Engine Trim

G

Gene&Mary

New member
Based on the engine trim gauge on my CD22, where does everyone set the engine trim when running at cruising speed?

Most times in the San Juans mine is trimmed a little short of full bow down.

Thanks
 
Gene,

I'm not sure there is a definitive answer as variables such as speed, wind, chop, current, etc. Do you have trim tabs and/or permatrims? We have both and with that combination and twin Honda 40's generally keep the trim so we are slightly bow down. We use the permatrims for fore and aft trim and that results in the engines being trimmed down but not (usually) all the way.
 
Gene,

That's where I set mine as well. I have a Suzuki 90hp. I think you do too?

As I recall, your boat was the 2005 Seattle Boat Show display boat and ours was built next.
 
Generally I trim for best fuel economy based on speed, boat loading, and sea conditions. Without a fuel flow meter the best rule of thumb I have found is to watch the "rooster tail" behind the motor. As you trim the motor up the rooster tail will eventually start to rise. When it does trim it back down until it drops back. That generally means your thrust angle is pretty much parallel to the direction of travel of the boat. I see a pretty positive correlation to the results on the fuel flow meter and the position of the rooster tail. On my Honda 90 trim guage that is about 1/3 of the way down from the neutral position.
 
I do similar to Tom--that is trim for most effeciency. I bring the boat up to a constant RPM on a plane, then trim up or down, to get the maximum speed for that throttle setting. (This corresponds with the best fuel economy by flow meter--which I also use). If you are running into chop, bow down, if down wind, bow up. Generally bow down will be slighly less effecient than a neutral stance.
 
Like Tom and Bob I agree, regardless of your set-up the basic principle remains the same. Once you get up on plane and approach your desired cruising speed start trimming up, with the same throttle setting adjust your trim for best speed. If you increase or decrease throttle you’ll have to re-adjust trim, and remember that as your speed increases trim will have more effect.

I have a single 90hp Honda with trim tabs and permatrim. When approaching about 16mph I adjust the motor trim to level than just fool with the tabs..That’s my program. What I have found to be true is as speed increases less down trim is required, to the point that at or above 25mph I’m at level trim.

Of course these recommendations are based on good to optimal conditions, rough weather trimming is another ball of wax.

Bob Austin wrote:If you are running into chop, bow down, if down wind, bow up. Generally bow down will be slighly less effecient than a neutral stance.
That hits it on the nail!!


Just enjoy your boat, life is short.....
 
Gene&Mary":122qfy8s said:
Does having permatrim make a difference?
Click to expand...

YES! YES! YES! :thup :thup :thup

1. It AMPLIFIES the effect of the motor trim.

2. It makes the boat plane earlier on power up.

3. It allows the boat to stay on plane at lower speeds by a few mph.

All this is possible due to the increased surface area at the back of the boat that is "trim-able" since it is attached to the motor leg.

This is just like adding another control surface at the rear of an airplane!

Makes one wonder what else would be possible if one were to experiment by changing it's shape, size, and adding other appendages. (?) :smileo

Joe. :teeth :thup
 
Although I have the "NFB" teleflex steering, I can still guage proper trim by the steering. Just my opinion, but it seems like when at proper trim not only is the speed the best as well as rpm, but it steers easier. It is really noticeable in my 16.
 
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