Re: [OMC-Boats] OMC Stringer Generation Naming

The term "Stringer" is derived from the fact that OMC designed the
units to transfer all engine/drivetrain thrust vectors directly to the
boats underlying "stringer" sub-frame. Since the entire units floats
without touching the transom, it can operate smoother and quieter. It
also benefits from sharper turner angles and there's only one hole to
punch in the transom.

If you remember how wooden boars were constructed with a series of
spars or ribs as part of their structure, then you know what stringers
are. Fiberglass boats have them as well, hidden under the sub-floor.

All other sterndrives, like MerCruiser and Volvo, use a gimbal the
mounts the engine to the transom. This results in much greater NVH as
well as requiring the transom to be heavily reinforced to encounter
and transfer the forces of thrust.

PS -- On the cooling issue -- Is is also possible to over grease the
pivot Left and Right trunnion/gimbals (under the end caps) and
accidently restrict water flow, just another thing you may want to
check. Sea Water needs to get thru a fairly small passage way at that
point, being pushed by the impeller on its way to the intermediate
housing the exhaust manifold elbows. (Any signs of leakage around the
end caps (other than the Starboard side tell-tale will also greatly
reduce the efficiency.)

On Aug 31, 2009, at 7:31 PM, Justin DeSantis wrote:

> Did we already cover why they call them "Stringers" to begin with?
> I've been wondering that. I think I saw an explanation once, but
> didn't read it carefully, and I haven't found it again.
>
>
>
> On Mon, Aug 31, 2009 at 8:28 PM, Lee Shuster<lks@...> wrote:
>> I've been thinking of breaking down the OMC Stringer Sterndrives in
>> broad
>> "GENERATIONS" of families to help make it easier to know what were
>> talking
>> about. The recommended lube discussion got me to thinking.
>>
>> I'm very fuzzy on the 1978 - 1986 (non-electric shift) Stringers.
>> But all
>> Stringers share basic design features: Ball gear drive, floating
>> intermediate housing, 75-degree power tilt, 120-degree steering,
>> stringer
>> mounting that transfers thrust to non-transom structural members of
>> boat
>> (stringers).
>>
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>> =====================================================================
>> From an original OMC BOAT-OWNERS perspective things are pretty
>> simple: Our
>> boats were all Gen-Zero, Gen-I or Gen-II powered.
>>
>> 1962 - 1965 Gen Zero = Outboard powered (the 1962 - 1968
>> high-end OMC-E/J outboards" 40, 75, 90, 100 hp featured available
>> electric
>> shift lower units)
>>
>> 1962 -1968 Gen One = The 1st OMC 480, 488, and 490
>> two-stroke,
>> "bullet-shaped" split gearcase lower unit. (Also used very
>> sparingly/rarely
>> on a few 1964-65 110 hp I-4 Chevy II) Built from Electric Shift,
>> Type C
>> gear case lube.
>>
>> 1964 - 1973 Gen Two = The "big brother" large gearcase,
>> one-piece gearcase, 14-inch prop. Used on 120, 150, 155, 165 185,
>> 200, 210,
>> 215, 225, 235, 245 GM engines. Four-bolt top caps (shimless) from
>> 1964
>> -1967-1/2. Five-bolt from late 1967 to
>> 1973 used
>> shims. Electric Shift, Type C gear case lube.
>>
>> 1973 - 1977 Gen Three = This generation introduced
>> Ford V8
>> engines 175, 190 and 235, along with the SelecTrim option on inline
>> GM
>> engines. TruCourse steering appeared, as did the shorter profile
>> drive, to
>> permit mounting the engine lower.
>> Down-firing exhaust rudder. Electric Shift, Type C gear case lube.
>>
>> 1978 - 1981 Gen Four = The 400 (120 - 140 ) 800 (all V-
>> engines)
>> thru-prop exhaust lower gearcase adapted from outboards, featuring
>> Visible
>> styling changes to exhaust housing. All are "short-leg." are
>> Hydro-assisted-mechanical
>> shift, OMC
>> Hi-VIS gear case lube
>>
>> 1982 - 1986 Gen Five = Similar to Gen Four but without the
>> Hydro-assist.
>> OMC Hi-VIS gear case lube
>>
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>> =====================================================================
>>
>> _______________________________________________
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>>
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Received on Monday, 31 August 2009