External transducer mounting on twin engine 270

[family affair]

I currently have an in hull transducer with a Ray marine c80. I'm likely going with a new Garmin with a transom mounted transducer. I really hate the thought of drilling a large hole anywhere on the boat for the cable, but I don't have any choice if I want side scan capability. At this point my plan is to put the hole in the vertical surface of the splash well and seal it with a Blue Sea side access cover plate. To avoid a stray wire in the splash well, I was thinking of zip tying it to an engine hydraulic line, then route it down between the engines. I will mount the bracket to a bonded plate to avoid drilling the transom.
I'm probably over thinking this, but I really want to avoid looking back and regretting were I put a hole, etc.
GG brain trust - thoughts?

 

[SkunkBoat]

I don't understand the "Blue Seas cover plate".

Are you mounting a GT51M-TM between the motors?

I had a CV51 (the "included in the box" cheaper model) mounted there. It worked well going slow. Not great at speed.

Mounted on a SternPad stick on mounting pad.
Ran the cable up between motors (two cable ties in transom with very short screws) into motor well, across and thru a clamshell in the the side wall where all of the motor cables go.

I have since removed it and mounted a thru-hull GT51M-TH on the centerline. Fantastic.

I put UW lights on the SternPad.

 

[seasick]

A hole with a sealed clamshell cover, installed above the water line would look better in my opinion. If you seal the inside of the hole with some thickened epoxy, and then caulk the area around the cable and the inside of the clamshell, water wont be an issue.
The problem with routing the cable along the engine rigging or steering lines is that is will be somewhat exposed and subject to possible damage from movement or just accidentally stepping on it. Plus running over the transom looks amateurish

Of course you can temporarily run the cable over the transom and deck just for testing that the ducer works well, before drilling the cable hole.

 

[SkunkBoat]

...running over the transom looks amateurish

hehehe call me amateur...I didn't drill a hole an inch above the waterline in a three inch thick transom that has some hidden aluminum reinforcing bar...just so I could hide the cable.

He has twins. He has to mount it between the motors. There is not a lot of space above the waterline to get into the lazarette from between the motors.

 

[family affair]

Ducer is a GT52.
The cover plate:

Amazon.com

Call me crazy, but I rather drill a hole in the hull than the transom. Yeah, a wire over the back does look a little "hackish" , but I'd rather that then be concerned about a leak or wet transom.
Running it over the top to check performance is a great idea before making holes. Between the water pick-ups and engine turbulence I am concerned I could have issues at different speeds.
I'll need to look at the thru hull option.

 

[family affair]

My ego can handle a cable running over the transom instead of making my wallet $700 lighter!
That is as long as the image is clean and consistent.

 

[SkunkBoat]

My ego can handle a cable running over the transom instead of making my wallet $700 lighter!
That is as long as the image is clean and consistent.

thru hulls are not cheap....but they do work better

 

[family affair]

I have no doubt they work better. I have been impressed by the in hull I have now, but the previous external on our 248 got the job done just fine for what we do. Considering how tight the engine spacing is on the back of the 270, I can likely hide most of the cable. I'll have to check with other 270 owners and see what they can tell me.

 

[seasick]

Wow, I didn't expect a lot of the feedback
For the record, the cable does not have to go straight up and through the center of the transom. I would route it up a bit above the water line and then across to the stbd side, another left turn up to the a spot below the gunnel and in an area that can be reached from inside the bilge or a locker and then into the rigging tube.

 

[Hookup1]

As FamilyAffair said - stay away from drilling holes in the transom. It cored and only bad things can happen. The hull is not cored.

 

[Scot Smith]

Yeah,
I opted for a thru hull with my new Garmin, but did not get the side view option - I figured clearvue would be enough cost $499
It was bigger than I expected and has a fairing the whole thing is like 2 inches wide and roughly 6-7 inches long
Garmin recommended 2 thru hulls for side view - That was too much for me

 

[family affair]

Because if the narrow beam and twins, you'd have to be directly behind the boat to see the wire. I routed it up towards the starboard engine and, gulp, over the transom. Hopefully it won't bring shame to my family.

 

[Chessie246G]

Running the wire with the engine rigging could possibly cause electrical interference. Happened on my bass boat with a Lowrance unit and 3in1 transducer. Anytime the engine was running it would cause terrible "chatter" on the screen. After some research, I moved the TD wire away from the engine harness and the picture cleared right up.

 

[Hookup1]

I installed a GT51M-TH on the centerline on my 268 Islander. SideVu, ClearVu and CHIRP. Could not use the existing transducer pads without blocking one side view or using the dual transducers with dual expense! No holes in the transom at all to possibly leak.

 

[family affair]

I installed a GT51M-TH on the centerline on my 268 Islander. SideVu, ClearVu and CHIRP. Could not use the existing transducer pads without blocking one side view or using the dual transducers with dual expense! No holes in the transom at all to possibly leak.

I decided to role the dice and place mine over the transom, just right of the drain plug mounted to a bonded mounting pad (no holes). I know a guy (who is not on the forum) with a 2004 270. He has the same unit as me installed 1 year ago. He has no issues with the transducer in the same location as mine with twins. My only concern is that I don't know if all 270's have dual water pickups under the hull. I have some concern that the water pickup will cause an issue at speed. I'll know for sure in a few weeks!
I don't see why the transducer that came with my unit couldn't be used for a thru hull. They look almost identical. I've read about others doing something similar with Garmin transducers, but I didn't want to punch a hole through my hull and find out the hard way it won't work!

 

[Hookup1]

I decided to role the dice and place mine over the transom, just right of the drain plug mounted to a bonded mounting pad (no holes). I know a guy (who is not on the forum) with a 2004 270. He has the same unit as me installed 1 year ago. He has no issues with the transducer in the same location as mine with twins. My only concern is that I don't know if all 270's have dual water pickups under the hull. I have some concern that the water pickup will cause an issue at speed. I'll know for sure in a few weeks!
I don't see why the transducer that came with my unit couldn't be used for a thru hull. They look almost identical. I've read about others doing something similar with Garmin transducers, but I didn't want to punch a hole through my hull and find out the hard way it won't work!

The bonded mounting pad is a good option. You could do the same for the wire going up. As far as the ascetics of a wire coming over the top - at 20 knots or 20 feet it will look just fine! I'm sure my bait well on my Euro Transom would cost me points in Palm Beach.

You should be fine at speed. Your pickups are in the same place as mine but you have a full running surface, about 2 feet more, all the way to the back. At "looking around" speed which is more important you will be fine.

I do have to say that I have not been impressed with Garmin SideVu or ClearVu. I have a943xsv and a 8612xsv and GT51M-TH and B744 transducers. Too busy fishing kite fishing or slow trolling live bait. Not as much bottom fishing to play with it. The few times I used it while fishing this year and last was so-so results. Shaded relief charting for FL looked great but I haven't been able to convince myself if its real or just pretty pictures.

SideVu


Shaded relief

 

[family affair]

What don't you like about the side and clear vu? I've heard pros and cons, but regardless it will be light years ahead of what was there previously for us. All I'm hoping for out of the sidevu is to help us locate schools more quickly without having to cover as much water. Great timing for fuel saving electronics!

 

[Hookup1]

See the image above. I have never seen fish off to the side. I have not dedicated enough time to tuning and testing so you should ask others about it.

The sounder technology will evolve rapidly the next few years.

Many of the high end million dollar plus rigs are fishing the Furuno Omni systems. This a something on the order of a $150,000 unit plus installation is a game changer. We don't have it on "Nasty Habit" (tournament boat - not my boat!) at least not yet. For now we do it the old fashion way.

I talked to one of the Captain's about his unit. Couple of his comments:
"I can see fish coming up ahead and usually tell which rod they will hit."
"If I see 4 fish I won't leave until I catch them all."

https://www.furunousa.com/-/media/sites/furuno/document_library/documents/brochures/brochures/csh8lmk2_brochure.pdf

I'm waiting to see what Garmin and the others come up with in my price range. We are in the "golden era" of sonar technology - more significant improvements in the last few year and it will get better and more affordable.

 

[family affair]

Ah, those images weren't there before. I see what you mean.
In these parts we can spend all the $$ we want on gadgets and gizmos and still have a boat load of Amish outfish everyone with next to nothing for tech!
Thankfully I don't have to fish for living. Until I do, I'm ok with some fish getting by us!

 

[SkunkBoat]

Here are some shots of sidevu. read thru this thread.
https://www.greatgrady.com/threads/...garmin-garmin-gpsmap-943xsv.31250/post-219976

You have to understand how the motion of your boat effects what you see and remember that sonar picture only shows you the past.

I absolutely love it for wreck/bottom fishing. Its great in combination with the traditional view.
I have't had much success using it for finding fish high in the water to the sides. I have to admit, I don't try to use it that way often. I have seen big schools of bunker that way but the big red blob on the traditional is easier to see.

As I said earlier, I had a transom mount the same way as yours and it worked great slow but not great on plane. Now its mounted thru hull just like Hookup and I can do big circles at 20mph and find wrecks when I know an "area" to look.