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Peck

Boat Motor Height Setup

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Generally if your rooster tail is much higher than the top of your motor, your most likely trimmed too high. What you're looking for is, with the throttle at the same position, as your trim out your rpm will increase AND YOU SPEED will increase. Then you hit a sweet spot where if you trim out anymore, your rpm rises but your speed starts dropping. The spot in between is where you wanna be generally, assuming mainly straight, long runs on gentle water. But, that's by no means set in stone. Wind, waves, sharp turns around winding river channels and it changes quick what's best for the conditions. One other reason to not stay trimmed all the way in, btw, and that's it costs quite a bit more fuel in my experience. So much more drag. 

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Well, with a 200hp carbureted 2 stroke I need to do everything I can do to save on fuel usage!!! :lol:

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Sounds like water pressure is going to be your limiting problem.  I wouldn't go much less than what you are getting.  When I drop down to that 7-9 psi range I starting seeing my engine temps start climbing quickly.  A lot of newer Merc engines will go into guardian with the low pressures like that.  Usually, the higher the jackplate, the less chinewalk you will see.  Try putting your hands at the 11 o'clock and 5 o'clock position when you starting getting up to the speeds that it wants to chine and just put a little pressure pulling down on the wheel with your left hand.  If you feel the left side of the boat start to lift, increase that down pressure, some times a short, slight jerk to the left will help it settle.  Then as the left side begins to drop, release a little of the pressure.  Seat time is usually all it takes to figure out what the boat wants.  It is better to make the boat react to your input before it actually starts to chine and then correct it.  Once you get it figure out, you will see higher numbers on top end as well. It will become second nature with time. Try to balance your load as well.  I wouldn't expect it to be as important on your hull as a pad boat, but until you learn to drive it and control the chine, it will help.  I'm a Yamaha guy, and I'm not sure if your 150 even has them, but it might be worth looking to see if you have poppet valves and they are clean and working properly as well as making sure you have a new impeller.  It doesn't seem you are overheating any, but the cooler water temperatures make it harder to see.  I would have thought you would have had higher pressures than what you are seeing.  Good luck with the new floater!

Edited by Tacsavage
fix it

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Here's two things worth something. One- make sure all your bolts on the mounts, jackplate, and steering are tight. Then check the steeering play and all the bushings. Any play in the motor will magnify chine walking. Two, and it costs money but worth every penny IMO- Bob's Nose Cone. No more water pressure worries ever again. 

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Donnie - +1 to Rusty's recommendation on trimming up in small increments, esp w/ that hi-powered motor.  Chine walking will be the first indication you've trimmed up too high or too quickly.  This is a hard (violent sometimes) side to side movement that's corrected only by slowing down dramatically.

 

Jackplate is another dimension to this that requires a lil bit of touch and feel (like the trim).  If you have a hydraulic jackplate it is possible to bring the motor up too high.  That results in a drop in water pressure (you'll notice on the water pressure gauge on your console).  Sometimes you'll get the sucking sound Rusty mentioned.  If you hear this bring the motor down a bit, in small increments.  Keep an eye on the water pressure gauge as you do this.  When the indicator needle stabilizes you know you're in a good place (setting).

 

Bassboats are designed to run differently than the bigger ships you've deployed on.  To optimize running speed and motor performance you want the absolute minimum keel in the water.  You've noticed boats running down the lake looking like they're riding only on the last 24" or so of keel"  That's what it looks like when you have it set correctly.  When the entire keel is in the water (when motor is trimmed all the way down) you maximize the friction between the boat hull and the water.  the drag generated in this scenario puts a huge strain on the big motor, causing it to eat up gas.

 

Rusty mentioned 'sweet spot'.  This is key.  There is a look and a feel to the boat when it's set in the correct position - trim and jackplate - while I'm under power.  I can feel the nose come up out of the water.  I can look back towards the transom and see water splashing off of the hull from only the final quarter or so.  I can also feel the boat wiggle a bit (earliest stage of chine walk).  It's not violent and it's easy to control.  I simply make subtle side-to-side corrections to keep it from getting out of control.  All of this comes together w/ time on the water (TOW) and practice.  I spent days doing nothing but holeshots and stops to get the feel for how my boat responds/reacts.  Now it's second nature.

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I think my biggest issue was time behind the wheel. The few times I've been out after raising the motor I haven't had any issues. No chine walk at all. I think it was a combination of the setup and the fact that I hadn't been in the boat before. The big bow rider I had before was very easy to drive, but it was also a tank. With this Nitro I've found you have to play around with the trim a lot more while running down the lake. It's not a trim it up and leave it like on the bow rider. I love the blinker style trim and the hotfoot. Both make it a lot easier to adjust speed and trim while on the fly. I still plan to try the 3 blade prop, but I have no complaints with the 4 blade and how it's running now with the current setup. The thing sips gas too which is a huge benefit as well. 

 

Thanks for all the tips and advice. Main reason I love this site. 

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That 4-blade prop will help a lot w/ stability.  Cuts down on the chine walking potential in a big way.  If you do switch to a 3-blade be prepared for it to get a lil squirrelly first couple shots out of the hole.  You'll make the adjustment quickly after that.

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