Unique engine room idea for new build XPM-781

In this week's Möbius World blog post, you can see all the tank tops being prepped and welded, and the engine room enclosure inside the workshop. It's like a room within a room, the idea being that it will be better to draw the heat out and ventilate the smaller enclosure around our Gardner 6LXB, and we can have the day tank and filters, etc. mounted outside the enclosure. There is still room inside to stand on both sides of the engine.

The area around the outside of the enclosure will be Wayne's workshop with plenty of room for benches and tools.

This photo doesn't do it justice, but Wayne shows it better in the video at the end of the blog.



What do you think of our idea?

Well, you first need to understand how engine rooms are ventilated while the engine is running. They are ventilated by the diesel pulling intake air in from vent louvers from the outside, then burning it in the engine and exhausting it. Any exhaust air blower is defeating this scheme. A blower that pushes more air in might help a little.


Maintaining engine room temperatures is more about having enough vent area than anything else.


Enclosing the engine room tightly such as your scheme won't change the ventilation a bit and probably increases engine room temps due to the radiation heat being trapped inside a small space.


A tightly enclosed engine room will help to contain the heat after engine shutdown and if you have an exhaust blower it will remove the heat from a small space quicker and keep it segregated from living spaces.


But all in all I would prefer to have the easy engine access of a single large engine room and less likely hood of a hot engine enclosure underway.


David

Very interesting isolating the engine in its own “box” to keep the outside workspace areas cooler and quieter. What will the walls be insulated with to hold in the noise? Some kind of lead-lined absorption material like Soundown maybe?

Since a Gardner engine turns slower than most, is it a quieter engine anyway?

Greetings,
Mr./Ms. CK. Will you have large inspection widows in the "engine room" walls? Opening a door/hatch to take a quick glance at the Gardner will partially defeat the heat limiting benefits IMO.

With smaller engines reliance on the combustion air for ER cooling can work, but as things get larger, additional mechanical exhaust air flow is required. There needs to be intake and exhaust vent/duct space to support the flow without undue restriction.

Usually it’s preferred to place mechanical assist (fans) on the exhaust side to create a slight negative pressure in the ER. That keeps heat an smells from being pushed out into the rest of the boat through voids. But intake fans can work too. They key is to be sure the exhaust path restriction is very low so you don’t develop pressure in the ER and push heat and smells into the boats interior.

It’s not rocket science, but there is some engineering involved. Cat has a good publication on cooling for generator rooms, and the considerations and calculations are the same for an engine room. You just need to adjust for differences in exhaust runs, radiator vs heat exchanger cooling, etc.

About a decade ago a very smart CA guy built the Sonata on his property in Delta country. He like the OP had the engine in a box, not unlike a sound shield for a genset. It worked well. Noise abatement was stellar. Viewing panels were easily removable. David has a point though, why do it?

For the OP, possibly easily removable enclosure panels would be an improvement. But it appears your route is taken. Try it and keep plan B in mind.

I typically don't critique other people's boats but since you asked about opinions. The tight engine enclosure would be a total non-starter for me. Why build a 80' boat with an engine room the size of 35 footer?

Yea, no fan of the engine box. One of the magic parts of having the engine in a wide open volume is you can work on your workbench and keep an eye on the machine.

Noise? Put on ear muffs.

Ventilation is an easy issue, a couple of supply and exhaust fans. I run in many engine rooms, some with big engines, some with small, and heat has never been a problem. Except at shutdown.

Maintenance and repair will get hindered by that box.

Noise? Some improvement especially with insulation inside, but low rpm non-turbo engines are pretty dang quiet already.

I would not build the box. That engine is a thing of beauty, last thing I would do is hide and bury it.

It might be of interest to read Gerr's two part articles in Professional Boat Builder regarding boat ventilation. The articles include design parameters for engine room ventilation.

The back issues are here, https://pbbackissues.advanced-pub.com/ and part one is in the Oct/Nov 2007 #109 magazine and part two is in the Dec/Jan 2008 #110 issue. They should have an index file somewhere that has a very extensive index of published subject articles.

The magazine is a treasure trove of information.

Later,
Dan

Hi Wayne and Christine. I love that you two are totally outside the box, “I did it my way [emoji445]” thinkers. You’re the only ones that make me look normal [emoji3]

However on this subject I agree with the masses, and would personally prefer to keep the room open. I have toyed in the past with the though of just hanging some sheets of heavy lead foam panels around my Jimmies to help absorb some of the racket. But not airtight.

C- when are coming out to Qatar??

Sal

Sorry for taking so long to respond to all these much appreciated comments and questions. Been a particularly busy week here at Naval Yachts with not only boat building but also building the new shipyard so I’m a bit behind on Emails, blogs and the like. I’ll go back and answer some of the individual posts but thought I could respond to some of the common questions and some of what led us to go with putting the Gardner 6LXB engine in a smaller volume dedicated engine room enclosure rather than the more typical larger full beam engine room between bulkheads.

As we have done with all aspects of designing our 24m XPM boat Möbius, we have tried to take a “do over” or blank slate type of approach by trying to use the sum total of all our past experiences on passage making boats, along with all the lessons learned by others, to design and build the “just right, just for us” Goldilocks boat. We have been doing this by creating a set of first principles and fundamental requirements and then design everything based on this “design envelope”. Sounds easy but this took us over a year to develop all together and we have come to value it more every step of the design and now build process. For those interested, the full description of our design requirements is in an early post on our Mobius.World blog here.

After all our years and nautical miles it was quite a challenge to try to start with no preconceived notions of “this is how it is always done” and instead stay true to the fundamentals that we have set out for each space or system. On the one hand we definitely wanted to take maximum advantage of all our past experiences as well as “standing on the shoulders of giants” by taking into account the lessons learned and recommendations from experts and others before us, and yet we also want to take a fresh approach and rethink each space and system such that it best meets the fundamental requirements we have laid out and is open to new ideas and ways of meeting our goals. So as oxymoronic as it may sound we try to use our design envelop “box” to help us think outside all other boxes.

In the case of the engine room, the fundamental requirements that we worked from were grouped into things we wanted to minimize and those which we wanted to maximize. Specifically we set out to design an engine room that would minimize heat, noise and maintenance and simultaneously maximize accessibility, ventilation, safety, longevity and comfort. In the interest of brevity, not usually one of my strong points, here is a bulleted outline of the specifics of how we addressed each of these requirements.

MINIMIZE:
• HEAT
o Reduce heat generation wherever possible by keeping as many such items outside ER
o Ideal = Nothing but the engine in the engine room.
o Minimize heat from engine into ER:
o Water cooled exhaust manifold
o Jacketed exhaust lines
o Wet exhaust with water separator
o External rectifiers & regulators mounted outside ER
• NOISE
o Contain all engine/CPP related noises within the ER space
o Significantly over insulate all ER surfaces with >50mm fire rated EPDM
o Wet exhaust with water separator to exit sea chest
o 50mm thick engine beds
o Integral water tanks on either side of engine beds
• MAINTENANCE
o No heat or vibration going to other systems and equipment by keeping them outside ER
o ER surfaces, walls, ceiling, floor smaller and easy to clean materials
o Contain the bilge area to be only within the ER and sloped forward
MAXIMIZE:
• ACCESSIBILITY for working on engine & CPP
o Headroom height > 2m
o Space between engine & walls > 800mm
o Space below oil sump > 300mm
o Nothing mounted on ER walls
o Floor area clear of any equipment
o Full sized overhead dogged hatch large enough to Re/Re engine & CPP assembly
• LONGEVITY of all machinery and equipment within the ER
o Move all equipment possible from ER to Workshop area
o Maximum supply of cool air, passive with fan assist
o No heat & vibration affecting other systems such as fuel, electrical, water maker, boiler, chiller, etc.
• VENTILATION
o Venting 40% over both recommended VCR Volume Change Rates and engine combustion air rates
o Delta-T < 25F/14C (air temp @ intake manifold – air temp @ inlet vent grill)
o Outlet airflow 15% higher than inlet
o Max intake manifold air temp < 122F/50C
o Dedicated engine air vent boxes & ducting (details below)
o More air changes per hour w/ smaller volume, vents & fans
o Lowered heat retention w/ outlet fans
• SAFETY
o All electrical items, batteries, rectifiers, regulators located outside ER
o All fuel systems located outside ER; filters, Alfa Laval
o Fully contained and fire proof ER
• COMFORT
o Maximum amount of air and light into ER via full size hinged ceiling hatch
o Keep heat & noise isolated from adjacent Workshop space (and rest of boat)

As I noted above, one of the key ways we are meeting our design requirements for the ER is by having 2 dedicated ER vent boxes on the Aft Deck so here is a quick summary of the main features of these
VENT BOXES:
• Aluminium vent boxes built into Aft Deck (one inlet air, one outlet)
• Sized and located to have no down flooding through full 360 degree roll over during self righting
• Demister grills to reject any water entry & remove humidity in inlet air
• Short straight Dedicated in/out ER vent ducting
• Inlet venting at floor, outlet vent at ceiling
• Automatic Fire dampners w/ manual override
• Dedicated fans on exhaust vent, run as needed (thermo switch & manual) and on timer after engine shutdown
• Solar powered vents for longer times at anchor or when leaving the boat

I fully understand that many of you would still prefer to have a full size ER but you can now perhaps understand our reasoning in going with this dedicated ER enclosure design and why it is “just right, just for us”.

Thanks very much for all your suggestions and comments and I look forward to more.

All very much appreciated and I will go back and respond to some of the more specific questions in earlier posts here.
- Wayne

djmarchand said:

Well, you first need to understand how engine rooms are ventilated while the engine is running. They are ventilated by the diesel pulling intake air in from vent louvers from the outside, then burning it in the engine and exhausting it. Any exhaust air blower is defeating this scheme. A blower that pushes more air in might help a little.


Maintaining engine room temperatures is more about having enough vent area than anything else.


Enclosing the engine room tightly such as your scheme won't change the ventilation a bit and probably increases engine room temps due to the radiation heat being trapped inside a small space.


A tightly enclosed engine room will help to contain the heat after engine shutdown and if you have an exhaust blower it will remove the heat from a small space quicker and keep it segregated from living spaces.


But all in all I would prefer to have the easy engine access of a single large engine room and less likely hood of a hot engine enclosure underway.


David

Click to expand...

Thanks David and all very valid concerns. I've just posted an overview of the criteria we used to decide to go with an engine enclosure and how I think we are addressing the points you made.

cardude01 said:

Very interesting isolating the engine in its own “box” to keep the outside workspace areas cooler and quieter. What will the walls be insulated with to hold in the noise? Some kind of lead-lined absorption material like Soundown maybe?

Since a Gardner engine turns slower than most, is it a quieter engine anyway?

Click to expand...

Yes, I expect the Gardner will be relatively quieter than most modern diesels in part due to its relatively low revs, we will likely cruise at about 1100 RPM, and it also helps that these engine castings and parts were so massively over engineered and mass usually reduces vibration and noise. We are also using mass to help reduce noise with extra thick plating for the engine beds and the whole boat's scantlings and having the whole below the WL area be integral tanks for water and fuel. In the ER there are two integral water tanks immediately along side the engine beds.

We value a quiet boat very highly so we are also doing things like going with wet exhaust with a water separator to reduce noise both inside and out when the engine is running and then by having this eXtremely well insulated ER enclosure sitting within an equally well insulated aft Workshop section of the boat.

Of course all this is theory and we won't know for sure till we splash and can test out the sound levels when underway but we have been doing everything we an to build the quietest boat possible.

RT Firefly said:

Greetings,
Mr./Ms. CK. Will you have large inspection widows in the "engine room" walls? Opening a door/hatch to take a quick glance at the Gardner will partially defeat the heat limiting benefits IMO.

Click to expand...

We are still working out the details on the inspection windows in the ER enclosure but expect to have at least one fully fire rated glass window either beside or in the ER door. In addition there will be a 360 camera within the ER which can be viewed from anywhere in the boat or even remotely so that will also help to let us see inside without opening the door or being in the ER.

twistedtree said:

With smaller engines reliance on the combustion air for ER cooling can work, but as things get larger, additional mechanical exhaust air flow is required. There needs to be intake and exhaust vent/duct space to support the flow without undue restriction.

Usually it’s preferred to place mechanical assist (fans) on the exhaust side to create a slight negative pressure in the ER. That keeps heat an smells from being pushed out into the rest of the boat through voids. But intake fans can work too. They key is to be sure the exhaust path restriction is very low so you don’t develop pressure in the ER and push heat and smells into the boats interior.

It’s not rocket science, but there is some engineering involved. Cat has a good publication on cooling for generator rooms, and the considerations and calculations are the same for an engine room. You just need to adjust for differences in exhaust runs, radiator vs heat exchanger cooling, etc.

Click to expand...

Hi Peter and double thanks for your thoughtful comments. One because are extremely busy yourself with the building of your new N68 Tanglewood II and the other thanks to you for your assistance with our ER design as I read over your posts about your experiences with venting your ER on Tanglewood.

Along with some great input and experiences from you and the likes of Dave Gerr, Steve D'Antonio, etc. I was able to come up with the basic requirements for ER venting and used these as some baselines for our ER. We have sized the vents and fans to be about 40% above the recommended minimums from engine manufacturers, Gerr and D'Antonio and have also sized the outlet air flow, both passive and fan assisted to be about 10-15% greater than inlet flow to create the optimal air flow as you pointed out.

As I've tried to outline in my other post here with the overview of our system and the thinking which led to this, I've tried to improve the overall ER characteristics by reducing the heat going into the ER in other ways by locating almost everything other than the engine outside the ER and going with things like wet exhaust and keel cooling, which has always worked out best in previous boats.

So thanks again for the help you provided thanks to your efforts in blogging about your experiences with Tanglewood and other boats. I'm especially enjoying what you've been able to write up so far about your new experiences with the N68 and trying to do likewise for others with weekly updates on our progress in building Mobius here in Antalya with Naval Yachts. Hope we might be able to share an anchorage and some time together when we get our respective boats in the water.
-Wayne

gsholz said:

I typically don't critique other people's boats but since you asked about opinions. The tight engine enclosure would be a total non-starter for me. Why build a 80' boat with an engine room the size of 35 footer?

Click to expand...

I had similar reservations and questions when our fabulous NA and designer Dennis first suggested it, but as we worked on this and kept going back to our first principles and design requirements for this space, the ER enclosure evolved and made the most sense for us You can check out the overview I have posted here with the rationale and design criteria and hope that helps further answer your question and why we think a dedicated engine enclosure is the best route for us.

Ski in NC said:

Yea, no fan of the engine box. One of the magic parts of having the engine in a wide open volume is you can work on your workbench and keep an eye on the machine.

Noise? Put on ear muffs.

Ventilation is an easy issue, a couple of supply and exhaust fans. I run in many engine rooms, some with big engines, some with small, and heat has never been a problem. Except at shutdown.

Maintenance and repair will get hindered by that box.

Noise? Some improvement especially with insulation inside, but low rpm non-turbo engines are pretty dang quiet already.

I would not build the box. That engine is a thing of beauty, last thing I would do is hide and bury it.

Click to expand...

Well we are certainly in "heated agreement" that the Gardner is a thing of beauty and that these are also very quiet engines to begin with. So for me, the ER Enclosure is a way to highlight the mechanical beauty that is a Gardner by having a dedicated room just for our Mr. G! I will have a plaque above the door so everyone knows this is the home of Mr. G and when you open that door all you will see is that 6LXB in all its glory!

dannc said:

It might be of interest to read Gerr's two part articles in Professional Boat Builder regarding boat ventilation. The articles include design parameters for engine room ventilation.

The back issues are here, https://pbbackissues.advanced-pub.com/ and part one is in the Oct/Nov 2007 #109 magazine and part two is in the Dec/Jan 2008 #110 issue. They should have an index file somewhere that has a very extensive index of published subject articles.

The magazine is a treasure trove of information.

Later,
Dan

Click to expand...

Thanks Dan. PBB is a treasure trove indeed and I too am a huge fan for many years now. I bought every back issue years ago before they made the whole thing available online for free a few months ago which I applaud them for. So PBB is one of my primary sources when I'm researching anything to do with our new boat and I find it to be an invaluable resource. So as you can imagine and suggested, I latched onto Dave Gerr's articles in particular, along with several others on the topic of ER venting and design and used his formulas and suggestions to help guide us in the design that we ended up with.

makobuilders said:

Hi Wayne and Christine. I love that you two are totally outside the box, “I did it my way [emoji445]” thinkers. You’re the only ones that make me look normal [emoji3]

However on this subject I agree with the masses, and would personally prefer to keep the room open. I have toyed in the past with the though of just hanging some sheets of heavy lead foam panels around my Jimmies to help absorb some of the racket. But not airtight.

C- when are coming out to Qatar??

Sal

Click to expand...

Hi Sal, glad we can help with your "normalisation" You can read over my other post here where I have tried to outline our thinking and criteria that led to our decision to go with this smaller dedicated ER Enclosure and you can see what you think.

Christine did get to Qatar 2 weeks ago but unfortunately she got quite sick and timed her visit to coincide with that huge rainfall you guys got so she spent a few days mostly in bed at my cousin's place there and then had to cut her visit short and fly back. However what she say and learned she just loved and we will both be making a trip over there as soon as we can and will let you know when we do.

Hope all is going well with your boat plans?

The only thing that can burn in an engine is fuel. With a serious fuel shut-off outside the box there is no risk that as fire can continue. Extinguishers inside the box are unnecessary.

Wayne now you have me thinking. We all know that heat is the enemy of batteries and inverters. Perhaps keeping the noisemakers in their own smaller engine room, with a separate electrical room, is the way to go. It hurts a man's ego to have a tight engine room on a big boat, but that's just emotional stuff

I might be able to chop one meter off the back of the engine room for this purpose. Will think about it more - thanks for the idea.

BTW, is your big boat equipped with just one noisemaker? You have no generator or aircon?

Lee Simpson's Sonata 620 - Bruce Roberts boat.

I don't know how many of you people are familiar with Lee Simpson's Sonata build. It is a custom Bruce Roberts design and he ran it in AK for a while. It was on YW a few years ago but I don't know where it wound up.

It is a metal 62' boat with a single JD engine in a cooled and sound insulated box. It was built by Lee's own crew of builders to his design. The engine room was fairly quiet underway.

I attached an article from PassageMaker magazine about sonata and its development. The center box in the engine room is the JD engine with all the doors closed.

In Sonata, the ER enclosure access doors are the key ingredient. Lee gave it a lot of thought and it turned out pretty well.

Xsbank said:

The only thing that can burn in an engine is fuel. With a serious fuel shut-off outside the box there is no risk that as fire can continue. Extinguishers inside the box are unnecessary.

Click to expand...

Quite right and one of the big benefits we saw in going with this ER Enclosure where we can keep pretty much everything but the engine itself outside of the ER. So we can have the fuel shut offs and indeed the entire fuel system itself all outside the ER with just carefully plumbed fuel supply and return lines inside the ER. We will still have a fire suppression system in the ER as well as in the Workshop that the ER is within and there are auto shut off dampeners to shut off the air supply into the ER as well.

Both the ER and the Workshop will be insulated with foil covered fire rated EPDM, temp and CO detectors and we are also doing everything we can to make it easy to keep all surfaces within the ER very clean and visible so I think we will have as good a fire prevention offense as we can.

makobuilders said:

Wayne now you have me thinking. We all know that heat is the enemy of batteries and inverters. Perhaps keeping the noisemakers in their own smaller engine room, with a separate electrical room, is the way to go. It hurts a man's ego to have a tight engine room on a big boat, but that's just emotional stuff

I might be able to chop one meter off the back of the engine room for this purpose. Will think about it more - thanks for the idea.

BTW, is your big boat equipped with just one noisemaker? You have no generator or aircon?

Click to expand...

We have indeed taken a similar "dedicated space" approach to all the systems and "noisemakers" on the boat from engines to motors to inverters.

In the case of the batteries they have their very own "home" in the form of sealed and vented battery boxes that are part of the integral tank grid of the hull. These are on center and in the middle of the hull and dropped down to run alongside the massive keel bar such that they serve double duty being part of our "lead ballast" in the boat as well. These are 24 huge 2000Ah 2v OPvZ Gel cells so they are sealed but will be bolted in place within their own fiberglass boxes and then vented in/out for cooling.


Inverters, chargers, isolation transformer along with lots of other electrical system items are located in the "Basement" which is its own WT space located below the floor of the SuperSalon. So this huge space is 1.2m high and we will install some partial walls within to create additional vertical mounting surfaces, gives me plenty of room to have all this equipment spread out for easy installation and access and the ability to both insulate and ventilate this area to keep the temp constant not only for all this equipment but more so for our wine cellar! Got to keep one's priorities straight right??!!

The eXtremely large Electrodyne alternators (2 @ 6kWP each) also help reduce ER heat as well by having completely external rectifier assemblies which we will mount outside the ER Enclosure and equip them with their own thermally activated cooling fans. So these alternators will add almost no heat inside the ER.

As for other "noise makers", no generator, I've designed Mobius to be a "DC concept" boat wherein ALL electrical power comes from the 24v House Battery Bank which is kept fully charged by the 14 solar panels. 12v DC will be provided by DC-DC converters and then all AC, both 120V 60Hz and 230V 50Hz will be provided by inverters. We will wire the boat for shore power connections even though we typically go many months to years between having such, but these only connect to the Isolation Transformer which in turn only provides power to the battery chargers.

There are other assorted noise makers such as a chiller, boiler, water maker, air compressor, etc. along with the many pumps aboard but none of these are located within living spaces, all are in either the Forepeak or Workshop all which are eXtremely well insulated for both thermal and noise suppression and will also be mounted with noise/vibration dampening.

As you can tell, I'm a bit obsessive when it comes to noise and smell abatement as for me this is part of the overall safety of the boat in that it increases our confidence and comfort on the boat and reduces stress when things get nasty so we think investments in these areas pay big dividends.

Look forward to seeing what you come up with for your new design so keep us posted on that please.
-Wayne

stubones99 said:

I don't know how many of you people are familiar with Lee Simpson's Sonata build. It is a custom Bruce Roberts design and he ran it in AK for a while. It was on YW a few years ago but I don't know where it wound up.

It is a metal 62' boat with a single JD engine in a cooled and sound insulated box. It was built by Lee's own crew of builders to his design. The engine room was fairly quiet underway.

I attached an article from PassageMaker magazine about sonata and its development. The center box in the engine room is the JD engine with all the doors closed.

Click to expand...

Thanks so much for alerting me to this boat and for attaching this great read. Two of our previous sailboats Bruce Roberts design so we know these designs quite well.

Lee & Diane certainly sound like our kind of people and they certainly had a very similar vision for Sonata as Christine and I do for Möbius. All the more interesting to see this being done over 10 years ago as their principles and priorities are what drove their design and match up very closely to ours.

Based on the article and what I can see in the pictures, their ER Enclosure is based on the same principles I outlined here earlier and we were just fortunate enough with our greater length to be able to create our ER Enclosure as a room with full standing room and access all around the engine and CPP but otherwise the principles are the same I think.

Thanks again for sharing this article and I'll spend more time looking through the details in the pictures.

Today I was in the fire pump room at my building project, running the diesel backup, a small John Deere 4 cylinder, and the racket was blowing my brains out. It just reminded me of how much I hated the noise from my old Jimmies, and why my new boat build is looking like it will have an NT855.

But when you look at the photo of Sonata's engine box you realize that it could very well be done with just a standard generator sound box used on any construction site. Easy to adapt. Plenty of access doors. A bit of torch work here and there, but it is possible.

Anyway, Wayne I'm getting close and am in final negotiations with a shipyard in Pendik (Turkey) as opposed to the one in China. I have 4 quotations from 4 different shipyards, for their different designs suited to my SOR, and all are within about 5% of each other. That is a good confidence builder. I'll let you know when pen hits paper!