day tanks- opinions

[Lou_tribal]

I'd be concerned that if I did that at my local fuel dock I would end up wet!

I am not worrying too much about fuel quality at my marina knowing that they have brand new tank and that the fuel is "car type" diesel but the day I will refuel in an unknown place I may be a bit less comfortable. For now it is nothing to worry about for me as considering the type of cruise I do and my fuel capacity I am only refueling 2 or 3 times a year and in 2 different places I am confident are safe on that side.

 

[psneeld]

Fuel system setup varies so much, some boats, especially smaller ones, you cannot use regular tanks like day tanks with good fuel management.

I have been running boats a long enough time both rec and commercial to have a feel for what works and what is overkill.

I have had crap and water in fuel, but never was stuck for more than a half hour or so to get going again. Like 3 times in many years of running small vessels.

It is just not that big a deal if you try and manage your fuel and do fuel checks when prudent.

 

[Sailor of Fortune]

I can't speak for large ships but on the tugs I work on your going to get "Bottoms" from tank farms, large areas of steel are subject to rust, condensation, welding slag etc. I have been through shipyard periods where th yard told us to "button up that tank shes' clean" and the chief engineer "dove the tank" and passed up staging planks, 5 gallon buckets of welding slag, rags, sand blast sand etc. Bottoms are bad enough. A 100,000 gallon load is ALWAYS going to get you junk. "Cappy" on here can vouch for this too. Fuel farms in NY/Nj turn over fuel quickly too. If its that contaminated here, its probably worse other places. Some of the best fuel we recieved was in Gibraltar on a wreck removal job. Unfortunately that was fuel that was warm weather and it Waxed up after a Winter transatlantic passage. We had to isolate it (thousands of gallons) until we were towing hard or went south.

 

[twistedtree]

Re operating off a day tank, we just make it part of periodic checks. Ours is good for around 30 hrs of run time, so if we are just day cruising we will check at the on-set of each day and fill up if needed, which is only required every few days. If running 24/7, we just keep an eye on it and top up as needed. We usually run the day tank between 25% and maybe 80% full. I have it alarmed at about 20% to help avoid stupidity on my part. When filling, we draw alternately from each of our main side tanks. That keeps the boat trim, and we adjust as needed if things start to get off.

 

[Lepke]

I have a 200 gallon day tank and another 1800 gallons in 3 main tanks. All my tanks can be filled from the deck. I have Detroit mains and each pump 35 gallons an hour and burn about 4+ @10kts. I add fuel to the day tank as it gets down to 1/4 full or when fueling the other tanks. I have a pair of 500 Racor filter housings and use 2 micron filters. I change the primary about 500 hours, about 4300 gallons burned and about 18,000 gallons thru the filter. Plus whatever the generators use. All fuel goes thru the Racor filters. I always use a conditioner/catalyst. I almost always buy fuel at commercial fuel dock or where tugs and commercial users fuel. Only in desperation at yacht marinas. I have found many small fuel sellers have no consistent filter maintenance and can have very old fuel. I personally fuel my own tanks. That way I don't get gasoline in my diesel.

 

[cafesport]

We have one on our 55 footer which is small but dual purposed. Since it is also our lowest tank, It has a built in sump which allows it to collect any water from the other 5 main supply tanks if the inlet valves are set for gravity feeding. Underway the valves are closed and all fuel must be drawn through a 10 micron racor. All return fuel is sent to the day tank, otherwise we could only run an hour as the the tank is only 30 gallons.

 

[diver dave]

An interesting spread of answers. Ranging from 100,000 gallon systems to 40 with day tanks. I don't suppose I'll be buying a steam plant so likely won't have to build a fire under any day tank to loosen up the fuel .

So, scaling up the situation in post #22. Let's say now that something like a GB42 is targeted for a day tank. One possible solution is make one existing tank the day tank. If doing this from scratch, that tank would not have a deck fill, would perhaps vent into the other tank, the engines/genset would only feed from the DT, and there would be no Y valves for the feed and the return fuel lines. You have a set of filters from the pumped main tank feed into the DT. Seems like things are getting simpler, not more complicated.

But here is an issue. It's time to refuel, and I need 300 gallons in each tank. The speed of the dock pump could far exceed the capability to transfer fuel. I'll take on 300 gallons, then have to wait until that quantity transfers to the day tank; then take on another 300 gallons. I think the dock boy and any waiting vessels are going to be not amused. The solution is a fast transfer system, and likely scaling up the Racors for 10x the normal rating. Beyond that, it appears to be a workable, minimalist system.
The other option is to add a real DT. Only works if space is available.

 

[Sailor of Fortune]

Seems to me to be a lot of work solving problem that doesn't exist. Multi stage filtration and tank access for cleaning would still be required with or without your day tank addition.

 

[psneeld]

An interesting spread of answers. Ranging from 100,000 gallon systems to 40 with day tanks. I don't suppose I'll be buying a steam plant so likely won't have to build a fire under any day tank to loosen up the fuel .

So, scaling up the situation in post #22. Let's say now that something like a GB42 is targeted for a day tank. One possible solution is make one existing tank the day tank. If doing this from scratch, that tank would not have a deck fill, would perhaps vent into the other tank, the engines/genset would only feed from the DT, and there would be no Y valves for the feed and the return fuel lines. You have a set of filters from the pumped main tank feed into the DT. Seems like things are getting simpler, not more complicated.

But here is an issue. It's time to refuel, and I need 300 gallons in each tank. The speed of the dock pump could far exceed the capability to transfer fuel. I'll take on 300 gallons, then have to wait until that quantity transfers to the day tank; then take on another 300 gallons. I think the dock boy and any waiting vessels are going to be not amused. The solution is a fast transfer system, and likely scaling up the Racors for 10x the normal rating. Beyond that, it appears to be a workable, minimalist system.
The other option is to add a real DT. Only works if space is available.

If you are serious about keeping some operating fuel clean, and not planning on crossing an ocean that needs all your fuel.....

Just never fill all your tanks at once, or not at the same place.

Not sure why the concern about filling up all at once....hopefully your day tank is full enough to get to and from a fillup.

You fillup and transfer filtered fuel to the day tank at a slightly greater rate than the fuel burn underway.

I really think you need to grasp the concept of getting clean fuel to begin with and how to get that to your engine(s). There are many ways to do it, with or without a day tank.

Pick a method that you like and fits both your boat and budget.

I worked enough commercial jobs to know the crap fuel passed around....from big tugs, dredges, barges, etc..etc...

But until you go to places that are rarely visited or are barrel farms or you get there with more than 1/2 your fuel gone......cruising in most of North America us not that scary when it comes to fuel.

I have had and friends have had very bad fuel for out helicopters that could have caused crashes. Only one resulted in a dual engine flameout, thankfully on the ground. None of my friends and coworkers that I know of had fuel isdues resulting in anything more than an engine shutdown and filter change. No drama.

Can it happen? Sure.

My 2 engine shutdowns in the last 12,000 miles were from air and I have received nothing short of excellent fuel between NJ and FL.

 

[balder]

We have one on our 55 footer which is small but dual purposed. Since it is also our lowest tank, It has a built in sump which allows it to collect any water from the other 5 main supply tanks if the inlet valves are set for gravity feeding. Underway the valves are closed and all fuel must be drawn through a 10 micron racor. All return fuel is sent to the day tank, otherwise we could only run an hour as the the tank is only 30 gallons.

Very interesting, reading all these posts; I wonder: what about the return fuel?

 

[sunchaser]

In this era of good clean fuel being available for most of us, mentioned above and worth repeating IMHO are two things.

First, buy your fuel at a known brand high turnover location. Second, check that the dock fuel pumps have in line fuel filters. These are not in lieu of a good on board fuel filter setup.

Fortunately on our DeFever one of the smaller tanks (80g) is continually being filtered from a bottom sump draw feeding the fuel delivery pump to the diesel heater. That tank, one of four, is our ultimate backup. The filter and bowl on that specific Racor have never shown water or debris. Knock on wood.

 

[diver dave]

But until you go to places that are rarely visited or are barrel farms or you get there with more than 1/2 your fuel gone......cruising in most of North America us not that scary when it comes to fuel.


My 2 engine shutdowns in the last 12,000 miles were from air and I have received nothing short of excellent fuel between NJ and FL.

My typical cruising grounds are Florida SE to Windward Isl.
I have picked up fuel from a pickup truck at San Sal, which was in an unknown drum and siphoned started by mouth, direct to my deck plate.

In one of the Georgetown's, a direct feed from a small tanker truck; although that in itself is likely a better arrangement against water.

Fuel at Sweeting's Cay comes in on 16' skiffs inside blue plastic drums. But that is predominately gas. MT drums are stored outside in the rain.

I've had to drain straight water out of an airplane wing during preflight, maybe a pint. This in a US airport, where there is very tight controls on fuel quality. Shaking the wings to get more to settle in the sumps.

Anyway, It just seems that there are threats out there, and if there is something easily doable to mitigate then it might make sense.

 

[psneeld]

You are a candidate if those are your cruising grounds, methods of refueling and your boat can be set up or needs a separate day tank.....no argument here.

I would do it too if I was routinely drum fueling.

 

[twistedtree]

An interesting spread of answers. Ranging from 100,000 gallon systems to 40 with day tanks. I don't suppose I'll be buying a steam plant so likely won't have to build a fire under any day tank to loosen up the fuel .

So, scaling up the situation in post #22. Let's say now that something like a GB42 is targeted for a day tank. One possible solution is make one existing tank the day tank. If doing this from scratch, that tank would not have a deck fill, would perhaps vent into the other tank, the engines/genset would only feed from the DT, and there would be no Y valves for the feed and the return fuel lines. You have a set of filters from the pumped main tank feed into the DT. Seems like things are getting simpler, not more complicated.

But here is an issue. It's time to refuel, and I need 300 gallons in each tank. The speed of the dock pump could far exceed the capability to transfer fuel. I'll take on 300 gallons, then have to wait until that quantity transfers to the day tank; then take on another 300 gallons. I think the dock boy and any waiting vessels are going to be not amused. The solution is a fast transfer system, and likely scaling up the Racors for 10x the normal rating. Beyond that, it appears to be a workable, minimalist system.
The other option is to add a real DT. Only works if space is available.

First, I don't disagree with others who suggest just buying clean fuel and not worrying about this. But you want to explore this which is also fine, so let's explore it.

I think using existing tankage like you have is problematic for the reasons you suggest. Also consider how off balance the boat could get, and/or how much more frequently you will need to transfer fuel as your tanks get low if you are trying to keep them in balance.

I think it works best when you have at least one center line tank that can act as day tank. Or a pair that are balanced side to side that you draw down together (this is how I use mine).

As for fill ups, what we do is transfer to the "day" tank in advance of filling up so it's already full. Then we just need to fill the main tanks and aren't waiting for fuel to transfer.

There is another consideration for transfer speed. If you are running 24/7, you want the transfer to be a good bit faster than your burn rate. Otherwise you will find yourself transferring fuel a large % of the time.

 

[petdoc4u]

Good discussion.
Alfamike,
I also have 5 tanks. I have been curious to try simultaneous multi tank supply. Do you find the fuel draw to be the same from, for example, 2 tanks if you are using them simultaneously or is there a disparity in fuel consumed from each tank?
Thanks,
-David

 

[FF]

The hassle with multiple tank feeds is some diesels return a lot of fuel, and you dont know where its going.

A small tank can be filled till the fuel vents from the air vent, much ungood.

Tanks used individually can help trim the vessel.

 

[captBrett]

I have a 200 gal day tank and love it most of the time. It is gravity fed via port or stbd wing tanks. Just don't let the mom adorable distract you when transferring fuel or you will over fill...