Tilt Adjustment and Tachometer

[tyler_bee]

Was reading through my manual and it mentioned watching the tach gauge while adjusting trim when underway.

What do they mean?

Or is the formula (or goal) to have Highest cruising speed vs lowest rpm via adjusting trim of the motor?

Thanks!

 

[Lyle29464]

Re: Tilt Adjustment and Tachometer

They want you to trim out to raise the bow so you have less wetted surface.

If your trim is all the way in your bow will be down and the engine working harder ie lower rpm as you trim out watch the tack increase in rpm with out touching the gas. you will feel the boat come onto its lines and the rpm increase. You trim up untill you hear the prop start to get air then you trim down just a hair. you should be able to make a turn with out the prop ventilating. I like to set mine so I can make a normal turn with out problem but a hard turn will cause it to vent a little.

 

[tyler_bee]

Re: Tilt Adjustment and Tachometer

They want you to trim out to raise the bow so you have less wetted surface.

If your trim is all the way in your bow will be down and the engine working harder ie lower rpm as you trim out watch the tack increase in rpm with out touching the gas. you will feel the boat come onto its lines and the rpm increase. You trim up untill you hear the prop start to get air then you trim down just a hair. you should be able to make a turn with out the prop ventilating. I like to set mine so I can make a normal turn with out problem but a hard turn will cause it to vent a little.

Ahh, that all makes perfect sense. I really appreciate it. Maiden Voyage tomorrow so I will play with that. I've just had tiller style boats previously, and smaller boats without power trim/tilt.

 

[DuckHunterJon]

Re: Tilt Adjustment and Tachometer

The only thing I'll add is it becomes a feel thing. Don't worry too much about the gages. You'll get the feel for it over time and not even realize your trimming in and out.

 

[geeco1]

Re: Tilt Adjustment and Tachometer

Agreeing with the above, but will add not only is it a "feel" but also a "sound". You should be able to hear your motor increase in rpms as well.

 

[seabob4]

Re: Tilt Adjustment and Tachometer

A good little trick is to mark the bezel of the trim gauge with a fine-point sharpie where the gauge needle sits when you have found the "sweet spot". That way you don't have to go through the process each time out...

 

[towtruck]

Re: Tilt Adjustment and Tachometer

Or is the formula (or goal) to have Highest cruising speed vs lowest rpm via adjusting trim of the motor?

Thanks!

The goal is to have the highest RPM for a given throttle setting because the engine is designed to work most efficiently at higher RPM, and also to minimize hull drag.

Given a fixed throttle setting, RPM will go up with boat speed, and boat speed will go up with reduced hull drag. Trimming the engine (really the whole boat) finds the lowest hull drag. The highest RPM is therefore your indication that you've found the lowest hull drag.

Seabob4 made a good point of marking your bezel. But remember this may be different for different throttle settings, so you probably only want to make a mark for WOT. Also, weight distribution in your boat (especially a small boat) makes a big difference. If you adjust for just yourself, it will be different for adding a big buddy. A big guy at the back of your boat is like nose-up trim, and a big guy in the bow is like nose-down trim.

Andy

 

[tyler_bee]

Re: Tilt Adjustment and Tachometer

The goal is to have the highest RPM for a given throttle setting because the engine is designed to work most efficiently at higher RPM, and also to minimize hull drag.
Andy

Got it.

Thanks for all the replies. Maiden voyage today Andy! (=