPM by just searching using Google.

 

[QC]

Re: a little confused about trimming

FWIW, peak torque RPM and peak torque values are only important if the throttle is wide open, and unless you are jumping on plane I submit that combination (WOT at Peak Torque RPM) never happens in a boat that is propped right. Bruce is right, too many variable to base anything on a paper torque curve except the ability to actually get on plane.

I also run my boat "like a cruiser" often. Plus I'll take all of the gauges and info I can get within reason. If you know what to do with that info why wouldn't you want it?

 

[bruceb58]

Re: a little confused about trimming

I will admit your situation is unique for most runabouts.

Where I boat...ocean, Lake Tahoe, Lake Powell, Lake Mead...cruising is definitely the norm no matter what type of boat you have except for a ski boat like yours.