To trim or not to trim?

[mandoman68]

I have an older Glastron(71) with a '96 Evinrude 90hp. The motor has power trim but no trim gauge. I plan on installing a gauge and other modern equipment but until then I need to know when to trim up and when to trim down. What to do during a big swell,ect? Do I used it in conjuction with my speed,tach ect? I would like to learn this stuff by feel just in case my "future" trim gauge should fail. Thank You for your time.

 

[mtrainTurbo]

Re: To trim or not to trim?

I have an older Glastron(71) with a '96 Evinrude 90hp. The motor has power trim but no trim gauge. I plan on installing a gauge and other modern equipment but until then I need to know when to trim up and when to trim down. What to do during a big swell,ect? Do I used it in conjuction with my speed,tach ect? I would like to learn this stuff by feel just in case my "future" trim gauge should fail. Thank You for your time.

Trim can for the most part be done by feel. Trim down when at slow speeds and before you go on plane. Once on plane, trim out "One Mississippi, two Mississippi, three Mississippi.." You should feel the boat accelerate slightly. If the bow starts porpoising (bouncing), trim down in "One Missi.." increments until the bouncing stops. If the boat starts "slipping" and the engine revs, you trimmed too high...trim back down in the "One Missi..." increments.

For top speed runs, you should trim out until the prop starts ventillating (slipping) and then trim back down till you get a solid bite.

When you come off plane, trim down again.

Simple.

 

[Fl_Richard]

Re: To trim or not to trim?

Trimming out a boat is analogous with using your gas pedal in your car. You use it differently depending on the situation. It's all done by feel.. after a while it will be so natural you'll forget your even using it. Just like the gas pedal, you don't think about it do you?

Before accelerating onto a plane its usually in the down position. As you gain more speed you trim up more and more depending on the speed and chop. The higher it goes the faster the boat will travel as the whetted surface area and drag decrease. Eventually the the boat will begin to porpoise up and down. This means the trim is too high. Move it down a couple of ticks and it will settle down. Slow down and start all over.

FYI the trim gauge is utterly useless. It wont tell you when trim is needed only the amount of trim currently in use. They are a waste of money. Trim is not difficult to master, after a few trips out you'll get the idea. Dont sweat it just do it.

 

[Home Cookin']

Re: To trim or not to trim?

agreed ^^^ better things to spend money on than a trim guage on an outboard. And where the motor is trimmed is not necessarity where the hull is trimmed, as your loads will vary.

 

[mandoman68]

Re: To trim or not to trim?

Thank you very much for your info and time.Just want to become a safe and helpful boater. Thanks again.

 

[mandoman68]

Re: To trim or not to trim?

Thanks to all the helpful folks that make iboats a great website!

 

[kailec00]

Re: To trim or not to trim?

Does it hurt anything if you leave it trimmed down the entire time? I took the new boat out yesterday and it was rough, seemed like I got a better ride out of it with the trim all the way down.

 

[haulnazz15]

Re: To trim or not to trim?

Does it hurt anything if you leave it trimmed down the entire time? I took the new boat out yesterday and it was rough, seemed like I got a better ride out of it with the trim all the way down.

It hurts your fuel economy, that's one of the major purposes of trim in the first place. Most of the time in chop, you want to have the bow high to break the waves, not down low crashing through them. It depends on how fast you are going, too.

 

[Fl_Richard]

Re: To trim or not to trim?

In the gulf with my boat I frequently trim down in the chop so I slice through the waves instead of bouncing over the top. It keeps my fillings in my teeth

Your waterways and vessel characteristics will dictate it's usage. Dont just leave it down and forget it's there. It's there for a reason, learn to use it properly and you'll be a better boater. Experement how your boat responds to trim in different conditions. Your passengers will also appriciate you using it properly, they will have a smoother ride.

The only thing you'll hurt by leaving it down is your wallet.

 

[a70eliminator]

Re: To trim or not to trim?

The only thing you'll hurt by leaving it down is your wallet.

And and your skeg, which is why I like my trim indicator guage.

 

[Fishing56]

Re: To trim or not to trim?

When teaching my friends and wifey how to drive my boat, I always say "speed up trim up, slow down trim down". And always all the way down for a hole shot. One other note, I have a 190 hp I/O with a deep v-hull. At slow speeds it tends to wander back and forth. I have found that this can be somewhat improved by trimming up some instead of completely down.

I totally agree with the non-use of a trim gauge. My sender broke after just a few years. You really need to learn the feel of being properly trimmed vs. using a gauge. Your trim needs are also effected by how you boat is loaded. More people aft will need more trim.

As someone else mentioned, trim is meant for a smoother ride and a more econimic ride. With trim positioned all the way down, as you increase speed the nose of the boat is driven into the water, causing more resistance, rougher ride and more water splashing into boat and passengers.

Bottom line, if you have an accessory like trim, learn to use it and appreciate it.

Fishing56

 

[Home Cookin']

Re: To trim or not to trim?

I used to always trim up in chop, on my lighter flat bottom boats. Now I have a heavier deep V and I trim down to cut off the chop, but 40 year old habits die hard!

I can't see how a trim indicator guage can protect a skeg, other than at the ramp.

 

[Fl_Richard]

Re: To trim or not to trim?

A quick glance over your shoulder will tell you more than any trim gauge.

 

[a70eliminator]

Re: To trim or not to trim?

I used to always trim up in chop, on my lighter flat bottom boats. Now I have a heavier deep V and I trim down to cut off the chop, but 40 year old habits die hard!

I can't see how a trim indicator guage can protect a skeg, other than at the ramp.

At the ramps exactly, I back my rig down, get out unlash my boat from the courtesy dock and proceed to drive up trailer, I glance at my trim guage as a reminder to trim up, I could get by without it but all my stuff works as design.
I see alot of skeg drag marks on the ramps, some very deep ouch!

 

[korygrandy]

Re: To trim or not to trim?

This is true for IO's although some might try to disagree. Once you are used to the wake and the way the water looks behing the boat you can tell how yer trimmed out.

I didn't know anything about trim but I did find out on my own that if I trimmed her up on plane the boat went much faster. My logical thinking put the rest of the pieces together for me...feels right, better mileage, less drag...etc etc.

I would just play with it like anything else until it's second nature, That's what I did and I don't even think about it now.

It is nice to have a gauge when retrieving. Drug my skeg once, will hopefully never do it again...it wasn't a pleasant sound.

 

[haulnazz15]

Re: To trim or not to trim?

The only thing a trim gauge helps with is verification. It lets you know when the trim is full down, or more importantly (only to I/O's) too far up. Trimming too far up, especially off plane could spell bad news for the u-joints in an I/O. The O/B guys don't have anything to worry about by trimming up too far as the prop will cavitate before anything bad happens.

 

[mandoman68]

Re: To trim or not to trim?

You guys are the best! Thanks for all your help.

 

[smokintoad]

Re: To trim or not to trim?

Keeping the out drive down all the time will do a lot more than kill your fuel economy and lower your top end; it will destroy your engine.

I know a guy that purchased a brand new Azure, he always kept drive all the way down, claimed it gave him the best ride. Within two years (115 hours) he had to have the engine rebuilt. It was not covered under the warranty because it was considered "abuse".

 

[kailec00]

Re: To trim or not to trim?

Smokintoad how would leaving the trim down hurt the engine? What was the reason this happened to the extent of having to rebuild the engine?

 

[smokintoad]

Re: To trim or not to trim?

When the outdrive is trimmed down (in) it is not only pushing the boat forward, it is pushing the stern up. That adds a lot of extra pressure on the engine. Unlike an automobile engine, a boat engine is always under load. There is a lot more stress on the engine getting to WOT than maintaining it. When the drive is down (in) the engine has to work harder to maitain RPMs.


I guess the best analogy (Although not perfect) would be driving a car up hill all the time.