I recently purchased a Pearson 36-2. The diesel engine is located under the galley sink and there is a blower in the engine compartment. The blower exhaust hose has disconnected from the deck clamshell at the stern and is laying in the bilge. Several people have told me I don't need a blower with a diesel engine and I can remove it. I would like to mount some other hardware where the exhaust clamshell is located. I was wondering if the blower might be there to help remove heat generated by the engine or if it only for fuel fumes. Do other boats with diesels have blowers and are the necessary for diesels?
Blower required for diesel?
- Thread starter Blue Eyes
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Diesels generate a fair amount
of heat. getting rid of that heat is a good thing to do, THAT'S why the blower is there. If you ventilate the engine compartment, you will also ventilate other spaces as well. the fuel vapors smell bad but are generally not dangerous.
of heat. getting rid of that heat is a good thing to do, THAT'S why the blower is there. If you ventilate the engine compartment, you will also ventilate other spaces as well. the fuel vapors smell bad but are generally not dangerous.
Keep the blower for diesel
Although diesel is less volatile than gasoline and less critical to use a blower, I do use it as a matter of habit for safety and you want to have the blower available to get rid of the heat and engine fumes that sometimes accumulate. Every diesel I'm aware of has a blower and you don't want to be the first without one....
Although diesel is less volatile than gasoline and less critical to use a blower, I do use it as a matter of habit for safety and you want to have the blower available to get rid of the heat and engine fumes that sometimes accumulate. Every diesel I'm aware of has a blower and you don't want to be the first without one....
Use the Blower
I had a Catalina 30 with a blower and used it all the time to keep the heat out of the engine compartment and the cabin. It does make a noticable diff in the heat of the day also, many times i motored for a full day and and night when i at anchor, not a hint of fumes. So far the score is 4 to nothin. Tony B
I had a Catalina 30 with a blower and used it all the time to keep the heat out of the engine compartment and the cabin. It does make a noticable diff in the heat of the day also, many times i motored for a full day and and night when i at anchor, not a hint of fumes. So far the score is 4 to nothin. Tony B
If using blower for removing heat...
do you run it the entire time the engine is running? Thanks for all the responses - its my first diesel and I've got a lot to learn.
do you run it the entire time the engine is running? Thanks for all the responses - its my first diesel and I've got a lot to learn.
Use em if ya got em
My diesel boat does not have a blower. No diesel boat I've been on has had one. That being said, If I had one I would use it. If nothing else but to keep the engine cooler and reduce engine smells while under way. Joe
My diesel boat does not have a blower. No diesel boat I've been on has had one. That being said, If I had one I would use it. If nothing else but to keep the engine cooler and reduce engine smells while under way. Joe
Time for the truth
On my H-36 in helps with heat a little. It helps the Wife a Whole Lot if you get any smell in the boat.
On my H-36 in helps with heat a little. It helps the Wife a Whole Lot if you get any smell in the boat.
Blower
I also just purchased a 1986 P36-2. It was told to me that when running the engine for a long period, the under the sink area will get hot and that the blower does a good job getting the heat out. My vent hose is broken off by the vent outlet. I am in need of replacing the deck vent (clam shell) as well as the entire hose/tube. How do you like the boat so far? We love ours, though we have many good projects. Greg Mt, Sinai
I also just purchased a 1986 P36-2. It was told to me that when running the engine for a long period, the under the sink area will get hot and that the blower does a good job getting the heat out. My vent hose is broken off by the vent outlet. I am in need of replacing the deck vent (clam shell) as well as the entire hose/tube. How do you like the boat so far? We love ours, though we have many good projects. Greg Mt, Sinai
engine blower
Ditto for us! we added a blower on our H356, use it to keep engine fumes and heat out of the cabin. normally, we only run it ant anchor/dock, but you could run it anytime the engine is running-it doesn't take many amps
Ditto for us! we added a blower on our H356, use it to keep engine fumes and heat out of the cabin. normally, we only run it ant anchor/dock, but you could run it anytime the engine is running-it doesn't take many amps
Diesel Ventilation
Diesel engine rooms (compartments) require ventilation for two separate purposes: -1- Combustion air -2- Engine cooling 1. Combustion air is required for the engines to operate at full R.P.M under Full Load. This figure should be available from your Engine Manufacturer spec sheet, usually written in cubic feet per minute. A general Rule of Thumb to size Combustion Air for a diesel engine is 2.5 CFM per BHP produced. 2. The Rule of Thumb to size the Ventilation Air, which removes the heat from the engine room from the rejected heat of the engines to ambiant, is from 4 to 8 CFM per installed H.P.. Generally speaking, an Engine Room change of air from one to two times per minute. For every 10̊ above 77̊ F. (delta T) an engine may lose 1% to 1.5%* of its power output. So the engine room must be supplied with cold air ducted as low down as possible. In general, the smaller the engine room the greater the need for a forced air ventilation system. The warm engine room air must be vented out from the top of the engine room, preferably with an exhaust fan. A slight negative pressure is preferred in the engine room to prevent fumes entering into the rest of the vessel. For this reason, the Exhaust ducts is often sized 120% larger than the Supply duct. * The British Standard derating for atmospheric temperature is actually 2% per 10̊F of delta T. ABYC Section ‘H-32' - Ventilation of Boats using Diesel Fuel is posted on the CruisersForum at: cruisersforum.com/photopost//showphoto.php?photo=1612 HTH, Gord May
Diesel engine rooms (compartments) require ventilation for two separate purposes: -1- Combustion air -2- Engine cooling 1. Combustion air is required for the engines to operate at full R.P.M under Full Load. This figure should be available from your Engine Manufacturer spec sheet, usually written in cubic feet per minute. A general Rule of Thumb to size Combustion Air for a diesel engine is 2.5 CFM per BHP produced. 2. The Rule of Thumb to size the Ventilation Air, which removes the heat from the engine room from the rejected heat of the engines to ambiant, is from 4 to 8 CFM per installed H.P.. Generally speaking, an Engine Room change of air from one to two times per minute. For every 10̊ above 77̊ F. (delta T) an engine may lose 1% to 1.5%* of its power output. So the engine room must be supplied with cold air ducted as low down as possible. In general, the smaller the engine room the greater the need for a forced air ventilation system. The warm engine room air must be vented out from the top of the engine room, preferably with an exhaust fan. A slight negative pressure is preferred in the engine room to prevent fumes entering into the rest of the vessel. For this reason, the Exhaust ducts is often sized 120% larger than the Supply duct. * The British Standard derating for atmospheric temperature is actually 2% per 10̊F of delta T. ABYC Section ‘H-32' - Ventilation of Boats using Diesel Fuel is posted on the CruisersForum at: cruisersforum.com/photopost//showphoto.php?photo=1612 HTH, Gord May
Blower Mounting
Gordon - thanks for that descriptive explanation. What would be the best mounting place for a blower? Closer to the engine room or where duct comes to exit the vessel? My blower rigt now is mounted up high below the cockpit gunnels just before my transom (where it is vented out). Thanks - Rob
Gordon - thanks for that descriptive explanation. What would be the best mounting place for a blower? Closer to the engine room or where duct comes to exit the vessel? My blower rigt now is mounted up high below the cockpit gunnels just before my transom (where it is vented out). Thanks - Rob
Rob, air, like water or electricity likes to have
the appliance push, not pull. Locate the blower as close to the engine room as possible.
the appliance push, not pull. Locate the blower as close to the engine room as possible.
Thanks
Yeah - thats what I thought I should do...it's on my list of things-to-do!!! Thanks - Rob
Yeah - thats what I thought I should do...it's on my list of things-to-do!!! Thanks - Rob
I'll be keeping the blower.
Thanks for all the responses. We haven't had a problem with fumes (yet) but it certainly is a possibility and the heat issue makes sense. I will be replacing the thru deck exhaust and reconnecting or replacing the hose. Access to the starboard side under the deck looks to be very difficult - have to squeeze by the rudder post and steering gear from the port side. Greg (NYSail), we love the boat so far - although we took delivery in Sept and didn't get to use it too much. The trip up from Pt Pleasant around Sandy Hook to the new home port was one of the best days I've had on the water. Hope to rin out to the sound this summer. What other projects do you have planned? Brad
Thanks for all the responses. We haven't had a problem with fumes (yet) but it certainly is a possibility and the heat issue makes sense. I will be replacing the thru deck exhaust and reconnecting or replacing the hose. Access to the starboard side under the deck looks to be very difficult - have to squeeze by the rudder post and steering gear from the port side. Greg (NYSail), we love the boat so far - although we took delivery in Sept and didn't get to use it too much. The trip up from Pt Pleasant around Sandy Hook to the new home port was one of the best days I've had on the water. Hope to rin out to the sound this summer. What other projects do you have planned? Brad
Locate Fan Above Bilge
Although the Ventilation Fan is called a “Blower”, is has no preference as to “pushing” or “pulling” air. The air velocity & volume is the same on both sides (in-out) of the fan. The higher pressure on the oulet side is a result of the Fan Static Pressure, and is a measure of the fan’s static efficiency. The system efficiency dependes upon the total static pressure (resistance), as does not have abny relationship to the fan location. The Fan should be located at a convenient location, out of the weather, and above the likely accumulation of water.
Although the Ventilation Fan is called a “Blower”, is has no preference as to “pushing” or “pulling” air. The air velocity & volume is the same on both sides (in-out) of the fan. The higher pressure on the oulet side is a result of the Fan Static Pressure, and is a measure of the fan’s static efficiency. The system efficiency dependes upon the total static pressure (resistance), as does not have abny relationship to the fan location. The Fan should be located at a convenient location, out of the weather, and above the likely accumulation of water.
Gord that's true measured right at the fan.
But the power of the motor is available to push air out of the boat, vs. the the restricted vacuum in a long suction hose that ends up pulling air. Without reinforcing, that hose would collapse. Just like a fire engine pumping out of a pond. Too long and the fan just spins it's 'wheels'. P.S. And 'lower pressure' at the fan outlet side??? Huh? P.S.2 OK you changed it.
But the power of the motor is available to push air out of the boat, vs. the the restricted vacuum in a long suction hose that ends up pulling air. Without reinforcing, that hose would collapse. Just like a fire engine pumping out of a pond. Too long and the fan just spins it's 'wheels'. P.S. And 'lower pressure' at the fan outlet side??? Huh? P.S.2 OK you changed it.
Projects on my P36-2
Well.....We got our boat in November, so I have only sailed her 1 time, and she performed great to say the least. Ours is the shoal draft with centerboard. We have been hard at work though with projects as the boat was neglected by the p/o. Currently I have removed the shaft and I am replacing the stern tube hose, new GFO packing for the stuffing box, new flexible coupling and cutless bearing. Also, the engine mounts are rusted and I think I will replace those as well. Seems a lot of sea water spashes around and rusts everything....my coupling was real bad. I am replacing/upgrading the electric bilge pump and manuel pump and adding a high water detector. Wife has removed and reset 4 windows...2 each side aft in main cabin. Also, all of the floor boards are up and she is refinishing these as well. I think we will also paint the bilge area as 20 years of neglect is there. I have removed most of the deck hardware as we are having the main deck re-cored this winter with nidacore (not balsa) and having a new rub rail put on. We are doing most of the work, however the re-coring of the deck is left to a professional. We got a great price for her that will compensate for the work needed to be done. We found that the P36-2 was the best design for this vintage boat. She is beautiful and very accomidating indeed. I am taking pictures of everything, so just ask if you wnat to see any. The boat will be practically new when we are finished..... Love to hear about your boat! I hope you don't mind if I pick your brain from time to time about things on the boat. Greg 1986 P36-2 #101 Four the Soul Oh yea....also am replacing the clam shell vent on the stern and running a new vent hose to the engine. I don't know how the hell I am going to get back there as I also have an auto pilot down below. I was thinking how useful a door would be in the aft cabin to access this area. Seems like a nice chunk of wasted space......
Well.....We got our boat in November, so I have only sailed her 1 time, and she performed great to say the least. Ours is the shoal draft with centerboard. We have been hard at work though with projects as the boat was neglected by the p/o. Currently I have removed the shaft and I am replacing the stern tube hose, new GFO packing for the stuffing box, new flexible coupling and cutless bearing. Also, the engine mounts are rusted and I think I will replace those as well. Seems a lot of sea water spashes around and rusts everything....my coupling was real bad. I am replacing/upgrading the electric bilge pump and manuel pump and adding a high water detector. Wife has removed and reset 4 windows...2 each side aft in main cabin. Also, all of the floor boards are up and she is refinishing these as well. I think we will also paint the bilge area as 20 years of neglect is there. I have removed most of the deck hardware as we are having the main deck re-cored this winter with nidacore (not balsa) and having a new rub rail put on. We are doing most of the work, however the re-coring of the deck is left to a professional. We got a great price for her that will compensate for the work needed to be done. We found that the P36-2 was the best design for this vintage boat. She is beautiful and very accomidating indeed. I am taking pictures of everything, so just ask if you wnat to see any. The boat will be practically new when we are finished..... Love to hear about your boat! I hope you don't mind if I pick your brain from time to time about things on the boat. Greg 1986 P36-2 #101 Four the Soul Oh yea....also am replacing the clam shell vent on the stern and running a new vent hose to the engine. I don't know how the hell I am going to get back there as I also have an auto pilot down below. I was thinking how useful a door would be in the aft cabin to access this area. Seems like a nice chunk of wasted space......
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