correct trim vs. steering ease/ PT 175-50h.p.

[Kenny Guess]

After searching hydrofoil and seeing that this will not solve my small problem, my question to the group is this: My PT175 2004 50 H.P. 2 stroke's steering is smooth and comfortable when running about 4000 rpms with the trim all the way down but if I trim it up for max rpms, it is very hard to make small steering adjustments. I thought that if less hull was in the water it should be easier to steer plus better fuel economy. My boat is stock, no changes have been made. If you have this same set up, let me know if you notice the same thing plus how do you trim your motor? My issue is more about steering ease than fuel economy since I usually don't make long runs to fish. thanks, kenny

 

[TOMMY RICH]

You do or don't have a foil?

 

[Kenny Guess]

DO NOT have a foil......kenny

 

[TOMMY RICH]

Sounds like the steering is sticking....is it lubed good and feel OK when it's out of the water?

 

[Kenny Guess]

yes, went it is trimmed down it steers fine. When I trim it up to get more of the hull out of the water , it is hard to steer.....

 

[KEVIN WERHAN]

I have an 06 pro guide with a 50 hp. I am not sure if you are talking about the actual force that is needed to turn the steering wheel or just the adjustments needed to keep the boat going straight. When my motor is trimmed up for max rpms, it is harder to steer, and the front of the boat does wander a bit, specially when it is windy. I think your condition is normal, as is mine. I guess I was accepting this type of steering because my last boat was a 14' alumacraft, tiller, with an 18 hp. The wind alone, would turn the front of that boat when I was up to speed. I am now curious to see what other people think of this.

 

[Lamar Gilbert]

My question is about your comment about trimming for max. RPM. You may be trimming past the "sweet" spot and that may be causing the difficult steering. If you trim too far, it can be an experience to say the least.

 

[Kenny Guess]

KW, The force to turn the wheel a little is hard when I trim up but it goes away when I trim it down all the way....of course more of the hull is in the water (bow down) when you trim it down but it turns easy and probably burns more fuel because of more drag. My bow doesn't drift ever that I notice.

Lamar, yes, I could be over-trimming. Sometimes you can feel the prop losing grip and then I trim down until it grabs.

I always thought that you wanted to trim up as much as you could to have less hull in the water for fuel economy and speed. Not that I am looking for more speed since I am happy with what my rig does. I will just trim her down to where it it comfortable steering and forget about the above mentioned.....

WHEN I AM RUNNING AT SAY 4000 RPMS WITH THE MOTOR TRIMMED DOWN ALL THE WAY, IF I START TRIMMING IT UP, THE RPMS WILL INCREASE TO ABOUT 4200/4300 WHEN IT IS TRIMMED ALL THE WAY. THIS IS WITHOUT GIVING IT MORE THROTTLE.

Anyway, thanks for all of you that responded. This is not a big deal, I just wanted to hear if others noticed the same thing and if what I was experiencing was more or less normal. kenny

 

[TOMMY RICH]

Could be a hook in the hull?...check the bottom.

It's wierd that yours is bass ackwards to what it should be. It should be really easy when trimmed out and yes your RPM will increase while trimming up.

See if the motor is mounted straight? Don't know what to say at this point:blink:

 

[Dan J.]

I thought that if less hull was in the water it should be easier to steer plus better fuel economy.

Aahh...that's where the vicious circle begins. You need RPM's for lift and speed. Fuel economy is acheived operating in the 70-80% (approx.)of the power band of your outboard. Max RPM's=Max Fuel consumption. (With minor exceptions, i.e: towing, engine problems, etc...)

I always thought that you wanted to trim up as much as you could to have less hull in the water for fuel economy and speed.

Your trim button will not overcome the laws of physics. 50HP pushing your boat will not provide optimum trim conditions for the loaded weight of your hull, which relies entirely on torque (holeshot), and thrust. (50HP is all a 50 Merc can do at the prop since '96, unless you crack some bolts and go inside.) You should try and gather a few props to see which one helps.



There are an enormous amount of variables that can exhibit the results you describe; engine mount height, prop size and condition, WEIGHT DISTRIBUTION (very important), hull damage, are a few that come to mind, just to hit the high points.



During the conditions you describe, what is the loaded weight (approx.) with fuel, livewells, gas amount? Is the prop clean or nicked up? Are you starting from an idle, trimmed down then rapidly throttling forward, tapping the trim up as the bow breaks over?

WHEN I AM RUNNING AT SAY 4000 RPMS WITH THE MOTOR TRIMMED DOWN ALL THE WAY, IF I START TRIMMING IT UP, THE RPMS WILL INCREASE TO ABOUT 4200/4300 WHEN IT IS TRIMMED ALL THE WAY. THIS IS WITHOUT GIVING IT MORE THROTTLE.

That's what is supposed to happen. Your angle of lift increases, decreasing some drag and adding some speed, after planing especially. If I had to guess, what you are sensing as wheel resistance under applied trim speed is actually the boat trying to break over the bubble and plane out. Your steering should stiffen slightly before the break over.



I really believe that some minor adjustments, and above all seat time, will improve your operating conditions. Good luck!

 

[Scott Hammer TOXIC]

As usual, listen to dan. My only advice is that trim adjustnents are best done in very small increments. Just because you can push the trim button doesn't mean you should peg it all the way up. My 225 does not like full trim and I guarantee you could not turn the wheel at full trim. 3/4 trim is MAX for my rig above that I get chinewalk and very hard steering. I am running 67-68mph so I knw my motor is giving me all she's got. BTW full trim and WOT is your worst gas mileage!! LOL!!



TOXIC