I have a 999ci and when I get over 10 mph, the transducer has trouble reading. I typically get a depth of about 100+ feet when actually in 15 ft. I obviously need to adjust my transducer but would like to get some thoughts before I drill new holes if needed. I have attached a couple pictures to show how it is mounted. I have lowered it down already from the original place I had it but still no luck. Appreciate any help.
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Side imaging transducers are not very good at reading depth at mid to higher speeds.
Add an additional 2d transducer and that will solve your issue
High speed will help, though I’ve ran on plane with one unit running off the high speed and one off the si (in std 2d mode) and aside from the one on the SI showing more interference they both held bottom. It does look to me like yours is set pretty low though, if maybe try raising it before adding another and see if it works well enough. I’ve got mine set so the middle of the duecer (right to left) has the ‘joint line of the upper and lower half of it flush with the bottom.
Thought #1: Install a mounting board. That transom looks like swiss cheese already.
Thought #2: It’s too low.
Thought #3: My 898 has the same transducer. I get good readings up to my max speed, which is 29 mph. It can be done, it just takes the patience to keep adjusting transducer position until you get it right. And when you get it right, you might need to jerry-rig a spray deflector.
Although it’s to low, that usually doesn’t hurt much except for rooster tailing on plane.
I’d say that’s a tough spot between the two rakes on bottom, especially sitting pretty close to the one. All those rivets are gonna cause issues
Great idea with transom board, sometimes only way to fix is to start bouncing it around and seeing what works best.
Good luck 
I would install a thick mounting board. Maybe an inch. It will push the transducer back a little bit from the turbulence and air bubbles created by the transom seam. I would also get and install one of the rubber plugs the go between the legs the the transducer mount. The plug will force the flow around the transducer. Helps reduce rooster tail and not split the flow (top to bottom).
Good luck 
I would install a thick mounting board. Maybe an inch. It will push the transducer back a little bit from the turbulence and air bubbles created by the transom seam. I would also get and install one of the rubber plugs the go between the legs the the transducer mount. The plug will force the flow around the transducer. Helps reduce rooster tail and not split the flow (top to bottom).
Good luck
Never heard of this Plug? What is the brand and where to buy?
THX
Here’s the plug, but I don’t think it’s for your transducer. I don’t think you need it, but you can wrap tape around the opening in the bracket to see if that helps.
https://www.humminbird.com/productDetail-Lifestyle.aspx?id=11782
Side imaging transducers are not very good at reading depth at mid to higher speeds.
Add an additional 2d transducer and that will solve your issue
X2 this took care of the problem for me.
I also have a funky hull. With your hull you have you should be able to get away with just the SI transducer mounted correctly.
Duecer is too low.
Mount so the parting line of the duecer is level with bottom of hull, in an area of least cavitation.
Get a duecer mounting board and quit drilling holes in your transom.
Google humminbird transducer install for several images of correct placement… Or check instruction manual.
A plug is not mandatory but can reduce spray when the duecer is mounted properly.
High speed duecer not necessary, but they are way more mounting friendly for those who cannot grasp proper si mounting procedures.
X2 on too low; dont need to buy another transducer
To low, also turn up your sensitivity untill you get a reading on plane. Ping speed can make a difference also. Put a straight edge on your hull and drop the transducer so it fits flush with the hull then tilt it downward about 1 degree in the back. A board helps get it away from the turbulents from the transom.
not only is it too low, its way too low. the info needed is above, and its not found in a second transducer, unless you wjust want more hardware.. This is on a 1750 Crestliner with no high speed transducer..
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Agree that it looks too low…and it might be too close to a hull strake.
SI transducers can work just fine at higher speeds if installed correctly.
You won’t get detail, but the fact that I have SI at the speeds below proves the point. 2D works fine all the way to max speed.
…and the transducer in play here is new MEGA SI transducer. The old HDSI transducers liek the one in the OP were much easier to get to work right.
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I have an 898 hd si and nothing works past 5 MPH. Not even 2D. Why would this be?
It must have bad placement. It was on the boat when it was bought and we havent messed with it.
I have been losing readings at high speed lately, and honestly I don’t care whether I have them or not… But I did notice my bracket got loose. Yesterday I noticed I’m leaving some really excess spray. My loose bracket slipped down and is now really dragging. I’ll just need to adjust it back up and tighten down.
Here’s a picture of a working transducer at full throttle.
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Hi… First post here… Been reading this thread with great interest. I have a pontoon (tri-toon) with a Helix 7 Si mega+gps, Gen3N. The marina where I bought it installed it before delivering the boat.
The transducer is installed on the “built-in” mounting bracket on the starboard (right) toon. It loses depth and side imaging as it gets above 10 mph. At that point the depth will either disappear completely from the screen or jump to 900-1000 ft (my lake max depth is around 60 ft, average 26 ft). It was initially parallel with the boat/hull/toons.
I have adjusted the tilt up one, and then two clicks (back higher than front) with practically no difference. I have not tried tilting it down (back lower than front) yet. I was hoping not to have to start moving the actual mounting bracket around, but if that is what it comes to, so be it. I have attached a picture, taken before adjusting. The reflection in the water gives a decent “bottom view”.
Any advice would be greatly appreciated. I will have it out of the water soon to get some unrelated modifications done, so that would probably be a good time to do whatever I intend to do.
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Jesse find a way to lower it about 2″ by the looks of it. Try a piece of 1/8″ thick aluminum as wide as the transducer bracket and as long as need be. Then mount it to the toon using the original ducer mounting holes and attach the ducer so the seam it is level with the bottom of the toon. Then to level it so it gets the best images go the speed you normally go when scanning structure and stuff and put a level on your railings and use coins or something to level the level. Now remember how many coins and where on the railings you had it. Put it on a trailer or something and put the level and coins on and adjust the boat so the level reads level now you can take the level off and align the center seam on the ducer so its level to the ground. Does this make sense? You want the transducer level to the ground and not the bottom of the boat since boats squat or plow at lower speeds.
Thanks for the reply catnip. If I understand what you are saying… Basically get the seam of the ducer lined up with the bottom edge of the toon (so that, in theory, the bottom half of the ducer is below the bottom of the toon and the top half is above the bottom of the toon), then tilt the ducer so that it sits level (with the earth) when at scanning speed.
It is clear that you are suggesting this will give me good scanning at “scanning speed” (which I would assume is somewhere between 3-6 mph)… but are you also saying this will allow me to get accurate depth readings and maybe even scans when running above 10, 20, even 30 mph? That is really my goal. I have heard (even in this thread) that some folks are able to achieve that.
Am I following your points correctly?
Yes thats correct. The transducer needs to be in contact with the cleanest water possible. and with a toon that has lifting strakes that is hard to do since the strakes are trying to deflect the water back down its even tougher to get good readings at speed. 30 might be pushing it but i think its achievable. And if for some weird reason it dosen’t get better tou didn’t have to make any new holes or do anything that can’t be undone. Leveling the transducer with earth has more to do with getting the best side imaging than 2d. 2d is a lot more forgiving about the angle. Getting it lower to less turbulent water is key to readings at speed.
Thanks again. This is my first boat, first fish finder, first everything. I just bought a house on Lake Hamilton in Hot Springs, AR, with a dock, and now a boat in the dock (as of 3 days ago). I was disappointed to find that I was not getting depth readings above 10 mph, especially since there are shallow spots in places that don’t look like they should be shallow. Already dug a trench, luckily in relatively “soft” sand at relatively low speed. Now I am skittish about getting above 10 mph anywhere that I am not sure is nice and deep. This boat will go 40 mph no problem. I’m not a speed demon, but this is a big lake (at least 15 miles at it’s furthest two points, with lots of area to explore in between) and I don’t want to spend all day getting to and from just because I don’t know when the bottom is going to come up and grab my prop. I’m perfectly happy to stick to 20-30 mph when in unknown territory, but 10 mph is a bit slow when I’m trying to get somewhere and I have $4,000 worth of tech that “should” be telling me how deep the water is.
Your welcome. Here’s what you need to know about depth finders
They only show you the past!
So while they are good at showing depth and structure you have already been there and at 20 30 or 40mph its way too late to avoid the bottom unless you are going slow enough to stop because the bottom does not always come up gradually. So get a hd map card for your lake if available and try to go slow untill you learn the lake and trust the map. And update the map with waypoints marking rocks, channels and sandbars and such that are not on the map. Then when you get more comfortable with the new boat and lake you can just watch the map and not the bottom. If you can color code your depths set red for less than say 3 to 4 feet and it makes it a lot easier to stay away from those areas.
This boat will go 40 mph no problem.
How big of a ‘toon and what’s hanging on the back? 40 in a pontoon is darn fast!
So while they are good at showing depth and structure you have already been there and at 20 30 or 40mph its way too late to avoid the bottom unless you are going slow enough to stop because the bottom does not always come up gradually. So get a hd map card for your lake if available and try to go slow untill you learn the lake and trust the map. And update the map with waypoints marking rocks, channels and sandbars and such that are not on the map.
X2. Lake Hamilton is very well mapped, just looking at the Navionics chart online. The lakemaster chip should be at least as good.
10 mph is a bit slow when I’m trying to get somewhere and I have $4,000 worth of tech that “should” be telling me how deep the water is.
1. Unless you bought 5 of those Birds I’m wondering how you get to $4k with that set up since they retail at $800? I’m not trying to be rude, I’m just curious if there is other equipment that’s part of this equation?
2. Like catnip said, you don’t need to know how deep the water “is” or “was” — you want to know how deep it’s going to be in XX seconds when you blast through there at 40mph. Your chart is your best option here. You can use your bird to make different depth ranges appear different colors so it’s very easy to spot the shallow spots when you’re running.
How big of a ‘toon and what’s hanging on the back? 40 in a pontoon is darn fast!
22 ft Suncatcher v322, Yamaha SHO 150
40 mph with only me in the boat and the bimini down is no problem.
I think that middle toon makes all the difference.
1. Unless you bought 5 of those Birds I’m wondering how you get to $4k with that set up since they retail at $800? I’m not trying to be rude, I’m just curious if there is other equipment that’s part of this equation?
2. Like catnip said, you don’t need to know how deep the water “is” or “was” — you want to know how deep it’s going to be in XX seconds when you blast through there at 40mph. Your chart is your best option here. You can use your bird to make different depth ranges appear different colors so it’s very easy to spot the shallow spots when you’re running.
1. Well, I was throwing in an Ulterra with I-pilot link, and some install costs… so forgive the exaggeration. Just thinking of the check I wrote. That said, I don’t care if it was free, if it is capable of reading depth at speed, then I want it to do that, and I will eventually get it to do that. That’s just how I roll.
I totally understand the depth is telling me where I was, not where I will be, but at least I would like to know if it is going from 40 to 30 to 20 to 10 to 5 ft… within 30 seconds… which should give me a clue, as opposed to thinking I am in 25 ft of water when I am actually in 2 ft, which is exactly what happened to me the other day. If I see the water getting shallower on the screen then at least I can slow down a little… And if the equipment is supposed to be able read at speed, and others have done it, then by golly that’s what I want it to do. I am simply not satisfied that I can only get depth up to 10 mph.
As for the chart, I get that, but sadly the lake I am on (Lake Hamilton in Hot Springs, AR) surprisingly doesn’t get coverage from the Lakemaster maps. Given the size and massive boating traffic on that lake I was shocked to discover that fact. I imagine with a little research I can find something to tide me over till I “Autochart” the areas I intend to play in, but out of the box I get shorelines, period, no better than google maps. Of course, I am literally just learning this stuff and will probably find out that I am missing something (literally less than 8 hours on the water so far, and only part way through the bird manual), so by all means let me know if there is something I can do to get depth maps / contours for that lake. I am admittedly clueless, which is why I am here. I noticed the depth-at-speed problem on the way from the marina where I bought the boat to my dock, which is about 10 miles on the water… So I decided to start searching the Interweb, which brought me here.
First thing I always do, is look at the back of the boat while under full power and look for the sweet spot left and right as to where the water is coming off the hull.(or in your case the toons). Even the best leveling cannot make up for cavitation coming off the hull. Maybe you can avoid it, maybe not.
Then go from there. The info you have regarding the seam is solid info. Now, were talking about the horizontal seam in the transducer, just to clarify. The problem is the 2 to 3 inch distance your transducer is away from the pontoon and trying to figure out how much to “lead” the water coming off the toon, because it will be different that where it comes off the pontoon.
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As for the chart, I get that, but sadly the lake I am on (Lake Hamilton in Hot Springs, AR) surprisingly doesn’t get coverage from the Lakemaster maps. Given the size and massive boating traffic on that lake I was shocked to discover that fact. I imagine with a little research I can find something to tide me over till I “Autochart” the areas I intend to play in, but out of the box I get shorelines, period, no better than google maps. Of course, I am literally just learning this stuff and will probably find out that I am missing something (literally less than 8 hours on the water so far, and only part way through the bird manual), so by all means let me know if there is something I can do to get depth maps / contours for that lake. I am admittedly clueless, which is why I am here. I noticed the depth-at-speed problem on the way from the marina where I bought the boat to my dock, which is about 10 miles on the water… So I decided to start searching the Interweb, which brought me here.
That stinks about the Lakemaster coverage. See if your unit can take a Navionics chip. Or worst case, install Navionics on your phone so you have at least something. It’s not a perfect app and your phone needs to have a decent GPS chip in it, but it will still give you a MUCH better sense of the depth of the water up in front of you than any sonar can. I understand wanting your new unit to read at speed, but it still can’t compare with keeping an eye on the chart.
Good luck!
https://webapp.navionics.com/?lang=en#boating@14&key=afcqE~oawP
Lake Hamilton is High Def on the Navionics Hotmaps chip, and will run in your H7.
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