Am I over trimming my boat

[Brendon]

I have a mercury 175 XRI EFI Mercury with a 4 blade 24p tempest prop. I noticed I get more speed when I trim up and have a rooster tail but I have less control steering. I’m new to owning a boat so I was wondering if this is what most people do or am I over trimming my motor. The engine is on a 20 ft 95 ranger 488vs

[J Francho]

As you trim out for speed, you have to learn to use steering inputs to avoid chine walk.  One thing to note, if you're chine walking, do not lift the throttle, trim down, then lift.  It took me several hours of seat time to bet my Bullet over 80 mph.  Be safe out there, and go in small increments.  I'd get comfortable at a certain speed, and literally just bump the trim and slowly learn how to drive it.  Some might say why so fast?  It's easier to control your boat at 55 mph if you know how to drive it at 75 mph.

[Way2slow]

Trim up in small increments until you get the feel of it. The faster the boat will run the lighter it will feel.  You should feel the bow start lifting and the spray out the sides start moving back.  The spray should get back behind the drivers seat if you are getting good lift and the boat will feel like its just skipping along on light chop.

As you trim out watch the speed and tach and pay attention to the sound of the motor and feel of the steering wheel.  If you get an increase in rpm and not in speed, you over trimmed.  If the motor changes sound, usually a hallow sound, you are probably over trimmed and getting cavitation. If steering feels less sensitive, it's probably over trimmed.

It's a by the seat of your pants learning experience based largely on your boats setup.

Engine height and type prop and set-back make a huge difference in how you trim your motor

[bagofdonuts]

^^^This.

[Brendon]

I appreciate the feedback guys I’ll give it a shot next time out and see how it does.

[A-Jay]

4 hours ago, Brendon said:

I have a mercury 175 XRI EFI Mercury with a 4 blade 24p tempest prop. I noticed I get more speed when I trim up and have a rooster tail but I have less control steering. I’m new to owning a boat so I was wondering if this is what most people do or am I over trimming my motor. The engine is on a 20 ft 95 ranger 488vs

Hello Brendon and Welcome to Bass Resource ~

 You've received some very solid & useful information here already.

Speed with less control is pretty much out of control.

There's a fine line between operation "on the edge" and operating safely.

Speed with less control is IMO on the Edge.  Why go there ?  Really. 

Operating on the edge leaves virtually ZERO room for error.  An operator's reaction time is reduced as well as his or her ability to maneuver suddenly to avoid whatever; object afloat, waves, wakes, other humans - whatever - when one attempts to maneuver suddenly / radically with "speed & less control"  it can end up looking like this ~ 

 

 

@Way2slow alluded to how "You should feel the bow start lifting and the spray out the sides start moving back.  The spray should get back behind the drivers seat if you are getting good lift and the boat will feel like its just skipping along on light chop."  While I will agree with this, I must add that one must ensure that TOTAL Control is maintained - at all times.  In most cases 'speed' is scarified.  This is what that looks like: 

 

Stay Safe

A-Jay

 

 

[J Francho]

The dude in the first video is already chine walking when he attempts to jump the wake.  Really poor driving, and he had plenty of time to react to the wake.  No, he was hot dogging it.

[A-Jay]

37 minutes ago, J Francho said:

The dude in the first video is already chine walking when he attempts to jump the wake.  Really poor driving, and he had plenty of time to react to the wake.  No, he was hot dogging it.

I do not disagree with you J

While I'll admit that may have been offered more just for effect it does appear that this unfortunate operator was using excessive speed which seemed to be a contributing factor to a significant loss of control.

 Some may call it bad judgement while others could chock it up to inexperience.

Either way it's the very definition of reckless operation. 

Miraculously, this human survived. 

Guess it wasn't his time.

A-Jay

[Brendon]

53 minutes ago, A-Jay said:

I do not disagree with you J

While I'll admit that may have been offered more just for effect it does appear that this unfortunate operator was using excessive speed which seemed to be a contributing factor to a significant loss of control.

 Some may call it bad judgement while others could chock it up to inexperience.

Either way it's the very definition of reckless operation. 

Miraculously, this human survived. 

Guess it wasn't his time.

A-Jay

Thanks A-Jay, that really cleared things up for me. I usually get my boat on plane and then when the steering feels easily controllable I stick with that spot, with a 175 on a 20ft boat I guess I was hoping to get more than 45 to 50 out of it but now looking back it had two full tanks, me, my father inlaw and all of our tackle so we were pretty loaded down. I agree that’s it’s best to stick with what’s safe and it’s probably a lot less stress in my motor also so it’s a win win.

[Way2slow]

Wow, I failed to notice the 20' Ranger part.

That size boat with a 175 is going to be very easy to over trim trying to get bow lift.

I would think ideal setup is going is going to be extremely difficult to achieve, and if you are like me and carry way more junk than you probably need, almost impossible.

The trim is to get bow lift, good bow lift goes along with getting enough speed for the water to lift the hull out of the water, all the way to going fast enough to get it fully up on the pad (then you learn what chine walk is)

Without the speed, you are depending on the motor to provide all the lift.  It can only provide so much, but you keep on trimming trying get more.  That's when you see boats running down the lake with the motor kicked out at extreme angles and throwing big rooster tails. 

Understand also though, an ideal setup is something very few achieve with most bass boats, un less it's something like a Bullet or Allison.  Only the last couple of feet of the pad is in the water, the motor is trimmed almost vertical and the rooster tail no higher that the top of the motor.  To achieve this, the setback is right, the engine height is right and the tune on the prop is perfect, and the person in the boat is driving the h**l out of it.

As you get away from this ideal setup, the trim angle increases to compensate for the lack of speed and errors in the setup and prop.  So when you get down to your power and speed the motor is working it's butt off just trying get bow lift.  A properly matched prop to your hull is critical.

Of course, then you start realizing why so many boats have such poor setups when you looking at the financial outlay and effort involved in seeking out that ideal setup. 

[NHBull]

I was lucky enough to take a ride in an off-shore racer. There was the guy at the wheel, the throttler and myself. Getting a boat to plane safely and consistenly, can make an Eskimo perspire. When the guys have it dialed in it seams like there is more motor than boat in the water. The throttle man biggest challenge is to stop the prop from over-reaving when the prop is out of the water in bigger seas. 

 

He did say that not catching it causes more high-speed accidents than people know and does apply to the recreational boater........

[Further North]

On 8/6/2018 at 10:02 AM, J Francho said:

Some might say why so fast?  It's easier to control your boat at 55 mph if you know how to drive it at 75 mph.

Yep.  Same with cars.  I wish more people would learn/do this rather than rollin' down the road in the left lane at 65...

[TOXIC]

First....If you don't have a Water Pressure Gauge, get one.  The easiest way to tell when you are over trimmed is the loss of water pressure.  Good way to pop a motor.  Second is just a rule of thumb and that is your rooster tail should be no higher than your motor cowling.  There are exceptions to this rule but for the most part it holds true.  Third is to maintain control.  Most of the performance hulls on boats that exceed 75mph will walk at some point in the power band.  You need to learn how to control it.  You also need to pay attention to your RPM's and what is max for your motor.  Over rev and stand a good chance of blowing it up.  You control RPM's with trim and prop selection.  You will notice when over trimmed your steering will be severely hampered.  Trying to squeeze the last few mph out of a motor puts you at the edge of all these factors and you really need to decide if it is worth the risk.  The "Go-Fast" boats have all sorts of tricks like low water pickups, cavitating props and are set up to run in the  upper limits.  Even though I have a 250 horse motor, I prefer to spend the majority of my time well within the comfort zone and will only air it out once in a while and when conditions permit, to make sure I have blown all the carbon out of the motor.  Anybody who has a boat that runs over 80 will tell you things happen fast and bad things can happen very easily.   

[Further North]

8 hours ago, TOXIC said:

Anybody who has a boat that runs over 80 will tell you things happen fast and bad things can happen very easily.   

I can't speak to boats, but I can speak to the truth of this with driving fast in cars.  The "compression" of things coming at you goes up very fast and what we are used to at normal speeds can't compensate.

 

At 45 MPH, we're going 66 feet per second, it takes 80 seconds to go a mile...we have about a second and a half to react to something 100 feet in front of us.

 

At 80 MPH, we're going 117 ¹/₃ feet per second, it takes 45 seconds to go a mile...we have about .85 seconds to react to something 100 feet in front of us.

 

That's worth thinking about.  We have to be looking way further out in front of us...

[Tennessee Boy]

That's a great video A-Jay.  I've had to many things happen at 25 mph that would have killed me at 50 mph.  I don't want to think about 70 mph.  I enjoy a nice slow ride across the lake at 30 mph and if I feel a little crazy I'll punch it up to 40 for a few seconds.