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-   -   boat operation ? (http://www.fishingbanter.com/showthread.php?t=9013)

Phillip July 20th, 2004 01:58 AM

boat operation ?
 
I have a question regarding a bass boat and a larger motor.

when I get my boat on plane I know is a small portion of the boat actually
on the water. What effect does trimming the motor up have on the boat, is
there more or less boat actually in the water?

Thanks



Bob La Londe July 20th, 2004 02:03 AM

boat operation ?
 
Trimming the motor up has the afect of changing the line of force relative
to the line of the boat. In affect it pushes the back of the boat down. In
many cases this will result in a shorter section of hull in the water
because the front of the boat lifts up.

In most circumstances this will give you more net speed due to reduced
friction with less surface area of the hull in the water. However!!!!! You
need to watch your tach. Many new bass boats are designed to not require as
much up trim. They are high performance racing machines. Trim up the motor
and watch the tach and speedometer at WOT. (assuming you are not under
propped or over propped) When the you stop gaining speed trim it down just
a hair and your boat will most likely be running its fastest under the
current load. Never over rev your motor. If you also have a jack plate you
will need to play with your motor at different heights on the jack as well.
You should have a water pressure gage, and if the water pressure starts to
drop you need to lower you motor immediately or you will overheat it.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Phillip" wrote in message
...
I have a question regarding a bass boat and a larger motor.

when I get my boat on plane I know is a small portion of the boat actually
on the water. What effect does trimming the motor up have on the boat, is
there more or less boat actually in the water?

Thanks





Bob La Londe July 20th, 2004 02:06 AM

boat operation ?
 
As a side note, when the water get rough you need to trim it back down to
hold the bow down to smooth out the ride. I reccomend reducing the speed in
rough water as well for safety reasons, but also so that you do not lug the
motor since it will be less likely to reach its top RPM at WOT.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Bob La Londe" wrote in message
...
Trimming the motor up has the afect of changing the line of force relative
to the line of the boat. In affect it pushes the back of the boat down.

In
many cases this will result in a shorter section of hull in the water
because the front of the boat lifts up.

In most circumstances this will give you more net speed due to reduced
friction with less surface area of the hull in the water. However!!!!!

You
need to watch your tach. Many new bass boats are designed to not require

as
much up trim. They are high performance racing machines. Trim up the

motor
and watch the tach and speedometer at WOT. (assuming you are not under
propped or over propped) When the you stop gaining speed trim it down

just
a hair and your boat will most likely be running its fastest under the
current load. Never over rev your motor. If you also have a jack plate

you
will need to play with your motor at different heights on the jack as

well.
You should have a water pressure gage, and if the water pressure starts to
drop you need to lower you motor immediately or you will overheat it.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Phillip" wrote in message
...
I have a question regarding a bass boat and a larger motor.

when I get my boat on plane I know is a small portion of the boat

actually
on the water. What effect does trimming the motor up have on the boat,

is
there more or less boat actually in the water?

Thanks







Bob La Londe July 20th, 2004 02:06 AM

boat operation ?
 
As a side note, when the water get rough you need to trim it back down to
hold the bow down to smooth out the ride. I reccomend reducing the speed in
rough water as well for safety reasons, but also so that you do not lug the
motor since it will be less likely to reach its top RPM at WOT.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Bob La Londe" wrote in message
...
Trimming the motor up has the afect of changing the line of force relative
to the line of the boat. In affect it pushes the back of the boat down.

In
many cases this will result in a shorter section of hull in the water
because the front of the boat lifts up.

In most circumstances this will give you more net speed due to reduced
friction with less surface area of the hull in the water. However!!!!!

You
need to watch your tach. Many new bass boats are designed to not require

as
much up trim. They are high performance racing machines. Trim up the

motor
and watch the tach and speedometer at WOT. (assuming you are not under
propped or over propped) When the you stop gaining speed trim it down

just
a hair and your boat will most likely be running its fastest under the
current load. Never over rev your motor. If you also have a jack plate

you
will need to play with your motor at different heights on the jack as

well.
You should have a water pressure gage, and if the water pressure starts to
drop you need to lower you motor immediately or you will overheat it.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Phillip" wrote in message
...
I have a question regarding a bass boat and a larger motor.

when I get my boat on plane I know is a small portion of the boat

actually
on the water. What effect does trimming the motor up have on the boat,

is
there more or less boat actually in the water?

Thanks







Bob La Londe July 20th, 2004 02:07 AM

boat operation ?
 
The above really only applies to high performance bass boat hulls. Other
boats will perform differently.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Bob La Londe" wrote in message
...
As a side note, when the water get rough you need to trim it back down to
hold the bow down to smooth out the ride. I reccomend reducing the speed

in
rough water as well for safety reasons, but also so that you do not lug

the
motor since it will be less likely to reach its top RPM at WOT.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Bob La Londe" wrote in message
...
Trimming the motor up has the afect of changing the line of force

relative
to the line of the boat. In affect it pushes the back of the boat down.

In
many cases this will result in a shorter section of hull in the water
because the front of the boat lifts up.

In most circumstances this will give you more net speed due to reduced
friction with less surface area of the hull in the water. However!!!!!

You
need to watch your tach. Many new bass boats are designed to not

require
as
much up trim. They are high performance racing machines. Trim up the

motor
and watch the tach and speedometer at WOT. (assuming you are not under
propped or over propped) When the you stop gaining speed trim it down

just
a hair and your boat will most likely be running its fastest under the
current load. Never over rev your motor. If you also have a jack plate

you
will need to play with your motor at different heights on the jack as

well.
You should have a water pressure gage, and if the water pressure starts

to
drop you need to lower you motor immediately or you will overheat it.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Phillip" wrote in message
...
I have a question regarding a bass boat and a larger motor.

when I get my boat on plane I know is a small portion of the boat

actually
on the water. What effect does trimming the motor up have on the boat,

is
there more or less boat actually in the water?

Thanks









Bob La Londe July 20th, 2004 02:07 AM

boat operation ?
 
The above really only applies to high performance bass boat hulls. Other
boats will perform differently.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Bob La Londe" wrote in message
...
As a side note, when the water get rough you need to trim it back down to
hold the bow down to smooth out the ride. I reccomend reducing the speed

in
rough water as well for safety reasons, but also so that you do not lug

the
motor since it will be less likely to reach its top RPM at WOT.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Bob La Londe" wrote in message
...
Trimming the motor up has the afect of changing the line of force

relative
to the line of the boat. In affect it pushes the back of the boat down.

In
many cases this will result in a shorter section of hull in the water
because the front of the boat lifts up.

In most circumstances this will give you more net speed due to reduced
friction with less surface area of the hull in the water. However!!!!!

You
need to watch your tach. Many new bass boats are designed to not

require
as
much up trim. They are high performance racing machines. Trim up the

motor
and watch the tach and speedometer at WOT. (assuming you are not under
propped or over propped) When the you stop gaining speed trim it down

just
a hair and your boat will most likely be running its fastest under the
current load. Never over rev your motor. If you also have a jack plate

you
will need to play with your motor at different heights on the jack as

well.
You should have a water pressure gage, and if the water pressure starts

to
drop you need to lower you motor immediately or you will overheat it.

--
** FREE Fishing Lures
** Weekly drawing
** Public Fishing and Boating Forums
** www.YumaBassMan.com


"Phillip" wrote in message
...
I have a question regarding a bass boat and a larger motor.

when I get my boat on plane I know is a small portion of the boat

actually
on the water. What effect does trimming the motor up have on the boat,

is
there more or less boat actually in the water?

Thanks









Todd Copeland July 20th, 2004 02:28 AM

boat operation ?
 
There is no way to know the answer to that question w/o knowing several
other factors and having a PhD in mathematics or the like.

Perhaps a better way to answer the question is to know _why_ your asking and
_what_ your trying to know from the answer.

Trimming the engine up moves the thrust angle of the engine in comparison to
the boat. Basically it usually pushes the front of the boat up and, to a
much lesser extent, the back of the boat downward. More importantly it also
points the thrust of the prop/engine upward and, when at an extreme angle,
out of the water. This is what causes a "fish tail" behind a boat (a spray
of water out and upward from the boat). When this occurs there is usually
less thrust power from the boat as it actually now has less resistance to
push upon. The stability of the boat is usually reduced at this point as the
hull of a boat usually has a steep angle in the front, flattening as it goes
backward.

"Phillip" wrote in message
...
I have a question regarding a bass boat and a larger motor.

when I get my boat on plane I know is a small portion of the boat actually
on the water. What effect does trimming the motor up have on the boat, is
there more or less boat actually in the water?




Todd Copeland July 20th, 2004 02:28 AM

boat operation ?
 
There is no way to know the answer to that question w/o knowing several
other factors and having a PhD in mathematics or the like.

Perhaps a better way to answer the question is to know _why_ your asking and
_what_ your trying to know from the answer.

Trimming the engine up moves the thrust angle of the engine in comparison to
the boat. Basically it usually pushes the front of the boat up and, to a
much lesser extent, the back of the boat downward. More importantly it also
points the thrust of the prop/engine upward and, when at an extreme angle,
out of the water. This is what causes a "fish tail" behind a boat (a spray
of water out and upward from the boat). When this occurs there is usually
less thrust power from the boat as it actually now has less resistance to
push upon. The stability of the boat is usually reduced at this point as the
hull of a boat usually has a steep angle in the front, flattening as it goes
backward.

"Phillip" wrote in message
...
I have a question regarding a bass boat and a larger motor.

when I get my boat on plane I know is a small portion of the boat actually
on the water. What effect does trimming the motor up have on the boat, is
there more or less boat actually in the water?




John C. French July 20th, 2004 11:34 PM

boat operation ?
 
Now there is an informative answer if I ever heard one.


"Eric Dreher" wrote


Less.




Steve @ OutdoorFrontiers July 21st, 2004 02:10 AM

boat operation ?
 

"Phillip" wrote in message
...
I have a question regarding a bass boat and a larger motor.

when I get my boat on plane I know is a small portion of the boat actually
on the water. What effect does trimming the motor up have on the boat, is
there more or less boat actually in the water?

Thanks


Finding the proper trim angle is going to be different for each boat, as
well as load, speed and water conditions.

Trimming the motor all the way down will lift on the transom, force down the
bow and cause the boat to get up on plane. However, once on plane with the
motor in this position will have the largest wetted surface, the most amount
of hull drag and the least speed.

As you trim the motor out, the thrust angle of the prop relative to the hull
is going to change, causing the bow to lift. As you do this, you reduce the
amount of wetted surface and hull drag is reduced, causing increased speed.
When a bass boat is up and running good, there is a small surface called
"The Pad" and a large portion of the boat's hull is out of the water. The
boat is actually balancing on the pad and is running at it's peak. Some
boats, particularly high performance boats have a small pad and the boat
will rock side to side. This is called Chine Walking and depending on the
boat, can be a real handful. A slight down trim or reduction in speed is
the prudent way to handle chine walking, but experienced drivers can
throttle through it and with proper application of some steering manuevers,
eliminate or reduce chine walking to a manageable level.

If the trim angle is proper, you should have a rooster tail behind the boat
approximately the same height as the engine cowl and you'll feel the boat
riding in what I call "The Sweet Spot". If the motor is overtrimmed, the
bow will start to bounce up and down, this is called porpoising. Either an
increase in throttle or a decrease in trim angle will reduce this condition.

Most boats will require a slight down trim in order to turn at speed as
well. Trying to turn at speed, while the boat is on the pad can cause
fishtailing, which unless you're experienced, can create a high pucker
factor.

One thing that you never want to do, unless it's an absolute emergency, is
to chop the throttle completely off while running on the pad. With most of
the hull out of the water, a sudden elimination of throttle can cause the
nose of the boat to drop and dig into the water, causing the boat to do an
abrupt 180! While it might look really cool, I've seen it happen and the
driver was ejected from the boat. Luckily, he wasn't injured, but he could
have quite easily been.

So, in answer to your question, YES!
--
Steve @ OutdoorFrontiers
http://www.outdoorfrontiers.com
G & S Guide Service and Custom Rods
http://www.herefishyfishy.com




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