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Old 21-07-2015, 03:44   #376
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Re: Bestevaer 49ST

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Originally Posted by Seaworthy Lass View Post
I thought I had actually , although it doesn't make much difference.
I will have a chat with my other half, but I may need to redo that.

SWL
Depends really on the pumps you use but the ideal is to have the filter before the pumps which is generally a non problematic configuration for a diesel but never the less I would still specify that the builders use anti vapour lock filters just in case which would be mandatory for a petrol system in an upstream configuration to stop vapour locks.
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Old 21-07-2015, 06:56   #377
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Re: Bestevaer 49ST

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. . .

Systems like this rely on a huge amount of care with which valves are open and shut and what pumps are left on, lots of possibilities of errors.

SWL
My electrical system is like that, and it's a serious weak point. If you don't set it just so, you can kill the batts in a heartbeat, or lose power, or other different serious problems. I do exercise a "huge amount of care" and have not had serious problems, but they lie in wait. Should be a high priority goal of systems design to reduce the risk of operator error; certainly the necessity of a "huge amount of care" is really undesirable.

Also, what is the consequence of error? Blow out a seal and pour diesel into the bilges? Ruin a pump? Pump all the diesel fuel out of a tank vent? This also needs to be thought through, and the really disastrous consequences prevented with interlocks or safety shutoffs if at all possible.

In this case, I don't know whether there could be a different system architecture which would be less vulnerable to operator error and still be practical and economical. Worth thinking hard about I would say. If not, then you need a really clear, well-practiced, step-by-step operating procedure, with posted diagrams, and some way of warning if something is done wrong. This is more feasible in your case, with only two operators, than it would be on my boat, where lots of people come and go.

Looks to me like the main risks are:

1. Pumping against a closed valve.

2. Overfilling the day tank.

3. Overfilling a main tank from day tank overflow or transfering from the other tank.

4. Running the engine against a closed valve.


For 1, I guess the problem is to specify the pump and seals to be capable of surviving this. If not practical, then pressure switches everywhere where this is possible.

For 2, overflow into both main tanks will solve it.

For 3, I don't know. Maybe a "tank full!" switch which can sound an alarm, maybe shut off the transfer pump. Or maybe more elegant -- lock the 3 way valves together in such a way that you have to disconnect the interconnection to pump from one main tank to the other, rather than circulating within the same tank.

For 4, I guess specify everything so that this will not cause damage.
Thanks for the feedback.

We are certainly very conscious of the drawbacks of a manual system like this. Several problems with automatic systems though. They can fail, causing just the problems you were trying to avoid. Then there is all the hassle of sourcing or keeping replacements and the possibility the system is incapacitated if they are not working,

Mistakes can be minimised by aiding ease of use eg putting levers used together close together and having them operate in the same direction, offering good visual cues.

We are only envisaging two of us will ever be operating the boat so in our case operator error will be dramatically reduced. We are both super careful. Just in case someone else needs to operate the boat, I agree it is important to provide clear diagrams and instructions. I keep meaning to update instructions for our current boat, and you have given me the necessary nudge.

Regarding the 4 specific issues you raise:

1. Pumping against a closed valve.
The main risk here is ruining a pump and they are pretty tough I think. Carrying spare pumps fixes this though.

2. Overfilling the day tank.
The overflow to the starboard tank handles this, unless the starboard tank is completely full. This is not something that will occur if that tank is always drawn on first ie don't use the port tank until the starboard one has been depleted a bit. Two errors would have to occur for overfilling to be a problem: leaving the day tank filling way too long PLUS using the port tank when the starboard one was near full.
As you suggest, overflow into both tanks would solve the issue, but this complicates things though, as the return tank would need to be selected according to what tank is being used. Just as much room for error here to select the wrong tank.

3. Overfilling a main tank from day tank overflow or transfering from the other tank.
Transferring for too long would be a real risk I think and we plan to avoid doing this at all. There is no need. The two tanks will have two separate external fills. The engine will operate from either tank via a 3 way valve. If you polish then the return is to the same tank. The capacity to transfer has been added, but should generally never be required.
It is nice to be able to keep the two tanks used independently and the fuel separate.

4. Running the engine against a closed valve.
To run the engine usually nothing would need to be done. The two valves from the day tank would generally be kept open, allowing instant start of the engine. If a valve is ever turned off there for some reason, just hang the engine key on the valve as a reminder.

Any suggestions on how to improve the system architecture to make it less vulnerable to operator error and still be practical and versatile and trouble free (while avoiding relying on automatic systems) would be very worthwhile if anyone can think of anything.

SWL
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Old 21-07-2015, 09:19   #378
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Re: Bestevaer 49ST

Hawk's system was somewhat similar to this . . .and I will say that in practice our only real world failure mode was forgetting to pump up to the day tank once every 12 hrs, thus letting it run dry, and stopping the engine, requiring a bleeding. This was just a matter of fatigue and distraction and stupidity. It happened (I think) twice in the time we had Hawk.

We had a sight tube on the day tank like you plan to.

You could add a low lvl alarm to the day tank, but it would be used so infrequently you would never know if it actually worked, and it would probably be hard to access. You could also add an automatic low lvl pump, but that would have the same problems.

We had a 'proceedure' to pump up the day tank full whenever we shut down the engine, so it would always be full on restart. Then we were 'supposed to' pump it at the change of watches, but forgot twice.
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Old 21-07-2015, 17:20   #379
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Re: Bestevaer 49ST

Seems to me if you tee'd the header tank overflow into the polishing system return, and used separate valves rather than the three way valve, you could use the polishing system as a completely independent fuel system by pushing the fuel up the return line if need be.

Another option would be to rig separate port and stb systems that can either be set up as a fuel supply, or for polishing. With a crossover incase of a failure in one side.

Either way a blocked filter or burnt won't be an issue, just swap to the other system.

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Old 21-07-2015, 17:53   #380
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Re: Bestevaer 49ST

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Originally Posted by Seaworthy Lass View Post
...

Although there is no counter (I presume you mean to see how much to put in the day tank?) K&M add a sight tube to indicate fuel level in the day tank.
...
Yep a counter to see how much fuel actually went into the tank.

With the newer electric controlled engines, maybe that is not needed, but I have calculated my MPG for every tank of fuel I have bought for my vehicles and it is a habit that is hard to break. How much fuel I pumped into the day tank would be nice for me know. Not sure it is a must have.

I recently read a reference to a water/fuel separator but I can't remember where... From what I can remember, the water/fuel separator was YAF(Yet Another Filter) inline with the fuel system to remove water from the fuel. Might be worth looking into as well as a water in fuel alarm.

Later,
Dan
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Old 22-07-2015, 02:26   #381
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Re: Bestevaer 49ST

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SWL, I would strongly encourage you to extend the return lines on the fuel polishing and transfer circuit to just above the bottom of the tank.
Are you concerned about foaming? The engine is not being fed from the main tank, so any foaming there has time to settle and I don't think is a cause for concern.

A few drawbacks for returning to near the bottom of the main tanks with the polishing:
- It risks the possibility of a siphon setting up if valves are not shut off correctly
- It also adds the complication of two more on/off valves being required in an already reasonably complex system
- Although it is a minor issue, there is worse mixing of fuel and drawing of unfiltered fuel if it returns to the bottom.

The day tank return from the engine is another issue. We will leave it to the builder to do what they usually do there, as they know what works.

What do others think?

SWL
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Old 22-07-2015, 03:06   #382
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Re: Bestevaer 49ST

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Originally Posted by Seaworthy Lass View Post
Are you concerned about foaming? The engine is not being fed from the main tank, so any foaming there has time to settle and I don't think is a cause for concern.

A few drawbacks for returning to near the bottom of the main tanks with the polishing:
- It risks the possibility of a siphon setting up if valves are not shut off correctly
- It also adds the complication of two more on/off valves being required in an already reasonably complex system
- Although it is a minor issue, there is worse mixing of fuel and drawing of unfiltered fuel if it returns to the bottom.

The day tank return from the engine is another issue. We will leave it to the builder to do what they usually do there, as they know what works.

What do others think?

SWL
After giving this some thought, My idea would be something like this.

I would set up the fuel polishing to go directly into the day tank.and recycle the cleaned diesel. The day tank would gravity feed the engines.


Basically, the fuel from one tank would go to the polisher, go to the day tank and that cleaned fuel would be returned to the SAME tank from the day tank but cleaned. THis would ensure that fuel polishing could be run for a while.

The system could then be swapped to the other tank with no mixing of tanks.

The gravity feed from the day tank is to the engines...... the circulatory system would have to be pump driven through the polisher. A manual back up could be set up in the event of an power issue.
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Old 22-07-2015, 03:28   #383
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Re: Bestevaer 49ST

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After giving this some thought, My idea would be something like this.

I would set up the fuel polishing to go directly into the day tank.and recycle the cleaned diesel. The day tank would gravity feed the engines.


Basically, the fuel from one tank would go to the polisher, go to the day tank and that cleaned fuel would be returned to the SAME tank from the day tank but cleaned. THis would ensure that fuel polishing could be run for a while.

The system could then be swapped to the other tank with no mixing of tanks.

The gravity feed from the day tank is to the engines...... the circulatory system would have to be pump driven through the polisher. A manual back up could be set up in the event of an power issue.
The advantages of a system like this is that the day tank can be kept full if a timer is put on the polishing. The day tank gets clean fuel everytime and the circulation puts cleaned fuel back in the main tank.
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Old 22-07-2015, 03:39   #384
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Re: Bestevaer 49ST

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After giving this some thought, My idea would be something like this.

I would set up the fuel polishing to go directly into the day tank.and recycle the cleaned diesel. The day tank would gravity feed the engines.


Basically, the fuel from one tank would go to the polisher, go to the day tank and that cleaned fuel would be returned to the SAME tank from the day tank but cleaned. THis would ensure that fuel polishing could be run for a while.

The system could then be swapped to the other tank with no mixing of tanks.

The gravity feed from the day tank is to the engines...... the circulatory system would have to be pump driven through the polisher. A manual back up could be set up in the event of an power issue.
Hi Weav
It is a bit like a game sorting through all the possibilities isn't it? Part of the fun of building is having all this to think about. My mind has been even churning in my sleep .

We wouldn't want the polishing system to go into the day tank for several reasons. The pick up for this is the very bottom of the sump with the possibility of grot and water. I know it is being filtered, but putting this straight into the day tank is not ideal.

At the moment we run a polishing system through a dedicated Raycor 900 (one fuel tank) drawing from the very bottom of the tank for a few hours each day. We started doing this several years ago with a cleanish tank and our fuel is now kept very clean. The filter from the main tank to the engine (another Raycor 900) remains absolutely spotless. This helps tremendously in keeping the engine running faultlessly.
It is a system that works extremely well and we are keen to reproduce this with the additional benefits of a day tank.

SWL
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Old 22-07-2015, 03:57   #385
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Re: Bestevaer 49ST

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Hi Weav
It is a bit like a game sorting through all the possibilities isn't it? Part of the fun of building is having all this to think about. My mind has been even churning in my sleep .

We wouldn't want the polishing system to go into the day tank for several reasons. The pick up for this is the very bottom of the sump with the possibility of grot and water. I know it is being filtered, but putting this straight into the day tank is not ideal.

At the moment we run a polishing system through a dedicated Raycor 900 (one fuel tank) drawing from the very bottom of the tank for a few hours each day. We started doing this several years ago with a cleanish tank and our fuel is now kept very clean. The filter from the main tank to the engine (another Raycor 900) remains absolutely spotless. This helps tremendously in keeping the engine running faultlessly.
It is a system that works extremely well and we are keen to reproduce this with the additional benefits of a day tank.

SWL
I have only have one fuel polishing system, so my experience is limited. It was similar to what I suggested above with an 18 gallon day tank and the fuel cleaned in the manner suggested. The fuel filter from the day tank never showed water or debris and I did start with a new main tank. I only polished once a week or when using the engines.

Location Florida, hot and humid.

Lucky I guess.
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Old 22-07-2015, 04:07   #386
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Re: Bestevaer 49ST

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I have only have one fuel polishing system, so my experience is limited. It was similar to what I suggested above with an 18 gallon day tank and the fuel cleaned in the manner suggested. The fuel filter from the day tank never showed water or debris and I did start with a new main tank. I only polished once a week or when using the engines.

Location Florida, hot and humid.

Lucky I guess.
Possibly you were running through fuel much faster than we do and filling with Florida fuel that was less likely to be contaminated and not drawing from the very very bottom of the tank?

It is nice for the day tank only to receive separately filtered fuel and to be kept very clean. If you were using it constantly for high volume polishing, some sediment may slowly build up, particularly if you were drawing from the very bottom of the main tanks (filters do not filter everything).

Less than spotless fuel is a common source for engine trouble. We have an independent polishing system from the very bottom of the tank that works so well now, that this is one thing we are keen to reproduce.

SWL
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Old 22-07-2015, 04:31   #387
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Re: Bestevaer 49ST

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Seems to me if you tee'd the header tank overflow into the polishing system return, and used separate valves rather than the three way valve, you could use the polishing system as a completely independent fuel system by pushing the fuel up the return line if need be.

Another option would be to rig separate port and stb systems that can either be set up as a fuel supply, or for polishing. With a crossover incase of a failure in one side.

Either way a blocked filter or burnt won't be an issue, just swap to the other system.

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Hi Ben
Thanks for the input.

In the last few replies to Weavis I have covered some of the reasons we wouldn't want fuel from the polishing system to run to the engine, even as a backup.

We have tried thinking about all the things that could go wrong. The beauty of a day tank is that it provides clean gravity fed fuel to the engine, which reduces the chance of problems.

If the engine is running and stops due to a problems with fuel from the day tank, we can quickly flip a valve and source filtered fuel directly from the tank (independent system and independent fuel).

The two main things that can go wrong with refilling the day tank system (apart from forgetting to top it up or overfill when the starboard tank is full) are pump failure or fuel filter failure. The urgency of sorting these problems out is reduced if the day tank is never allowed to run near empty before filling it. You have time to sort it out by replacing a pump or filter.

Both filling problems can also be temporarily solved by simply manually filling the day tank with the 20 odd litres of emergency fuel kept in a jerry can. An easy fill, as it is is done in the sheltered dry conditions of the huge cockpit lazarette.

Although a line could be teed in from the polishing system it introduces a couple more valves and these always have the potential of leaking fuel out or air in and introduce the risk of error with inadvertently being left on.

We have a polishing system that would be used daily as we do now for ensuring clean fuel and the ability to bypass the tank using the "normal" system and an additional backup of filling the day tank manually, so having a facility to use the polishing system seems like overkill while adding the potential for more trouble.

So that was the logic behind deciding to keep the polishing and engine supply systems separate.

SWL
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Old 22-07-2015, 05:20   #388
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Re: Bestevaer 49ST

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Originally Posted by Seaworthy Lass View Post
Thanks for the feedback.........

Any suggestions on how to improve the system architecture to make it less vulnerable to operator error and still be practical and versatile and trouble free (while avoiding relying on automatic systems) would be very worthwhile if anyone can think of anything.

SWL
Well you are getting lots of feedback and from quite knowledgeable people so I will endeavour to be brief

Think of the fuel system as completely seperate components and try to keep the commonality between the different components to a minmum.

In essence you have three components.
1. Fuel supply to engine and heater ie Day Tank
2. Fuel storage ie port / starboard tanks
3. Fuel polishing.

If it was me, I would want the day tank to KISS as in really KISS. Gravity feed, sight guage, easy access drain point, fuel input from
storage tanks into the top, fuel out from near bottom, big manual filling cap. Vent very high and protected from water ingress. No overflow (reasons below). Engine fuel return back into top of Day Tank. Consider this tank as the only fuel tank as far as the engine is concerned.

With your storage tanks you can be a little complex if that suits your
style or you can still go KISS. I would keep both sides seperate but have one gravity crossfeed valve for equalization if one day it is needed. But really, the storage component is not critical, make it any way you
want, just don't incorporate it with the Day Tank, apart from the plumbing from the pumps to the top of the Day Tank. Any issue with one side shouldn't incapacitate the other side.

Fuel polishing, again complexity here doesn't really matter too much but I would still keep all the parts of the polishing separate from the storage tanks parts and again any failure of the polishing system shouldn't compromise the storage components and certainly not have anything to do with the Day Tank.

To help make management of the various components more foolproof, I suggest the parts of each aspect be kept physically apart. That is to say, the polishing pumps, filters valves etc all be located in one area, say on one bulkhead or whatever while the storage transfer pumps, valves, filters etc be somwhere quite different. Even keep say the port storage tanks bit and bobs on port side and sthe starboard ones on starboard.

Day Tank bits take care of themselves as they will be (or should be)
right near the engine in the engine room. If the storage or polishing parts have to be in the engine room, keep them way way way away from the Day Tank stuff.

OK, why no overflow on Day Tank. Really just want to keep it simple. Overflow is only required if you overfill the Day Tank. I would suggest other ways to solve this potential problem. In nothing is done, the
overfilling will escape though the vent. Make the vent exit somewhere conspicuous so you will see the fuel running out b of it . Or have an alarm or pump interupt circuit when Day Tank is full or a pressure sensor in storage delivery piping. The pressure will rise considerably as soon as fuel is forced up the vent pump. Or have a fluid sensor half way up the vent pipe. Lots of ways really but all belong to the storage aspects, not the Day Tank aspects.
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Old 22-07-2015, 05:28   #389
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Re: Bestevaer 49ST

Thanks SWL, good to get more info on the logic behind your system.

I didn't realise the polishing system draws from a much lower point than the fuel supply. The logic makes a lot of sense now.

I still like the idea of a easy backup, but that's only because I hate the idea of having to fiddle with diesel lines in rough seas, but if the polishing system does it's job, then the primary filter should not block, so all will be fine, and diesel should not need to be spilt into pristine bilges!

Looks like a fine design, and I like your simple approach.
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Old 22-07-2015, 06:29   #390
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Re: Bestevaer 49ST

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Well you are getting lots of feedback and from quite knowledgeable people so I will endeavour to be brief

Think of the fuel system as completely seperate components and try to keep the commonality between the different components to a minimum.

In essence you have three components.
1. Fuel supply to engine and heater ie Day Tank
2. Fuel storage ie port / starboard tanks
3. Fuel polishing.
Wottie, that is almost exactly our thought process behind the design (apart from the day tank overflow).

- Three separate systems (feed to engine, polishing, main storage) TICK

Day tank:
- Gravity fed TICK
- Sight gauge TICK
- Easy access drain point TICK
- Fuel input from storage tanks into the top TICK
- Fuel out from near bottom TICK
- Big manual filling cap TICK
- Vent very high and protected from water ingress TICK
- Engine fuel return back into top TICK

- Don't incorporate the storage/polishing with the Day Tank, apart from the plumbing from the pumps to the top of the Day Tank. Any issue with one side shouldn't incapacitate the other side. TICK

- Fuel polishing, again complexity here doesn't really matter too much but I would still keep all the parts of the polishing separate from the storage tanks parts and again any failure of the polishing system shouldn't compromise the storage components and certainly not have anything to do with the Day Tank. TICK

- Consider this tank as the only fuel tank as far as the engine is concerned Consider this tank as the only fuel tank as far as the engine is concerned: in some emergency it is useful to be able to pump fuel directly from the main tank (just involves one short line and one three way valve).
NOT QUITE: in some emergency it is useful to be able to pump fuel directly from the main tank (just involves one short line and one three way valve).


Quote:
Originally Posted by Wotname View Post
To help make management of the various components more foolproof, I suggest the parts of each aspect be kept physically apart. That is to say, the polishing pumps, filters valves etc all be located in one area, say on one bulkhead or whatever while the storage transfer pumps, valves, filters etc be somwhere quite different. Even keep say the port storage tanks bit and bobs on port side and sthe starboard ones on starboard.

Day Tank bits take care of themselves as they will be (or should be)
right near the engine in the engine room. If the storage or polishing parts have to be in the engine room, keep them way way way away from the Day Tank stuff.
Excellent idea to keep these well apart . They will all probably go into the technical area next to the engine bay though, which is close to the tanks rather than on separate sides of the boat.
I will add yet another bit in the specs regarding this.

Quote:
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OK, why no overflow on Day Tank. Really just want to keep it simple. Overflow is only required if you overfill the Day Tank. I would suggest other ways to solve this potential problem. In nothing is done, the
overfilling will escape though the vent. Make the vent exit somewhere conspicuous so you will see the fuel running out b of it . Or have an alarm or pump interupt circuit when Day Tank is full or a pressure sensor in storage delivery piping. The pressure will rise considerably as soon as fuel is forced up the vent pump. Or have a fluid sensor half way up the vent pipe. Lots of ways really but all belong to the storage aspects, not the Day Tank aspects.
This is only thing you have mentioned that we have specified differently. Only because there seems to be no drawback to adding an overflow. It will never be relied on. The day tank is small and will fill quickly, we won't aim to have it filled to the brim and we will watch it like hawks (it is not something you turn on then go do something else). But just in case we miss that it is nearly full, rather than spilling out fuel or introducing sensors, the fuel can briefly overflow to the top of one main tank (no siphon issues). What potential problem can you see with an overflow? It is only if our eagle eyes miss when the day tank is getting full that we would need it anyway and it is just one simple downhill line with no valves etc.

Thanks for your response. It is very valuable to have holes poked in our schemes, but it is also actually very nice to have someone confirm our ideas are reasonable.

SWL
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