Conference vicki::boats

    
    Nelson,
    
    	A 17 pitch prop with 75Hp on a boat that small should pull
    a skier fairly well, I would think.
    
    	My first guess would be the vertical position of the engine
    on the transom. Help here guys... Wouldn't mounted too low cause
    this loss?
    
  	Of course a Nautique runs a 13 pitch prop!
    
    Rick

    
    Try adjusting the trim angle of the motor. With the motor
    tucked in close to the transom you should be able to pull 
    a skier right up, but will lose a little on top end. With
    the motor trimmed out away from the transom you'll gain some
    speed, but acceleration will definitely suffer, especially
    while pulling up a skier.
    
    My 14' boat with a 40hp Evinrude is very sensitive to trim
    angle, so I adjust it almost every time I go out, depending
    on the load I'll be carrying.
                             
    Rick W.

    
    
    	Correct me if I'm wrong here, but I believe that mainly just
    the skeg should be below the hull??

    Nelson,
    
    	Since you have a Tri-Hull, have you attempted to place 1-2 passengers
    up front to help get the boat up on plane easier. This should help, have
    you tried this, and if you did....what happened?
    
    	Too bad you don't have tach, that would help out a great deal.
    
    							-mike-

    Engine is all the way down (closest notch to the transom)
    People always in the front
    Even with just me in the boat and no skier,planing is slow and sluggish
    
    It feels as if about half way on plane it gets a burst of power,
    I thought possibly getting into the torque range of the motor. 
    I have change the plugs, but no help.
    How about timing?  Has anyone experienced setting the timing on
    this motor?  How critical is it?
    
    Nelson ( felling very frustrated)
    
    

    RE: 42..3
     
    >>	Correct me if I'm wrong here, but I believe that mainly just
    >>  the skeg should be below the hull??

    Rick,
    Unless you've got a surface-piercing drive or a cleaver type
    prop you need more than just the skeg below the transom. With
    a conventional outboard and prop you'll get some nasty cavitation
    if the prop isn't below the transom.
    
    Rick W.

    
    
    	RE: .6  Oh well, thanks for correcting me... If it ain't an
    inboard..... :-) :-)
    
    	I know a friend had similar problems and solved them by merely
    raising the motor on the transom, come to think of it it's also
    a 14 foot boat, although a Glastron.
    
    	Isn't there some way to eyeball this measurement? I assume
    the author of .0 has put this combination of boat/motor together..??
    
    Rick

    I believe that you need about 1" of clearance between the top of
    the anti-cavitation plate and the keel. There's definitely a problem
    there and it could be many things. Too rich a mixture, retarded
    timing, improper dwell angle (unless you have electronic ign.),
    wrong motor for boat (long shaft on a short shaft boat), improper
    trim angle (too high OR too low), or, maybe there's a problem in
    the lower unit, such as a frozen bearing anywhere down there. One
    other possibility (but not much probablility!) is that the throttle
    linkage is incorrectly assembled. My last outboard (circa 1967)
    was an Evinrude which uses a sliding ignition base plate to advance
    the timing as you increase the throttle, all in synch. Maybe this
    contraption is not calibrated, such that when throttle is given,
    the ignition is advancing too soon with little or no increase in
    throttle plate opening. A quick check would be to open the throttle
    all the way, with engine off, cover removed from engine. Check that
    the throttle linkages have moved to the wide open position. Make
    sure they have BOTH opened! Now, move the lever back to idle postion,
    slowly, while observing the rotating ignition base advancing plate.
    Did the plate move? (is there a plate? or has history eliminated
    this technology?) 
    These are some things that nearly anyone can do, saving the money
    of having your OMC-professional do them for you. 
    
    Let's get your boat running right!!!
    
    Mike

    	I had a problem with performance when I bought a new prop for
    	my older Johnson.  I tried a 13" 15" and a 17" pitch and could
    	not get the same pick-up and high end performance, I had a tach
    	also but it did'nt help explain the problem.    I final found
    	a rebuilt 17"  to replace the original 17" and it was then that
    	I realized the older props had no "cupping".   All of the new
	props I tried had "cupping" and it was the "cup" that was robbing
    	my low end as well as the high end.	This may not be your
	problem but I thought that I would pass along the information
    	in case you start trying out new props.   Try to get a dealer
    	to let you try out the props before you decide on the best one
    	for you.

    re .8	that brings to mind the little old o/bs that I've been
    playing around with lately.  To cut a long stor<cut..>   The twist grip
    connects through a bevel gear to a vertical shaft which connects to a
    linkage to rotate the magneto's base plate.  Mounted on the magneto's
    base plate is a throttle plate, in fact its a very large flat cam, this
    actuates the throttle lever on the carb.  There are some
    incompatability problems with carb levers with/without rollers working
    against cams that were designed for specific carbs without/with
    rollers.  I've been tuning by twiddling, but somewhere there has
    to be a procedure to set everything down to zero and start from
    scratch, if anyone has the basic set up procedure please post it ?
    	
	Reg
    
    {'61 head on a '56 lower, and it WORKS !}
    
    

    Thanks for the advise so far.  I payed for the a rebuilt motor,
    now a rebuild so all the return trips are not costing me anything
    till it gets fixed.
    
    The shaft is the right length on the motor.  The prop is a cupped
    prop but I was under the impression that this was desirable.
    
    Technology has changed since the 1968(?) motor listed earlier. 
    However, thottle flaps are fully open and spark is advancing fully
    but there is an adjustment on the max spark advance.  Ignition is
    electronic and firing on all 3 cyninders.  Mixture is not adjustable
    on these carbs, but they are rebuilt with proper jetting.  
    
    The motor seems to run okay, just slow planing.  I plan to borrow
    a couple of props from the mechanic and see what happens.
    
    The hull is rated up to a 70hp motor and I have a 75hp so I should
    have enough power if I'm set up right(engine and prop)
    
    I have tried diffent trim settings and I think I'm okay there.
    
    Again, thanks for all your help.  I'm open for more suggestions.
    
    Nelson

    Hey, ODIXIE::Nelson_Wilkinson:
    
    Maybe it's just a "Southern" motor, and *prefers* to take its time
    getting up on plane!
    
    Y'all are in 'Lanta, right? Maybe you're hitting the bottom of the
    lake (I saw on your local news that the levels are WAY down)
    
    On the more serious side, are all the carbs getting gas??? A dragging
    cylinder could cause poor acceleration, but not hamper the engine's
    high end running speed in a 3-cylinder config... (But not for too
    long) With a 75 HP on a boat rated for a 70 HP, I'd expect a
    rocket-sled-like performance. A 17" pitch prop is leaning in the
    power direction of pitches, which should give you better acceleration
    out of the hole. One other prop-related question: Is this prop made
    for this motor? By that I'm asking if the engine is set up for exhaust
    thru the prop and possibly you have a closed prop?
    
    Just a wild guess. 
    
    One thing to check is uniformity of spark plug burn color. This
    would give you some direction as to even carburetion in the cyl's.
     
    Gotta go... Sorry for the sick southern humor. I like 'Lanta!
    
    Mike

    I put a tach on the boat Wed. and took it out after work yesterday.
    With one person in the boat it topped out at 5200 RPM.  I noticed
    also that coming out of the hole the engine had a noticable increace
    in power at 3200 RPM.  So from 5200 I started backing off the throttle
    in small steps.  At 3200 ths engine lost power (skipped?).  I later
    talked to a prop shop that said the 17'' pitch should be fine. 
    I called the mechanic back who rebuilt the motor (he is now getting
    quite defensive) Said he has checked the carbs 3 times, changed
    the coils and the whole block is rebuilt(pistons, rings, bore, reed
    box) Said he will call the OMC training center this morning and
    see what they say.
    
    Yes it is a thru the hub exhaust prop.  Nice guess though.
    
    Lake Lanier is down 9 ft. now out of 130 ft. Lots of new shoreline
    showing.  Rocks that use to be 9-12 ft under are now lurking just
    below the surface.  Farmers will be losing a lot of crops if we
    don't get rain in the next 10 days.  No significant rain since 
    April.
    
    I'll keep you updated.  Thanks for the help.
    
    Nelson

    Well, I bit the bullet for a new 15'' pitch prop which I'll get
    to try out next weekend.  This passed weekend I had 6 people in
    the boat for a cruise and only turned 4200 rpm and took 30-45 seconds
    to plane so maybe this new prop will help.  
    
    I talked to my  mechanic this morning and he offered to take it
    to a shop that had a dyno to check it out.  I'll keep this updated.
    
    BTW the new prop had a note in it which said that it was a cupped
    prop and that this is to allow the prop to run at a shallower depth
    without sucking air. So you could raise your motor up on the transom
    and run faster.  If your old prop wasn't cupped, you might have
    to go one size less on pitch than your old prop.    
    
    Nelson
    
    

    when you say to get on plane it took 30-45 seconds, what is the
    tach doing for the forty five seconds? waht does the motor sound
    like during this period?
    Silly question but how did the boat run before you put this motor
    on it? Did you research the possibility of the bottom having a bad
    hook in it or the core being saturated. Have you inspected tyhe
    bottom since you first put it in the water? Did something delaminate?
    Sad questions but they had to be asked if you want to get to the
    bottom of this. I honestly don't think the prop has much to do with
    your problem. A 14 ft boat of less tah a thousand pounds should
    come out of the hole like a raped ape with a 75 hp on it even if
    pitched 2 or 3 sizes off in either direction.
    
    regards ,
    
    Bill
    

    Bill,
    
    It has been a while since I have seen a raped ape, but I'll assume
    they move quickly. :^)
    
    I keep the boat on a trailer so the bottom is silk smooth.  Likewise,
    the inside stays dry.  Time to plane is about 8 sec. 1 person, with
    3-4 people , 15 sec.; with 6 people 30-45 sec.  Won't plane at all
    with 2 people in the boat and one trying to slalom (drug me in the
    water for about 30 sec.).  I got another prop but haven't had a
    chance to try it.  The boat is new to me but was used by friends
    with a 50 hp motor for skiing before.  I did weigh the rig and found
    out boat, motor and trailer are 1500 lbs.  Tach while trying to
    plane is 2500-3000 rpm.  
    
    If the new prop dosen't get it, back to the mechanic.
    
    Nelson
    
    

    I HAD A SIMILAR PROBLEM WITH MY 70 EVIN. ON A 15' GLASTRON.
    HERE'S WHAT TEAM EVINRUDE TOLD ME TO DO:
    
    FOR LIGHT LOADS(ALONE/1 PASSENGER -LIGHT-) THE 13 X 19" PROP
    SST, DRILL HOLES IN THE HUB AT SPECIFIED LOCATIONS. THIS ALLOWS
    EXHAUST GASSES TO EXIT THE HUB IN FRONT OF THE BLADES AND BRINGS
    YOUR RPMs UP FAST AND YOU SHOOT OUT OF THE HOLE.  ALSO HAD TO 
    RAISE THE ENGINE SO THE HORIZONTAL PLATE NEXT TO THE TOP OIL HOLE
    ABOVE THE PROP IS EVEN WITH THE BOTTOM OF THE BOAT.
    
    I'VE DONE THE SAME WITH A 13 X 15 ALUMINUM BLADE, A LITTLE SMALLER
    HOLE AND THE RESULTS WERE FANTASTIC. 
    
    
                   BUT! (AND I REPEAT) BUT!!
    
    
    
    
               DON'T USE A 15" WITHOUT A TACH, OR YOU'LL FIND
               YOUR ENGINE ALL OVER THE PLACE.
    
               WITH MY 19"SST, I TURN 5800 AND DO AROUND 40MPH + -.
               WITH THE 15", I ALONE CONTROL THE BOAT,NO ONE ELSE  
                                                                   
 SHIP ME YOUR ADDRESS AND I'LL TRY AND FIND THE LITERATURE ON DRILLING
 THE HOLES THEY SENT ME.  ALSO, IF YOUR HULL HAS ANY GROWTH ON IT OR
 YOU HAVE WAXED IT, THIS WILL SLOW YOU DOWN. WAX, ALTHOUGH SLIPPERY
 AND WATER BEADS ON IT, PUTS THE BRAKES ON. GET THE GROWTH OFF AND 
 WET SAND WITH FRONT TO REAR STROKES WITH 600 GRIT PAPER.
    
    LET ME KNOW
    
    FRED         
    
    
    
    

    I finally got to try my 13 3/4 X 15 prop last weekend, it works!
    The boat pulled me up skiing slalomn.  With 3 poeple in the boat
    top end was 5500 RPM. I still experience some skipping in the motor
    under 2800 RPM. Of course the boat isn't on plane at that low of
    a RPM. Is this just normal 2 cycle behavior?  When I give the boat
    the gas (full throttle) It skips for about 1/2 to 1 second the takes
    off. Normal?  Thanks for all the help. I look forward to hearing
    from Fred in .17 about the SST prop with holes. Any comments on
    that?
    
    Nelson
    

    
    
                        HANG LOOSE NELS,

                   I'M LOOKING FOR THE PAPERWORK.
    
                   IT'S IN THE GARAGE SOMEPLACE.

                            FRED

    No problem, I'm hanging!

    Im still hanging too..........