Pontoon Boat & Deck Boat Forum

I purchased my 20 foot pontoon in early July and love it. I try to get out every weekend. My question is, how do I know when the boat is trimmed properly. My pontoon has a Tachometer, Trim/Tilt gage, and just installed a speed sensor on my HumminBird Matrix. My prop is a 14 inch diameter, 13 pitch aluminum (I plan to get a Stainless Prop once my engine is completely broken in) One more thing, I have a 75hp 4 stroke Honda, and am breaking in.

How do I know when the boat is trimmed? I was told that about 1/4 trim should be ok, but am not sure.

When the motor trims down, does the nose rise? Does the nose go down when the trim is up?

Thanks,
Ron

When the motor is trimmed up the prop ends up being pointed down and pushes the stern of the boat down. This causes the bow to rise. So when the motor is trimmed up the nose goes up.

When the motor is trimmed down the prop ends up being pointed more even or up and pushes the stern up. This causes the bow to go down. So when the motor is trimmed down the nose goes down.


Trim is not a set it and forget it sort of thing. It may need adjusting frequently depending on conditions.

Finding proper trim is more of an art than a science. It will be different for each boat and even for each speed on that boat.

You want to achieve maximum efficiency (speed) with maximum smoothness of ride. If you trim too low you end up plowing through the water and in some cases even taking water over the bow. (Which is OK for washing the carpet but not a whole lot of good for anything else). If you trim too high you end up either porpoising as the bow is pushed up and then drops back down or you lose speed as the prop comes out of the water (RPMs will go way up).

Take the boat out on a calm day and set a straight course. Set your throttle to a steady RPM and play with the trim. Start about 1/4 up and slowly adjust it up and down. watch your GPS to find where your fastest speed is for that RPM. Remember that setting. Do this for a range of different RPMS and it will give you a starting point for your next trip out.

The trim setting will vary from day to day due to boat load, weather conditions, phase of the moon and whether the boat just feels like behaving or not.

You may also need to adjust trim in turns (I do on my boat as I lose grip a bit in very tight turns).

Just go out and have fun playing with it.

I trim for steering. Up or down till there is no steering pull

I trim for steering. Up or down till there is no steering pull

I've got power steering. This is my first boat and I've never experienced pull. Didn't know you have to trim to account for it.

Learn something new every day here

I find that my trim is handy when I have people sitting up at the front so I can get the bow up, I am pretty much always tweaking it while I am driving... You will just sort of get a feel when your boat is balanced...

The bow rider I had in the 80's had a 150 merc with a trim limit switch, the idea being once you had it set, you could just hit the trim until it stopped. Not really sure why they stopped using them. Once you get up to speed trim the motor slowly while watching tach,speedo (even though it may not be accurate) and trim gauge. When the prop loses bite with the water, trim down a little and note the reading on trim gauge. You will also hear the prop break loose from the water. This reading on the trim will let you know in the future where to trim to but may vary a little depending on load and a few other things.
doc

Agree with JohnO. Trim is a dynamic process, changing with speed, load weight & distribution, wind, top up or down, etc. For me a GPS is essential to reach best trim. I have had my boat for a short time and have made only a few runs in it. I have developed a bsic feel for what is too low or too high. What the GPS does is allow trimming for "best speed" and/or possibly best efficiency for a particular machine.

With the lifting strakes on my toon it is the difference between a basic good ride on step or a good ride on step at least 5+ mph faster. I can't immediately feel the 5+ mph but can see the increase with the GPS and know if I am trimming in the right direction. I can watch my RPM come up with speed as the trim is adjusted. I can back off the throttle and , with proper trim, maintain step at a lower RPM (possibly more efficient). Trim really has an effect on handling of my toon; good trim on step really makes it pretty nimble in the handling department. If you can set a trim limit it may keep you from cavitating the motor. I did trim to the point of cavitation several times in the learning process (duh - I am a slow learner).

My steering is basically neutral with no pull due to power assist but I remember the pull on my dad's Monark from the early '70s.

Have fun!

As the others said, trim is more art than science, more feel of the wheel than set-it-and-forget it.

That being said, there is a way to figure out the proper trim for your toon. You will need a GPS and pretty ideal conditions-flat water, not a lot of wind, etc, and a lot of room to play with.

Set your throttle at a fixed rpm, somewhere around 75% of WOT.
Make sure your GPS is on and have it set to display speed.

Trim up (bow goes up) a bit, and watch your rpms and speed. Your rpms will continue to go up as you trim up, but at some point your speed will go down. Back off the trim until you are at max speed, and that should be that.

If you change the weight distribution in the boat, you get to start all over...but at least you will know what perfect trim feels like.

JohnO wrote:

I trim for steering. Up or down till there is no steering pull

I've got power steering. This is my first boat and I've never experienced pull. Didn't know you have to trim to account for it.

Learn something new every day here

Not having power steering just reg I have found trimming up or down till my wheel can be turned with a finger. If just right I don't even have to steer It will run straight without any help from me

Wow thanks everyone, this is great information.
I will play with it this weekend.
I did notice sometimes steeing got very stiff, so now I know what to look for.

lakerunner wrote:

JohnO wrote:

I trim for steering. Up or down till there is no steering pull

I've got power steering. This is my first boat and I've never experienced pull. Didn't know you have to trim to account for it.

Learn something new every day here

Not having power steering just reg I have found trimming up or down till my wheel can be turned with a finger. If just right I don't even have to steer It will run straight without any help from me

Same here. Trim it until it stops pulling to the right at a fixed RPM.