Engine compartment blower

Keith in Corpus · Post by **Keith in Corpus** » Wed Oct 12, 2016 2:16 pm

So I am in the process of trying to understand the intentions of the last person who attempted to do wiring under the dash of my boat. This is not rocket science so it was not a Nasa employee. There had to be more than one person under there "not at the same time" cause it took more than one guy to make that mess. I'm not an electrical engineering graduate but the folks under that dash before me had no idea of what those different color wires do but knew if they cut the wire it would release the demons that were causing the problems. It's like climbing under the house with no flashlight and knowing you can find the clog in the sewer pipe by just feeling around. There I got that out of my system I feel better. I have a breaker in the cabin for a blower which is on the starboard side of the cockpit by the stern. It has a problem with a lack of lubrication and screams like a mini Detroit in the basement. I also have a toggle switch on the dash labeled blower but I can't find a second unit. What can you tell me about a second blower? The first blower switched on the power panel in the cabin do you turn that one on and run it continuously? The second unit where would it be and in what manner do you operate it? I hope you guys in the path of Mathew came thru with as little or no damage as possible. Thanks Keith

franklyprice · Post by **franklyprice** » Wed Oct 12, 2016 5:48 pm

On my '87 SF the control panel switch controls the blower for the generator and the switch on the dash controls the blowers in the engine bay. The typical use for a blower would be on a gas powered boat to evacuate any potential gas vapors for a few minutes before you start the engines. On a diesel it isn't much of a safety issue but most people, including mysef, leave it after a diesel conversion. I admit, I'm not sure if it's actually required with diesel power but suspect it might be.Hope this helps.

Rick · Post by **Rick** » Thu Oct 13, 2016 6:18 am

I agree with Frank BUT....A diesel Viking from my marina had an explosion off of Menemsha back in August, guys had to get in the life raft (where I've seen Mako's jumping around) and wait for help. The boat made it without sinking but is completely burned inside. They were having engine trouble all Summer, I'm sure the mechanic is being scrutinized as we speak. On my boat, there is a breaker for the blowers on the circuit breaker panel in the cabin, then there is the actual blower switch on the fly bridge. The way I know a blower is going bad is when the breaker starts tripping. Rick Ticket 85 SF Merc 454 MPI's Falmouth, MA

h2ojst · Post by **h2ojst** » Thu Oct 13, 2016 6:34 am

Keith, There are 2 blowers total. They are each located behind the access panels above the engine hatches on the Port & Starboard sides. One is for the main engines & the other is hosed to the aft generator spot. Both exhaust forward & out the topside scoops. The Main Panel has a breaker for both blowers and then each are independently controlled. The Generator blower switch is also on the main panel by the generator start switch and the other is on the bridge as you found. At least that's how my 88 SF was wired. Hope this helps. I run the main engine blower at idle & slow speed and the geny blower whenever it's running.

Keith in Corpus · Post by **Keith in Corpus** » Thu Oct 13, 2016 7:12 am

So the breaker in the cabin on the main 12 volt panel turns the gen. blower on not thru a toggle in my boat and supplies the power to the toggle at the helm which controls the engine compartment blower? I found no other switch in the cabin for the gen blower. There are 3 toggles at the helm I have as yet to figure out. I have an 88 SF but have as yet found 2 blowers in place but will either find a froze up unit or wires hanging. Thanks for the info guys.

h2ojst · Post by **h2ojst** » Fri Oct 14, 2016 4:34 am

Keith, The 12V breaker on the left side of the panel supplies the "hot" to the bridge switch and a separate switch that on mine is located next to the Generator start/stop switch which is on the right side of the main panel just under the A/C Breakers. My boat was wired with a remote start/stop for the generator and this was optional, so yours may not have this.

Rick · Post by **Rick** » Fri Oct 14, 2016 8:12 am

Interesting....my fly bridge blower switch turns on the blowers for both engines, one of each side. There is totally separate switch on the breaker panel for the genny. Go with Joe Keith, you have identical years built Rick Ticket 85 SF Merc 454 MPI's Falmouth, MA

Keith in Corpus · Post by **Keith in Corpus** » Mon Oct 17, 2016 12:28 pm

Ok I have the gen. blower switch on the right panel but it turns on nothing. The breaker turns on a noisy blower in the cockpit strbd side. So someone as referred to earlier may have altered the wiring and or switches in my boat?? Wow I bet that's a first for you guys to hear. Joe you say that both blowers pipe forward and exhaust thru the aft facing scoops. What vents from the stainless grills on the Port & Stbrd at the back of the boat? I have vent hoses hanging beside the stbrd eng. that are not attached to anything. Before I fixed the exhaust leak below the deck I had a lot of soot on the stbrd side at that stern grill. Leak is fixed and I did not have the soot back the last time out. I guess what I am asking is what is piped in or out of the scoops and side vents?

retman · Post by **retman** » Tue Oct 18, 2016 3:42 am

Keith, I have a FBC and the blower switch on the bridge controls the port and starboard blowers which vent thru the louvered grills in the side of the hull. The starboard aft blower is switched at the electrical panel and vents thru the louver next to it. These blowers probably get exposed to a lot more salt than is healthy and seize up.

Keith in Corpus · Post by **Keith in Corpus** » Tue Oct 18, 2016 5:33 am

Thanks Bill where are the main engine blowers mounted? I have vent hose hanging by the engines but it appears they may have been removed when the Cummins were installed! When I turn on the blower switch on the right breaker panel the unit blows out of the vent on the stbrd at the stern. So the vent on the port side is the inlet for the gen. blower?? There is no blower behind the panel on the port side of the cockpit.

asher · Post by **asher** » Tue Oct 18, 2016 9:59 am

Keith, since you are diesel I wouldn't worry too much about the blowers. The only time I use mine is after shutting down the engines. When I get in from a fishing trip I'll shut off the mains and start the blowers. Then I start unloading all the fishing stuff off the boat and washing it. After 20-30 minutes I'll turn off the blowers. I just use them to keep some airflow in the engine room to help everything cool down. Unless you have large engine room ventilation fans installed like on the large custom boats, your blowers do very little in the way of cooling the engine room. Their intended purpose on our vessels is to expel the bilge and engine room areas of dangerous and explosive gasses.

retman · Post by **retman** » Wed Oct 19, 2016 3:31 am

If the same as the FBC they are flange mounted blowers attached directly to fiberglass boxes which are attached to the hull directly behind the louvers.

Keith in Corpus · Post by **Keith in Corpus** » Thu Oct 20, 2016 4:15 am

So Asher you don't run the blower for the generator either, I would have thought having the blowers running would help keep the warm air moving especially while you are sitting still fishing?

asher · Post by **asher** » Thu Oct 20, 2016 9:52 am

I have two blowers in my main engine room and none for the generator. My generator is located in the original placement on the 35 underneath the aft cockpit. Some people run their blowers when they run the boat, some do not. Tony Athens has an article written on the subject on blower placement and operation, etc. It's a pretty good read. The main thing I take away from his article is that an engine at speed / under load (such as the generator) will be pulling in more fresh air from outside the compartment to effectively cool it and the space more than any little 12v blower can. When shutting off the generator I typically switch over to shore power and then continue to run the generator for 10 minutes or so with no load to help cool things down. I'll try and find the article for ya.

Keith in Corpus · Post by **Keith in Corpus** » Fri Oct 21, 2016 3:10 pm

Thanks for the help guys I am not as concerned with it now but I will still follow it up and hook them up just for my own satisfaction. Asher have you been out much I haven't seen another of your fishing reports. I was watching for some do's and don'ts and the Port A way!