Boat lists due to wanting fuel only from 1 side

[rlsimmonspi]

I have a 1987 Jefferson. Although it’s called a motoryacht I run it like a trawler for fuel efficiency. Purchased on the Chesapeake in 2001. Winter 2003/2004 took it down to Melbourne, Fl. Began to notice that after several hours of cruising, I began listing to starboard. The only remedy while underway was to shut off fuel from the port tank, forcing the engines to feed off the starboard side. I can’t get to anything having to do with a tank vent, except the crome end on the outside hull. I had to install a fuel transfer pump to level the boat in the slip even after short day trips. Any thoughts?

 

[dhays]

I have a 1987 Jefferson. Although it’s called a motoryacht I run it like a trawler for fuel efficiency. Purchased on the Chesapeake in 2001. Winter 2003/2004 took it down to Melbourne, Fl. Began to notice that after several hours of cruising, I began listing to starboard. The only remedy while underway was to shut off fuel from the port tank, forcing the engines to feed off the starboard side. I can’t get to anything having to do with a tank vent, except the crome end on the outside hull. I had to install a fuel transfer pump to level the boat in the slip even after short day trips. Any thoughts?

Welcome.


Do you have fuel level gauges and or sight glass for each tank? Does it show that your starboard fuel level becomes greater than the port?



I know nothing about your boat, but the first thing I would check would be your fuel return. Where do your engines return their fuel? Some boats have fuel manifolds that can allow you to return fuel to one tank or the other. Maybe your fuel is being returned to the starboard tank?


Does the boat run equally well on either the port or starboard tank?


Do you have a vacuum gauge on your primarily filter and does it show the same regardless of which tank you are drawing from?


If you are running on the starboard tank only, do you ever develop a list to port?


Smarter folks than I will have some better suggestions.

 

[Shrew]

Are these Diesel engines? It sounds like the fuel return is only returning to the STBD tank when both feeds and returns are open. When the Stbd fuel feed was shut, was the return also shut?

 

[Shrew]

Moved from "How To Use The Forum, Site News & Account Concerns" to "General Dsicussion".

 

[DLP]

I have a 1987 and it has a valve manifold for fuel lines in the engine room bulkhead. I will get a picture of the settings and valves to see if it is close to yours. Like noted above check your return lines from engines to tanks for proper setting and you might have a crossover line for both tank to equalize them also.

 

[rlsimmonspi]

The boat runs the same on either tank. There are sight glasses on each tank whic show individual level. I no longer open the crossover because it only adds to the problem if the boat is stationary. I’ve always thought that the gauges on top of the primary filters were pressure gauges since the tanks are rated for 2psi. Both gauges were full of fuel and useless since I bought the boat. If I overdo it with the starboard tank, it will begin to list to port. I need to take a close look at the fuel lines. I know that the genset returns to the port tank and I always assumed that each engine returned to the corresponding tank.

 

[rlsimmonspi]

Yes on the diesels, no to the returns also being shut.

 

[rlsimmonspi]

Yes they are dreidels and no, the returns are not also shut off.

 

[dhays]

The boat runs the same on either tank. There are sight glasses on each tank whic show individual level. I no longer open the crossover because it only adds to the problem if the boat is stationary. I’ve always thought that the gauges on top of the primary filters were pressure gauges since the tanks are rated for 2psi. Both gauges were full of fuel and useless since I bought the boat. If I overdo it with the starboard tank, it will begin to list to port. I need to take a close look at the fuel lines. I know that the genset returns to the port tank and I always assumed that each engine returned to the corresponding tank.

You mentioned that you have installed a transfer pump. At the dock, what happens if you use the transfer pump to equalize the fuel level in the tanks based on the sight glasses? If the tanks are equal, is there still a list in the boat? If so, then I would start to look at other potential reasons for the imbalance. That could include stowage of gear, unequal water tanks, a bilge space that has taken on water etc...

 

[Great Laker]

I am assuming you have a tank on each side of the boat with a crossover. If the crossover is open at the dock, and the fuel imbalance increases to one side or the other, the cause is most likely due to a weight imbalance on the boat. The fuel will always seek to be level across the tanks. Try moving stores or adding weight to the side with the least fuel overnight and see if the levels don't even out.

 

[motion30]

A balance tube from one tank to the other. I'm surprised it was not originally set up that way

 

[dhays]

A balance tube from one tank to the other. I'm surprised it was not originally set up that way

I am not familiar with a balance tube...?

 

[cmgreeniv]

Need pictures or a sketch. I have a 89 Chung hwa, same yard most likely. It will do the same thing if heavy wind on one side or too many fat friends on one side and I have the tanks open from side to side. I pickup and return all three engines to one tank and swap them about ever 3 hours u derway. I have two 150 gallon tanks plus two 165ish tanks. I run off the 150s and polish from the 165s to the 1503 when the 150s get down to 20 gallons or so. Works good and lets me keep boat level.

 

[BruceK]

I am not familiar with a balance tube...?

Same as a crossover or equalizer?

 

[rlsimmonspi]

Yes, it is a cross over tube. At the bottom of each tank, forward, are gate valves with a copper tube running between the two. If the boat is listing, ever so slightly, the list will get worse as the fuel attempts to level off and keeps flowing toward the listing side. So, if I don’t pay close attention and maybe i’m out in rough seas, I put into into slip with a bad list to starboard, which is avoided if I shut off the feed from the port tank while underway. Thus the fuel transfer pump. Glad to hear that i’m not the only one experiencing this issue.

 

[markpierce]

I have no "cross over" connections among four fuel tanks supplying a single engine. Manifolds select the fuel source and the return for whichever tank selected. The tanks are on either side of the boat. Usually draw/return from/to one tank at a time, switching among tanks to maintain boat's balance every few hours, like six or more. Have a pump/fuel-circuit to transfer fuel among tanks if needed. Am free to select any tank for fuel source, and any tank for return.

 

[cappy208]

I would suspect a partially blocked fuel suction line from the side that becomes the low side. Fuel wants to flow from the least restricted source. But the return will flow evenly (since it isn’t being held back by filters or valves). Has this issue been since you bought the boat? Have you recently ‘cleaned the tanks’? Did you use ‘oil absorbent wipes’ when cleaning the tank?

 

[ABfish]

My boat began drawing unevenly due to a blocked VENT line.

I did not figure it out until I began having much difficulty filling that tank. I could only fuel that tank very slowly without causing a geyser of fuel from the fuel fill (and yes, I took the worst diesel bath that I've ever had, and that includes thirty years of working around construction equipment).

The culprit in my vent line was an insect nest of some sort. My vent was totally clogged.

I gently pressurized my tank through the fuel fill with a 12 volt shop vac. There was no air coming from the vent. At the point, I knew the vent or vent line was clogged.

 

[ktdtx]

I assume twin engines.
Have you tried running the port engine from the port tank and returning fuel to the same tank and running the starboard engine from the starboard tank and returning to the same tank with the fuel crossover valve closed?
Then see what happens?

 

[Chrisjs]

I agree with ktdtx

Most likely if you are running with both returns open, one path has more difficult flow path (partly blocked, crimped, longer path, more vertical direction, etc) causing fuel to favor the other route. Once this occurs fuel accumulates in the favored tank causing the imbalance listing. To make matters worse, the greater the list the more the fuel favors that (downhill) flow path, causing even greater listing. It sounds like even if you do have a balance (crossover) line either it is not functional or the vessel has a natural list that is causing the problem. So, apart from fixing any obvious weight distribution issue (probably difficult) the simple solution is as suggested - return only to the tank of origin, pay attention to the vessel's levelness, and adjust fuel usage accordingly.

 

[rlsimmonspi]

Boat listing

Can’t tell you how much I appreciate all of the great advise. Unfortunately, the tanks are walled in with acoustic tile over plywood and inches from the walk around deck at the top. I sure do miss my 135 Perkins. I’m a little (really a lot) Leary about applying air presure as my biggest nightmare is a leak in a 275 gallon cast iron tank that won’t come out without first extracting an engine. I did build in a small racor with a two micron element in the fuel transfer system. So, at least the starboard tank should be somewhat clean, considering all of the times that I pumped fuel out and over to the port tank.

 

[ljk]

The boat runs the same on either tank. There are sight glasses on each tank whic show individual level. I no longer open the crossover because it only adds to the problem if the boat is stationary. I’ve always thought that the gauges on top of the primary filters were pressure gauges since the tanks are rated for 2psi. Both gauges were full of fuel and useless since I bought the boat. If I overdo it with the starboard tank, it will begin to list to port. I need to take a close look at the fuel lines. I know that the genset returns to the port tank and I always assumed that each engine returned to the corresponding tank.

??? Every diesel boat I have ever owned had a crossover, which I kept open all of the time. That way, gravity insures the fuel level will be the same in each tank. If yours doesn't work that way, perhaps something is wrong.

 

[ABfish]

My boat has crossovers, which allow fuel to be drawn from and return to both tanks simultaneously. Or you can close the valves, and run each engine from it's respective tank, and only return to that tank.

That's not the same as an equalizer. Older over the road trucks have an equalizer line that comes from the bottom of each tank, and allows the two tanks to equalize automatically, thanks to gravity and assuming the truck is on a relatively level surface. Newer trucks don't use the true "equalizer" but rather a splitter valve to direct the fuel return.

If boats had a true "equalizer" they would not develop a list as fuel is drawn from one tank.

 

[Lepke]

You probably have some restriction in your plumbing that may be difficult to find.
A couple ways to solve your problem: split the fuel system so each engine draws fuel and returns fuel to the tank on the same side.The engines should burn about the same amount of fuel, and if not that would be good to know. Also bad fuel or water in the fuel on one side doesn't stop both engines. Or install a day tank like bigger boats and ships have. A tank that holds about a days amount of fuel. Usually mounted on the center line or on the opposite side of added heavy equipment. As the day tank goes down, fuel is transferred from the other tanks. I have a 200 gallon day tank on my boat.
I don't think your fuel tanks are cast iron, probably mild steel. Cast iron for fuel tanks hasn't been common since riveted hull construction was being replaced with welding. About 1925-1930 in the US. Air tanks of cast iron lasted a little longer because people didn't trust welding with pressure. My 1942 tanks are mild steel. So are ship tanks. They last a long time, usually the life of the ship, especially with fuel conditioner.

 

[Riverguy]

??? Every diesel boat I have ever owned had a crossover, which I kept open all of the time. That way, gravity insures the fuel level will be the same in each tank. If yours doesn't work that way, perhaps something is wrong.

Our Mainship 390 has a crossover, our Bayliner 4788 does not (not possible given the tank layout). Instead, it has a pump that can move fuel from port to stbd and vice-versa.

 

[HopCar]

I had a similar problem with Possum. If I tried to run from both tanks and return to both tanks. Eventually it started drawing more from the Starboard tank so I started switching tanks every few hours. I did not have a cross over tube.

Eventually it wouldn’t run from the port tank so I went crazy looking for the problem. I went through the whole fuel system, even pulled the pickup tube from the tank. I thought the screen at the bottom might be clogged but there was no screen.

After about a year of this I decided to pull the pickup tube again. This time I realized the tube was screwed into the fitting at the top. I unscrewed the tube and the damn screen was at the top of the tube! I threw that damn screen as far out in the water as I could while calling it things my Mama would not approve of. I did the same thing to the Starboard tank and never had another problem.

 

[Great Laker]

An crossover by itself does NOT ensure a boat with uneven fuel levels in each tank will be level side to side when sitting at rest.

It only works to accomplish that if the boat is load balanced such that it is level side to side with NO fuel in each tank when sitting at rest.

 

[greysailor]

An crossover by itself does NOT ensure a boat with uneven fuel levels in each tank will be level side to side when sitting at rest.

It only works to accomplish that if the boat is load balanced such that it is level side to side with NO fuel in each tank when sitting at rest.

[emoji651] X2..... Salty has a natural starboard list due to generator position. I keep the crossover valve closed and about 40 gallons more fuel in the port tank to achieve level. The aft tank is centerline, is used as a daytank, and is filled as needed via polishing system from the P/S tanks.

 

[catalinajack]

My boat began drawing unevenly due to a blocked VENT line.

I did not figure it out until I began having much difficulty filling that tank. I could only fuel that tank very slowly without causing a geyser of fuel from the fuel fill (and yes, I took the worst diesel bath that I've ever had, and that includes thirty years of working around construction equipment).

The culprit in my vent line was an insect nest of some sort. My vent was totally clogged.

I gently pressurized my tank through the fuel fill with a 12 volt shop vac. There was no air coming from the vent. At the point, I knew the vent or vent line was clogged.

I had the same problem, a blocked fuel vent. At the suggestion of another member (Angus99) I picked at the tiny vent hole. Out came some spider web-like stuff. Then, I used a compresdor to blow air back into the vent. I actually heard the line clear with pressure. I left the fill cap open.

In addition to fuel being drawn mostly from one tank, the real telltale was the whoosh from a vacuum being released when opening the fill cap on the tank. After clearing that vent line I have run 3,500 miles with nary a problem.

 

[Mainguy]

Me Too

The Admiral and I have an 2002 Jefferson MY with exactly this problem. It's clearly nothing to do with fuel supply, crossover lines etc. because, as you said, with the fuel tanks at the same level and the engines not running the fuel will transfer itself from Port tank to Stbd tank and the boat will list. What's happening is that the boat is too heavy to Stbd and the fuel will move to the Stbd side because of this. With the boat sitting at it's natural list to Stbd the fuel will actually be balanced in both tanks relative to the horizon but the Stbd tank has much more fuel in it than the Port tank. Underway I keep the port tank supply line cracked open but not fully open and manage to keep close to level but I have to adjust it several times or transfer fuel during the day which is a real PIA. If their is any movable ballast in this boat I've not found it.