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Trimming

Javajoe

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Ok guys...here it goes
So I’m new to the whole deck boat thing. Wondering how far up you guys trim when cruising pretty fast. I’ve heard different opinions like finding the sweet spot etc. I noticed this weekend when I was beached that I can trim to the top of my gauge at about a 9 and it still has a lot of trim up to go which I guess is a good thing so you don’t over trim. Are you guys running let’s say at a 7 or so? I know it depends on water condition etc. Just looking for some advise to work with. I know you want to pack some air under there for less drag. Boat get on plane quick so no issues there. 28’ Magic 625 Ilmor.
 

Javajoe

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You need to take someone out with you that understands what trim is and can show you .
Yea I did, my SIL and he said he ran his boat like at an 8 or 9. Doesn’t mean he is right though. I understand the concept. I just always like to get different opinions.
 

GRADS

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If you trim up too far the prop will start to blow out, rpm's will go up and speed will drop. Also you trim differently for different water conditions...like waves, swells etc.

Also, do not rely on your gauge, rely on how it feels. Gauges can be off or not accurate.
 

Rayson1971

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Depends on conditions. If it's smooth you can trim higher to a point. If rough you don't want to trim high . The chop will be like a launch ramp and you'll be bouncing all over the place.
 

Rayson1971

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Maybe go out and drive it at every trim number to learn what the boat does at full throttle and cruise speed
 

JeremyJoyce

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21&3/4” from center to center of trim cylinder bolt for Mercury drives is the max angle that is ok for the drive shaft while running. Since the gauges can all be different trim it up on the gauge and measure it to figure out what your max trim is without breaking anything. Then you figure the rest out by feel while you build seat time in the boat. My trim changes depending on water condition, speed, and weight on the boat. Even front seat vs rear seat passengers makes a big difference.
 

02HoWaRd26

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Just the thought of trimmed to a 9 tells me you’re getting horrible information. First thing i did when i got my new to me boat was set my Zero on the drive and mechanical gauge. Then played from there and have no reason to ever exceed 3 while on plane.
 

HBCraig

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Yea I did, my SIL and he said he ran his boat like at an 8 or 9. Doesn’t mean he is right though. I understand the concept. I just always like to get different opinions.
Hold on, 8 or 9 on a different boat might not be apples to apples. Are there tabs?
How long are the tabs?

What outdrive?
4 blade or 5 blade prop?

Be careful if you are talking to someone with your same setup.

Just my opinion but you need to run this boat and go from negative or 0 trim all the way til it it will aerate. The sweet spot will be just below the trim when your RPMs go higher and tiur speed does not. That's your sweet spot
 

Desert Whaler

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1st things 1st . . . water pressure to the power-plant, and a RELIABLE gauge that tells you where you're at.
Then you can fiddle with props, heights, trim, etc.
 

Javajoe

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Hold on, 8 or 9 on a different boat might not be apples to apples. Are there tabs?
How long are the tabs?

What outdrive?
4 blade or 5 blade prop?

Be careful if you are talking to someone with your same setup.

Just my opinion but you need to run this boat and go from negative or 0 trim all the way til it it will aerate. The sweet spot will be just below the trim when your RPMs go higher and tiur speed does not. That's your sweet spot
Yea my SIL had a HTM so I figured not apples to apples. I would not take boating advise from him regardless. I’ve kept it at a 3 not knowing. Good advise about the sweet spot. I’ve heard that before. That’s why I posted what boat I have. Makes sense.
 

rivermobster

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If you trim up too far the prop will start to blow out, rpm's will go up and speed will drop. Also you trim differently for different water conditions...like waves, swells etc.

Also, do not rely on your gauge, rely on how it feels. Gauges can be off or not accurate.
This. It's a "feel" thing.
 

lbhsbz

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I have an outboard with a jackplate so I have more buttons to play with but the concept is the same....but I can adjust my X dimension and you can't. That being said...

Trim up until....and then back off a wee bit

1: RPMS start rising while speed decreasing
2: handling/stability gets sketchy
3: your water pressure gauge starts dropping

With your LU deeper in the water #3 probably won't happen, but the other 2 will. Find the sweet spot.
 

ONE-A-DAY

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It’s not possible to answer your question. If your asking how to trim your boat on a forum that’s your first mistake. Every boat is different, every trip out it will be different depending on load, prop selection and water conditions, etc.

The gauge is useless until you Find neutral trim, once done take a sharpie and mark the gauge. 0 on the gauge is not likely to be neutral.

Once you have found neutral you can adjust from there, my Daytona runs best at slightly more than neutral, majority of people over trim their boats and nothing is gained and risks of bad things increase when doing so.

Black mark is neutral trim on my boat, its at 2, not zero. At 130 mph my boat runs at about 3, so just one line beyond neutral, that’s all that is needed, beyond that you are not going any faster and just losing control of the boat.

And go on Amazon and get a digital level so you can find neutral before you even begin to try and figure things out.

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02HoWaRd26

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It’s not possible to answer your question. If your asking how to trim your boat on a forum that’s your first mistake. Every boat is different, every trip out it will be different depending on load, prop selection and water conditions, etc.

The gauge is useless until you Find neutral trim, once done take a sharpie and mark the gauge. 0 on the gauge is not likely to be neutral.

Once you have found neutral you can adjust from there, my Daytona runs best at slightly more than neutral, majority of people over trim their boats and nothing is gained and risks of bad things increase when doing so.

Black mark is neutral trim on my boat, its at 2, not zero. At 130 mph my boat runs at about 3, so just one line beyond neutral, that’s all that is needed, beyond that you are not going any faster and just losing control of the boat.

And go on Amazon and get a digital level so you can find neutral before you even begin to try and figure things out.

View attachment 989491
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Rather than using a marker, why wouldn’t you adjust the pins to zero once you set your drives to zero? Specially if your zero is that far down from zero on the gauge it’s hard to believe both your drives zero at the same spot.

Set your drives again at zero then allow your rods on the rams to slide back a little to get nearer to Zero. Then climb in the boat and use the set screws (5/16 wrench is needed) to get the pins exactly at zero on both sides while the drives are at zero.
You can also easily remove the pins to paint or dip into paint the tips to make them more eye catching. I just did mine green to match my soon to arrive new gauges and it’s day and night better for the quick glance.
 

MK1MOD0

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I set my drives / mechanical trim gauges ( offshore style) so that 5 was neutral. That way I knew exactly where my neutral was and I could go plus or minus from there.
 

ONE-A-DAY

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Rather than using a marker, why wouldn’t you adjust the pins to zero once you set your drives to zero? Specially if your zero is that far down from zero on the gauge it’s hard to believe both your drives zero at the same spot.

Set your drives again at zero then allow your rods on the rams to slide back a little to get nearer to Zero. Then climb in the boat and use the set screws (5/16 wrench is needed) to get the pins exactly at zero on both sides while the drives are at zero.
You can also easily remove the pins to paint or dip into paint the tips to make them more eye catching. I just did mine green to match my soon to arrive new gauges and it’s day and night better for the quick glance.
Definitely the thing to do, the sharpie was a quick fix after I took Tres' class, I will adjust neutral back to zero on the gauge.
 

02HoWaRd26

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Definitely the thing to do, the sharpie was a quick fix after I took Tres' class, I will adjust neutral back to zero on the gauge.
So Tres told you to use the digital level on the trim ram? Curious as i understood to use a 3-4’ level on the inner part of the relief on the boat, then match the flat of the actual drive to that, or best yet the prop shaft.
 

ONE-A-DAY

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So Tres told you to use the digital level on the trim ram? Curious as i understood to use a 3-4’ level on the inner part of the relief on the boat, then match the flat of the actual drive to that, or best yet the prop shaft.
I zeroed the digital level on the hull and zeroed it out on the cav plates of each drive
 

Dirtbag

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My trim has always been an 8 or 9, once or twice I plowed through a 2 or 3 but that was only in shitty conditions with no buddies on board and alcohol was definitely a factor
winner winner
 

instagator

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If you trim up too far the prop will start to blow out, rpm's will go up and speed will drop. Also you trim differently for different water conditions...like waves, swells etc.

Also, do not rely on your gauge, rely on how it feels. Gauges can be off or not accurate.
Said perfect ! Agreed, also outboard jack gauges are off as well .
 

C08H18

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So Tres told you to use the digital level on the trim ram? Curious as i understood to use a 3-4’ level on the inner part of the relief on the boat, then match the flat of the actual drive to that, or best yet the prop shaft.
Either method works. Point being you must find neutral trim and know exactly where neutral is on the gauges

From there make very slight adjustments and monitor changes to speed, RPM, handling, and porpoising.

Trimming up tends to loosen the boat while gaining speed. Trimming down tends to tighten handling and reduces any porpoising.

I adjust trim more often than I adjust throttle. But that too varies by boat.


Sent from my iPhone using Tapatalk
 

rivermobster

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I have an outboard with a jackplate so I have more buttons to play with but the concept is the same....but I can adjust my X dimension and you can't. That being said...

Trim up until....and then back off a wee bit

1: RPMS start rising while speed decreasing
2: handling/stability gets sketchy
3: your water pressure gauge starts dropping

With your LU deeper in the water #3 probably won't happen, but the other 2 will. Find the sweet spot.
You have a Stoker??
 

Bpracing1127

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It’s a feel thing. Seat time will help with this. In my dads daytona with 800 hp. Trim was positive 1/2 way of the cycle or just above half on the gauge. My dads nordic 1100 hp trim was just below half on the gauge for the sweet spots. I only ever use the gauge to check if the drive is “trailered”
 

Blackmagic94

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Cruise trim is this

Trim up till you porpoise then trim down a touch till it stops. The steering will feel lighter as you go to high as well

Trim and max speed are a whole different rodeo
 

Scapegoat

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I don't really pay attention to the trim gauge except when I lower the drive to take off or raise it on the trailer and in shallow areas. Each boat is different. Once on plane and cruising I will trim up till the nose bobs up and down then click the switch down till it stops. Water condition, weight, and speed can affect what the trim level this why I don't rely on it except to get a base line.
 

Racey

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Rather than using a marker, why wouldn’t you adjust the pins to zero once you set your drives to zero? Specially if your zero is that far down from zero on the gauge it’s hard to believe both your drives zero at the same spot.

Set your drives again at zero then allow your rods on the rams to slide back a little to get nearer to Zero. Then climb in the boat and use the set screws (5/16 wrench is needed) to get the pins exactly at zero on both sides while the drives are at zero.
You can also easily remove the pins to paint or dip into paint the tips to make them more eye catching. I just did mine green to match my soon to arrive new gauges and it’s day and night better for the quick glance.
This is good as long as the zero spot on your mechanical indicator still allows for full downward travel, otherwise the trim rams will just smash the indicator slide until it moves or breaks, something to think about when setting it up as every boat has a slightly different keel to transom angle etc. You always need to make sure you don't over exceed the downward travel of the indicator first.

Upward travel doesn't matter since at a certain point the cable runs out of travel and the indicator plunger loses contact with the drum on the trim pin and stops reading at the the top of the scale.

May take a little bit of messing around with the threaded cable end adjustments on each end and AND the position of where the indicator body is clamped to the trim ram.
 

02HoWaRd26

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This is good as long as the zero spot on your mechanical indicator still allows for full downward travel, otherwise the trim rams will just smash the indicator slide until it moves or breaks, something to think about when setting it up as every boat has a slightly different keel to transom angle etc. You always need to make sure you don't over exceed the downward travel of the indicator first.

Upward travel doesn't matter since at a certain point the cable runs out of travel and the indicator plunger loses contact with the drum on the trim pin and stops reading at the the top of the scale.

May take a little bit of messing around with the threaded cable end adjustments on each end and AND the position of where the indicator body is clamped to the trim ram.
Yea wasn’t a five minute job for sure lol. But my pin is a hair over 0 and that left me a little less than a hair till the pin hit the outer edge on full in on the gauge.
 

LHC Kirby

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Anyone familiar with the Volvo Penta set up..... My gauge is way erratic and not reliable. It doesn't move and than jumps a lot...up and down. Was suppose to be a winter project, but have not made the trips I planned during this past "off season" aka To do list season ... lol
*2001 Mariah
 

Javajoe

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Well, I found out my neutral trim reading is 4.5. My gauge goes from 0-9. Once at 9 is still has a ton of trim left to go if I keep trimming. I’ll check it out once I get it in the water as it relates to RPM’s and speed as mentioned. Thanks for the advice
 

MK1MOD0

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Well, I found out my neutral trim reading is 4.5. My gauge goes from 0-9. Once at 9 is still has a ton of trim left to go if I keep trimming. I’ll check it out once I get it in the water as it relates to RPM’s and speed as mentioned. Thanks for the advice
That’s basically how my set up was. I used a small piece of red pin stripe tape at neutral. Made it real easy to see even out of the corner of my eye.
 

Ziggy

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Well, I found out my neutral trim reading is 4.5. My gauge goes from 0-9. Once at 9 is still has a ton of trim left to go if I keep trimming. I’ll check it out once I get it in the water as it relates to RPM’s and speed as mentioned. Thanks for the advice
My Nordic deck runs best at neutral but I'm only running a 520. It'll slow down if I trim up or down from there...I tend to run heavy on fuel most times too. With the power your 625 produces you should be able to trim up some beyond neutral. Just go out and try it in small increments, you will see. Btw, any weight you carry, persons and other stuff, you will notice a difference too.
 

Nanu/Nanu

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Not sure if this will help I run a 25' Eliminator Eagle.

I find my best neutral trim is about a 3 any shorter and I get itchy. But when I'm at about a 7 the wife says im like a gorilla. 😁

In regards to the boat i think you've got your sweet spot figured out. I personally don't trim up much in fear of blowing up a drive by over trimming.
 
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