Frequent trim adjustments

To find the right balance between engine rpm, speed and stability, at a high spoed plane I find myself making a couple trim adjustments per minute to my stern drive. Is the trim motor designed to handle related adjustment or is it better to set it and adjust it when absolutely needed. For example if she starts to porpoise I adjust the trim down and it settles, although I loose speed in the process, she responds more smoothly than reducing throttle.


She is a four winns sundowner 225 with a Volvo 5.7gi sx

Re: Frequent trim adjustments

I play with mine a bunch too, I don't know if its made for it but I have yet to have a problem with it. I like to squeek every MPH out of the boat, then sometimes I want the bow in the water because of a decent wave or something, different speeds require a little different trim its all part of the deal si i wouldn't worry too much about it, but keep in mind your load can have a lot to do with it as well, moving my overweight mother in law for instance, "ok four on the tube Granny on the bow...."

Re: Frequent trim adjustments

LippCJ7 said:

I play with mine a bunch too, I don't know if its made for it but I have yet to have a problem with it. I like to squeek every MPH out of the boat, then sometimes I want the bow in the water because of a decent wave or something, different speeds require a little different trim its all part of the deal si i wouldn't worry too much about it, but keep in mind your load can have a lot to do with it as well, moving my overweight mother in law for instance, "ok four on the tube Granny on the bow...."

Click to expand...

Ballast. Rofl. I have just the person in mind!

Re: Frequent trim adjustments

I've found that boats that are porpoise happy tend to respond well to adjusting weight balance, and usually behave quite well. If you can move the battery, a fuel tank, or even the anchor to the front, it might be all you need.

Re: Frequent trim adjustments

The more experienced of a boat operator you become, the less you'll have to constantly adjust your trim. You'll find the sweet high spot and know where it is and when to use it.

Trimming up to porpoise to trim back down, to trim back up to porpoise looks like someone learning how to ride a bike without training wheels to other boaters.

Re: Frequent trim adjustments

jigngrub said:

The more experienced of a boat operator you become, the less you'll have to constantly adjust your trim. You'll find the sweet high spot and know where it is and when to use it.

Trimming up to porpoise to trim back down, to trim back up to porpoise looks like someone learning how to ride a bike without training wheels to other boaters.

Click to expand...

Then how I do it seems reasonable. Power upto 80% of wot. Start adjusting trim up to get to the sweet spot - higher rpm & speed. Then throttle back to 80% wot and cruise & burn that 94 octane. Maybe a little tweak to the trim or throttle to get her growling just right. If speed or conditions start to create a condition where i could porpoise I trim down to stabilize. I find throttling down results in a more deceleration than I would need when a porpoise is developing. A tip of the trim down slows me just enough to Stop the porpoise without slowing significantly.

Re: Frequent trim adjustments

i like to use trim too.
while i've had my boat long enough now to know where the sweet spot is for most speeds. conditions usually require extra use of trim. i use it whenever i want. i assume the most severe treatment i give it is a drag race with against someone else's boat. my hole shot starts at full trim in. then full throttle, as soon as i'm on plane i'm starting to trim out. still full throttle. i can't image the stress it takes to raise the drive under full throttle and still gaining speed. while i don't do that often, i do do it. so far w/o ramifications. i also don't have trim limit (it's broke). but for best speed (top end wot spec), i'm trimmed out pretty far. still within the gimble ring by a lot though.
"i use my trim whenever i want" is the crux of my comment. the trim system seems to take the abuse repeatedly...

Then how I do it seems reasonable. Power upto 80% of wot. Start adjusting trim up to get to the sweet spot - higher rpm & speed. Then throttle back to 80% wot and cruise & burn that 94 octane. Maybe a little tweak to the trim or throttle to get her growling just right. If speed or conditions start to create a condition where i could porpoise I trim down to stabilize. I find throttling down results in a more deceleration than I would need when a porpoise is developing. A tip of the trim down slows me just enough to Stop the porpoise without slowing significantly.

Click to expand...

to me, yep, that seems most reasonable.... more reasonable than the way i do it for sure. as i'll trim while still gaining speed under max load..
fwiw, so i don't come off as a speed freak. my normal operation is not even 80% of full throttle to get on plane. a slow roll on of throttle till on plane @2100 rpm, then set cruise speed between 2300-2800. very minor trim up. done while i'm still gaining speed. the trim adjustments are very minor for me at these speeds. from full down, to just barely raised.. not the harsh abuse i'm initially talking about. just using that as an example of what abuse the trim system will take...

Re: Frequent trim adjustments

So I continued with my periodic trim adjustments today and the trim switch stopped responding when I tried to trailer. Worked fine on the water, but when e were about to leave, nothing. A quick post on the volvo forum and Good ol Don S came though in The clutch.. Led me to he fuse on the trim motor (as i could not find one in for the trim nearthe other fuses) and away we went. Not sure if the fuse was just bad luck, or from something I did. Glad to have this forum either way.

Re: Frequent trim adjustments

Depending on the boat, the amount of power available and the skill of the operator, it sometimes possible to "power through" porpoising. Most people tend to throttle back or play with trim when they experience this. If you are not at full throttle, throttle up and adjust the trim. If the boat gets wildly out of shape then you've discovered that what you've been doing was ok. But you might find that the boat settles down and hauls butt if you get it right. The experimentation phase is not for those that are "faint of heart" so don't experiment with a boat full of people.

Re: Frequent trim adjustments

Am I on one of my flying forums???

There is some corrolation here.

*New* pilots like to mess too much with the trim on landing, when they SHOULD be making fine adjustments in glideslope with power. Trim-up/down constantly makes for a "shark-tooth" approach profile(basically porposing)and with more practice will straighten itself out.

I find that rather than the constant trimming, I will make small changes in course to "tack" on and off wave period to lessen the effects of wave amplitude repitition.

Remember...when possible quarter into your sea for the best possible ride. That may, and probably will mean frequent course changes...but hey, the responsibility of command at sea is yours alone!

Happy boating to all, and happy fathers day to those fellow "dad's".

Now get out there and drag the brats around!

Re: Frequent trim adjustments

Silvertip said:

Depending on the boat, the amount of power available and the skill of the operator, it sometimes possible to "power through" porpoising. Most people tend to throttle back or play with trim when they experience this. If you are not at full throttle, throttle up and adjust the trim. If the boat gets wildly out of shape then you've discovered that what you've been doing was ok. But you might find that the boat settles down and hauls butt if you get it right. The experimentation phase is not for those that are "faint of heart" so don't experiment with a boat full of people.

Click to expand...

Thank you. I had already found out that throttling down doesn't work well, so I had been experimenting with trimming down to lessen the porpoise. Never considered more gas. I like it.

Re: Frequent trim adjustments

Oshkosh1 said:

Am I on one of my flying forums???

There is some corrolation here.

*New* pilots like to mess too much with the trim on landing, when they SHOULD be making fine adjustments in glideslope with power. Trim-up/down constantly makes for a "shark-tooth" approach profile(basically porposing)and with more practice will straighten itself out.

I find that rather than the constant trimming, I will make small changes in course to "tack" on and off wave period to lessen the effects of wave amplitude repitition.

Remember...when possible quarter into your sea for the best possible ride. That may, and probably will mean frequent course changes...but hey, the responsibility of command at sea is yours alone!

Happy boating to all, and happy fathers day to those fellow "dad's".

Now get out there and drag the brats around!

Click to expand...

Ride the waves better. Aye aye captain.

Re: Frequent trim adjustments

The small changes in course seemed to help more than throttling up. great tip