Boat lists due to wanting fuel only from 1 side

rlsimmonspi · 08-02-2018, 12:25 PM

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 · 08-02-2018, 12:51 PM

Quote:

Originally Posted by 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?

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** · 08-02-2018, 01:05 PM

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** · 08-02-2018, 01:07 PM

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

DLP · 08-02-2018, 01:18 PM

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 · 08-02-2018, 03:02 PM

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 · 08-02-2018, 03:06 PM

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

rlsimmonspi · 08-02-2018, 03:08 PM

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

dhays · 08-02-2018, 07:57 PM

Quote:

Originally Posted by 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.

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 · 08-02-2018, 08:21 PM

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 · 08-02-2018, 08:24 PM

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

dhays · 08-02-2018, 10:24 PM

Quote:

Originally Posted by motion30

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 · 08-02-2018, 11:02 PM

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 · 08-03-2018, 12:22 AM

Quote:

Originally Posted by dhays

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

Same as a crossover or equalizer?

rlsimmonspi · 08-03-2018, 01:19 AM

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 · 08-03-2018, 02:36 AM

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 · 08-03-2018, 11:22 PM

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 · 08-14-2018, 09:18 AM

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 · 08-14-2018, 10:34 AM

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 · 08-14-2018, 11:29 AM

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.