twin stern drive vs. twin inboard
George Jefferson
go with twin stern drive (i/o). In looking at dozens of
makes only SeaRay offers a twin inboard ( v-drive actually)
option. The inboard is not good here for draft reasons I
i think, but I was suprised that the searay guy claims the
inboard is *more* maneuverable. With the i/o you cant
properly independantly reverse one prop. Is this
true? I'd have thought the i/o gave superior low speed maneuvering.
(a single i/o is better than a single inboard no?)
While I'm at it, would anyone argue in favor of a single big block
with a bravo3 (dual prop) over say twin 5.0's or maybe twin 4.3's?
Personally I think two motors will bring twice the headaches,
but then I'll never have a boat that big to need twins.
(when I get that old you can shoot me)
--
george
geo...@mech.seas.upenn.edu
br...@lehigh.edu
There is nothing more easily manuvered than twin inboards. This is due to a
phenomonen known as 'sidewise blade pressure'. Go into the FAQ's and try to
find some of my discussions regarding this topic. In a nutshell, *any* I/O
will have a mind of its own and it will do damn well as it pleases to do
relative to external (wind, tide) factors...AND, you will have to learn to
live with this. Sometimes the boat 'will' and sometimes it 'won't' do what
you want.
IMHO, if you are considering something in the 30 foot range then by all
means go with twin inboards.
Just a side note: There are an enormous amount of gears in outdrives. There
are only a fewer amount in V-drives. BUT...there are considerably less than
either of the previous drives if you choose to go straight inboard. My
recommendation and I've owned them all.
***** Brent Rhoads
Lehigh Univ. Health Center
doug lewis
ability necessary with practice. Carry a small outboard kicker in case
of engine failure and for trolling (and powering the dingy). Twin
engines just give you twice as much stuff to go wrong and I/O's mean that
you have to haul the boat anytime any little problem comes up. Just
a little tiny leak will cost you a fortune. With twins the engine
compartment is crowded (especially with twins and V-drives -- more stuff
to go wrong!)
The only advantage I can find to the I/O is you can tilt them up to land
on a beach, and they will tilt up by themselves if you hit something big
in the water. I don't land my boat on the beach ever, and I hope I don't
ever hit anything big. (Although I did lose the bottom half of my dingy
outboard on a log last year.)
Good Luck!
George Jefferson
:farther back than it ought to be. If you have room for an I/B configuration,
:go for it.
I dont think a true inboard is even an option on this class boat, the v-drive
engine evidently sits in the same spot more or less as the stern drive.
:I've never heard of any issue involving maneuverability of any kind of twin
:screw vessel. That's one of the advantages of twin screws. You can
:separately
:run either screw in forward or reverse on a twin sterndrive. I don't know
:where you are getting your info.
Thats what I thought. The 'info' originated with the guy trying to sell
the v-drive of course, but now in discussing it i've had several confirmations
that basically leave me confused.
Can you independantly shift twin merc i/os???
To be honest, my experience with a single merc i/o is that shifting
is a hit-or-miss operation. The linkage deliberately momentarily stalls
the motor as you shift and, well, you only need to lose the motor once
to develop a cringe each time you need to shift. I suppose for that reson
maybe some people try to maneuver without too much shifting.
--
george
geo...@mech.seas.upenn.edu
Jim Swist
Now I would have thought this was a no-brainer. The sterndrive is a mechanical
kludge which at best is failure prone, hard to service, and ages quickly with
so much of the mechanism in saltwater. They also force the engine block weight
farther back than it ought to be. If you have room for an I/B configuration,
go for it.
I've never heard of any issue involving maneuverability of any kind of twin
George Jefferson
:
: phenomonen known as 'sidewise blade pressure'. Go into the FAQ's and try to
: find some of my discussions regarding this topic.
I would very much like to look at that. Where is the FAQ?
--
george
geo...@mech.seas.upenn.edu
George Slade
SNIP
>
> Can you independantly shift twin merc i/os???
>
SNIP
YES. Lets stop the silly rumour started by the dishonest sales person.
But I would still go for the I/B over the I/O
George Slade
Jim Swist
In article <DDtqK...@hpcvsnz.cv.hp.com>, doug lewis <do...@lsid.hp.com> writes:
|> My Puget Sound-based '78 Bayliner Bounty 28.5 Command Bridge cruiser
|> (which I would like to sell) equiped with twin Volvo AQ200c's and 270
|> I/0's have counter rotating props despite the fact that both engines turn
|> in the same direction.
|>
I presumed that on outboards and I/Os, counter-rotation was accomplished
by the gear arrangement in the outdrive (switch forward and reverse gears?)
and hence the basic engine is always built to run in one direction.
But what happens on straight inboards? The whole engine must run in
the opposite direction. Yes/No?
George Jefferson
:Can anyone confirm whether or not twin I/Os use counter-rotating props?
I'll confirm that I have seen them both ways. Pretty bone headed to
not be counter rotating I thought, though I guess its a little cheaper (?).
Honestly, I havn't noticed if this is the case or not on the boats
we've been looking at. Thanks for the pointer.
:Bravo drives are cone clutch equiped, and as such do not require the ignition
:cut out.
Is that true of the bravo3 as well?
Also I just once saw a twin bravo3 set up (looked like a race boat).
I really missed the point of that.
--
george
geo...@mech.seas.upenn.edu
Mike Burroughs
>>
>> It all depends on the quallity of the skipper. If you notice
>> virtually all fish boats etc are single screw Inboard. They are
>> that way for a number of reasons. Mostly for fuel consumption
>> and speed. Any time you add a second leg or screw you add drag.
>> Every test I have seen proves single gas is the fastest, Single
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>I think this need clarification... I don't believe my 19.5' boat will
>run faster with one 270 hp engine that it will with 2 270 hp engines. It
>will use more gas (about twice as much) doing it though. So what did you
>mean by this statement?
>
>If a single engine is fastest, why do off shore boats use 3 (or 4) of
>them?
If you do an apples to apples comparison the single screw philosophy holds
true. A single 270hp engine is faster with better fuel consumption than
twin 135hp engines. Drag and weight are reduced with the single
powerplant. I have driven all combinations (single inboard, single I/O,
twin inboard and twin I/O as well as sinle outboard) and would select any
of them based on a variety of criteria.
The twin inboard is the most manueverable combination you can get. The
twin I/O is also very manueverable, however, they take alot of practice
and the two handle very differently. Don't expect to jump into your first
twin screen and drive like a pro. If there is no overriding reason to go
with inboard or I/O consider things like cabin layout and servicability.
If you want minimal mechanical headache consider twin diesel inboards. If
you are going to trailer the boat go for the I/O's. One of the issues
that has only been mentioned briefly is that of safety. Yes, with twins
there is twice as much to break, but if something breaks there is still
one left. Having been stuck 8 miles from shore in a twin when one decided
to have an electrical problem, I was glad to have the second engine.
Granted it was a slow go and difficult to keep going on any planned
course, but I didn't have to pay for the tow. If the safety and
manueverability are not big issues go with the single. For the casual
boater I would suggest an I/O as a single I/O is easier to handle than the
single inboard, especially when backing down.
Just my two cents.
Mike Burroughs
Darrell Irvin sptekwv2
|> Go with the inboard. A single screw will give you all the manuevering
|> ability necessary with practice.
Having owned such a boat for 12 years, I wouldn't go quit so far. Single screw
is tricky in reverse. I find I have little control over my bow. My slip
is often subject of a stiff breeze from starbord. I also need to turn to
starboard on exiting. If the wind is slight, natural prop walk will take my
stern to port and exiting is a breeze (no pun intended!). In a stiff breeze
I am fighting the natural tendancy of the bow to point downwind. If one is
not careful with backing and filling you can get turned so far the wrong way
you can't get back in the narrow confines of the row of slips. One or twice
I have had do do a 360!
With twins I could simply adjust throttle and/or fwd/rev shift to compensate
for the wind.
You also can't "walk" a single screw sidways the way you can twins.
Since I do a lot of solo boating I find I have to **THINK** a lot about what
is going to happen, make use of spring lines, boat hooks, and just plain avoid
some situations.
But one thing is for sure. Single screw will make a better boat handler out
of you quicker than any other type of powerboat propulsion. I also like
the simplicity of the system, less to go wrong, easier to maintain.
|>Carry a small outboard kicker in case
|> of engine failure and for trolling (and powering the dingy). Twin
|> engines just give you twice as much stuff to go wrong and
Yea, but you may still have one functioning engine to get home on and not
have to try and fix your only engine or call for a tow.
|>I/O's mean that
|> you have to haul the boat anytime any little problem comes up. Just
|> a little tiny leak will cost you a fortune. With twins the engine
|> compartment is crowded (especially with twins and V-drives -- more stuff
|> to go wrong!)
|>
--
=========================================================
= Darrell Boots Irvin bo...@orca.WV.TEK.COM =
= Network Displays Engineering =
= Tektronix Inc. =
=========================================================
doug lewis
in opposite directions: one clockwise and one counter-clockwise. This
means the starters and districutors, etc., are not interchangable.
doug lewis
John S. Holmes
My dad always said twin screws are just twice the problem.
Compounding that, outdrives are also expensive complications
to an otherwise simple mechanical operation. I have found no
real benefit for outdrives, they just rot quick and are expensive
to repair/replace. My current boat is a 28 ft. twin screw inboard
and I like it. My other boat (still trying to sell it, a nice SeaRay
24' Weekender) in an I/O. Nice since it sits on a trailer instead
of in the water. At 28-30 feet, your friend's boat will be in the
water all the time I presume. If fresh water, only moderate
problems, mostly due to seals and wear. If in salt, expect alot
of corrosion - the little zincs disappear at an alarming rate.
>In article <41de88$6...@netnews.upenn.edu> George Jefferson writes:
>my friend is looking at 28-30ft boats, and will probably
>go with twin stern drive (i/o). In looking at dozens of
>makes only SeaRay offers a twin inboard ( v-drive actually)
>option. The inboard is not good here for draft reasons I
>i think, but I was suprised that the searay guy claims the
>inboard is *more* maneuverable. With the i/o you cant
>properly independantly reverse one prop. Is this
>true? I'd have thought the i/o gave superior low speed maneuvering.
>(a single i/o is better than a single inboard no?)
>george
>geo...@mech.seas.upenn.edu
>>
Walt Bilofsky
On my twin Volvo-Penta inboards, everything is identical except the
shift cable which is connected at the shifter handles to move in
opposite directions on the port and starboard transmissions. In other
words, there is no forward and reverse in the drivetrain - just
clockwise and counterclockwise - and then left and right handed props.
(I discovered this when installing a lower helm station - looked at
the existing flybridge shifter, saw a cable attached to the 'push'
side, connected both lower shift controls that way, put them both in
forward - the starboard engine went into reverse. Went back and
looked more carefully at BOTH sides of the original shifter - big
duh!)
Is there an advantage to having the engines actually counter-rotate?
Walt Bilofsky
Golden Phoenix (Cape Dory 30 Poweryacht)
Mike Burroughs
>by the gear arrangement in the outdrive (switch forward and reverse gears?)
>and hence the basic engine is always built to run in one direction.
>
I/Os do acheive counterrotation via gearing in the outdrive.
Mike Burroughs
pa...@kahuna.nrl.navy.mil
>I don't know about outboards, but on inboards the engines actually turn
>in opposite directions: one clockwise and one counter-clockwise. This
>means the starters and districutors, etc., are not interchangable.
On Mercruiser "ALPHA" drives, most are not counter rotation, but you can buy
a special lower unit to counter rotate one drive. On "BRAVO" drives, you just
rig the shifters so the one drive runs in "reverse" of the other. "TRS" drives
can also be reversed internally, not sure of the exact details on those.
-Greg
>
Dave Kinzer
>I presumed that on outboards and I/Os, counter-rotation was accomplished
>by the gear arrangement in the outdrive (switch forward and reverse gears?)
>and hence the basic engine is always built to run in one direction.
Outboards and I/O's are built to perform better in one direction
over the other. The bulk of the strain when in forward will be
carried by the stronger bearing at the front of the lower unit,
and the helical gears are cut for minimized wear when turning
in this direction. Some outboards and I/O's are available with
a different lower unit with the gear cut to turn the prop the
other direction.
>But what happens on straight inboards? The whole engine must run in
>the opposite direction. Yes/No?
Some transmissions are built to wear less in one direction rather
than another (sound familiar). It may be the case that there
is essentially a straight through coupling when in forward, and
a gear set (or extra idler gear) engaged when in reverse. For
these transmissions, one engine must turn opposite the other in
order to have counter rotating porps.
Other transmissions (mine included,) don't care if they are run
in one direction over another, and are simply hooked to the
controls so that when in forward, one of the transmissions
is in 'reverse.' In this setup, both engines (and transmissions
for that matter) are identical.
-dave
sil...@seattle.com
I find it silly to argue
I know of one boat builder in Vancouver B.C. that has build two or three
50+ foot boats with twin outdrives!!! And the People that have then are
VERY HAPPY with them! It all deppens on what you like and want. I my
self have run both and I think the twin O/Ds would turn tighter. But
then again they were not the same boat so you can not compair them
fairly!!
Kristine
sil...@seattle.com
BA>>I've never heard of any issue involving maneuverability of any kind of twin
BA>>screw vessel. That's one of the advantages of twin screws. You can
BA>separately
BA>>run either screw in forward or reverse on a twin sterndrive.
BA>I've never owned a sterndrive, but the guy in the next slip got a twin
BA>sterndrive. Even though he was an experienced boat handler (single I/B),
BA>he could never get used to the I/O and eventually got rid of it. The
BA>problem, I'm told, is that while you can independently reverse twin I/Os,
BA>many of them do not use counter-rotating props like the twin inboards.
BA>This would prevent you from "walking" the stern sideways in reverse, a big
BA>advantage in a twin inboard. I suppose you could always turn the I/Os
BA>to control the stern when backing, but this is yet another variable to
BA>contend with.
BA>Can anyone confirm whether or not twin I/Os use counter-rotating props?
Yes the Volvo Penta could be changed from right hand to left hand
rotation. If they were the 270 and the 280 drives. ANd it is about a
five min job to switch them. I'm not sure if the new OMC/Volvo can do
the same thing or not.
Kristine
Jon Hokanson
says...
>
> Outboards and I/O's are built to perform better in one direction
>over the other. The bulk of the strain when in forward will be
>carried by the stronger bearing at the front of the lower unit,
>and the helical gears are cut for minimized wear when turning
>in this direction. Some outboards and I/O's are available with
>a different lower unit with the gear cut to turn the prop the
>other direction.
>
Volvo outdrives use straight gears, and are reversable by changing the shift
linkage and switching props. They run as well in both directions.
Jon
Atasales
consider. In modern boats, Inboards in smaller boats (25-30') usually
mean a loss of cabin space. Since the opposite is desired, Stern drives
are typically used, and the "Engine room" is turned into an aft cabin.
Such is the case with my 291Catalina Flybridge. Also, in Florida, a
considerable amount of water would not be navigable without stern drives,
or outboards. Finally, when it comes time to inspect, change, or clean
the prop, I can bring the mountain to Mohammad by tilting the drive up and
sitting on my dive platform!
Dennis L. Copfer
One comment about Florida navigation, jet boats may be more
inefficient, but they usually can go into shallower water, can be
aided with steerable rudders and are easier on the manatee.
Unfortunately, they are a little bit too far away from some of the
other outboard advantages you covered so well.
dc
acss...@acs.eku.edu
> doug lewis <do...@lsid.hp.com> wrote:
>
>>I don't know about outboards, but on inboards the engines actually turn
>>in opposite directions: one clockwise and one counter-clockwise. This
>>means the starters and districutors, etc., are not interchangable.
>
> shift cable which is connected at the shifter handles to move in
> opposite directions on the port and starboard transmissions. In other
> words, there is no forward and reverse in the drivetrain - just
> clockwise and counterclockwise - and then left and right handed props.
>
>
> (I discovered this when installing a lower helm station - looked at
> the existing flybridge shifter, saw a cable attached to the 'push'
> side, connected both lower shift controls that way, put them both in
> forward - the starboard engine went into reverse. Went back and
> looked more carefully at BOTH sides of the original shifter - big
> duh!)
>
> Is there an advantage to having the engines actually counter-rotate?
I think so... the torque completely balances out. In your setup the boat
might have a tendency to list to one side or the other from engine
torque. Since your props counter rotate, it is partially corrected
though.
dsc
Dudley Cornman
Systems Programmer
Academic Computing Services - EKU
ACSS...@ACS.EKU.EDU
Michael Cohen
>From: geo...@mech.seas.upenn.edu ( George Jefferson )
>Subject: twin stern drive vs. twin inboard
>Date: 22 Aug 1995 20:21:28 GMT
>my friend is looking at 28-30ft boats, and will probably
>go with twin stern drive (i/o). In looking at dozens of
>makes only SeaRay offers a twin inboard ( v-drive actually)
>option. The inboard is not good here for draft reasons I
>i think, but I was suprised that the searay guy claims the
>inboard is *more* maneuverable.
First, the sterndrives draw more water than inboards, including v-drives, so
i'm not sure what you mean "not good here for draft reasons"
At slow (headway) speeds, inboards track straighter than i/o's due to stern
walk. so, yes, he's right.
With the i/o you cant
>properly independantly reverse one prop. Is this
>true? I'd have thought the i/o gave superior low speed maneuvering.
>(a single i/o is better than a single inboard no?)
Most stern drive controls use a single lever to control throttle and
forward/reverse. Inboards use two sets of levers. It is far easier to
maneuver the boat using just shifters rather than using stern drive levers
with gear interlocks and the sometimes stalling that low speed shifting of
inboards are known for.
>While I'm at it, would anyone argue in favor of a single big block
>with a bravo3 (dual prop) over say twin 5.0's or maybe twin 4.3's?
>Personally I think two motors will bring twice the headaches,
>but then I'll never have a boat that big to need twins.
>(when I get that old you can shoot me)
>--
>george
>geo...@mech.seas.upenn.edu
Having owned both, i'd never buy a stern drive boat again.
acss...@acs.eku.edu
> In article <41de88$6...@netnews.upenn.edu> geo...@mech.seas.upenn.edu ( George Jefferson ) writes:
>>From: geo...@mech.seas.upenn.edu ( George Jefferson )
>>Subject: twin stern drive vs. twin inboard
>>Date: 22 Aug 1995 20:21:28 GMT
>
>>my friend is looking at 28-30ft boats, and will probably
>>go with twin stern drive (i/o). In looking at dozens of
>>makes only SeaRay offers a twin inboard ( v-drive actually)
>>option. The inboard is not good here for draft reasons I
>>i think, but I was suprised that the searay guy claims the
>>inboard is *more* maneuverable.
>
> First, the sterndrives draw more water than inboards, including v-drives, so
> i'm not sure what you mean "not good here for draft reasons"
I find that hard to beleive. Inboard props hang down a considerable
amount and when a outdrive is trimmed up (part way) I think it would be
as high (if not higher) than the inboards prop. Plus, you could
momentarily overtrim it to get over a spot of minimal clearance. You
gant do that with an inboard. If you bump something at idle speed with
an i/o you probably won't hurt anything, not sure the same is true for
inboard.
I think the major advantage to inboards (as told to me by inboard owners)
is less maintenance and less expense. Outdrives can be troubelesome at
times and whey they are they can be expensive to fix.
Terry Kester
I have had sterndrives and currently have inboards. The sterndrives
win hands down for draft because of the ability to trim them up
(like someone pointed out). As far as maneuverability, inboards
are unbeatable. (This applies to twins only. You couldn't pay me
to own a single inboard) With very little practice you can do 180/360
degree turns with inboards in your own space. (Spinning around)
You can even get the boat to "walk sideways" with some practice.
I haven't had as much maintenance with the inboards as with the
sterndrives, but then again, I haven't hit anything yet. (Knock
on fiberglass) It's easy to change a prop on a sterndrive, but not as
easy on an inboard, unless you're a fish.
Terry K.
Dennis Aki
JH>Volvo outdrives use straight gears, and are reversable by changing the shift
JH>linkage and switching props. They run as well in both directions.
I don't know about this. As far as this non-engineer can see, all the
gears in the Volvo leg are helical cut gears.
As for handling, I have single Duo-prop on my boat. It's different from
the single prop. I can't kick the stern over like I could with the
single prop. You have to steer more at docking.
I've also run a twin engine Duo-prop and it seems to me that there's a
difference in backing down and turning the boat using engines only.
Single inboards require more work as far as I'm concerned. At low
speeds, steerage is poor especially in boats with small rudders.
Backing down can be white knuckles all the way.
Twin inboards with outboard turning props (left hand on port and right
hand on starboard) are the ultimate in close quarter handling. You can
practically turn one on a dime. You can even get one to nearly slide
sideways up to a dock. Having two engines is a comfort in the knowledge
that should one fail, you can still make it to port on the other
(assuming it's not the fuel from a common tank). Sure, it's more
equipment to go wrong, but with proper maintenance, there shouldn't be a
time where both engines go down at the same time, unless of course it's
a fuel problem from a common tank.
Engines in a twin installation do not have to turn in opposite
directions, however it does help under certain conditions. Most of the
higher priced boats that I've seen have counter-rotating engines. Not
only do they operate opposite from each other, but they're mirror images
of each other. For instance, filters can be on the inboard side on both
engines.
Now, for the discussion on which is better, stern drive or inboard, that
depends on what you want. If you want simplicity and moderate
maintenance, go with inboards. If you want speed and efficiency, go
with stern drives. Stern drives on the other hand are more complicated
and require more maintenance. Stern drives also don't lend themselves
to being constantly in the water. They'll last longer on a trailered
boat given the same amount of maintenance.
You can also run most stern drives (at least the Volvo 290 leg can) with
the leg partially raised in shallow water. Can't do that with inboard
installations.
If I ever have the urge to get another boat, I will be looking for one
with twin inboard diesels. I don't particularly care about speed
anymore. Going 40 knots is not much fun these days when there's a
choppy sea. 30 knots is plenty fast for me.
By the way, the Volvo 290 legs can run in either direction equally well.
Twin engine installations are a snap. Simple switch in where shift
cable is attached in the leg and you can install counter-rotating props.
There are many boats setup this way here and I know of none that have
more wear in one leg than the other. Of course, you can go with twin
Duo-props and not have to worry about counter-rotation. That twin
Duo-prop boat, I've run that boat at over 30 knots and there's no pull
in either direction.
By the way, any of you out there have the 290 DP legs with diesel
engines? Here in Hawaii, boats with this setup are going through cone
clutches every 500 to 600 hours. For some reason, they're getting
glazed and when that happens, the clutch doesn't catch right away. when
it does catch, it really shakes the boat with a bang when it catches.
Switching to synthetic gear oil doesn't help. Running cool water over
the upper gearcase while planing doesn't help either. Anybody have this
problem solved?
Isaiah Laderman
>>>Subject: twin stern drive vs. twin inboard
>>>Date: 22 Aug 1995 20:21:28 GMT
>>
>>>my friend is looking at 28-30ft boats, and will probably
>>>go with twin stern drive (i/o). In looking at dozens of
>>>makes only SeaRay offers a twin inboard ( v-drive actually)
>>>option. The inboard is not good here for draft reasons I
>>>i think, but I was suprised that the searay guy claims the
>>>inboard is *more* maneuverable.
Twin screws give you the maneuverablilty that you would have with outdrives or an
outboard.
Frank Timpano
Inboards are more maneuverable because the props are under the boat, not
hung off the back, this puts them closer the the center of the boat.
The turning center is then within the boat's length rather than two feet
astern. Inboard props are often further apart, as well, creating a better
turning moment than stern drives. Stern drives offer advantages as well,
including thrust vectoring at slow speeds (where rudders are ineffective)
by steering the drives, shallow water operation, and at least where I boat,
the ability to cut off mangled crab pots from the swim platform with wire
cutters instead of diving/haulout to clear inboard props.
Stern drives cost more to maintain, but give more interior room in smaller
boats.
WRY26
twin stern drive setups are much less manuverable than twin inboards.
Two reasons:
Placement - stearn drives are farther from the center of the boat
operation in reverse - SDs are very inefficent in reverse (exhaust gas is
blown out through the propeller hub) puting one engine in foward and the
other in reverse to execute a tight turn is not nearly as effective with
twin SDs.
OTOH having the exhaust go through the hub makes for a much quieter and
less smelly ride.
Doug Antill
I guess a lot of it is actually what you prefer! My current boat has
twin Mercruiser 205hp V6 engines on Alpha One sterndrives and I think
they are great. Full helm with the opposite engine either ahead or
astern and the boat turns in little more than its own length anyway.
By going astern with the port engine and with full port helm the boat
lifts off the pontoon sideways (or starboard engine and starboard
helm). Impresses everyone who sees it.
The rest of the time you just have to remember no drive, no steerage!
Doug
G Fischer
adventure myself, after a number of years with a single 260hp.
The boat is a sea Ray 270 with twin 190-s, and the owner simply raves
about the ease of twins, so I-m looking forward to taking it for a
test spin.
A question though. Does mercruiser always provide counter-rotating
drive units for twin installations? I (dumb) forgot to ask!
Doug Antill
of the lower legs has to be exchanged. I don't know if there is a cost
to do this when buying a new boat. My own boat, which I bought
secondhand, does not have counter rotating props. I'd be interested
to know if anyone has made the conversion and if so how much did it
cost and how difficult is it to do.
Frank Timpano
>>
>Nope, Mercruiser Alpha One legs are not normally counter rotating. One
>of the lower legs has to be exchanged. I don't know if there is a cost
>to do this when buying a new boat. My own boat, which I bought
>secondhand, does not have counter rotating props. I'd be interested
>to know if anyone has made the conversion and if so how much did it
>cost and how difficult is it to do.
>
Alpha One stern drives (305 CID, 230 hp Mercruisers). I had to replace
the port lower unit when it self-destructed (I understand that is a
problem on earlier C-R units). Lower unit retails for about $2400. Cost
me about $3600 for repairs since the gears got all chewed up in the upper
unit as well due to metal shavings from lower unit gears. I have seen
VERY few twin stern drive installations with counterrotating drives.
Another possibility is to go with duo-props, in which case both drives
can be identical! My advice is get counterrotating if the cost
differential is small, but realize that if out cruising, repairs may be
a problem because parts for the counter rotating drive are not stocked
like the standard drive.