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04-24-2017, 06:53 AM
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#1
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Senior Member
City: Chesapeake, VA
Vessel Name: Grace
Vessel Model: 1982 Grand Banks Motoryacht
Join Date: Apr 2013
Posts: 134
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Single Engine Fuel System Operation
New to us GB 42 Hull 803, Single Lehman Diesel.
Wondering what the recommended or pros/cons of operation off of ONE fuel tank at a time.
Based on my research there is a shutoff for both tanks, but only one return to STBD tank from the engine. Seems the STBD tank would fill up if you are only using the PORT tank for fuel.
Attached is a fuel system diagram.
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04-24-2017, 06:57 AM
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#2
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Guru
City: Gulf Shores, Ala.
Vessel Name: Ulysses
Vessel Model: Romsdal 1963
Join Date: May 2013
Posts: 878
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Your assumption would appear to be correct unless there is an equalization line between the two tanks.
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04-24-2017, 07:07 AM
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#3
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Enigma
City: Slicker?
Join Date: Oct 2007
Posts: 16,540
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Greetings,
Mr. kr. I see no disadvantage to running with both fuel valves open. Doing so should allow tank equalization thus maintaining trim. Your thought of the STBD filling up if running on PORT is correct. I believe although Lehman's are reputed to return very little fuel to a tank IF you start with both tanks full you run the risk of an overflow on the STBD tank.
The only problem I can foresee is if you fill one tank with contaminated fuel, you may cross contaminate the other.
__________________
RTF
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04-24-2017, 08:47 AM
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#4
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Guru
City: Carefree, Arizona
Vessel Name: sunchaser V
Vessel Model: DeFever 48 (sold)
Join Date: Apr 2008
Posts: 10,179
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Or you could have a valved return line to both tanks and return fuel to the same tank you are drawing from. We have 4 tanks so this option is pretty important. But, it seems to have worked well for a few decades on your vessel as is
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04-24-2017, 09:11 AM
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#5
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Technical Guru
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,194
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Non standard plumbing. Are you sure about the routing? All would be well if there is a low mounted cross tie line, check for that.
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04-24-2017, 09:53 AM
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#6
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Senior Member
City: Buffalo
Vessel Name: Almost Perfect
Vessel Model: Kadey-Krogen 48
Join Date: Dec 2015
Posts: 232
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My previous boat had a similar tank layout, and we could never leave both fuel valves open as even if the boat had only a slight list, the fuel would flow by gravity from the higher tank to the lower and increase the list.
Also, you should have the capability of returning fuel to the same tank that you are drawing from for both the main engine and the generator.
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04-24-2017, 10:14 AM
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#7
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Guru
City: League City, TX
Vessel Name: Pelago
Vessel Model: Wellcraft 3300 Coastal
Join Date: Aug 2011
Posts: 1,069
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Install one of these, problem solved . . . . . all of them.
The FV-65038 has 3 positions, left, right and off.
The FV-65038-A has 4 positions, left, both, right and off.
With either configuration, the the supply and return are switched together. One valve, one handle. It couldn't be simpler.
__________________
Larry
M/V Pelago
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04-24-2017, 10:26 AM
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#8
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Veteran Member
City: Gressvik
Join Date: Apr 2017
Posts: 46
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@Rossland: You are very correct. Leaving an open crossfeed is a big nono, and has been pointed out as a contributing factor in several fatal accidents. Recreational craft designers tend to assume that the user won't understand this, so sufficient margins are built into the boat to prevent it from having serious consequences, but it's still a bad practice.
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04-24-2017, 10:32 AM
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#9
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Enigma
City: Slicker?
Join Date: Oct 2007
Posts: 16,540
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Greetings,
I was not aware of the potential problems. I stand corrected and thank you.
__________________
RTF
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04-24-2017, 11:07 AM
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#10
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Guru
Join Date: Jun 2008
Posts: 5,034
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My fuel plumbing is the same as the OP diagram and I have a crossover line the is always open.
__________________
Jay Leonard
Ex boats: 1983 40 Albin trunk cabin, 1978 Mainship 34 Model 1
New Port Richey, Fl
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04-24-2017, 11:44 AM
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#11
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Master and Commander
City: Vallejo CA
Vessel Name: Carquinez Coot
Vessel Model: penultimate Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 12,559
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Have fuel returns to all four tanks. I use one tank at a time.
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Kar-KEEN-ez Koot
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04-24-2017, 11:50 AM
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#12
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Moderator Emeritus
City: Chicago, IL
Vessel Name: Bay Pelican
Vessel Model: Krogen 42
Join Date: Oct 2007
Posts: 2,993
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I have run single engine boats with two or more fuel tanks for years. Although not required I suggest you would be better off adding a valve that allowed you to return fuel from the same tank from which it was drawn.
I have always used a separate pump to drain one tank right before fueling so that I have one tank with old(good) fuel and one tank with the new fuel. If you must return the fuel only to the starboard tank you will contaminate both tanks if you take on bad fuel.
One approach with a single engine boat is to operate off the starboard tank one day and the port tank the next day. Thus equalizing out. This requires the ability to direct the fuel return.
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Marty
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04-24-2017, 12:22 PM
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#13
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Guru
City: Gig Harbor
Vessel Name: Kinship
Vessel Model: North Pacific 43
Join Date: May 2015
Posts: 9,046
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When I bought my NP43 the manufacturer recommended that the fuel crossover line be left closed due to the potential for a progressive list. Actually not an issue on my boat as I have a fuel transfer pump and the impeller keeps the fuel from passing through.
For a boat with a single fuel return all the OP needs to do is run first on the starboard tank and then the port tank. The time on the port tank will be less than the starboard tank.
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04-24-2017, 12:27 PM
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#14
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Guru
Join Date: Oct 2007
Posts: 22,553
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On some engines that have a high return the selector vave that also sets the return is the way to go.
No fuel filling unknown tanks overcapacity , and its much easier to handle the fuel heat that goes with the returned fuel.
Labeled valves are fine , but a drawing with the tanks valves etc is even easier to understand.
In the future YOU may not be moving those valves.
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04-24-2017, 06:20 PM
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#15
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Guru
City: Fort Myers, FL... Summers in the Great Lakes
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 12,818
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My boat is now setup where the engine and generator draw and return to the starboard tank. I fill only the port tank. Then I transfer fuel as needed with a pump through a Racor 1000 that is a satisfactory fuel polisher. This allows me to watch new fuel going through the bowl to check for water and other contaminants. The plumbing is also setup to be able to polish the Starboard tank. The process also helps to use the older fuel first.
Ted
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Blog: mvslowhand.com
I'm tired of fast moves, I've got a slow groove, on my mind.....
I want to spend some time, Not come and go in a heated rush.....
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04-24-2017, 08:22 PM
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#16
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Guru
City: Kitimat, North Coast BC
Vessel Name: Badger
Vessel Model: 30' Sundowner Tug
Join Date: Jul 2012
Posts: 5,946
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Just curious...how often does one get "bad fuel" when boating in North America?
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"The most interesting path between two points is not a straight line" MurrayM
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04-24-2017, 10:56 PM
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#17
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TF Site Team
City: California Delta
Vessel Name: FlyWright
Vessel Model: 1977 Marshall Californian 34 LRC
Join Date: Apr 2008
Posts: 13,728
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He's not boating in North America. His boat's 'down south".
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04-24-2017, 11:38 PM
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#18
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Guru
City: Kitimat, North Coast BC
Vessel Name: Badger
Vessel Model: 30' Sundowner Tug
Join Date: Jul 2012
Posts: 5,946
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Quote:
Originally Posted by FlyWright
He's not boating in North America. His boat's 'down south".
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South America? Australia?
I see lots of elaborate fuel containment/delivery/filtering/polishing systems and it makes me wonder...is it really that common to get bad fuel, and how often has it stopped anybodies engine?
__________________
"The most interesting path between two points is not a straight line" MurrayM
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04-25-2017, 12:30 AM
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#19
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Master and Commander
City: Vallejo CA
Vessel Name: Carquinez Coot
Vessel Model: penultimate Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 12,559
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Had my boat's builder install a polishing system despite his contrary recommendation. My boatyard also disdained the need. As a result of miscommunication, the boatyard bypassed the polishing system. Nevertheless, the remnant system is still useful for transferring fuel among several fuel tanks, and haven't yet experienced a need here for polishing. Do have on-engine filters and dual Rycors.
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Kar-KEEN-ez Koot
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04-25-2017, 07:13 AM
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#20
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Guru
Join Date: Jun 2008
Posts: 5,034
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Quote:
Originally Posted by MurrayM
South America? Australia?
I see lots of elaborate fuel containment/delivery/filtering/polishing systems and it makes me wonder...is it really that common to get bad fuel, and how often has it stopped anybodies engine?
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I got a bad load of diesel in Mystic, CT (my home port) once. That was in the early 90s. It was bad enough to shut me down 2 times before I got it cleared out.
I found out months later that someone else in my marina also fueled up that same day and had the same issues. The "crud" looked like large coffee grounds. They were actually large enough to get stuck in the fittings of my copper fuel lines.
__________________
Jay Leonard
Ex boats: 1983 40 Albin trunk cabin, 1978 Mainship 34 Model 1
New Port Richey, Fl
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