understanding trim

[double3fd]

hey guys, im still fairly new with boating.  ive been out on my new boat a couple times but still dont understand the trim.  i only use it to lift the motor and drop the motor.  i was under the impression that once you are in the water, u leave the motor as far down as it will go.  i was talking with another guy who was talking about adjusting the trim as he was taking off. 

can anyone explain how to use the trim properly on the motor, just some key points or any helpful info about how to use it effeciently??? i have a trim gauge on my dash but dont understand how to read it or use it.  it has DN on the left side and UP on the other with a needle between it.  how do i read this gauge when driving?

- thanks

[Luna Sea 5]

if you keep the engine low, it pushes your bow down, it you trim it up, your bow comes up...just keep it level.. and your good to go.

[CapBob]

I am taking from your post you do not have trim tabs, but are talking about just trimming the motor.

You trim the motor to make your boat get up on plane.  
you can tell how the boat is riding by watching your rooster tail and (water kicked up by engine) and how the boat is sitting and how long it takes you to get up on plane.

When you excelorate and come up to higher RPM if your bow is riding high, you would have to trim your motor up to bring the bow down and the boat to come to plane.

Read this link and it should help:

http://www.tropicalboating.com/powerboating/tilt-and-trim.html

[Reckless]

  I drop mine all the way to get on plane once there I adjust up. Watch your speed. You can gain MPH. You can gain some fuel efficiency by getting it in the right spot.

[Hotrod]

If you are in a head sea..  you want your bow down.. plowing into the waves.. If you are in a following Sea.. it's good to get the bow up a tad..  In most cases  .. motor all the way down  and your good to go