I've been going up to the areas mentioned for 20 plus years now and ended up buying a cabin in the Bovey area. Looking to hear and share some fishing reports about the surrounding lakes. Never keep much besides some pesty northerns and panfish (which are plentiful) for the occasional lunch. So, I highly respect the area, but if you know the area at all, you will never be able to fish all its lakes in a lifetime... so some well informed fishing reports is always welcome. Again, I emphasize "smaller lakes," because the bigger ones (Jessie, Round, Wabana, etc) all have fishing reports available. Post if you're interested and lets get a good conversation going.
I would agree with the above answers, that the line of rivets are creating dirty water for you. I would move to the left as well.
Also, I would guess you may need to lower the transducer some as well. Get the transducer as low as you can without it making a large roostertail at speed. If you have a good square or quality straight edge at home, place vertically along bottom of the hull, extending out from the stern. The top of the straight edge should cover at least the bottom 2/3s of the transducer on the inside (motor side), maybe more if the pitch of the hull is greater. Transducer should also have a slight downwards angle from transom.
2 more things, make sure the transducer is level(left to right) with a small level. Compare the level of the boat to the level of the transducer. Boats don't always sit level on a trailer obviously.
One thing to remember with side imaging is you beam going out towards the motor is often interfered with the outboard itself. As you trim up the motor, that side will become clearer.
Well I don't have any inside info on a hot bite but have heard it's still a jig and minnow bite on the edge of flats in 7-12 of water. If the wind is pounding into a flat I would recommend heading shallow and trolling cranks. This would be a good option to at least find a spot to slow down and jig the edge once you've cover water and find fish. I've done well on these flats all summer long if the wind is blowing into them.
I forgot about the speed issues with these transducers. I also have a high speed dual frequency transducer mounted. I run it as my primary and do a split screen when I want to see the side imaging. Generally the side imaging works best under 6 mph with 2-3 mph being optimal.
I agree you need to move it left to get away from the line of rivets. Then it's a matter of adjusting vertically and tilting it front to back/ up or down. The newer monster size SI ducers can be tough to get positioned right. That's why lots of guys run a second 2d ducer with a splitter cable which automatically switches in when the 2d signal from the SI ducer is lost. My boat is a Alumacraft Classic 165 tiller 50hp, top speed 29 mph. I was able to get position tweaked on it so I have SI, DI and 2d on plane, but it took a lot of adjusting. I resorted to mounting a camera on a mini tripod and holding it over the transom to video the ducer underway. That helped, but still a PITA. Good luck.
I would try moving it about 1-3 inches to the left. It's sitting right behind a row of rivets which would cause turbulence and issues with readings. You might also be picking up prop turbulence in that location that close to the centerline and on that side. Seems the side imaging transducers are more sensitive for placement due to the issues your having and blocking the signal one side or the other. The other side of the outboard could be a better option unless you have something else mounted there to help with prop turbulence.
New 2020 1875 Pro Guide. Helix 12 Mega SI graph. Can't read bottom when up on plane. I was going to adjust the transducer and this is what I found. Isn't the first rule in transducer placement to put it where there is "clean", undisturbed water flow?? It is below the bottom of the boat, maybe too far. It's a side imaging transducer so I feel the riggers wanted it close to the center of the boat. Where have others placed a side imaging transducer and have it read bottom when up on plane? I don't think you can move it closer to the center line. If you move it to the left of it's current position, the is the power strake in the front 1/3 of the boat. Any help is appreciated!!