Conference vicki::boats

 Dave,

 The main purpose of a bilge blower is to remove any fumes prior to starting
 your engine. I don't know of an "automatic kind". Its just something you
 do before you start you engine. While running, your boat/engine area is vented
 through a series of ducts, thats why its not neccessary while running. 

 How would the automatic know when you planned to start your engine? other
 than putting a delay in your starting, which would be no good cause sometimes
 you need to start/take off quickly... I have seen some boats with the fans
 on 5 minute timers.... But, when at idle you'd always consider keeping
 the blower on...

 - Good luck

Yeah Dave,

	I know exactly what you mean.... There you are almost to Merrimack
after launching in Lowell..... and.... "Geez I never turned that stupid
blower off!".....

	My first thought upon reading your note was some sort of switch that
would make contact (or break contact whichever way was needed to wire the
foolish thing) whenever some significant bow-rise was experienced. This
circuit could be wired to shut off the blower and it would usually do it
upon first taking off. (It would need to be sensitive on inboards! :-) )

	Then .-1's thought of a timer isn't all that crazy... A simple
"Oven-type" timer on the dash rather than the binary switch that's there
today would do the trick. 

	1) Get in the boat...
	2) Spin the timer for 5 minutes til shutoff, on comes blower...
	3) The official 4 minutes later, start the engine
	4) Drive away....
	5) Blower shuts off 1 minute later... And the cookies are done!

	I bet a timer like this could be found in the Bliss, Overton's
or E&B catalog... got room on your dash?

Rick

 If it doesn't exist I should get the patent. Actaully I saw the timer
 gizmo on a few boats. Looked like an adjustable timer from a bass boat live 
 well. These were definately home grown Radio Shack inventions.

 =Dave

    I would like to introduce my self.
    
    I am currently a certified MRECRUISER/MERCURY OUTBOARD technician
    with five years in the trade up till 2.5 months ago.
    
    1. If your boat is in good condition the need to use the blower
    is minimal,
    2. I always instructed new/old boat owners that the smart~correct
    thing to do is to lift/remove your engine cover and do a vissual
    check on your engine,check the oil,the power steering fluid if so
    equipped,check your bilge pump{audible}/bildge area for oil/gas
    fumes or anything that may be leaking!!!
    
    After you have done this( which should be done every 24hrs.or if the
    boat has been sitting off for seveal hrs) once you have at least
    lifted the engine cover you have evacuated the dangerous gas fumes
    
    using the blower at idle speeds is up to you I personaly dont use mine
    at all 
    
    The coastgard statement is only a recomendation 
     
    THE LAST REPLY IS THE RIGHT IDEA THOUGH
    
    aquire a timer circut from a bass boat the only problem is what power
    source do you hook up to?????
    
   1. If you hook it up to the battery and you forget to turn off the timer
    you will kill the battery
   2.If you hook it up to your purple wire (ingnition on) then you have 
    defeted the blowers purpose because it wont turn on until you turn the
    key.
   3.Installing a mercury switch is still an after thought (the boat is 
    allready running)
    
    bottom line, keep it just the way it is and refer to the owner/operator
    responsibility of checking your boat properly before using it! 

	The timer that I pictured would not require power. Remember the 
old timers that Grandma used when she placed the pie in the wood stove?
It must have used a coiled spring setup or something, cuz it required
no power yet the pie was never overdone! :-)

	If a "spring" type timer could be found then simply replacing
the current On/Off blower switch with the timer'ed switch would do the trick.
No additional wiring would be needed.

Rick

Damn, we must really need to go skiing if we're this concerned about
extra hours on our blowers! The Nautique's first blower lasted 6 years
and then was only replaced cuz the housing was beginning to melt away
from all those hours in the vicinity of an exhaust manifold.

    How about a "wind speed sensor"?  Less than 5 mph, the blower comes on,
    and more than 5 mph, the blower is off.  No worries about leaving the
    blower on while trailering, except at red lights or being caught in
    traffic :^)...
    
    OH, it must be winter...%*]
    
    Doug

	I have a question on this blower thing. I have an outboard so it's
 for withdrawals/inquiring mind thing.

	Turning on the bilge blower would be to me like putting in the drain
 plug, turning on the bilge pump, etc..... But why turning it off???? While
 the engine is running, the alternator should have no problem supplying power
 to the boat accessories, and I do not think that the suction would starve the
 engine of air.

	So again, why turn it off unless you're gonna park the boat/anchor/
 trailor??? Is it because of wear????

	Norm

RE: .1  
	Using the blower for the obligatory 4 minutes before starting the engine
is *usually* not my problem, but as Rick suggested, turning it off after getting
underway is *frequently* my problem.  The idea of a mechanical timer, in
parallel with the normal switch would take care of that quite nicely.

RE: .4
	My '93 (dare I say it here :*)) MC is in fine shape and I follow your
inital inspection routine closely, plus the few minute exhaust purge.  I also
try to follow the manual's recommendation of 'use the blower at idle and/or
slow speed.'  We frequently pull novice skiers and spend not insignificant time
just getting someone up.  I like to have the blower on then, but usually forget
to turn it off during the run.

	I'd thought of Doug's idea, on/off as a function of windspeed which
would work fine on the river, probably not so fine on my lake unless it switched
on/off high enough to compensate for the prevailing winds.  My current thought
is triggered off the tach (switch at ~1500rpm) and interlocked with the
gearshift so you could use the manual switch for initial start/override.

Dave

ps. Rick... it is a sign of withdrawal isn't it.  But it has started some
chatter in an otherwise VERY QUIET conference :*)

pps. Sorry Dave... patent already pending...

I think I may have a solution to your timed blower!

You should go to your local home depot or hq type store and look for

a heat lamp type timer similar to what is used in hotel room bathrooms

just make sure the timer is mechanical not electricaly driven.

If it is mechanical, hook it up like this.



                                  (blower switch)
12vdc to blower switch                  /
...>....[20amp fuse]......>............/  *.......> to blower
                                |              |
                                |              |
                                |....[timer]...| 


Hope this answers your mind BLOWING delema!!!!!!!

    
    	The other option is to look and see if something alread exists on
    the market.  A quick look at the Boat/U.S. comes up with almost what you 
    are looking for an automatic timers turn it on and it runs for 5
    minutes and lights an led saying you can start up the motor.  It will
    run the blower for 5 more minutes and turn itself off.  Also has a
    manual mode.  Price for this charmer is $65.                   
    
    
    Forrest

 You know its winter. Boy, we are grasping here.

 re: -3 the outboard guy, as an *fyi* In the past boat manufacturers put their
 bilge blower fans in the most horrific place in the bilge. They are usually
 a dredded nightmare to replace. So, using them only when you need to can 
 increase the motors life and the owners sanity.

 -Its going to be a COLD winter

The mechanical timer approach is a good one for the initial purge, and after any
long break. I'm beginning to get the feeling that I'm in the minority trying to
remember to turn the blower on at low speeds, and off when back up to speed.
For example, at camp we start/stop skiers from the dock. Frequently a few
minutes pass where I'm idling near the dock as skiers change.  Remember, this is
Maine, so no one's in a hurry.  I like to run the blower during this time, then
off during the next run.... but I usually forget to turn the blower off.  A
timer would work here too, but that assumes I remember to turn it on :*).  Am I
overly conservative?  Should I be running the blower during these few minutes?
I'm assuming that cycling the blower IS extending its life... safe assumption?

Forrest, your idea of checking the catalogs is right on.  After having designed
a nice rudder position indicator (proto costs ~$100), I found a real nice one
in Ski Limited for $26.  It just lacked that personal touch.

dave
 

    
    
    	You can also get gas sniffers that will turn on you blower if fumes 
    are detected. I have one for my (sail) boat. Keeps the peace of mind..
    
    

    There are several timer products on the market.  The basic idea is to
    prevent the ignition from operating until the blower has been running 4
    or more minutes.
    
    I second the use the old mark one nose before turning anything on.
    Blowers included.
    
    KC
    
    

    
    Hmmm....
    
    The reply about never using the blowers because of lifting the hatch
    and doing a visual and olfactory check don't seem quite right.
    I thought gas fumes were heavier than air and therefore end up
    "trapped" in the engine compartment.
    
    Which brings me to my next question, placement of the tubes for the
    blowers.  I just picked up a Scarab III, all 4 blowers are there but
    the ducting is missing. Anyone know where the intake ends of these
    should be positioned when I replace them???  If gas fumes sink I assume
    they should be near the bottom.
    
    Garrison.
    

    You're right that fuel fumes are heavier than air and will sink to the
    bottom of the bilge. The ideal setup is to mount the blower towards the
    top of the engine compartment and let the input hoses drop to the
    bilge. The end of the hose should be a couple inches off the bottom to
    ensure you only pick up fumes, not water. Larger deadrise angles help
    keep foreign objects out of the hoses.
    
    --Harlan

As far as gas fumes go lets talk!

1.  I personaly have had my head in approximatly  3000 engine compartments.

2.  very rarely have I ever smelled strong gas fumes. usually on older
    boats that have been poorly maintianed are the fumes more noticeable.
    not to say that there are none,
    You must remember that one of the reasons marine electrcal parts are so 
    exspensive is that they are spark arrested.

3.  whether or not the fumes are heavier then air, the openning of or the
    removal of the engine housing/hatch creates a great deal of air turbulance,
    which should in my opinion displace most of the gas fumes with fresh air.
    At least that has been my experience.

4.  I am not saying not to use the blower, but if your engine compartment
    is in good clean shape the time the blower is used can be kept to a          
   minimium. 
     
 To answer your blower tube placement question!            

 All boats have vents on both sides, near the rear of the boat.
 
 one side the vent opening fases forward and the other side vent opening faces   
aft.

 all the exhaust blower tubes should be going the the vent(s) that are faceing   
aft.

 the intake side of the blowers should be as you assume pointing towards the 
 bildge area under the engine(s). make sure that they do not go to deep
 they might get covered in (water/gas/oil/excess paper/beer cans /soda cans
 toilet paper/beech towels etc.)  :>)

 all hoses should be secured to the blowers with st. steel screws (3/8-1/2") and 
to the boat floor with one ss screw(3/8-1/2") per hose. hose clamps are ok
 but they may loosen in rough conditions. 

 Make shure the blowers are pointing the right way, away from engine(s).

 Also it is a good idea to have the blowers in a vertical position so water
 cant accumulate and prematurely ruin the blower motor.
 
 any other questions especialy about the "meckinics end of things" please let me
 know. 
						JACK				
										
				

    If you want to see exactly how gas fumes behave, the try this:
    
    Hang a white sheet up in the garage. Position an open container of
    gasoline on a table by the hanging sheet. Then position a source
    of bright light so that you can see a silhouette of the container
    of gas on the other side of the sheet. You will also see, very plainly,
    the gas fumes coming off the gas and flowing out along the table top.
    I saw a this done once during training while I was fighting forest 
    fires out west in the 70s. The person doing the demonstration took
    a piece of cardboard and actually "pushed" a ball of fumes up a ramp.
    
    It takes only a very small amount of gas to make a big cloud of fumes.
    In an enclosed space, such as an engine hold or airplane wing, it
    makes a wonderful bomb. One spark and ka-blooie! No more boat. I
    haven't had my head in any engine holds except my own, but I have 
    seen a boat blow up at a fuel dock. Pretty scary stuff. I've never been
    able to figure out why boats aren't wired so that the starter won't
    engage unless the blower is on. It's not Nuclear Physics. It would 
    have saved a few boats, and even some lives.

    > I've never been able to figure out why boats aren't wired so that the 
    > starter won't engage unless the blower is on.
                   
    One reason is that that is not sufficient.  The recommendation
    for blowing is 4 or 5 minutes before starting? Yes, a 5 minute delay
    before the boat could be started wouldn't be rocket science either
    but I believe that a large number of users would not like that feature
    and either not buy the product or would disable it.                      
    
    Bill
    

    True ... I just didn't elaborate for the sake of brevity. A delay
    feature would be very simple, with an over ride for situation where
    the blower isn't needed. I'm surprised the Liability Insurance
    companys for the boat builders don't insist on it.
    
    Any way ... it's all rehtorical ... you can only protect the general
    public from a certain amount of their own stupidity, and then they
    are on their own. I know fellow pilots who have quit using checklists
    in their own airplanes. Familiarity breeds complacency more often than
    contempt.

 Yes, IT IS Winter....The only thing blowing today is my snow-blower.

 3 months to St. Pattys Day

 - Dave

    Thanks all,
     for the info on position and mounting for blower pickups.
    
    Garrison