What is your version of Cruising Speed

I appreciate the input- I normally leave them running all the time. We tend to poke our way through the 1000 Islands region, running about 1200-1600rpm most of the day. I open the throttles up for a bit on the way home to give the 8.1S Horizons a good work out.

I have had to replace blowers on previous boats and expect to have to on this one as well. I agree that safe is better than sorry. I have yet to find a HIGH end quality blower that lasts more than a season.
 
This is why I love this site !!! MY first i/o and always thought it was the way I said...I thought I was being fanatical as I religiously turn em on before start up and during warmup ,also after fueling..........now I'll leave em on as long as its running !

thanx
 
i've never found blowers dying to be a problem (??)

cruise at 3250rpm, making about 18mph (sorry, not a KNOT guy), depending on which way the wind blows. into small craft type wind, i'll struggle to make 16mph at that rpm. rarely run at speeds that put me into the secondaries. IMMENSE drop-off in economy (wow, "boating" and "economy" - talk about oxymorons)
 
Count me in with "I leave it on because I forget to turn it off" group.

We all know why we turn them on; I wonder how many of us personally know of a situation when someone forgot to do it and blew their boat up?
 
I wonder how many of us personally know of a situation when someone forgot to do it and blew their boat up?
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i do. that little 1965 chris craft cavalier on the right side of the pic was owned by a good friend of my parents and it blew up back in the summer of (circa) 1974 leaving the gas dock. the owner suffered 2nd degree burns over 50% of his body and the crew of one escaped unharmed as he was on the bow and just jumped overboard. that was a long time ago and i'm not sure if they even had blowers back then, but it certainly can happen. i think, more important than blowers, is getting your head down n the bilge fairly frequently and looking around. if there are problems or leaks, you'll smell them and possibley avert disaster. also, a good sniff of the bilge after you're done refueling is a great idea too. one good thing about my boat - no seats to remove, no buttons to push, no s..l...o...w unveiling of the ER. reach down, pull one hatch and look around. great adjunct to blowers and probably what people did in the olden days.

ps: the owens with the black stripe was my dad's and the first one i can remember as a kid - got it when i was 3, sold it when i was 8.
romadii2.jpg
 
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For me, it takes about 10 minutes from the dock to the end of the "no-wake" zone.

I usually turn off the blowers about 5 minutes away from the dock. Yes, I frequently forget.

I STRONGLY believe in opening the engine hatch for a quick look before taking the boat for a ride. One time, I found that one of the belts was nearly off the power steering pulley.Sticking a nose down there will do a lot more to detect fuel leaks than sitting at the helm.

I also believe in running the blower when at the fuel dock. Not hard to get a few drops where you don't want it.

I do NOT personally believe in running the blower for giggles when running at idle. I can't believe it would do that much good if something bad happens when running. Call me a contrarian.
 
I always leave them on while running on bigger boats. On small boats like 30 and below I'll usually just open the engine hatch for a sniff test. Some real big boats have air systems that run while the engines are running, such as the Delta-T systems. In all of the boats I have been associated with I can't remember one that needed to have blowers replaced. I vaguely remember a blower or two in the past needing replacement but can't remember any specific boats, so at least in my experience it is not a part prone to failure.
 
You are not supposed to run them while fueling. Fueling is another time when gas can end up in the wrong places. After fueling, check for unusual fumes, then turn them on for 4 minutes. I always check the smell of the blower exhaust on BOTH sides before starting any engine. Then blowers draw air from the bottom of the bilge, under each engine. These areas are isolated on my boat, so checking only one may not reveal a gas leak.
 
I cruise at 1000 rpms below wot, in my case about 3800 rpms. As for the blower, I shut it down after about 5 minutes of being under way.
 
I run my blowers for as long as I can stand the noise. They are pretty much on from about 10 min before I leave the dock to about 1/2 hour after i reach my destination. I can't hear them while i'm running and I figure the air circulation isn't a bad thing.
 
On my old 17' SeaRay if I came to idle speed (no wake) I had to turn the blower on, the air would heat up under the little engine cover and when you hit the throttle to go it did not want to. Turn the blower on to keep the air circulating and cool and you were good to go. So I got used to leaving it on in that boat and now do not remember to cut it off, even at cruise speed of 3500 and 34 to 36 mph gps.
 
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comsnark said:
I also believe in running the blower when at the fuel dock. Not hard to get a few drops where you don't want it.

I do NOT personally believe in running the blower for giggles when running at idle. I can't believe it would do that much good if something bad happens when running. Call me a contrarian.
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In Canada at least, our marinas will not allow any source of ignition or spark to be operating while being fueled. This includes blowers, radios, cell phones, etc. As well, ALL passen gers including the furry four legged ones MUST be off the vessel and away from the pumps.

I've always been taught to run the blowers below crusing speeds, but have always pondered what consitutes cruising speed.

Thanks for the great responses.
 
comsnark said:
I do NOT personally believe in running the blower for giggles when running at idle. I can't believe it would do that much good if something bad happens when running. Call me a contrarian.
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Red balls for you.

For my diesels anyway, the only time the blowers run is to cool the engine room down. Mine are plumbed to suck air off the top of the engine room air space (not the bottom like a gas engine room) and they come on as soon as I come off plane. If you put your hand over where they exhaust on each side of the boat, they are blowing very hot air... like your post!
 
My cruising speed depending on wind direction between 22mph to 26mph @ 3,200 rpm to 3,400 rpm. Conditions that effect performance #people, (weight of some relatives), Fuel (Full tank or half tank)
 
I wasn't clear on the question if it was just a "what's your cruising speed" question or "at what speed should I turn on blowers" question.

When you are humming along at cruise (whatever it is), your engines are going to be evacuating a lot of air out of the engine room. Far more than a blower will. If I recall correctly, a 4 inch blower will evacuate about 200 CFM. My engines will evacuate anywhere from 1500 to 2000 CFM (for both) at cruise. The CFM on air intake for the QSM-11 is about the same as the RPM reading... so my whole thought process revolves around keeping the CFM high enough to keep the engine room cool. If the engines are sucking out 1200 CFM (idle), turning the blowers on to get another 400 CFM makes sense.

But that's just my thought process and you can all red ball me to death.

My "cruise speed" is anywhere from 14 knots to 26 knots depending on sea conditions and load (fuel, water, etc). If it's a flat calm day like yesterday, I'll start out at 23.5 knots and end up at 25.5-26 knots as the fuel is burned off... but I carry over 3000 pounds of fuel.
 
Like most, I never quite understood when (other than before starting your engines) you really should run your blowers. I do run them until I remember to shut them off, and always run them when the genny is running!

Cruising speed for us is somewhere around 3450 rpm @ 23 +- mph, burning around 28gph. Normally when we are just relaxing I run at 2150 rpm @10 mph burning right at 10 gph.
 
one person once suggested that it is NOT a good idea to run blowers at cruise b/c you could conceivably deprive the engines of the ER air they need. thoughts(?)
 
The owners manual for mine states that it should be run 5 mins before startup and then remain on while under cruising speeds.
It may differ on newer boats as mie is an 83
 
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