Helix 9 Mega SI Transducer Location

JohnnyG

Member
I just recently purchased a Helix 9 Chirp Mega SI GPS G2N unit that comes with a MEGA SI, MEGA DI, DualBeam PLUS transducer (XM 14 74 MSI T). Can this transducer be placed to where it picks up depth at high speeds on plane and not lose bottom or is that not an option? I know I can only get SI and DI at idle speeds but I wanted to know about high speed depth reading and placement. Reason is because I don't want to have to purchase another transducer just to read at high speeds using a Y cable. Would like to save those $$$s if I can lol. Here are some pictures of the back of my boat, it's a 1988 Norris Craft. I have an older Lowrance 7 Elite Chirp transducer on it now from my previous unit. Would love some advice on this issue as to where to mount. And if some of you think I should go with the higher mounting level for idle SI and DI readings and add another transducer with Y cable for high speed depth readings, feel free to let me know which ones/parts as I am pretty much a novice on electronics, trying my best lol. I would really love if you were able to resend pic with circled location of best placement as well, that would be extremely helpful. Thanks.
 

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djsmarinelectronics

Active member
No picture....took a while for them to download, sorry.
 

djsmarinelectronics

Active member
The "mega" transducer location is no different than any other transom mount transducer. Thoroughly read the instructions that come with it for proper placement. If you lose sonar on plane then exercise the y-cable option: M SIDB Y Cable part #720101-1 and an XP-9-20 Transducer part #710164-1.
OR you can run a Lakemaster Map Card with that new unit and not worry about the sonar signal. I would much rather know it was shallow way before I got to it than know it when the back of the boat got over it (probably too late then).

I have inventory of all these items at my shop in Ringgold
 

djsmarinelectronics

Active member
If you don't lose sonar where it is located now, you wont lose it with the "mega". Only thing I don't like about that location is it is not protected and easily knocked off. Mega is a $300 transducer. I would have put it in the center near the live well filter where it is at least protected by the pad. OR you can use a flat bottom mount position just up under the transom lip using a Transducer Shield and Saver
 

JohnnyG

Member
Thanks. I do use a map card, Navionics at the moment and know when I'm about to get shallow because I only run the maps when I'm on plane at high speed. However, it's just having that depth accurate at high speeds just gives me peace of mind lol. Going to download the Lake Master maps of the lakes I do fish and try them out. Thanks.
 

JohnnyG

Member
The only thing I worry about is when the water is down. Navionics doesn’t allow for depth changing unless you’re using an iPad or phone app. Lake Master does allow for water level adjustments but some of the lakes I fish aren’t on Lake Master such as South Holston. Some of Cherokee and some of Douglas is on Lake Master but only one county of each and I don’t fish those counties as much as I do the other ends of both lakes.
 

JohnnyG

Member
Rob Lee, do you have a shoot thru Hull 2d transducer and Y cable? I ordered those so when I have my unit installed, those will be installed as well. Hopefully that will help. Thanks DJ, I did some homework after your posts and my boat should b able to get a good thru Hull reading with the 2d added. I also now better understand where my Si ducer needs to be mounted for idle speed readings. Thank you.
 
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