Engine room heat

[rslifkin]

If you add more exhaust blowers and want to see if that helps the temperature, you can always try running with the engine room door open (to allow make-up air) until you confirm it works well enough and figure out additional intake vents.

 

[Mako]

Mambo, if you really want to ventilate your engine room then switch out your engines for a couple of Jimmies. That will get the air flowing [emoji3]

 

[Mambo42]

If you add more exhaust blowers and want to see if that helps the temperature, you can always try running with the engine room door open (to allow make-up air) until you confirm it works well enough and figure out additional intake vents.

@ rslifkin


Up until now I have been running with the ER door open and the hatch to the lazarette removed, so basically a big open hole in the transom. As a temporary solution it is OK, but I want to work to something more permanent so that the hatch can be closed.

Am not afraid of water coming in during heavy seas, because we are not aiming to be out at sea during heavy seas, but people and animals falling in the hole is a big risk. On top of that it means that area cannot be used by people who want to sit there and that is a pity, it is a nice place to relax.

 

[twistedtree]

Here's a bunch of info on the engineering around ER cooling, and how I addressed the issue on a past boat.



Adventures of Tanglewood: Engine Room Cooling


To keep the ER temp down you need to move air through the ER, pulling cool outside air in, and pushing heated ER air out. Short of adding air conditioning, there is no way around it. And you need MUCH more air flow than most people guess. We are talking about low thousands of CFM, not hundreds. The other top ranking mistake is making the intake and exhaust paths too small, and/or too long. Both add air flow resistance and will significantly reduce how much air a fan actually moves compared to it's specs. I had a big-ass 1200 CFM blower that was only actually moving about 350 CFM because of duct resistance.



FWIW, a very common operating temp limit for equipment is 130F, so you are WAY over temp and it will take a toll on equipment longevity, not to mention your health. Even 130F is dangerous to your health to work in for more than a very short time. If you have a problem underway, you could be faced with a decision between endangering yourself or whoever needs to spend time in the ER fixing stuff, or endangering the boat because it's disabled. It's not a good choice to have to make.


And if it's any consolation, I think a lot of boats suffer from inadequately vented/cooled ERs.

 

[Mambo42]

Here's a bunch of info on the engineering around ER cooling, and how I addressed the issue on a past boat.



Adventures of Tanglewood: Engine Room Cooling


To keep the ER temp down you need to move air through the ER, pulling cool outside air in, and pushing heated ER air out. Short of adding air conditioning, there is no way around it. And you need MUCH more air flow than most people guess. We are talking about low thousands of CFM, not hundreds. The other top ranking mistake is making the intake and exhaust paths too small, and/or too long. Both add air flow resistance and will significantly reduce how much air a fan actually moves compared to it's specs. I had a big-ass 1200 CFM blower that was only actually moving about 350 CFM because of duct resistance.



FWIW, a very common operating temp limit for equipment is 130F, so you are WAY over temp and it will take a toll on equipment longevity, not to mention your health. Even 130F is dangerous to your health to work in for more than a very short time. If you have a problem underway, you could be faced with a decision between endangering yourself or whoever needs to spend time in the ER fixing stuff, or endangering the boat because it's disabled. It's not a good choice to have to make.


And if it's any consolation, I think a lot of boats suffer from inadequately vented/cooled ERs.

Thanks Twistedtree !
Read your article with great interest and immediately realized that I won't be able to get rid of so much air as you described. I had been calculating indeed with 600 cfm total, but now realize that It is going to be much, much more.



I also realize that getting that amount of air in and out of the engine room via the small vents is not going to work. And then it just hit me that the maximum amount of airflow, without tearing down the whole boat will be if I use the existing vents to draw air in and to use the hatch in the lazarette to get it out again.

That does mean I will be having a hole while underway, which is indeed dangerous, but If I make a steel frame (like the ones you see on air vents on the streets) and fit that over the hole while underway, I may just save that problem as well. When I am back in port or on anchor I will just put the original hatch back in.



It could become a problem in case we would encounter very heavy seas unexpectedly, but the chances of that happening is about zero. We have already decided we are all about comfort. If the seas are too heavy, causing water to get into the transom area..............we are not going out, we will stay in port.



Thanks again for publishing your findings and your calculations, also good to hear and read that I am not the only one with these problems of excessive ER heat. Makes you wonder why the yards to focus on it more ?

 

[Comodave]

If you make a new metal hatch to vent the hot air I would use aluminum not steel. It would be lighter and won’t rust.

 

[Mambo42]

If you make a new metal hatch to vent the hot air I would use aluminum not steel. It would be lighter and won’t rust.

Aluminum is a good idea as well, is also lighter than steel and does not corrode
Wood could also be possible. We have 4 dogs on board so need to make sure they don't break their paws/ legs.



And as for ventilators I will look at a line of 4 or 5 ventilators from a walk in freezer / cooler. They are not massive, but can still do the job. I should be able to fit them easily to the ceiling of the ER, so that could be a quick fix for this August / September. Then I can work on a more solid solution during the winter.
Or I can buy 2 of these for now and just get at least the air moving this summer. https://nl.trotec.com/shop/ventilator-ttv-4500-s.html

 

[rgano]

I would add that sucking air out while not simultaneously BLOWING it in could leave the fan competing with the engines. I went through a couple of exhaust fans before I realized that they were intended/suitable for after engine shutdown rather than while underway.

 

[Comodave]

Unless the boat is new, it has been running like that for years. You might just get through the summer and then do the work next winter as you have time available..

 

[Mambo42]

I would add that sucking air out while not simultaneously BLOWING it in could leave the fan competing with the engines. I went through a couple of exhaust fans before I realized that they were intended/suitable for after engine shutdown rather than while underway.

Luckily my engines get their air from dedicated air vents, connected with hoses. So they don't take their air from within the ER.



I have 2 other vents to which the current ER blowers are connected and then I have the ER door, which leads to the lazarette, which again leads to a hatch of about 6 - 8 sqft.

The solution of the open hatch is not going to win a beauty contest, but as long as it does the job I will be happy for now.

 

[Mambo42]

Unless the boat is new, it has been running like that for years. You might just get through the summer and then do the work next winter as you have time available..

@Comodave,


The boat is not new, is 43 years old, but originally the boat was sold in the Netherlands (I have been able to trace the boat back to mid 90's). The last owner moved the boat from the Netherlands to Greece, but how they used the boat is not clear to me.

Also have the idea that the former owner never even thought about ER temps. He did have a lot of spare parts on board, but the way that he has connected some equipment really raises a lot of questions in my head.



I have the idea that they just started the engine, got underway and that was it. Don't think that they ever thought about the consequences of high ER temps. The fact that the engines were so clogged up with carbon tells me that he also never thought about technical issues.

Now that I have the boat, and with my back ground as a pilot, I think about all these little issues, because I know they can create bigger problems in the future.

In a way it does me good to read that more people have been thinking about this same issue a lot.

 

[guy with a boat]

Mambo,


I'm going to point out what you already know which is that leaving the laz hatch open is a terrible idea. We can plan all we want to only travel in nice weather, but to risk your boat on the premise that you won't ever have unexpected water entry through a large hole is not a great plan. Keeping water on the outside of the boat is how to stay safe and afloat. Allowing a huge water entry opening to exist is a bad idea. Boats that sink do so because of unexpected water entry.



Also, don't underestimate the importance and accuracy of Twisted Tree's comments and his article on ER cooling. Your ER is way overtemp, and small fans aren't going to fix it. For lots of good reasons, its worth figuring out how to do it right. High ER temps are far too common because its not easy to fix it. But it is possible and it is worth doing it right. Study the existing configuration and figure out what changes are necessary to move LARGE amounts of air in and out of the ER. Running at the temps you now have is way too hard on equipment and humans. Tiny fans and small changes won't get it done.

 

[Martin J]

I did extensive work on my last boat to lower the ER temeprature (boat in the eastern Caribbean). At the finish I knocked around 30F of the engine roomand got it down to 120F. I vented the air intake blowers directly at the engine air intakes. Result was better engine performance (Cooler denser air). In general pumps, belt, batteries etc are all happier. I worked on engine requirements and doubled it, also installed extraction fans correctly placed running at half of intake volume.

I have also done the same on my new (to me) boat. I did put Caterpillar engine ventilation manual in the forum's library along with various other information

Was it worth doing? Absolutely! ER is cooler engines run better, and ER equipment lasts better when running in a cooler ER. On a last note placement of fans and ducting is very important.

 

[twistedtree]

I would add that sucking air out while not simultaneously BLOWING it in could leave the fan competing with the engines. I went through a couple of exhaust fans before I realized that they were intended/suitable for after engine shutdown rather than while underway.

Yes, very important. It really comes down to making sure you don’t have excessive intake air flow resistance. If you have intake restrictions, then the engine and exhaust fans will create a vacuum in the ER. The engines are fine with some restriction (check the specs to see how much), but if excessive it will impact performance. Air intake temp impacts performance too, which is another reason to keep the ER cool. If you have intake restrictions, intake fans can help overcome that, but the ideal is to not have the restriction in the first place. That’s just easier said than done on a boat that’s already been built.

 

[Martin J]

Here are some interesting articles on the subject.
Well worth a read / study.
https://www.powerandmotoryacht.com/maintenance/how-to-properly-ventilate-your-boats-engine-room
https://www.proboat.com/2015/06/venting-the-engineroom/
https://www.passagemaker.com/technical/the-holy-place-let-it-breathe-engine-compartment-ventilation

 

[Mambo42]

Mambo,


I'm going to point out what you already know which is that leaving the laz hatch open is a terrible idea. We can plan all we want to only travel in nice weather, but to risk your boat on the premise that you won't ever have unexpected water entry through a large hole is not a great plan. Keeping water on the outside of the boat is how to stay safe and afloat. Allowing a huge water entry opening to exist is a bad idea. Boats that sink do so because of unexpected water entry.

@ Guy with a boat,


Thanks for your thought and I fully agree with you that leaving the hatch open is dangerous and it should not be done. However...........I see it as a choice between 2 bad choices.
Twisted tree also stated that high temps in the ER may make work in the ER impossible in case of an emergency, which is 100 % true. So I have the choice, for this summer at least, between high temps in the ER or coming up with a temporary solution.

The way we use our boat is perhaps different than many other people use their boat. We will use the boat as a means of transportation to get from one island to the next, where we will be on anchor for a couple of days before we move on. Once on anchor the hatch is closed, since we don't need to run the engines or the generator.

The traveling part is the dangerous part, but we are comfort sailors. We don't need to go out if the weather is bad, we don't have a schedule to keep. Normal conditions in Greece and Croatia are pretty calm waters with hardly any waves (max 1 to 2 feet). At the speed we are going the boat hardly rolls at all and freak waves we don't have.

So it is a calculated risk to leave the hatch open while we are underway. Normal passages are max 2 to 3 hours, no more, all early morning when there are usually no waves at all, not even a wrinkle. We have no need to go for a 24 of 100 hour passage, we just go from one bay to the other, that is the beauty of Greece and Croatia.

If we do have to make a longer passage or if we do run into foul weather we can always close the hatch. That option is there. We take out the roster we fabricated ourselves and put in the hatch. ER temps will be higher, but most likely we will start looking for a sheltered bay anyway...........since we are comfort cruisers.
And just in case we might get water in the lazarette............I do have a 30 cbm/hr gasoline waterpump on my boat. I keep it for emergencies and to be able to help others in case they run into trouble. Having a high capacity pump (not electrical) on board is something that goes back to my days working SAR in the Caribbean. Boats start to make water, have no pump on board and they sink for basically no good reason. They could have stayed afloat if they only had a high capacity pump onboard.

Also, don't underestimate the importance and accuracy of Twisted Tree's comments and his article on ER cooling. Your ER is way overtemp, and small fans aren't going to fix it. For lots of good reasons, its worth figuring out how to do it right. High ER temps are far too common because its not easy to fix it. But it is possible and it is worth doing it right. Study the existing configuration and figure out what changes are necessary to move LARGE amounts of air in and out of the ER. Running at the temps you now have is way too hard on equipment and humans. Tiny fans and small changes won't get it done.

The fans of a walk in freezer that I had in mind can move enormous amounts of air, they have to, otherwise the walk in freezer simply won't function. That was my first 'brain fart', but then shortly after I found a different fan and I posted a link to that one. Found it online

It is an axial fan and it can displace about 2400 cfm. So two of them will bring me to almost 5000 cfm. Exhaust is not going to be a problem anymore with the open hatch. Bringing the air in might be more difficult, but with 2 vents and the open hatch I should at least get some cooling going this summer. It is not going to be optimal, but it is better than nothing.

And then you are right, in the winter time I can look for a more long term solution. However, drilling holes in the ER is not going to be one of them.

 

[marcs]

Luckily my engines get their air from dedicated air vents, connected with hoses. So they don't take their air from within the ER.

I'm no expert in this area, but I'd wonder if the dedicated air vents may be helping the engine temperatures (at least the combustion temperatures) but hurting the engine room temperatures by not allowing the engines help draw warm air out.

Then you could possibly re-use those vents for more air intake.

 

[twistedtree]

I'm no expert in this area, but I'd wonder if the dedicated air vents may be helping the engine temperatures (at least the combustion temperatures) but hurting the engine room temperatures by not allowing the engines help draw warm air out.

Then you could possibly re-use those vents for more air intake.

I think that’s very likely on both counts. The ducted intake air is to feed cool air to the engines since the ER is so hot. But in doing so it makes the ER hotter. If the ER temp can be brought down, then the dedicated ducts aren’t needed for the engines and can reused as part of the overall cooling design.

 

[Insequent]

I think Mambo indicated that they cruise at relatively slow speeds, thus low engine loads. I'd be tempted to at least try the engine induction direct from the ER. The higher air temps probably wont impact engine performance very much at the low loads. Then the engine would be a big help in cooling the ER. It is definitely worth trying just to get a data point!

 

[RT Firefly]

Greetings,
Mr. M. Rather than moving one of your AC's in the SALOON to the ER, might you more easily run ducting to the ER and leave the AC's where they are? Perhaps duct BOTH to the ER...

 

[Mambo42]

I wanted to post a picture here, but have no idea how to do it.

Was thinking about the options a bit more thorough and the open hatch idea is still there, since it will be the quickest solution for the short term.

The idea is to use an axial ventilator with a capacity of about 3000 cfm, connected to a 25'' duct. The ventilator will be hanging in between the engines and the duct will be connected to the outlet part of the ventilator. The duct will then be guided via the ER door into the lazarette and out via the hatch.

At the same time there will be an axial ventilator with also 3000 cvm drawing air through the hatch and straight into the ER.

That should create enough air movement (I hope) to cool down the ER.

I know access to the ER underway will be difficult, but switching off the blowers will deflate the ducts and make entry easier. Once in port or on anchor it is a matter of putting the blowers aside.

Feel free to shoot holes in this idea.

 

[Mambo42]

Greetings,
Mr. M. Rather than moving one of your AC's in the SALOON to the ER, might you more easily run ducting to the ER and leave the AC's where they are? Perhaps duct BOTH to the ER...

@ RTFirefly,


Would be a nice idea if there were any openings running to the ER, but unfortunately there are none.

 

[Mambo42]

I think Mambo indicated that they cruise at relatively slow speeds, thus low engine loads. I'd be tempted to at least try the engine induction direct from the ER. The higher air temps probably wont impact engine performance very much at the low loads. Then the engine would be a big help in cooling the ER. It is definitely worth trying just to get a data point!

@ Insequent,


So you mean removing the duct from the engine intake and add an air filter there, which would create a draft in the engine room ?

Could be an idea, it would give me 2 more vents through which I can draw fresh air into the ER.

 

[Mambo42]

I'm no expert in this area, but I'd wonder if the dedicated air vents may be helping the engine temperatures (at least the combustion temperatures) but hurting the engine room temperatures by not allowing the engines help draw warm air out.

Then you could possibly re-use those vents for more air intake.

@ Marcs,


Thanks for the tip. It might be an idea. To be honest I have no idea why the engines have their own air supply via 2 vents. Just installing an air filter instead of the duct would help adding 2 vents to the ER.

 

[Insequent]

@ Insequent,


So you mean removing the duct from the engine intake and add an air filter there, which would create a draft in the engine room ?

Could be an idea, it would give me 2 more vents through which I can draw fresh air into the ER.

Yes, that's my suggestion.

My previous 2 x 270HP Cummins were setup like that. ANd my new (10 years ago) 201HP John Deere's are setup that way The loss in engine efficiency isn't something that anybody has estimated for me, and as I also run relatively lightly loaded (1600rpm & ~8kn) I think its a non-issue.

 

[Mambo42]

Yes, that's my suggestion.

My previous 2 x 270HP Cummins were setup like that. ANd my new (10 years ago) 201HP John Deere's are setup that way The loss in engine efficiency isn't something that anybody has estimated for me, and as I also run relatively lightly loaded (1600rpm & ~8kn) I think its a non-issue.

@ Insequent,


It is worth the try. If it doesn't work I can always re-install the old system again. If however it does draw out a lot of heat it would make removal of the remaining hot air easier as well, less air to move out.

Nice idea

 

[twistedtree]

Check out the attached document from Caterpillar on engine room ventilation. It should be required reading for every boat builder. Much of the focus is on stationary generators in buildings, but it's largely applicable to marine engine rooms as well.

 

[HypnoBob]

First up, the two blowers are not both blowers. I had a DeFever 49 CPMY and made the same misidentification. One of them pulls air into the engine room and the other blows it out. Make sure you have this happening. Sometimes, someone will put two blowers into the engine room and then get concerned because it won't cool down. Check the wiring. Motors will run backwards, overheat and trip the switch too soon. Been there done that and have the proverbial T-Shirt.

Second, they are not continuous operating "blowers." Check the specs, they should be high volume and after a few minutes they should automatically shut off.

Third, how hot is hot and where is it that hot in the engine room? You'll find that temps change throughout the engine room. Hot spots, sure. And the place where the batteries are located in their insulator fiberglass boxes will be cooler. Batteries can take a lot of heat. But, won't charge at high temps. That's your clue to know that the temp in the room is too hot. Tape some cheap thermometers around the engine room, in the battery boxes or on top. Make sure the lids sit down on the boxes. If they're angled up due to extra wires directly on the batteries, re-route those through fuses or breakers - check standards. Get an NMEA/ABYC certified electrician. I was a USCG Aviation Electrician's mate and there is a difference between working on a house, boat or airplane. A very big difference.

Next, check the vent boxes on either side of the boat. The clothes dryers vent through there and do tend to fill them up with lint style debris. Ours vented on the starboard side engine vent box. You can sometimes tell this is an issue when you notice lint floating around the engine room when the dryer is running. Talk about an underwear changing event first time you see that LOL. Also, as an aside, check the vent hoses from the dryer to make sure they're clear. Poor drying will clue you into clogged vents (we changed our hoses out).

Get an Infrared Thermometer, Digital Laser Gun is Non-Contact Thermometer with a Temperature Range -4 to 752-Degree Fahrenheit ($30) to check the engine room, engines, etc. Make sure your Lehman's aren't running extra hot. Call American Diesel (804) 435-3107 https://americandieselcorp.com/ or email lehmandiesel@gmail.com for the temps, spare parts lists, and so on.

Finally, you might want to join the https://www.defevercruisers.com/ forum for additional help. I know several 49 PH owners and they would love to help you with specifics about the boat as they are all currently cruising on them.

We actually met with Art DeFever and three other people in the engine room of a 49 CPMY when we were a rendezvous. Before passing, he made all but a couple of them.

The 49 PH is a bullet proof vessel with four inch thick hull at the keel moving on up to .75" at the gunnels. The Lehman Ford's are also bullet proof if you take care of them.

Bob

 

[Xlantic]

I think a 200 hp engine is itself a 500 cfm blower. If the exhaust path is cool and the engine intake vents are at the furthest point from the engine air intake, then the engine itself should ventilate the room pretty decent taking cool air in and exhausting the hot air outside the boat.
My engine rooms only get truly uncomfortable after I shut the main down on a hot day.
The main does run pretty cool though at around 78 C under load.

Totally agree.

The problem with the OP's ER it that is has ZERO ventilation: 1) the engines draw air directly from outside the boat through ducting and 2) the blowers in the engine room don't work. So there is no forced air ventilation of the ER whatsoever. I am surprised it is not even hotter.

Solution: fix the blowers or get rid of the ducts and allow the engines to draw air from within the ER, drawing outside air into the ER though the existing vents.

(BTW, the talk about air-conditioning the ER was joke, right?)

 

[HypnoBob]

Actually, we have some friends who leave the engine room door open while they're running the forward AC to add cool air to the engine room. Yeah, I know. Really? But, they noticed their batteries weren't charging and this solved the problem.