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Old 06-22-2022, 02:28 PM   #21
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Originally Posted by Mako View Post
Mambo, my buddy had a Mainship 34 with twin Lehman naturals. Always running hot. So I helped him to install two small bilge blowers, stuck up inside by the opening. We then ducted the blowers directly to the intakes of the engines. It dramatically lowered the op temperature down to normal levels. Focus on fresh air intake versus hot air exhaust

@ Mako


Great solution. If I may ask: 'where did you get the outside air from ?' Did you have to cut a new opening to the engine room or were there already opening pre arranged ?
My ER is below the salon and is basically an airtight space. To the front is a bulkhead and to the rear is a bulk head with an opening to the lazarette. The lazarette however also does not have any openings, other than a hatch. So in May we were running the boat the whole time with the door from the ER to the lazarette open as well as with an open hatch to the lazarette. Bit dangerous to have an open hole like that, but could not think of any other quick solution to bring cool air into the engine room. We ran the boat one day with door and hatch closed, it became a complete sauna after running the engines for 2 hours.



I think I will have to focus on the aft air vents and see if I can draw more air in via those vents. Or to have one vent draw the air and use the other as an exhaust.
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Old 06-22-2022, 02:34 PM   #22
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Originally Posted by OldDan1943 View Post
I have my water maker in the ER and I am told, the the high temps in the ER will have a definite effect on the output.
Consider adding a couple of 12vt compartment fans to maybe stir up the ER air and lower the temp??

@ OldDan,


Thanks for your thoughts on this one.

I agree I need something to stir up the ER air, but am thinking I also need some movement of fresh air into the ER and hot air out.


Getting the fresh air in I think I can find a way to do that, but I have no clue where the hot air should go.



Am even thinking to open up a hole through the bulk head to the master stateroom (I know, bad idea) so that I suck in the air from the master stateroom into the engine room, through the engine room and then out via the aft vents on the side deck.

The master stateroom will then also get ventilation since that will start sucking in air via the portholes or via the stairs to the pilot house.

Weird idea, but perhaps it works.
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Old 06-22-2022, 04:45 PM   #23
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I am doing a similar project now. I have the benefit of a sister ship with a working cooling system to copy. My engine room has vents on each side of the boat . They are port and starboard at a height just above each engine and centered on each engine. My sister ship has two blowers attached to the starboard vent. They are controlled with a thermostat switch. When they kick on, they force air out of the engine room, which in turn, pulls air in from the port vent. On another boat I owned, I installed a blower to draw from the outside air and direct it towards the intake of the engine. This worked well. IMO if your forcing cool outside air in, the hot air has to go somewhere-hopefully out another vent, no matter where it's located.
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Old 06-22-2022, 08:32 PM   #24
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Ours has 4 inch PVC tubes X 6 inside ventilated lockers coming from 2 ft above front deck level down into front of the ER.

Hot air is vented at back of ER by big Davies Craig 24v radiator fans X 2 into ducting, up through a passageway through all levels and out through the rooftop funnel

Actual air the engine breathes comes from front of rooftop funnel, down into a box with a K&N filter and to the engine.

Have never seen more than 37c / 98f after long mid summer runs.

I do leave the ER door open, it's at front of boat in the forepeak, engine noise is minimal when underway.
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Old 06-22-2022, 08:58 PM   #25
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[QUOTE=OldDan1943;1106870]I have my water maker in the ER and I am told, the the high temps in the ER will have a definite effect on the output.
/QUOTE]

Membrane product flows are rated at 77°F. Higher water temp more product, lower temp - less. The maximum operating temperature at which my membranes can be operated is 113°. Above 113° the membranes degrade. Membranes need to be kept wet, so even if you're not making water in high temps, the water could be evaporating away from the membrane.

I run in cool climates and cold waters so use a inline heater to bring the water close to 77°.
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Old 06-22-2022, 09:41 PM   #26
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My 49 RPH has air intakes via the PT& STBD steps from salon level (aft) deck to PH deck level. They open into ER just aft of forward bulkhead, above the stabilizers. There are additional vents from the aft side decks adjacent to the fuel tank vents. Both my JD 225 HP (&generator) use ER air with no ductwork and create a significant in draft through all 4 of these sources. Still, ER temps and battery temps routinely 100-105 deg. F underway at cruising speeds so my alternator often gets hot enough to decrease output and my Sterling Alternator to battery charger, hits the high temp limit, most summer days, after an hour or two of running. Batteries are in the ER, inverter is in the lazarette. 3 AC compressors add significant heat too if running. Running the blowers while cruising doesn’t change ER temps significantly but does help after we anchor along with opening aft ER door & lazarette hatch.

Would it be worthwhile in your situation, to temporarily disconnect the dedicated engine intake ducts, see if that entrains more outside air, and cooler temps?

I have 2 Jabsco 250 cfm blowers. PT: draws air in from intakes near tank vents, blows across front of engines. STBD blower exhaust air over aft fuel tank to STBD intakes. Blowers shut down spontaneously once the bearings start to go, just hard to hear the squeal over the engine noise
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Old 06-22-2022, 11:22 PM   #27
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Quote:
Originally Posted by Mac2 View Post
I am doing a similar project now. I have the benefit of a sister ship with a working cooling system to copy. My engine room has vents on each side of the boat . They are port and starboard at a height just above each engine and centered on each engine. My sister ship has two blowers attached to the starboard vent. They are controlled with a thermostat switch. When they kick on, they force air out of the engine room, which in turn, pulls air in from the port vent. On another boat I owned, I installed a blower to draw from the outside air and direct it towards the intake of the engine. This worked well. IMO if your forcing cool outside air in, the hot air has to go somewhere-hopefully out another vent, no matter where it's located.

@ Mac2


Like your solution a lot. I do have the vents, so could adjust the blowers to draw from one side and have it blow out via the other vent. I will leave the vents for the engine as they are, otherwise I may open up another can of worms.

But great to hear you can copy from an existing boat where the cooling does work.
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Old 06-22-2022, 11:43 PM   #28
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Originally Posted by Flatswing View Post
My 49 RPH has air intakes via the PT& STBD steps from salon level (aft) deck to PH deck level. They open into ER just aft of forward bulkhead, above the stabilizers. There are additional vents from the aft side decks adjacent to the fuel tank vents. Both my JD 225 HP (&generator) use ER air with no ductwork and create a significant in draft through all 4 of these sources. Still, ER temps and battery temps routinely 100-105 deg. F underway at cruising speeds so my alternator often gets hot enough to decrease output and my Sterling Alternator to battery charger, hits the high temp limit, most summer days, after an hour or two of running. Batteries are in the ER, inverter is in the lazarette. 3 AC compressors add significant heat too if running. Running the blowers while cruising doesn’t change ER temps significantly but does help after we anchor along with opening aft ER door & lazarette hatch.

Would it be worthwhile in your situation, to temporarily disconnect the dedicated engine intake ducts, see if that entrains more outside air, and cooler temps?

I have 2 Jabsco 250 cfm blowers. PT: draws air in from intakes near tank vents, blows across front of engines. STBD blower exhaust air over aft fuel tank to STBD intakes. Blowers shut down spontaneously once the bearings start to go, just hard to hear the squeal over the engine noise

@ Flatswing,


Thanks for the input, nice to hear from someone who also has a Devefer 49 and as I understand you have the same issue. I have not had an overheating alternator, but am guessing I will get to that point in August. OAT will be about 50 to 60 degrees higher than what I encountered in May. Coupled with the much warmer water temperature I will be in for a treat.

But understand you disconnected the dedicated air intakes for the engines ?

Am a bit weary to copy that idea. Understanding that your blowers, in the current set up, don't really make a big difference in ER temperatures, I am leaning more to copying the idea of Mac2. Connecting to blowers to one vent and simply blowing it with force over the engines, perhaps even installing some air hoses (like you see in big shops) to disperse the air evenly and let it subsequently escape via the other aft vent.

I read you have actually 500 cfm total, which is much more than I initially had in mind, so need to upgrade to your level at least.



You state that you have 3 airco's running. Are they air cooled or water cooled ? If they are air cooled, then indeed they do add more heat to the ER. I have 3 water cooled airco's, have no problem with them generating heat. Only problem could be that the cooling water is a bit too warm, resulting in less cooling capacity, but I guess I will also find that out in August.

The opening of the hatch of the lazarette is something I am indeed also familiar with and it does indeed help. Only is a bit of a problem if that is exactly the area where you want to sit or where you constantly need to pass by when you go for a swim. On top of that, we have 4 dogs on board and 2 of them already fell in the lazarette while in port, so I need to find a solution where I can keep the hatch on.

But again, thanks for your input.
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Old 06-23-2022, 12:15 AM   #29
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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.
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Old 06-23-2022, 12:40 AM   #30
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Quote:
Originally Posted by Simi 60 View Post
Ours has 4 inch PVC tubes X 6 inside ventilated lockers coming from 2 ft above front deck level down into front of the ER.

Hot air is vented at back of ER by big Davies Craig 24v radiator fans X 2 into ducting, up through a passageway through all levels and out through the rooftop funnel

Actual air the engine breathes comes from front of rooftop funnel, down into a box with a K&N filter and to the engine.

Have never seen more than 37c / 98f after long mid summer runs.

I do leave the ER door open, it's at front of boat in the forepeak, engine noise is minimal when underway.

@ Simi


I wish I could install that kind of cooling pipes, that surely does work.

Unfortunately there is no way for me to get a 4" pipe into the ER without cutting holes in either the salon or the master cabin. In itself I have no problem cutting into the master cabin, but I must be sure it will be an improvement, otherwise am not going to gamble.


Any case thanks for your insight.
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Old 06-23-2022, 06:31 AM   #31
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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.
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Old 06-23-2022, 07:29 AM   #32
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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
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Old 06-23-2022, 10:49 AM   #33
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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.
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Old Yesterday, 10:47 AM   #34
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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.
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Old Yesterday, 11:09 AM   #35
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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 ?
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Old Yesterday, 11:21 AM   #36
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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.
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Old Yesterday, 11:36 AM   #37
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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
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Old Yesterday, 11:54 AM   #38
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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.
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Old Yesterday, 11:58 AM   #39
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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..
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Old Yesterday, 12:22 PM   #40
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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.
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