1976 Boston Whaler Re-power Question
 

1976 Boston Whaler Re-power Question
 

On Thu, 04 Mar 2010 19:49:25 -0500, Larry wrote:

John H wrote:
On Thu, 04 Mar 2010 13:36:01 -0500, wrote:


On Wed, 03 Mar 2010 19:58:58 -0500, wrote:


A fishing buddy of mine is re-powering his early 1976 Boston Whaler
Sport 15 with a new 60hp 4 stoke Mercury. He is replacing a 2 stroke
Mariner that is an 80's model.

He has no gauges and the layout of the console is like a skiff - the
steering wheel is horizontal. He's not concerned about a speedometer,
and shouldn't be, but I think he should have a tach. The 4 stroke will
be heavier and act differently than the 2 stroke. The props are
interchangeable in size and hub configuration so he plans on putting his
SS prop on the new boat. I'm trying to convince him to find, or make, a
spot for a tach so he can make sure the boat is propped properly (say
that 5 times fast!). He's not convinced. The boat is rated for a 75 so
the 60 will still weigh about the same as a 75 2 stroke so the transom
weight will be fine.

Has anyone attempted a similar replacement? Should he need a different
prop? Can you attach a tachometer temporarily for testing purposes?

Thanks in advance,
Larry


I made the exact same repower on my boat (Mariner 75 2S to 60 4S Big
Foot)
The weight was close but the prop had to be changed (does he need a
15p, I have one in SS, make offer)
The tach is a 2 wire hookup from the gray wire to ground (port side of
motor) and you could certainly do this temporarily if he can borrow a
tach.
This actually picks up the unrectified output of the charge windings
but there is also an output from the computer. (there are 2 gray wires
on the motor). They both seem to work the same on my motor.
If you just had a meter with a frequency counter you could interpolate
that with a little simple math. Use the idle speed as a sanity check
(700 or so) then see what WOT works out to. You have a pretty wide
"acceptable" range.5500-6000 with the rated HP right in the middle.
I would shoot for close to 6000 with the boat empty. It will always
get heavier as time goes by. ;-)

A '76 Whaler may already be a heavy boat. Lots of foam and wood under the deck
to hold moisture.

It's been babied and stored well. It's quite light for a boat that
size. I was surprised the first time I was on it.

Larry

Super. I absolutely loved my Whaler. Used to take it into the Chesapeake and
have a blast.
--
John H

All decisions are the result of binary thinking,
which is why conservatives can see in black and white.

1976 Boston Whaler Re-power Question
 

On Mar 4, 6:52*pm, Larry wrote:
wrote:
On Thu, 04 Mar 2010 14:03:22 -0500, John
wrote:

On Thu, 04 Mar 2010 13:36:01 -0500, wrote:

On Wed, 03 Mar 2010 19:58:58 -0500, *wrote:

A fishing buddy of mine is re-powering his early 1976 Boston Whaler
Sport 15 with a new 60hp 4 stoke Mercury. *He is replacing a 2 stroke
Mariner that is an 80's model.

He has no gauges and the layout of the console is like a skiff - the
steering wheel is horizontal. *He's not concerned about a speedometer,
and shouldn't be, but I think he should have a tach. *The 4 stroke will
be heavier and act differently than the 2 stroke. *The props are
interchangeable in size and hub configuration so he plans on putting his
SS prop on the new boat. *I'm trying to convince him to find, or make, a
spot for a tach so he can make sure the boat is propped properly (say
that 5 times fast!). *He's not convinced. *The boat is rated for a 75 so
the 60 will still weigh about the same as a 75 2 stroke so the transom
weight will be fine.

Has anyone attempted a similar replacement? *Should he need a different
prop? *Can you attach a tachometer temporarily for testing purposes?

Thanks in advance,
Larry

I made the exact same repower on my boat (Mariner 75 2S to 60 4S Big
Foot)
The weight was close but the prop had to be changed (does he need a
15p, I have one in SS, make offer)
The tach is a 2 wire hookup from the gray wire to ground (port side of
motor) and you could certainly do this temporarily if he can borrow a
tach.
This actually picks up the unrectified output of the charge windings
but there is also an output from the computer. (there are 2 gray wires
on the motor). They both seem to work the same on my motor.
If you just had a meter with a frequency counter you could interpolate
that with a little simple math. Use the idle speed as a sanity check
(700 or so) then see what WOT works out to. You have a pretty wide
"acceptable" range.5500-6000 with the rated HP right in the middle.
I would shoot for close to 6000 with the boat empty. It will always
get heavier as time goes by. ;-)

A '76 Whaler may already be a heavy boat. Lots of foam and wood under the deck
to hold moisture.

I know a Whaler is heavy, that is why I was curious about whether he
might need the 15p prop.It was just a little too much for my 20'
pontoon. He is probably taking off a 17 or even a 19 with that 75. I
had a 17p with the 75 but that was really just about perfect for the
18' MFG the 75 came off of when I got it. I bet a 17 Whaler is about
the same in the water.

He's swapping a 60 for a 60 but your prop may work. *What's the diameter
of the 15" pitch SS prop? *Three or four blade?- Hide quoted text -

- Show quoted text -

Larry, I'd think tha even though the engines are rated for he same hp,
there is a torque factor to be considered between a 2 and a 4 cycle
engine, though. two cycles have a 'power band' of RPM where they run
the best, where 4's seem to have a broader range e and more torque on
a lower rpm. .

So, I'm wondering if the prop pitches between the two are really hat
compatable.

1976 Boston Whaler Re-power Question
 

1976 Boston Whaler Re-power Question
 

1976 Boston Whaler Re-power Question
 

Tim wrote:
On Mar 4, 6:52 pm, wrote:

wrote:

On Thu, 04 Mar 2010 14:03:22 -0500, John
wrote:


On Thu, 04 Mar 2010 13:36:01 -0500, wrote:


On Wed, 03 Mar 2010 19:58:58 -0500, wrote:


A fishing buddy of mine is re-powering his early 1976 Boston Whaler
Sport 15 with a new 60hp 4 stoke Mercury. He is replacing a 2 stroke
Mariner that is an 80's model.


He has no gauges and the layout of the console is like a skiff - the
steering wheel is horizontal. He's not concerned about a speedometer,
and shouldn't be, but I think he should have a tach. The 4 stroke will
be heavier and act differently than the 2 stroke. The props are
interchangeable in size and hub configuration so he plans on putting his
SS prop on the new boat. I'm trying to convince him to find, or make, a
spot for a tach so he can make sure the boat is propped properly (say
that 5 times fast!). He's not convinced. The boat is rated for a 75 so
the 60 will still weigh about the same as a 75 2 stroke so the transom
weight will be fine.


Has anyone attempted a similar replacement? Should he need a different
prop? Can you attach a tachometer temporarily for testing purposes?


Thanks in advance,
Larry


I made the exact same repower on my boat (Mariner 75 2S to 60 4S Big
Foot)
The weight was close but the prop had to be changed (does he need a
15p, I have one in SS, make offer)
The tach is a 2 wire hookup from the gray wire to ground (port side of
motor) and you could certainly do this temporarily if he can borrow a
tach.
This actually picks up the unrectified output of the charge windings
but there is also an output from the computer. (there are 2 gray wires
on the motor). They both seem to work the same on my motor.
If you just had a meter with a frequency counter you could interpolate
that with a little simple math. Use the idle speed as a sanity check
(700 or so) then see what WOT works out to. You have a pretty wide
"acceptable" range.5500-6000 with the rated HP right in the middle.
I would shoot for close to 6000 with the boat empty. It will always
get heavier as time goes by. ;-)


A '76 Whaler may already be a heavy boat. Lots of foam and wood under the deck
to hold moisture.


I know a Whaler is heavy, that is why I was curious about whether he
might need the 15p prop.It was just a little too much for my 20'
pontoon. He is probably taking off a 17 or even a 19 with that 75. I
had a 17p with the 75 but that was really just about perfect for the
18' MFG the 75 came off of when I got it. I bet a 17 Whaler is about
the same in the water.

He's swapping a 60 for a 60 but your prop may work. What's the diameter
of the 15" pitch SS prop? Three or four blade?- Hide quoted text -

- Show quoted text -

Larry, I'd think tha even though the engines are rated for he same hp,
there is a torque factor to be considered between a 2 and a 4 cycle
engine, though. two cycles have a 'power band' of RPM where they run
the best, where 4's seem to have a broader range e and more torque on
a lower rpm. .

So, I'm wondering if the prop pitches between the two are really hat
compatable.

That's the question and I told him he needs a tach to determine that.
The 80's motors were rated at the prop and the new motors at the shaft
(or vice versa), right?

Thanks,
Larry

1976 Boston Whaler Re-power Question
 

On Mar 6, 1:00*am, wrote:
On Fri, 05 Mar 2010 20:11:15 -0500, Larry wrote:
Larry, I'd think tha even though the engines are rated for he same hp,
there is a torque factor to be considered between a 2 and a 4 cycle
engine, though. two cycles have a 'power band' of RPM where they run
the best, where 4's seem to have a broader range e and more torque on
a lower rpm. .

So, I'm wondering if the prop pitches between the two are really hat
compatable.

That's the question and I told him he needs a tach to determine that. *
The 80's motors were rated at the prop and the new motors at the shaft
(or vice versa), right?

If this is late 80s they were rated at the prop. The difference will
basically just be the torque curve. If he is not a WOT all the time
guy he will really like the 4 stroke.
It is really nice if you do a lot of close maneuvering at slow speeds.
You don't have that 2 stroke "cough, stall and a puff of blue smoke"
problem just at the time when you were going to make that perfect dock
approach.

LOL! I've seen that many a time. And have noticed on older engines in
need a bit of tuning, the power was never there when you needed it the
most. But plenty of sputtering for everybody!

1976 Boston Whaler Re-power Question
 

On 3/6/10 9:49 AM, wrote:
On Sat, 6 Mar 2010 05:46:33 -0800 (PST),
wrote:

On Mar 6, 1:00 am, wrote:
On Fri, 05 Mar 2010 20:11:15 -0500, wrote:
Larry, I'd think tha even though the engines are rated for he same hp,
there is a torque factor to be considered between a 2 and a 4 cycle
engine, though. two cycles have a 'power band' of RPM where they run
the best, where 4's seem to have a broader range e and more torque on
a lower rpm. .

So, I'm wondering if the prop pitches between the two are really hat
compatable.

That's the question and I told him he needs a tach to determine that.
The 80's motors were rated at the prop and the new motors at the shaft
(or vice versa), right?

If this is late 80s they were rated at the prop. The difference will
basically just be the torque curve. If he is not a WOT all the time
guy he will really like the 4 stroke.
It is really nice if you do a lot of close maneuvering at slow speeds.
You don't have that 2 stroke "cough, stall and a puff of blue smoke"
problem just at the time when you were going to make that perfect dock
approach.

LOL! I've seen that many a time. And have noticed on older engines in
need a bit of tuning, the power was never there when you needed it the
most. But plenty of sputtering for everybody!


After you get a 4 stroke you start being a snob. You see a an engine
belching along with that tell tale smelly oil smoke trail and say "2
stroke"


Most of my two stroke outboard experience was in the 1950s and early
1960s...and I simply don't recall any particular problems with any of
the engines. Back then, I thought the oily smoky trail smelled
like...like...VICTORY!

I had a two stroke Merc 90 and a 115 in the early 1990s, and they both
ran very well. Each of them blew stators, though. I never liked the
smell of the OptiMax oil in my late 1990s Merc, though.

Since then, I've had a couple of four stroke Yamahas. Two decades ago, I
wouldn't have said this: I'd never even consider buying *any* sort of
two stroke outboard these days. They are not competitive in any
important way with four stroke engines.







--
Which one is the girl?

http://tinyurl.com/ycpsnzz

1976 Boston Whaler Re-power Question
 

On 3/6/10 11:57 AM, wrote:
On Sat, 06 Mar 2010 10:19:55 -0500,
wrote:

I had a two stroke Merc 90 and a 115 in the early 1990s, and they both
ran very well. Each of them blew stators,

My 75 Mariner/Merc blew a stator too (basically the same engine as the
90, or a Yammy mid range) I guess it was just a design flaw.


Apparently, it was, because at the time my dealer said Merc had a huge
run of bad stators, and changes were made at the OEM supplier. Changed
colors, too.

--
Which one is the girl?

http://tinyurl.com/ycpsnzz

1976 Boston Whaler Re-power Question
 

On Mar 6, 10:57*am, wrote:
On Sat, 06 Mar 2010 10:19:55 -0500, Harry
wrote:

I had a two stroke Merc 90 and a 115 in the early 1990s, and they both
ran very well. Each of them blew stators,

My 75 Mariner/Merc blew a stator too (basically the same engine as the
90, or a Yammy mid range) I guess it was just a design flaw.

That's the way it was, too. even though they were low output, they
were a primitive construction and due to the vibration of the engine
itself, the windings would evenually short against each other by
rubbing the enamel coated insulation off themselves and call it a day.
Things are much improved by now.