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Larry[_4_] March 4th 10 12:58 AM

1976 Boston Whaler Re-power Question
 
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

John H[_2_] March 4th 10 01:16 AM

1976 Boston Whaler Re-power Question
 
On Mar 3, 7:58*pm, Larry 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


This might provide some useful information regarding prop size. The
tested boat was a Boston Whaler 150 Montauk, which is probably pretty
close to the boat he's got. I had a 15' Whaler center console I bought
new in 1985. It came with a 70hp, Johnson 2-stroke. Screaming little
boat. He should get good performance with the 60hp, unless the boat is
water-logged.

http://tinyurl.com/yd8r5zl

The propellor specs are in the lower right of the page.

mgg March 4th 10 02:04 AM

1976 Boston Whaler Re-power Question
 


"Larry" wrote in message
...
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


Sure, you can hook up a tach temporarily, but he may as well do it right.
There is no way he is going to get the prop pitched properly G w/out a
tach. And, he needs one he can see at WOT... not clamped to the transom
"temporarily." It's not a hard gauge to install at all.

---Mike


Larry[_4_] March 4th 10 02:05 AM

1976 Boston Whaler Re-power Question
 
John H wrote:
On Mar 3, 7:58 pm, 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

This might provide some useful information regarding prop size. The
tested boat was a Boston Whaler 150 Montauk, which is probably pretty
close to the boat he's got. I had a 15' Whaler center console I bought
new in 1985. It came with a 70hp, Johnson 2-stroke. Screaming little
boat. He should get good performance with the 60hp, unless the boat is
water-logged.

http://tinyurl.com/yd8r5zl

The propellor specs are in the lower right of the page.

Thanks, John. That's a Bigfoot in the chart. They have a different
gearcase. The numbers are still quite good for a boat like that!

Larry

I am Tosk[_3_] March 4th 10 06:38 AM

1976 Boston Whaler Re-power Question
 
In article , says...

"Larry" wrote in message
...
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


Sure, you can hook up a tach temporarily, but he may as well do it right.
There is no way he is going to get the prop pitched properly G w/out a
tach. And, he needs one he can see at WOT... not clamped to the transom
"temporarily." It's not a hard gauge to install at all.

---Mike


My VOM (Volt, Ohm meter) has an inductive pickup I can hook on a plug wire and
watch tach. Maybe you can get a cheapo one at Pep Boys or something. Of course
I would first consider the suggestion of others of a permanant one.

Scotty

--
Can I haz Cheezeburger?

John H[_2_] March 4th 10 07:03 PM

1976 Boston Whaler Re-power Question
 
On Thu, 04 Mar 2010 13:36:01 -0500, wrote:

On Wed, 03 Mar 2010 19:58:58 -0500, Larry 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.
--
John H

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

Larry[_4_] March 5th 10 12:44 AM

1976 Boston Whaler Re-power Question
 
mgg wrote:


"Larry" wrote in message
...
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


Sure, you can hook up a tach temporarily, but he may as well do it
right. There is no way he is going to get the prop pitched properly
G w/out a tach. And, he needs one he can see at WOT... not clamped
to the transom "temporarily." It's not a hard gauge to install at all.

---Mike

I agree. He's had the Mariner forever and it's worked fine. He doesn't
think the 4 stroke in the same size will be much different.

Thanks,
Larry

Larry[_4_] March 5th 10 12:45 AM

1976 Boston Whaler Re-power Question
 
I am Tosk wrote:
In , says...

wrote in message
...

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

Sure, you can hook up a tach temporarily, but he may as well do it right.
There is no way he is going to get the prop pitched properlyG w/out a
tach. And, he needs one he can see at WOT... not clamped to the transom
"temporarily." It's not a hard gauge to install at all.

---Mike

My VOM (Volt, Ohm meter) has an inductive pickup I can hook on a plug wire and
watch tach. Maybe you can get a cheapo one at Pep Boys or something. Of course
I would first consider the suggestion of others of a permanant one.

Scotty


If I can't convince him to install a permanent tach, that is a good
alternative.

Thanks,
Larry

Larry[_4_] March 5th 10 12:48 AM

1976 Boston Whaler Re-power Question
 
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. ;-)


It's not the Big Foot so he may not be able to take you up on your
offer, but I will pass it on. Good point on the max RPM's. I doubt his
old Mariner has a 6000 RPM redline.

Larry

Larry[_4_] March 5th 10 12:49 AM

1976 Boston Whaler Re-power Question
 
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

Larry[_4_] March 5th 10 12:52 AM

1976 Boston Whaler Re-power Question
 
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?

John H[_2_] March 5th 10 05:00 PM

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.

Tim March 5th 10 05:33 PM

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.

Larry[_4_] March 6th 10 01:07 AM

1976 Boston Whaler Re-power Question
 
wrote:
On Thu, 04 Mar 2010 19:48:08 -0500, wrote:


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. ;-)


It's not the Big Foot so he may not be able to take you up on your
offer, but I will pass it on. Good point on the max RPM's. I doubt his
old Mariner has a 6000 RPM redline.


If it is not a big foot he won't be using his old prop either. The big
foot is a 14" prop, same as the 75 Mariner.. The non-bigfoot one is
12 1/2".

Neither has the Big Foot gear case.

Larry[_4_] March 6th 10 01:08 AM

1976 Boston Whaler Re-power Question
 
wrote:
On Thu, 04 Mar 2010 19:52:14 -0500, wrote:


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?

OK I misunderstood. I read the 75 comment and thought that is what he
had before. My prop is 14". He is limited to a 12.5" if this is not
the big foot.
60 for 60 should swap right over., sorry for any confusion.

They are interchangeable but I think he will see different results from
a new 4 stroke compared to the old 2 stroke.

Larry[_4_] March 6th 10 01:11 AM

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

Tim March 6th 10 01:46 PM

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!

Harry[_2_] March 6th 10 03:19 PM

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

Harry[_2_] March 6th 10 05:29 PM

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

Tim March 6th 10 05:55 PM

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.

Harry[_2_] March 6th 10 06:13 PM

1976 Boston Whaler Re-power Question
 
On 3/6/10 12:55 PM, Tim wrote:
On Mar 6, 10:57 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.


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.



That's the first explanation I've seen for the problem...thanks.

--
Which one is the girl?

http://tinyurl.com/ycpsnzz

Larry[_5_] March 7th 10 03:29 AM

1976 Boston Whaler Re-power Question
 
Harry wrote:
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.


Stators are $700+ and you replaced two of them? That's some very bad luck!

Larry

Harry[_2_] March 7th 10 03:43 AM

1976 Boston Whaler Re-power Question
 
On 3/6/10 10:29 PM, Larry wrote:
Harry wrote:
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.


Stators are $700+ and you replaced two of them? That's some very bad luck!

Larry



I don't know what they cost...Merc replaced 'em each time under
warranty. Three, actually. The stator on the 115 blew twice. The "newly
redesigned" third stator did not blow.

In May, Yahama is coming out with a 300-hp, 4.2 liter fourstroke that
will be substantially lighter than its current 300-hp engine.

--
Which one is the girl?

http://tinyurl.com/ycpsnzz

Larry[_5_] March 9th 10 12:09 AM

1976 Boston Whaler Re-power Question
 
wrote:
On Sat, 06 Mar 2010 22:29:53 -0500, wrote:


Stators are $700+

I think I paid about $150 for mine (aftermarket part) and another $50
or so for that special puller you need to get the flywheel off. No big
deal when you have that.
BTW you can make one if you can find a metric (36MM ?) threaded pipe.
Those Mercs are really Yamaha blocks. That is why all the block bolts
are metric and all the bolt on "Mercury" parts are SAE

Didn't Mercury and Yamaha get into a ****ing match and end their
partnership? I'm reasonable sure the new Mercury 4 strokes are all
Mercury in that size.

Larry


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