Freedom 235 proper trim

[DennisG01]

Down and foward are the same thing, up and back are the same thing. Down/up are a little confusing because your engine starts up high before you put it water and put the engine down. But you go in the down direction enough and most, if not all, outboards will go past the 90 degree straight up and down and tilt the plate forward a bit. So it acts like a trim tab.

"Generally" speaking, the industry as a whole (at least from my 35 years in the industry) will use the terms "in/down" and "out/up". I realize that "down" isn't technically correct over the entire range of trim because after the engine is trimmed down to vertical it then starts to go up again. But we don't worry about that technicality - it's just a general term. In fact, many trim buttons (including something like a stand-along rocker switch) will actually have one of those two sets of terms used. Forward and backward, while logically correct, aren't really used.

Referring back to what I said above about the anti-vent plate... it only slightly works like a trim tab... and really only until the boat gets on plane. The primary force of either lifting the stern or pushing it down comes from prop thrust.

 

[glacierbaze]

In/down/forward or out/up/backasswards, everyone reading this knows which way the motor is moving, and I have heard mechanics who have "been in the industry" for 20-30 years refer to the "cavitation plate". I don't correct them, I just hope that they have the correct solution to my problem.
Grammar policing, when the meaning is clear, even though the term may not be your choice, and resume` waving, make for tiresome reading, and do not really answer the OP's question.

 

[seasick]

In/down/forward or out/up/backasswards, everyone reading this knows which way the motor is moving, and I have heard mechanics who have "been in the industry" for 20-30 years refer to the "cavitation plate". I don't correct them, I just hope that they have the correct solution to my problem.
Grammar policing, when the meaning is clear, even though the term may not be your choice, and resume` waving, make for tiresome reading, and do not really answer the OP's question.

Perhaps using the exact terminology is not that critical ( I somewhat disagree as an engineer) but referring to a percentage of the possible bars on the trim/tilt gauge means nothing to me.

My earlier reference to a volume knob setting was based on a conversation I overhear in a deli many years ago, before walkmans, way before iPods and other portable entertainment gizmos. A young fellow was carrying a boom box into the deli and another young fellow behind the counter asked how loud his boom box was. He answered that it was so loud, the volume dial goes to 12 instead of 10

 

[glacierbaze]

Sounds like a Spinal Tap(1984) fan, but the Walkman was out a few years prior, so maybe he just had the same idea.

volume 11 - Google Search

 

[DennisG01]

In/down/forward or out/up/backasswards, everyone reading this knows which way the motor is moving, and I have heard mechanics who have "been in the industry" for 20-30 years refer to the "cavitation plate". I don't correct them, I just hope that they have the correct solution to my problem.
Grammar policing, when the meaning is clear, even though the term may not be your choice, and resume` waving, make for tiresome reading, and do not really answer the OP's question.

Interesting comment.

 

[FREEDOM!!!]

In/down/forward or out/up/backasswards, everyone reading this knows which way the motor is moving, and I have heard mechanics who have "been in the industry" for 20-30 years refer to the "cavitation plate". I don't correct them, I just hope that they have the correct solution to my problem.
Grammar policing, when the meaning is clear, even though the term may not be your choice, and resume` waving, make for tiresome reading, and do not really answer the OP's question.

Around here, everyone uses the terms up/down to refer to trimming the engine (outboard). Trim all the way up and the engine is out of the water. Trim all the way down and the engine is straight down as far as it can go. Most people tend to cruise with their engine trimmed up a certain amount. Keeping the engine in the down position and using trim tabs to manage the bow is very inefficient. It can be done, but it's not ideal unless maybe in very rough water.

The OP just asked about trimming the engine on a 235. I thought I answered it pretty accurately with pictures. It's a heavy boat and doesn't bounce around as much as other similar sized boats. 50% up trim (5 blips on the engine monitor, which the OP has on his boat), is a good place to start. If you leave the engine all the way down and set the throttle at 4000rpms then start trimming the engine up you will notice the rpms and speed increase without adding any additional throttle. That's when the engine is running the more efficiently. Keep trimming upward and eventually you will hear the engine start to cavitate. That's when you trim down just a bit and enjoy the ride. By now you are likely around 4200-4300rpms and about 2-3mph faster than when you started and your gph is most efficient.

By the way, the OP hasn't been back since the original post.

 

[seasick]

Sounds like a Spinal Tap(1984) fan, but the Walkman was out a few years prior, so maybe he just had the same idea.

volume 11 - Google Search

I love that movie

 

[Coastboater]

Hard to quantify something that has so many variables. Smooth water sure, but near shore there’s wind, waves, tide, wakes and everything else that is determined to soak you and the contents of your boat with seawater.
Sea conditions, wind direction relative to desired course, etc. dictate trim attitudes. A slow rolling 3’ following sea will have you working the throttle and trim from wave to wave, whereas heading in the opposite direction you’re varying throttle and trim to minimize hull pounding and/or wind driven water.

 

[DennisG01]

Around here, everyone uses the terms up/down to refer to trimming the engine (outboard). Trim all the way up and the engine is out of the water. Trim all the way down and the engine is straight down as far as it can go. Most people tend to cruise with their engine trimmed up a certain amount. Keeping the engine in the down position and using trim tabs to manage the bow is very inefficient. It can be done, but it's not ideal unless maybe in very rough water.

The OP just asked about trimming the engine on a 235. I thought I answered it pretty accurately with pictures. It's a heavy boat and doesn't bounce around as much as other similar sized boats. 50% up trim (5 blips on the engine monitor, which the OP has on his boat), is a good place to start. If you leave the engine all the way down and set the throttle at 4000rpms then start trimming the engine up you will notice the rpms and speed increase without adding any additional throttle. That's when the engine is running the more efficiently. Keep trimming upward and eventually you will hear the engine start to cavitate. That's when you trim down just a bit and enjoy the ride. By now you are likely around 4200-4300rpms and about 2-3mph faster than when you started and your gph is most efficient.

By the way, the OP hasn't been back since the original post.

No, you did fine. The "%" part was a little confusing until you clarified - but you were just relaying information that you knew to try and help. Nothing wrong with that!

Now, I'm going to continue on my mission of correct terminology, despite what some may say. Personally, I like seeking education and knowledge and always appreciate when someone helps me better understands things. But hey, some people aren't interested in betterment and that's totally fine - different strokes for different folks.

With that in mind, Freedom, when your engine is trimmed too high it will ventilate, not cavitate. They are two totally different things. Ventilation is catching/sucking air. Cavitation is when air bubbles collapse on a surface and cause damage.

 

[FREEDOM!!!]

No, you did fine. The "%" part was a little confusing until you clarified - but you were just relaying information that you knew to try and help. Nothing wrong with that!

Now, I'm going to continue on my mission of correct terminology, despite what some may say. Personally, I like seeking education and knowledge and always appreciate when someone helps me better understands things. But hey, some people aren't interested in betterment and that's totally fine - different strokes for different folks.

With that in mind, Freedom, when your engine is trimmed too high it will ventilate, not cavitate. They are two totally different things. Ventilation is catching/sucking air. Cavitation is when air bubbles collapse on a surface and cause damage.

Thanks for the clarification. I just know it sounds different when it happens. That's my queue to bring the engine down a few clicks. Happens a lot when making a hard turn at speed. Here's a good video I just found.

 

[DennisG01]

Thanks for the clarification. I just know it sounds different when it happens. That's my queue to bring the engine down a few clicks. Happens a lot when making a hard turn at speed. Here's a good video I just found.

Good video - the "marks" that he references on the prop (from cavitation) is spot on. It ends up looking like little pock marks on the prop blades - especially with a painted aluminum prop. It will start as small pock marks (maybe 1/8" diameter) where the paint is "erased". Eventually, it will also create pock marks/craters in the aluminum blade. Often this is from damaged blade edges - the blade edge only needs to be damaged SLIGHTLY - sometimes just an irregularity in the edge (or rough edge) will do it. The bubbles then collapse (implode) on the surface. There's actually some pretty neat science behind this!

 

[Halfhitch]

If you have interest in learning about cavitation, this is good reading.

https://www.theshipyardblog.com/propeller-cavitation-explained/

 

[FREEDOM!!!]

Another good video:

 

[thePearlyWhite]

The revs definitely change depending on how much work the boat is doing without any adjustment in throttle. I have noticed that pulling kids tubing and making turns. Thanks for the replies. Someone indicated using mpg. While that seems good for determine what's most efficient if at full throttle, still may be able to achieve more speed by getting more hull out of water and be less efficient. I'm getting the feel for it. Like I said all previous boats I've used, were different hull designs and could really feel some chine dancing and hear well when too far. I've had a hard time with this boat feeling and hearing it for sure.