Twin Fuel Tank Configuration

S

Sealizard

New member
Been searching the site for information on twin fuel tank configuration and have not found an answer to our concern.

We have twin tanks for our 40HP engines. They are setup so that you run both engines off one tank, then switch to the other tank as needed.

We are considering re-configuring the system so that each engine runs on its own tank. In addition, we would retain the capability for each engine to switch to the other tank.

Any thoughts about this strategy before we make the big leap?
 
Hi there. First thing comes to mind is there any problem with running your tank as is? Seems most of us would be plumbed this way and it makes it easy to track what tank you're on. Two tanks out to one switch to one racor then off to two engines. Run for an hour or two then switch tanks. You'll be building a manifold, bigger more complex boats do this... but we're little and simple. Adding complexity to fuel delivery isn't high on my boat project list. Others may have ideas but I like it simple and bullet proof. Fuel issues and electrics being the two trouble makers aboard. George
 
For my twin 40's I have a single tank for each engine. No switching. Separate fills and separate racor filters, and no combining. Works for me. Easy to keep track of which engine runs more if I am running single.

Harvey
SleepyC:moon
 
hardee":15nt0u1v said:
For my twin 40's I have a single tank for each engine. No switching. Separate fills and separate racor filters, and no combining. Works for me. Easy to keep track of which engine runs more if I am running single.

Harvey
SleepyC:moon
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x2
 
My tomcat was initially configured to have each engine burn from it's own tank. While this has some advantages, a serious disadvantage is that with such as system, if one engine fails, the fuel associated with that engine is not available to the other. In such a situation, your expected range is cut down considerably. Also, most of us with twins can't get on plane with a single engine. So, if we lose one engine, we're left with the choice of running at hull speed to get decent fuel economy or running faster and taking a big hit in fuel economy since we can't get over the bow wake (further reducing range). This is especially a concern for long offshore runs or situations which require long runs between fueling stations.

Since I frequently fish 40-70 miles offshore, if I lose an engine, I don't want to come back at 6kts to conserve fuel and extend my range. So I had my fuel system re-plumbed with a manifold and cross over valveSlide1.sized.jpg
 
I have always thought a cross over is a good idea with twin tanks and two engines. The boats I have had with twins have been inboard diesels, and I usually ran on one tank for both engines, but always had the capability of both running on two tanks (one for each engine) or transfering fuel from one tank to the other.
 
My boat has a seperate tank for each engine and I like it this way. If I get fuel contamination problems, it should only effect one engine.
As far as being able to use the fuel in the other tank in a single operation, I can just unclip the fuel lines from the engines and clip the other one onto the engine that is running.
Jerry C Nile
 
jerry97230":3s12vqu1 said:
My boat has a seperate tank for each engine and I like it this way. If I get fuel contamination problems, it should only effect one engine.
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Now that I'm buying fuel more often (and don't have sails), it's something I think about. Do you only fill one tank at each fuel stop, and so just stop twice as often (to fill the other tank)?

With two fuel filters, then I guess you can do it like one does with a double bowl "big engine" Racor and just switch to the other filter if you have problems, then deal with it later. That would be nice (even nicer if the same fuel is not in the other tank).

I haven't C-Dory'ed enough to have things set for sure yet; my idea so far is that I have the auxilliary engine (I have a large main/small auxilliary) normally connected to the main tanks, but with a quick connect (to the fuel filter fitting), and then a third small portable tank (3 gallons; came with Honda). The idea being that that small portable tank would always have fuel "left over" from the previous (known good) fuel stop. Still, I can see it's not always going to be practical -- like say now, where I have put the boat to bed for a period of time, so will want to start over with fresh fuel before the next trip. I suppose I could stop at two separate fuel stops for the main and small tanks, but then, how would I know the small tank stop was good fuel? I can't see myself testing that fuel and then going back again to re-fill the tank (now that's three stops). But I suppose on a multiple stop trip like Powell it's useful, as I know the first tanks were good, and that's what's in my small tank, just in case I take on bad fuel at a subsequent stop.
 
BRAZO":h787s5xw said:
hardee":h787s5xw said:
For my twin 40's I have a single tank for each engine. No switching. Separate fills and separate racor filters, and no combining. Works for me. Easy to keep track of which engine runs more if I am running single or I'm running single.

Harvey
SleepyC:moon
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x2
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Xmany. The fuel lines from the racors to the engines are long enough, so if need be I can switch them making the use of all fuel aboard available if the engine quits connected to fuel tank with the most fuel in it.

Jay
 
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