Help with fuel consumption please

Uncle Joe

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A friend of mine owns a 1997 Marlin with twin 1997 Yammi F250's on the back. He and I are planning a tuna trip for the next decent weather window. I am trying to calculate anticipated fuel consumption for the day. I believe the boat has 2 tanks 150 gals each.....we will have 5 guys on the boat....so we will be pretty loaded for the first half at least.

He thinks he burns 20 GPH at cruising speed of 20 kts or so.........I am kind of worried because I ran the same engine as a single on an Offshore and I think I only got 1MPG or so.

Any thoughts would be appreciated.

Thanks all.
 

Uncle Joe

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How far to the fishing grounds?
Apx 70 miles..then trolling at 7.5 kts.

If we get his 20 gph at 20 kts....roughly 1mpg we are golden.....if it is closer to the 1 mpg per engine then we are right at our limit without carrying extra fuel on deck.....which I would rather not do.
 
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PrinceofThieves

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With 300 gallons, you will be fine. You should be achieving 1mpg at cruise with that boat and motors, even if you were getting less on the way out say .8 mpg, thats 90 gallons out +/- and lets say you get 1mpg coming back, that's 70 gallons making for 160 gallons running to and from. At 7 knot trolling speed you probably burn at most 6 gallons an hour (assuming older motors) x 12 hours trolling + 72 gallons (though my guess it will not be that much at troll). Total puts you at roughly 232 gallons, leaving plenty in reserve. My OPINION is that you'll burn 200 +/- gallons at most, but reconfirm all this with the Capt. - he should have this math down tight if he's running 50 + miles offshore.
 
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Uncle Joe

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With 300 gallons, you will be fine. You should be achieving 1mpg at cruise with that boat and motors, even if you were getting less on the way out say .8 mpg, thats 90 gallons out +/- and lets say you get 1mpg coming back, that's 70 gallons making for 160 gallons running to and from. At 7 knot trolling speed you probably burn at most 6 gallons an hour (assuming older motors) x 12 hours trolling + 72 gallons (though my guess it will not be that much at troll). Total puts you at roughly 232 gallons, leaving plenty in reserve. My OPINION is that you'll burn 200 +/- gallons at most, but reconfirm all this with the Capt. - he should have this math down tight if he's running 50 + miles offshore.
Thanks POT........I appreciate you taking the time to give me your insight.

In this case the Captain is a bit less experienced than I am regarding a trip like this....so it is kind of up to me.

The run is actually 40 miles + - offshore.....his boat is docked in Long Island Sound and we have to run down the East River and through NY Harbor and out the Narrows first.
 

PrinceofThieves

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I happen to be very familiar with those waters and all points offshore from the narrows out (my living room window looks onto the Narrows :). Where are you guys leaving from on the sound and where do you intend to go offshore?
 
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Uncle Joe

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I happen to be very familiar with those waters and all points offshore from the narrows out (my living room window looks onto the Narrows :). Where are you guys leaving from on the sound and where do you intend to go offshore?
He is moored in New Rochelle...........the plan is arrive at the Mudhole at first light...start trolling....looking for birds etc....head toward the N side of the Glory hole....even to the Chicken Canyon if fuel and conditions permit. Hope to hit fish on the way.

I did this run on 9/1 in my Offshore from Jamaica Bay and was catching fish until an East wind and building seas made me run for home.

I probably waved to you while drifting fluke inside Nortons Point. :)
 

DennisG01

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Joe, I think you may not be remembering correctly what your F250 gave you. I have a 2-stroke 250 on my Offshore. I consistently get 11-13 gph when running in the 25 to 30- mph range (about 21 to 26 knots). Not accounting for current, but to get a pretty good rough average and estimating on the safe side... If I use 25mph and 12gph, that's pretty close to 2mph. I would expect your numbers to be better, still..
 
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Uncle Joe

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Joe, I think you may not be remembering correctly what your F250 gave you. I have a 2-stroke 250 on my Offshore. I consistently get 11-13 gph when running in the 25 to 30- mph range (about 21 to 26 knots). Not accounting for current, but to get a pretty good rough average and estimating on the safe side... If I use 25mph and 12gph, that's pretty close to 2mph. I would expect your numbers to be better, still..
Thanks Dennis....it is very possible that I was mistaken on what my old 250 gave me.
 

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1997?? Are they F250s or OX66 250s?

I have twin ox66 225s on a 265 express. I average 1 mpg cruising between 22 mph and 33 mph on offshore trips. Sometimes I troll on one motor as it does save some gas when under 8mph vs trolling on two.
I cannot imagine that F250s would get worse milage than me so if you assume 1 mpg you are probably safe.
Just make sure you top off the tanks and don't rely on the gauge.
If they are ox66s make sure you have enough oil, plus some.

If you are running down the Mud Hole, there are always pots on the west side of the hole( just east of the Shark river reef) in 160 -200ft. There are mahi there as of last week. The east side near the Monster ledge was devoid of pots when I was there. Glory hole pots were loaded with mahi. Can't miss the pots there...there are a thousand.
 
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SkunkBoat

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You might want to scout a fuel dock in Jamaica Bay or Staten Island for the return trip.(check closing times)

I am so glad to be in Manasquan river one mile from the Inlet!
 
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Uncle Joe

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HA! I looked right past the 1997 and only saw the "F". In that case, as noted, 1mpg-ish is about right.
My fault Bro!
I was wondering why everybody got better mileage than me! :oops:
 

Uncle Joe

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You might want to scout a fuel dock in Jamaica Bay or Staten Island for the return trip.
Skunk....already thought of that.... I have one in Mill Basin, Jamaica Bay and Mansion Marina in Staten Island lined up....although for 3 days I can't get Mansion on the phone.
 

PrinceofThieves

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Skunk....already thought of that.... I have one in Mill Basin, Jamaica Bay and Mansion Marina in Staten Island lined up....although for 3 days I can't get Mansion on the phone.
Threw me off for a moment as well! Now that i look back i see the years of hull and motor and that could not be F250's. I STRONGLY second Skunboats thoughts on consumption and refueling options with OX66's on that run. You have 63 nm straight run to the start of the Mudhole, 22 nm to the Glory from there and another 12nm to the start of the Chicken. So from your start point to potential endpoint you have 34 nm, putting you almost 100 nm out from home after a 5 hour troll and your fuel consumption at troll i don't even know what it is anymore on those motors, but it's higher than 4 strokes in any case - maybe skunkboat could weigh in on that. You would almost have to troll right back down that same path back to where you started to conserve fuel. However, in those spots (you have the recent report from Skunkboat), to the best of my knowledge the bluefin scene is pretty much over, for now at least, it's a mahi game for the most part. Also, for the tuna, it's a run and gun game till you find them, I don't want to say trolling is a waste of time, if you want to target mahi and alabcore etc, but it is if you're targeting tuna it is. Running and gunning, burns fuel though. Mill Basin and Tamaqua close at 7pm, however, Hudson Yacht club self-service pump is open till sundown, giving you an extra 40min-hour. I'm in Gateway btw.
 
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Tuna Man

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I may be able to offer a little insight. Please keep in mind with the older boats, I may be a little off in my numbers.
Our 2006 Marlin with twin 2006 Yamaha F250 outboards does a little better than 1mpg on a typical loaded for bear canyon trip (also holds roughly 300 gallons). When we troll between 6 and 8 miles per hour we burn about 3 gallons per hour, combined, which results to getting better than 2mpg.

On a 1989 Marlin with twin 1989 Evinrude 225 outboards it did about .8mpg on a typical loaded for bear canyon trip (also held about 300 gallons). When we trolled at the same speeds as above we averaged about 8 gallons per hour, combined for roughly .8mpg.

On our 1992 Explorer with single 2000 Yamaha OX250 outboard we averaged about 1.8 mpg on a canyon trip, loaded. When we trolled for tuna we consumed about 7 gallons per hour.

What I'm trying to say is yes, our "modern" four stroke Yamaha outboards are more efficient than the older two strokes when running (about twenty percent I guess). However when trolling offshore, our four stroke outboards burn about half that of the old two strokes. Best bet is to fill the gas tanks (bring extra oil after topping off), go the Mud Hole or perhaps the Glory Hole and head back and fill gas tanks. I can tell you that if you cruise at 4200 or less and troll at 6 or 7 mph you'll do much better on fuel.
 

crazy lady

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on our 97 marlin on a trip out of Cape May to the Wilmington canyon ( 70 mi ) and trolling all day with ox 66's would burn about 210 gallons
with 5 guys and all loaded up.
 
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GradyChris

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I don't fish much but use my Grady for long cruising with my family (2 adults, 2 kids)
Our big trip this summer was a week from Portsmouth NH to Cape Cod to RI to Cuttyhunk, back to Portsmouth.
Approx 375 miles and at cruise I was getting about 0.9 all told but again no real trolling going on but boat was pretty loaded up with fuel/ice/gear/humans. I had both tanks full nearly the entire trip (filled at each stop) just to make sure we were good.

A couple weeks ago my wife and I ran the boat to Portland ME (55 miles each way) and were getting 1.0 on average. 110 miles and burned 114 gallons (.96 mpg)
This was running at 3400-3600 RPM's
Kids weren't on board and I only used the main tank while aux only had about 20 gals in it.

All told I've run the boat probably 600 miles this season.
1998 Sailfish 272 with twin Yamaha OX 66's 225 HP

Best advice I've heard in here is make sure you bring extra TCW3 oil.....they love the stuff.
Pennzoil XLF is my blend of choice
 
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