Skookum Maru

[stromborg]

Re: Skookum Maru

It will be interesting to follow the continuing evolution of Skookum Maru.

I have a thought regarding the potential replacement of your existing engine. Assuming your current engine is in good repair and you run it efficiently, it might be more "big picture" environmentally friendly to keep it. The carbon footprint of producing that engine was made long ago and can't be undone. I can't imagine there is much of a second-use market for old marine diesels so it would most likely be consigned to the scrapheap at which point you are starting a new carbon footprint producing whatever replacement would have to be built. Much like your bus, it takes relatively little resources to keep it running compared to replacing.

[ron ll]

Re: Skookum Maru

I had the starter motor replaced on Snoose a few days ago. The mechanic is a Detroit specialist so we chatted about a few other things re: my 3-71. One of my questions was, what happens when it dies? He said first of all, it won’t. But if it did, it really can’t be rebuilt in place so it has to be taken out. And you probably wouldn’t want to put it back in. So he suggested probably a turbo Cummins or a turbo Yanmar, and mechanical versions, not electronic. So I was getting all dreamy eyed thinking about a smaller quieter engine with real motor mounts and a chance to reline the engine room with soundproofing and more room to crawl around and work on it. Then he destroyed my dreams by saying first, it probably wouldn’t be that much smaller, plus it would cost 10g to get this one out and 30-40g for the new engine. My noisy old DD just started sounding a little quieter.

[Garret]

Re: Skookum Maru

I realize it's a much smaller engine (53HP) - but I replaced the Perkins 4-108 with a 4JH3E Yanmar in Neoga 20 years ago. Not much smaller, but oh so much quieter & burns 1/2 the fuel.

Local dealer quoted 16K for the motor & transmission + 10-15K for removing the old & installing the new. I found the same motor from another Yanmar dealer for 10K (with a bigger/ heavier duty transmission) & did the swap myself. I figure it took about 20 hours of my time & 5-10 of a friend's (2 people taking out the old & putting in the new makes a big difference).

Not saying a bigger motor like Snooze's or SM's would be an easy swap - just that dealers can get mighty pricey on this sort of work.

[cstevens]

Re: Skookum Maru

Ah, well I see we are jumping in at the deep end! Although I did start us off there with my comment about electric propulsion systems. I do want to tackle a few easier things first - like a gray water system, biodiesel conversion for the engine and stove, etc., but I agree that a few thoughts on electric/hybrid systems would be useful here.

I have spent an enormous amount of time researching and thinking about options for full electric or hybrid power, starting with Petrel well before Skookum Maru was even in the picture. So I have some pretty specific and well-developed thoughts on the subject. At the same time I would very much like to tap into the knowledge and ideas of the group as well. For example I did know know that Steyr had a hybrid option (although I'll note that I can't find any recent info on it at all so I'm not sure what the status of it is?) It's a huge topic and I expect we will spend some time on it but here are a few things I think about it right now, for debate and comment:

First, Skookum Maru is a cruising boat. I certainly want to at least preserve her current range between shore visits. Which is approximately 1000nm or around seven days, limited mostly by fresh water capacity right now. Given these parameters any electric system that does not include a significant amount of solar charging is pretty useless. Without solar you have maybe a half-day of battery cruising and then you are relying on shore power or a generator to recharge. We don't want to have to tie up to recharge and the second law of thermodynamics tells us that using an engine to charge the batteries will always be less efficient than using the engine to propel the boat directly.

Given those parameters, the question around viability of any electric propulsion solution comes down to "what percentage of our current diesel-based energy use can be replaced by solar power?". Everything else is just mechanics. If, for example, we could reduce our reliance on diesel fuel by 10% I think that would be a pretty significant benefit. And I think that may be possible after doing some back of the napkin calculations, but more about that later.

Then, as Steve suggests (and Ron confirms), there are strong reasons to keep as much of the existing propulsion system as possible. Even as a cost-is-no-object exercise, simply replacing the Detroit with a more efficient engine would likely never pencil out given the number of hours we would have to run to make up the resource and carbon debt incurred with a new motor. However there might be other reasons for wanting to replace the Detroit, mostly having to do with the perceived value of Skookum Maru. If she would be more likely to be cherished and maintained if she had a more modern engine then that's something to consider. At the same time we have no plans to ever sell her, and any engine that we might install now would just be another old motor in twenty years or so, when we might be thinking that a big old wood boat is just too much work to maintain, leading us start looking for a nice, low-maintenance fiberglass trawler... (kidding!).

With those thoughts as the background, I have considered a few different options, all of which would need further definition and some math to determine how effective they would be.

1. Keep the existing setup as-is, but run biodiesel. This option seems pretty easy to accomplish, at least in comparison to the others. There are some logistics to deal with in sourcing and storing biodiesel but I think that it's doable.

2. Keep the 3-71 but add a part-time electric power option with solar panels in a parallel hybrid configuration, in which both the engine and the electric motor can propel the boat directly, and the engine can be used to recharge the batteries by spinning the motor.

3. Keep the 3-71 but add a full-time electric power option with solar panels in a serial hybrid configuration, in which the engine is used only to run a generator to charge the batteries, and all propulsion is from the electric motor.

4. Repower with a new diesel engine in either a parallel or serial hybrid configuration. Various solutions exist for this approach right now. Elco has motors that can be configured in a serial or parallel configuration with any suitable diesel engine or genset. Beta has parallel hybrid power packages in a range of sizes. I'm sure there are others as well.

Finally, as a thought exercise cost is no object, but in the real world it is very much a consideration. Any of these options would have to be doable within a certain budget that has not been determined and may not actually exist given the priorities of keeping the kid fed and clothed and a roof over our heads. But I am very much looking forward to the ideas and discussions and I do hope to come away with a plan that we can actually implement.

[rgthom]

Re: Skookum Maru

If you are thinking of solar maybe the first question is how much area is available for panels without ruining the appearance of the boat? It looks to me like not a lot of rooftop which is not already in use or partially shaded.

-Rick

[Garret]

Re: Skookum Maru

I don't see how any significant time underway can be gained by solar unless you have some crazy array way bigger than the boat.

200 watts per panel for roughly 2'x5' panels. 20 of 'em = 10'x20'. In direct overhead sun, that'll produce 4000 watts. 1 HP is just under 750 watts - so you'll get the equivalent of just over 5HP - at noon on a clear sunny day.

These #'s are all very rough (& I know you live in an area with 100% sunny days) - but you'd need an array 5x the size of the boat to go anywhere I'd think.

[cstevens]

Re: Skookum Maru

If you are thinking of solar maybe the first question is how much area is available for panels without ruining the appearance of the boat? It looks to me like not a lot of rooftop which is not already in use or partially shaded.

-Rick

Still to be determined but I think it might be possible to get as much as 200 sqft of solar panels. It would require placing panels over the aft cabin and I have some ideas on how to do that without permanent modifications or ruining her looks but that's definitely a topic for discussion. 200 sqft equals about 3kW right now, which I think is about 10% of our power use at cruising speed in calm conditions, or maybe just a bit less. But there are some improvements in solar panel efficiency that look like they will become commercially available soon (perovskite panels in particular) which might double the available solar power. And a 20% decrease in diesel use would be huge. All these numbers are very rough though, so more math is needed to detemine what is realistic.

[cstevens]

Re: Skookum Maru

I don't see how any significant time underway can be gained by solar unless you have some crazy array way bigger than the boat.

200 watts per panel for roughly 2'x5' panels. 20 of 'em = 10'x20'. In direct overhead sun, that'll produce 4000 watts. 1 HP is just under 750 watts - so you'll get the equivalent of just over 5HP - at noon on a clear sunny day.

These #'s are all very rough (& I know you live in an area with 100% sunny days) - but you'd need an array 5x the size of the boat to go anywhere I'd think.

I think those numbers are about what I get as well. And you are right, it doesn't translate to any significant electric-only time underway. But it might still translate into a useful energy input into the system. More on the subject later though. I need to get some paying work done!

[BBSebens]

Re: Skookum Maru

Ah, well I see we are jumping in at the deep end! Although I did start us off there with my comment about electric propulsion systems. I do want to tackle a few easier things first - like a gray water system, biodiesel conversion for the engine and stove, etc., but I agree that a few thoughts on electric/hybrid systems would be useful here.

All the systems must coexist peacefully. A change in the drivetrain could have major repercussions on the rest of the systems, either in the work needed to remove and replace said lump o' iron, or new accessories required by the new system.

For example, the addition of an electric drive would require space for the motor, mechanism to connect it to the prop shaft, a suitably large and heavy battery pack, and a significant and specific set of electrical cable.

I think you ought to at least settle on a drivetrain plan, before embarking on the surrounding systems.

[cstevens]

Re: Skookum Maru

All the systems must coexist peacefully. A change in the drivetrain could have major repercussions on the rest of the systems, either in the work needed to remove and replace said lump o' iron, or new accessories required by the new system.

For example, the addition of an electric drive would require space for the motor, mechanism to connect it to the prop shaft, a suitably large and heavy battery pack, and a significant and specific set of electrical cable.

I think you ought to at least settle on a drivetrain plan, before embarking on the surrounding systems.

Ah, that's an excellent point Ben. Ok, so drivetrain first it is. And really it's the fun part so why not enjoy ourselves before getting into the dull bits involving plumbing. Back in a bit.

[lukes]

Re: Skookum Maru

You could always make your own hybrid based on the existing engine. Do you have any room to move the engine forward?

https://loganclutch.com/flexadrive-product

Get one of those 5 output units and you could have an engine driven bilge pump for emergencies, a couple of hydraulic systems for the davits, and then stack up the electric motors.

More realistically, years ago on fishing boats in the FL Keys, the price difference at the dock vs. the street was enough that we would often spend off days hauling 25 gallons at a time to the boat using the roll around fuel dollies. Doing the same now with Biodiesel wouldn't be that difficult. I'm not sure how your marina would feel about it, but in practice, it's no different than using the pump.

[cstevens]

Re: Skookum Maru

You could always make your own hybrid based on the existing engine. Do you have any room to move the engine forward?

https://loganclutch.com/flexadrive-product

Get one of those 5 output units and you could have an engine driven bilge pump for emergencies, a couple of hydraulic systems for the davits, and then stack up the electric motors.

More realistically, years ago on fishing boats in the FL Keys, the price difference at the dock vs. the street was enough that we would often spend off days hauling 25 gallons at a time to the boat using the roll around fuel dollies. Doing the same now with Biodiesel wouldn't be that difficult. I'm not sure how your marina would feel about it, but in practice, it's no different than using the pump.

Funny you should post a link to the Logan site Luke. I've spent quite a bit of time there myself recently

This is going to be a fun discussion I can tell already.

[_QB_]

Re: Skookum Maru

I replaced the Perkins 4-108 with a 4JH3E Yanmar in Neoga 20 years ago. Not much smaller, but oh so much quieter & burns 1/2 the fuel.

Interesting. I gotta know, what do you base that 50% reduction in fuel use on. Because I've never heard of any two small diesels -- turbocharged or not -- actually differing by more than 10% in brake specific fuel consumption.

This is kind of relevant, since if repowering only lets Chris reduce CO2 output by 10%, that's not really re-imagining the boat. 50% on the other hand...

[_QB_]

Re: Skookum Maru

...

5. Convert the diesel fuel tanks to hydrogen fuel cells. Electric motor.

Yes there are some infrastructure issues. But don't you think you should at least pencil this one out?

[cstevens]

Re: Skookum Maru

Interesting. I gotta know, what do you base that 50% reduction in fuel use on. Because I've never heard of any two small diesels -- turbocharged or not -- actually differing by more than 10% in brake specific fuel consumption.

This is kind of relevant, since if repowering only lets Chris reduce CO2 output by 10%, that's not really re-imagining the boat. 50% on the other hand...

Well, perhaps the term "reimagining" is a bit grandiose for what may end up being a few incremental changes but I don't think 10% is negligible. I probably wouldn't repower just to get that much of an improvement but I would certainly consider it worth some effort to achieve. Especially if doing so opens up the potential for further savings as the technology improves.

However I agree that a 50% fuel savings is a stretch (sorry Garret). I went looking for some data just to check what sort of improvement might be possible in replacing the 3-71 though. I can't find a fuel/power curve chart for the 3-71 but I did find one for the 4-53, which is roughly equivalent in hp rating. And I found one for the Beta 110, which is also roughly equivalent. Given some even more rough assumptions I get:

Skookum Maru HP at 7kts: ~30 (based on David Gerr's HP requirement formula and assuming a displacement of 25,000 pounds)
DD 4-53 Fuel Consuption at 30hp: ~2gph
Beta 110 Fuel Consumption at 30hp: ~2gph

It's really hard to get anything accurate here because the fuel curve charts are anything but precise and I had to extrapolate the DD chart down to 30hp because it doesn't actually go that low. However we do burn about 2gph on average so it's probably close enough. But in any case I don't think that the Beta could possibly be 50% more efficient than the DD. Which makes sense. I'd bet that most of the savings to be had in a modern, electronically-controlled motor is going to come from precise metering of fuel under changing loads. Under a constant load it's just a matter of stochastic ratios. Oxidation of a certain amount of air and a certain amount of fuel results in a certain amount of power, no? As long as you aren't losing unburnt fuel out of the exhaust that is. And 50% would be a lot to lose. Although I suppose it would be possible to run the engine leaner with more precise metering which would make it more efficient. However I'm just speculating here and would welcome correction or further information.

5. Convert the diesel fuel tanks to hydrogen fuel cells. Electric motor.

Yes there are some infrastructure issues. But don't you think you should at least pencil this one out?

Sure, but is fuel cell technology really mature enough right now? I do see some projects along those lines but nothing that looks ready to power a small boat from Seattle to Alaska. I'd probably put this in the "future technology" bucket. Something that might allow us to move completely away from diesel at some point, and which would be a natural next step once we have an electric motor in the the system, but not a solution that we would adopt immediately. My thinking here is that the big step is to add an electric motor with sufficient power to travel at hull speed in all conditions that we are likely to encounter. Once that's done then the power and charging systems could be updated as better technology is developed - more efficient solar panels, better batteries, fuel cells, etc.