What is the carbon footprint for the US MSD program?

[newhaul]

This thread is showing its MMGW roots and really going down that rabbit hole quickly.

[a64pilot]

Discharge of human waste can be a problem, a bad problem.
It all depends on dilution, get a whole bunch of boats discharging into an estuary that has very little flow and you can have a problem.

However I am of the opinion that this too is used politically, it's an excuse to get rid of those boats that we don't want to look at.
How effective can this concern be on getting rid of boaters? Well it was effective enough so that the State of Georgia passed a law pretty long time ago making it illegal to reside on a boat in the State for more than something like two weeks a year, and years later that is slowly being undone.

My mistake, its 30 days
http://criminaldefensetucson.com/spe...orgia-illegal/

[Mike OReilly]

Originally Posted by Dockhead

Few kg? A full 120 liter tank on a 10 tonne vessel is 1% of mass. I think that's well beyond the rounding error range. Half full it's over half a % -- still beyond rounding error range. Those who care about carbon emissions definitely care about 1% improvements in whole sectors, even if our sector is a relatively small one.



We are talking about the CONTENTS, not the TANK, correct?

Sure, but we could play out specific scenarios all day and still not get any closer to knowing the real impact. And as A64 says, it's not obvious that mass and fuel consumption are a 1 to 1 correlated for displacement hulls. My sense is they are not.

I think the question is worth asking. I'm just not sure how to reach a meaningful answer.

All poop can be damaging to the environment if it is concentrated. Nothing special about human poop -- except it carries pathogens and parasites that like to infect humans. Concentrate dolphin poop and it will damage the ecosystem as well. This is why holding/treatment tanks are necessary for cruisers who go to places where water flow/volume is limited. Without some sort of holding/treatment system you are potentially damaging the place you apparently value.

[Dockhead]

Originally Posted by Mike OReilly

Sure, but we could play out specific scenarios all day and still not get any closer to knowing the real impact. And as A64 says, it's not obvious that mass and fuel consumption are a 1 to 1 correlated for displacement hulls. My sense is they are not.

I think the question is worth asking. I'm just not sure how to reach a meaningful answer.

There is a precise engineering answer to this question. Which I don't have. But add weight to a boat or ship, and it sinks proportionately, increasing wetted surface of the hull.

I don't have the formulas, but I believe that if you add 1% of mass to a displacement vessel, you will get almost exactly a 1% increase in fuel consumption.

Someone on Boat Design Forum will be able to give a more precise answer.

Edit: OK, a couple of minutes of Googling turns up this -- fuel consumption as a function of load is governed by the Admiralty Coefficient.

That formula is this:



I think it means that, all other things remaining constant, power (and therefore fuel) required will vary as a function of the cube root of the total mass of the vessel squared. So it's not linear, but it's definitely a function of loading.

Originally Posted by Mike OReilly

All poop can be damaging to the environment if it is concentrated. Nothing special about human poop -- except it carries pathogens and parasites that like to infect humans. Concentrate dolphin poop and it will damage the ecosystem as well. This is why holding/treatment tanks are necessary for cruisers who go to places where water flow/volume is limited. Without some sort of holding/treatment system you are potentially damaging the place you apparently value.

Completely agree.

[valhalla360]

Originally Posted by DotDun

But, but, but.....what about the case where a full MSD tank improves weight/balance and improves fuel economy??

Presumably, if they didn't have to design for a holding tank, they wouldn't have designed in the imbalance that it solves.

[valhalla360]

Originally Posted by Dockhead

I think some people -- and some regulatory agencies -- take the attitude that we shouldn't discharge anywhere, period -- at least not within territorial waters. They don't care that this prohibits discharging in perfectly harmless places -- like miles offshore. They don't care because they just assume that there is no cost involved, other than to the convenience of a few boaters whom no one cares about.

More likely it's simpler to police when all discharge is illegal. You don't have to worry about if it was 2.95miles offshore and how do you measure offshore, etc...

Discharge is only a problem when highly concentrated. Assuming you aren't dumping in a marina or tiny cove with dozens of other boats and negligible flow, by definition, pleasure boat discharge is not concentrated.

A far as fuel burn goes, keep in mind at least in the states, the vast majority of cruising boats are NOT displacement boats. On a planing boat, extra weight can have a significant impact, particularly if the boat is under powered and struggles to get on plane.

[Kenomac]

Our poop seacock is always open, nothing to haul around. Eco foot print is minute compared to land based life forms. I now run the generator less than an hour once every three days (.3 gallons of diesel) thanks to new solar panels by Solbian, and sail almost everywhere on a new set of sails. We make our own water using two Spectra 380c units and ride around on folding bikes.

Life is very..... green.

[denverd0n]

Originally Posted by valhalla360

Presumably, if they didn't have to design for a holding tank, they wouldn't have designed in the imbalance that it solves.

No. Talk to some boat designers and you'll find out that it doesn't work that way. What happens is that, after building a new design, they find out that there is some imbalance, so they move water, fuel, and waste tanks around to solve it.

[Mike OReilly]

Originally Posted by Dockhead

Edit: OK, a couple of minutes of Googling turns up this -- fuel consumption as a function of load is governed by the Admiralty Coefficient.

That formula is this:

Attachment 152192

Thanks DH, great find .

So, to take your example, adding 1% to our 10 T vessels alters the Displacement factor from:

461.32 to 464.38, which is then multiplied by the Velocity-cubed (in knots), which is then divided by this Admiralty Coefficient.



So… as I interpret this equation, this would make added displacements of the amount we are discussing negligible in the power calculation. A far greater impact (by nearly four factors) is Velocity. So the real answer is to slow down if you want to reduce your carbon footprint.

Originally Posted by Kenomac

Our poop seacock is always open, nothing to haul around.

And I assume you never visit enclosed anchorages or marinas where flow is minimal, or where there are too many other boats doing the same thing Mr. Green.

[Dockhead]

Originally Posted by Mike OReilly

Thanks DH, great find .

So, to take your example, adding 1% to our 10 T vessels alters the Displacement factor from:

461.32 to 464.38, which is then multiplied by the Velocity-cubed (in knots), which is then divided by this Admiralty Coefficient.



So… as I interpret this equation, this would make added displacements of the amount we are discussing negligible in the power calculation. A far greater impact (by nearly four factors) is Velocity. So the real answer is to slow down if you want to reduce your carbon footprint.

Can't argue with math.

But I don't think we're talking about actually BEING green. I think we're talking about demonstrating that there is actually an environmental cost to hauling around sewage. Is it negligible? Why don't you run some numbers -- we're not comparing it to slowing down by the way, just seeing if it really is "negligible". If it's not nothing, then it could still be something to talk about.

[thinwater]

Originally Posted by valhalla360

Reality: It's a rounding error in the big picture of sewage treatment...

And so is fuel consumption, boating, and most things, compared to celestial cycles, and yet they all, cumulatively, matter.

While the question is interesting, "rounding error" arguments are irrelevant. It is about risk (infection) and damage (COD, nutrients) per unit cost to avoid. Cost is that of installed equipment, labor, and maintenance. Different people weigh each of these factors differently.

Since the risk and damage impact more people than sailors, and the cost is born only by sailors, what do you think the chance is of a well-rounded discussion? How would you feel if all harbor-side homes and marinas were allowed to route their sewer out under your slip? On the other hand, the "whale poop" argument is sound well at sea. The "land based organism" argument less so; we installed sewage treatment to fix that.

On one hand, combined sewers do result in large overflows during heavy rains in some areas, and salt water does disinfect most germs. On-board treatments systems do sanitize, but do they treat (nutrients, TSS, COD), and are there chlorination residuals (POTWs cannot chlorinate high COD waste)?

It's complicated, and like many rules, right or wrong, I think it is locked in a stable compromise position. That is the reality. Anything perceived as backsliding just aint' happening.

[sailnow2011]

Originally Posted by SecondBase

I'm trying to estimate our annual carbon footprint for the Marine Sanitation Device program here in the States to the nearest ton.

You are joking, right? Is this what we are reduced to now? Estimating our "carbon footprint"? For what? Self guilt? Persecution of carbon offenders? Carbon is unimportant, Recent studies have found it to be a non-issue.

[Dockhead]

Originally Posted by sailnow2011

You are joking, right? Is this what we are reduced to now? Estimating our "carbon footprint"? For what? Self guilt? Persecution of carbon offenders? Carbon is unimportant, Recent studies have found it to be a non-issue.

If you read the thread, you will find that there are good reasons to be analyzing this, whether or not you believe that "carbon is unimportant".

[Dockhead]

Originally Posted by thinwater

And so is fuel consumption, boating, and most things, compared to celestial cycles, and yet they all, cumulatively, matter.

While the question is interesting, "rounding error" arguments are irrelevant. It is about risk (infection) and damage (COD, nutrients) per unit cost to avoid. Cost is that of installed equipment, labor, and maintenance. Different people weigh each of these factors differently.

Since the risk and damage impact more people than sailors, and the cost is born only by sailors, what do you think the chance is of a well-rounded discussion? How would you feel if all harbor-side homes and marinas were allowed to route their sewer out under your slip? On the other hand, the "whale poop" argument is sound well at sea. The "land based organism" argument less so; we installed sewage treatment to fix that.

On one hand, combined sewers do result in large overflows during heavy rains in some areas, and salt water does disinfect most germs. On-board treatments systems do sanitize, but do they treat (nutrients, TSS, COD), and are there chlorination residuals (POTWs cannot chlorinate high COD waste)?

It's complicated, and like many rules, right or wrong, I think it is locked in a stable compromise position. That is the reality. Anything perceived as backsliding just aint' happening.

Yes, but discharge rules which prohibit our tiny discharges, miles out to sea, are just idiotically stupid, and hugely burdensome to us. I think it is a good fight, to try to roll back some of these, and I think the proposition of the OP that the environmental cost of not being allowed to discharge even a couple miles out to sea is not zero, could really help.


No one disputes that discharging close to shore, and especially in coves and anchorages and near beaches, is bad, and we are not arguing about that, nor about whether holding tanks should be required or not (for the record, I am not against requiring them, but it's not relevant to the discussion).

[Mike OReilly]

Originally Posted by Dockhead

Can't argue with math.

But I don't think we're talking about actually BEING green. I think we're talking about demonstrating that there is actually an environmental cost to hauling around sewage. Is it negligible? Why don't you run some numbers -- we're not comparing it to slowing down by the way, just seeing if it really is "negligible". If it's not nothing, then it could still be something to talk about.

There definitely is a cost to hauling extra mass around, but I think the equation shows this cost (in power usage) to be minimal in the context of the existing mass of a vessel. Minimal is not zero, for sure. But if we’re thinking about it in terms of eco-utility, then there are easier ways to achieve much bigger improvements.

Dumping straight overboard in all places would reduce the power cost of moving crap around to zero. BUT as we both agree, this produces far greater environmental impacts in local areas compared to the carbon cost associated with hauling our poop around.

… or maybe I’m not really understanding what we’re really discussing .