Transducer Mounting Opinions Needed

[Husertim]

First, this forum is awesome and thank you to everyone who has helped me so far. I have been running this transducer in the location below (in the red circle) for two years, since I bought the boat. but have discovered that others with the exact same setup are running 10-15MPH faster than I am. I thought this was due to a hydrofoil the previous owner installed, but when recently removed I saw no improvement which got me digging in and through help on BBC I found out I am at about 28% prop slip. I kept racking my brain until I realized that my transducer, though mounted 4 inches right of the outside of the prop (11" from the center), it is forward on the stepped hull and likely causing some pretty good turbulence and keeping my prop from getting clean water. the front of the transducer is 24" from the prop at cruising trim. I will remove the transducer next time out, and if I get some or all of that speed back I will want to relocate this transducer.

Thoughts on this causing my slowdown? I have read on here about others losing 10mph after mounting a transducer similarly.

I do not need it at speed, just when going 5mph or less as I use it for sideVu and downVu

Where do you all suggest I mount the transducer? My initial thought is the X below the tie down. high and out of the way except when the ass end is in the water.

transom 1.jpgtransom 4_LI.jpgtransom 3.jpg

[MikeT1973]

Most guys are mounting on the bottom of jack plate using a transducer shield and saver or other bracket. Keeps it up and out of harms way.

[Riccochet]

See where that sealed hole in the transom is, just below where the motor is mounted? I'd mount it there. Or, really, anywhere on the stepped part of the transom. That part of the transom is not going to be in the water at speed.

[Rip Bass]

I would not keep drilling holes in the transom. You could fabricate a bracket and mount it to the side of the power pole bracket,near the engine. Or drill and tap the sacrificial annode at the bottom of the engine bracket.If similar rigs are actually running that much faster,I would compare their set to yours and see what the difference is,maybe try a little more set back and a four blade prop. Those small diameter props don’t have the lift that larger props have so you might need to get more hull out of the water. I doubt you are losing that much speed due to the ducer where it is located now.

[ECobb91]

Check into a stern saver block. You install it using 3M adhesive and that’s what you drill into, no worrying about drilling holes into your transom and if you already have the holes, plug them up with a silicone to make sure no water gets in

[fishin couillon]

If that ducer does 2d sonar, keep in mind that if you move up that far you will not get 2d readings unless you are idling.....

[IndianaBassMan]

I can't see losing 10-15 mph due to that ducer. I would move it to the right and down a few inches from your green X....so it is flush with the bottom edge

[Husertim]

I plan on using a stern saver block, and mounting it just below and to the right of the engine mount, on the other side of the tie down from the X I mentioned. I have another sonar that runs 2D for depth at speed that is shoot-through.

[Husertim]

I can't see losing 10-15 mph due to that ducer. I would move it to the right and down a few inches from your green X....so it is flush with the bottom edge

I thought the same thing, but I have read a few other places that guys have removed similarly mounted transducers and gained 10MPH. The theoretical speed of my setup is 55MPH at 5750rpm. I will be happy getting to 50, and any more real revs (vesselview mobile in route) will be icing on the cake.

[Riccochet]

You have an 18' boat with a 115, dual power poles, a G31 and dual G27 batteries.....you aren't going to see 55 MPH. You'll be luck to see 50 MPH.

No, I'm not being sarcastic.

Have you thought about dropping a pitch on that prop? That's a f'ton of weight to be pushing with a 115.

[Husertim]

You have an 18' boat with a 115, dual power poles, a G31 and dual G27 batteries.....you aren't going to see 55 MPH. You'll be luck to see 50 MPH.

No, I'm not being sarcastic.

Have you thought about dropping a pitch on that prop? That's a f'ton of weight to be pushing with a 115.

Dave, I definitely understand the logic here, and you are probably right. The boat gets out of the hole well (for a 115) and runs perfectly now at 40mph as far as lift, but 28% prop slip still seems pretty high. The power pole setup with the brackets, plus the difference from moving from a 27 class battery to the 31 AGM nets me right at 100lbs, but it is the furthest point back in the boat. Others are getting over 50 with the same setup minus the poles, and the kicker is I actually gained 1MPH when I put the powerpoles on the boat. I am just hopeful that moving the transducer will net me something. I wont be heartbroken if I don't gain anything. I was just curious if anyone had experienced an issue with transducer turbulence. I appreciate the input, honestly. I'll likely continue to run my five mile long lake (with an idle zone right in the middle) at 40MPH. By the time I get going its almost time to slow down. I just can't help but look to get the most out of her.

[Astyle954]

My .02.
The xdcr has nothing to do with your speed. You are asking a lot of a 115. My initial thought is you are doing the same thing I did. You are trying to make it more than it is. Sure you can "fine tune" what you have but you have to realize it is what it is and that's it. I had a 90 Evinrude and played with engine height, added a jackplate all this and that and it was and will always be a 40 mph boat. I got a new to me boat. Much larger engine and much much faster. I was happy.
At any rate, back to your original question. I'd mount it in a manner consistent with the xdcr manufacturers Recommendation as non intrusively as possible and roll on. It don't need to be fast. Reliable is key. If you want to haul ass. Get the proper equipment. Not trying to be an ass, just trying to save you some money. Or spend more lol.
Tight lines.