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Old 12 May 2014, 17:22   #1
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Using the Trim Properly

This is a super boat 101 question so please bear with me. I just got a Mark II with a 40hp Mercury with automatic trim. I tried to do some research online but couldn't find anything specific to ribs.

Problem, I don't really understand how the trim is intended to work, when to adjust it, and what adjustments to make in different scenarios. I realize I can control the bow, etc.. with it but when I bought the boat I was told the bow normally raises up until it starts planing. Then someone else told me I should use the trim to control that and remain confused. I don't want to do something stupid and flip my boat. Also, the trim allows the motor to come all the way up (obviously) but also down pretty far. Thanks for any help on this.
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Old 12 May 2014, 17:41   #2
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Automatic trim? Not heard of that one! Post a pic of the motor and controls please.
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Old 12 May 2014, 17:45   #3
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Sorry, didn't mean automatic trim! I mean the trim is electronic and operates via switch as opposed to manually moving it up and down. I have a switch on the motor and on the console shifter.
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Old 12 May 2014, 17:56   #4
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Basically you can use the trim to obtain optimum fuel economy and performance.

When moving from rest onto the plain it is best to have the engine trimmed all the way down (so the energy from the prop forces the boat at an angle up and out of the water)
As you get onto the plane, trim up until the outboard is at a 90 degrees (in flat conditions) to the transom. You will notice a change in speed and RPMs when trimming out. But trimming out you are allowing the bow to drop so the boat moves more efficiently through the water.

Henry
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Old 12 May 2014, 17:57   #5
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I'd suggest taking a basic boating course like those hosted by the power squadron. United States Power SquadronsĀ® Safe boating fun thru education

They can help you understand trim.

The proper use of the trim will depend on the sea state, the number of people and load aboard, and the distribution of that load. Its not something which can be learnt very well via the internets.
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Old 12 May 2014, 18:10   #6
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Quote:
Originally Posted by henryfreston View Post
Basically you can use the trim to obtain optimum fuel economy and performance.

When moving from rest onto the plain it is best to have the engine trimmed all the way down (so the energy from the prop forces the boat at an angle up and out of the water)
As you get onto the plane, trim up until the outboard is at a 90 degrees (in flat conditions) to the transom. You will notice a change in speed and RPMs when trimming out. But trimming out you are allowing the bow to drop so the boat moves more efficiently through the water.

Henry
Henry, you need a lesson in using trim.

Set off with the motor trimmed at 90 degrees to the keel. Increase the trim angle (trim out) til you're skimming along nicely when you're planing. You'll feel the 'sweet spot'.
On an inflatable, be careful of trimming out too far, specially if it's windy as you can flip the boat. You'll know if it's too far as the boat will start to feel 'loose'.

If you're heading into the waves, trim in to keep the bow down to stop the boat coming over backwards.

A pretty good guide to being trimmed correctly is that if it's right, your comfort level will be noticeably better. You'll get the minimum of slamming and the tendency to 'double slam' and porpoise will be less-specially when you're trimmed out too far.


As Capnjack says, take the course-you'll learn it far better with experience and training than just trying it.
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Old 12 May 2014, 18:19   #7
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Quote:
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Henry, you need a lesson in using trim.

Set off with the motor trimmed at 90 degrees to the keel. Increase the trim angle (trim out) til you're skimming along nicely when you're planing. You'll feel the 'sweet spot'.
On an inflatable, be careful of trimming out too far, specially if it's windy as you can flip the boat. You'll know if it's too far as the boat will start to feel 'loose'.

If you're heading into the waves, trim in to keep the bow down to stop the boat coming over backwards.

A pretty good guide to being trimmed correctly is that if it's right, your comfort level will be noticeably better. You'll get the minimum of slamming and the tendency to 'double slam' and porpoise will be less-specially when you're trimmed out too far.


As Capnjack says, take the course-you'll learn it far better with experience and training than just trying it.
I did a pb2 in swansea bay and that was what I was taught

maybe I should go elsewhere to a more reputable place

Problem is they are so expensive and after paying for one....well I have always fancied a garmin 451s
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Old 12 May 2014, 18:29   #8
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Quote:
Originally Posted by henryfreston View Post
I did a pb2 in swansea bay and that was what I was taught
Trimming out makes the bow rise, and some motors will trim right in , pushing the bow right down making the bow 'plough' if the trim limit pin is too far in.
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maybe I should go elsewhere to a more reputable place
Might be a recall problem?
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Originally Posted by henryfreston View Post

Problem is they are so expensive and after paying for one....well I have always fancied a garmin 451s
More experience is all you need Get the boat out
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Old 12 May 2014, 18:33   #9
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Quote:
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Trimming out makes the bow rise, and some motors will trim right in , pushing the bow right down making the bow 'plough' if the trim limit pin is too far in. Might be a recall problem?

More experience is all you need Get the boat out
Once exams are over
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Old 13 May 2014, 01:14   #10
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Thanks everyone, very helpful.
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