# New G3 Tunnel



## dave g (Jan 25, 2013)

Bought a new G3 bay tunnel 2 weeks ago. Have had it in the water 4 times. Got a 90 Yamaha SHO. I'm on the second water pump and may need a third. Also can't get the Lowrance 3 in 1 transducer to hold depth past 12 or 13 mph. I've never owned a tunnel hull before but have owned 8 or 9 different boats. My problems are 1; how do you get water through that @#%&^ motor ,2; how to get a sonar reading at speed in that boat and 3; would anyone give me $35,000 for it? I'm at my wits end. My dealer has been good but is tired of hearing from me. HELP!


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## MrFish (Aug 21, 2009)

Post a pic of your transom.


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## dave g (Jan 25, 2013)

I'll do that tomorrow. Pouring out right now. Thanks


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## CurDog (Nov 14, 2010)

I'm guessing either the cavitation plate isn't at proper depth, being too high above bottom of boat. And/Or you're running it with trim too high not allowing proper water flow into the lower unit. 

As for the transducer, it's most likely not in the best location. So here is a link to where the best placement should be on your boat. g/l 

http://bb.sideimageforums.com/viewtopic.php?t=5377


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## X-Shark (Oct 3, 2007)

> Also can't get the Lowrance 3 in 1 transducer to hold depth past 12 or 13 mph.


 It doesn't matter if it's Lowarance, Garmin or whatever? It's the nature of the beast with a flat bottom boat. They induce air under the hull....That inturn goes across the face of the X-Ducer and you loose bottom on your screen.




Waterpump.......chewed up.....or burnt up?


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## dave g (Jan 25, 2013)

*G3 Transom*

Here are 4 pics of my transom. You can see where the transducer is mounted from dealership. The second photo is the only place I can see where clean water flow would be. I would have to mount it on the back of the starboard side flotation pod on the far right corner. Might be a little fragile. Any help would be greatly appreciated because where I'm fishing is shallow and lots of oyster bars. Thanks again.


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## catchenbeatsfishen (Nov 25, 2007)

*Jack Plate?*

Do you have a Jack Plate on it?
If not, you may want to consider it to be able to keep the motor at the proper trim angle and elevation in shallow water.


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## dave g (Jan 25, 2013)

Yes there is a 5" jack plate. No problems at all when planed out with jack plate up 4 1/2". Get 25lb of water pressure. When it is warmed up and you restart, it sometimes takes 1 1/2 to 2 minutes to pee water out. Not all the time. But enough to scare the hell out of you knowing you got 12 grand in that motor.


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## RMS (Dec 9, 2008)

If not already doing so, trim down and Lower the jackplate all the way down when you start the motor and wait for water pressure before you raise it or throttle up. The pump is too high relative to the waterline to prime. Not unusual for a tunnel hull.


Looks like your transducer isn’t level and mounted too high.

First you need to make sure the transducer is level. The following video mentions down and side imaging but also applies equally to traditional sonar.







If you still don’t get proper performance at speed then your transducer is mounted too high and you have no more slot adjustment. Drill another pair of mounting holes at least as low as the bottom of the bracket slots in their present position in the hull’s transducer mounting plate and lower as needed.

Flat aluminum hulls usually require lower mounting than other hulls, usually to the point that the transducer kicks up a noticeable rooster tail.


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## dave g (Jan 25, 2013)

Wow, great video. I'm gonna try that and lower the mount. Thanks a lot. I had watched a video that Lowrance has that showed how these transducer cavitate terribly if they are deep or not level with the bottom of the boat. so in doing what they showed, it is worse than before. So thanks again. Soon as I can get out fishing again I'll post about what I find.


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## X-Shark (Oct 3, 2007)

That Vid has some good info......But!


They are talking about idling along and talking about side imaging.


From your explanation that is NOT the problem. Also you have a different style hull.


The fact is that if air is induced across the face of the X-Ducer.....Your going to loose bottom.


So.....Everything in that Vid has nothing to do with your problem.


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## MrFish (Aug 21, 2009)

1.5-2 minutes for it to pee and your alarm isn't going off? Mine goes off if it doesn't start peeing within 15 seconds.


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## RMS (Dec 9, 2008)

X-Shark said:


> That Vid has some good info......But!
> 
> 
> They are talking about idling along and talking about side imaging.
> ...


His transducer and unit dues have side and down imaging, so he needs to level his transducer, which is also critical to achieving the best possible traditional sonar performance. 

It is more critical than ever before to level these longer, all in one transducers to get proper performance out of all modes (down and side imaging , and traditional sonar). This Includes minimizing air turbulence under the transducer ONCE IT IS LOWERED SUFFICIENTLY INTO CLEAN WATER.

G3 is a reputable manufacturer and they have welded a mounting bracket in a position on bottom of the hull that they have determined to be optimum. This is a situation where the dealer has not properly installed and adjusted the transducer. This is obvious after viewing the photos provided after successfully installing several of these types of transducers on many typed of hulls, including aluminum.

This is a problem that can be fixed with a little trial and error effort that most dealers are not willing to put forth.


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## X-Shark (Oct 3, 2007)

And yet the nature of the flat bottom and the strakes that trap air that slides from bow to stern and then across the face of the X-Ducer.


The air must be eliminated....This happens when speeds are less than 12 to 13MPH.


After that the air is Rammed under the hull.


Some experimenting may.....or may not eliminate the problem. It may also cause other problems.


Folks don't seem to like it when the roster tail of spray hits the side of their engine right at the seal between the lower and upper Cowl.


The boat in the Vid is a fiberglass bass boat....Probably in the range of aprox 8deg of deadrise. This is not a FLAT bottom boat and will not have the air induced and trapped to exit at the transom where the X-Ducer is.


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## dave g (Jan 25, 2013)

I lowered the transducer about 2 inches with the ability to drop 1 more. I also put a temporary baffle over the top to block any rooster tail. I will update after I've had a chance to try it. I do remember having to do the same on a jon boat I was using here.


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## dave g (Jan 25, 2013)

THANK YOU to everyone who posted trying to help me with the transducer placement. Lowering it solved the problem. It reads at speed like it is supposed to now. All I need to do now is make up a good baffle to prevent the rooster tail from soaking everything. You guys brought a new perspective to someone who thought he was somewhat intelligent. Thanks to all again.:thumbup::thumbup:


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## X-Shark (Oct 3, 2007)

Good... Here is a link to a shield. https://www.amazon.com/Rig-Rite-200...+shield&qid=1577454765&sr=8-2#customerReviews


I think that is just a idea maker.....Using that design......But improving on it.


Using some larger PVC pipe and length slicing it to create a curved roof, so to speak. Building some alum bracket / brackets that attach to it and also pick up on the same mounting holes that mount the X-Ducer.


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## salty_dawg (Mar 21, 2013)

This stopped the rooster tail on my traditional sonar transducer. I also have the same SS/SI transducer as you on the port side but it doesn't create a rooster tail. This was just a piece of rigid plastic with a bend in it.


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