Transom mount transducer.

Xplicitlnck

Xplicitlnck

Well-Known Member
Jan 2, 2012
4,030
Long island ny
Boat Info
330ec
Engines
Twin 7.4 straight drive
I'm pretty sure I know the answer to this but I'm gunna throw the question out there anyway. Keep in mind I have full scuba gear. Can I install a transoms mounted transducer while still in the water? I have a cored hull. I know 5200 can be installed underwater and I can screw the screws in by hand with a screw driver but an I just being stupid and be patient and wait for my next haul?
 
Which type/model of transducer?
 
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Fiberglass is a very rigid material, and to attach screws you almost have to follow the same procedure as prepping metal, or concrete. A proper sized pilot hole is a must otherwise the Fiberglass just cracks, not good below the waterline. So if you want to carry one you will a hand drill. I keep one on the boat that looks like an old fashioned food mixer. It does not require power, and it's safer in a gas bilge than an electric drill.

My big concern is that no mater how hard you try no to, you will still trap water between the screw and fiberglass, and come winter layup that water will turn to ice and expand.

I hate to say it this early in the season, but waiting for the next haul out may be the best course.

Henry

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Hey Jonathan I am pretty sure your boat is the same as mine we do not have Cored hulls ,solid fiberglass I believe the 37 express cruiser has a cored hull


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Henry Boyd said:
Fiberglass is a very rigid material, and to attach screws you almost have to follow the same procedure as prepping metal, or concrete. A proper sized pilot hole is a must otherwise the Fiberglass just cracks, not good below the waterline. So if you want to carry one you will a hand drill. I keep one on the boat that looks like an old fashioned food mixer. It does not require power, and it's safer in a gas bilge than an electric drill.

My big concern is that no mater how hard you try no to, you will still trap water between the screw and fiberglass, and come winter layup that water will turn to ice and expand.

I hate to say it this early in the season, but waiting for the next haul out may be the best course.

Henry

Sent from my iPad using Tapatalk HD
Click to expand...

Yea that was my only concern. Maybe I'll do a short hall mid season
 
joeyleggz said:
Hey Jonathan I am pretty sure your boat is the same as mine we do not have Cored hulls ,solid fiberglass I believe the 37 express cruiser has a cored hull


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Click to expand...

How certain of that are you? That would be very nice but for some reason in thinking I mine is cored. What about from the rubrail up? Is that solid glass to?
 
roberteb said:
If you can't wait, can be installed also in-hull..
Click to expand...

Please explain that one. . I would most likely just wait but I am curious on what would work. I know speed and temp wouldn't work and how accurate would the soundings be
 
If you're going to haul out, maybe consider a thru hull? I was told by quite a few dealers a transom mount on my boat would be problematic with any speed due to the gurgling going on back there. Ended up doing a B75M (chirp) thru hull with a Garmin unit and am real happy. Excellent sounding/fish aspect along with temperature down to a tenth of a degree - and GPS speed from the Garmin unit which has really allowed me to dial in the most efficient trim tab position at cruise.

My original transducer was tiny compared to the diameter of the new one, so re-drilled around the outside of the original transducer hole (because I didn't want to add another whole new hole). A bit nerve wracking, but the results were worth it.

Also I was told to use the 3M 4200 quick cure, not the 5200. Apparently a very similar performance seal once cured, but the 4200 will allow removal if desired down the road where the 5200 is pretty much permanent - or at least extremely difficult to reverse. Ironically, water helps the cure process of each.

We put in my new ducer - let it sit for about 20 hrs, then put her back in the water. Left her in the slip for another 24 hours to further cure, and have had zero issues. This was completed about a week ago.

Best luck whichever way you go.....
 
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If you go the transom route, I highly recommend using a "stern Saver" which is a plastic block with an epoxy glue. Then the transducer screws to the block. I did that on my boat.

Advantage is no holes in the glass at all, and the transducer can be moved or replaced without drilling more holes. It comes in black, which matches bottom paint for a clean look. I installed a "fish hawk" that way (cannot be mounted in hull). Here is my install before I repainted the bottom paint around it. (You sand it off to the gell coat to bond the epoxy):
e5fded89f961f3390974e2ff364f3dbf.jpg
 
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I have a shoot thru transducer mounted in my 300 DA and connected to a Garmin blackbox sounder. The unit works great, shows fish well, even shows temp but is slower to react to temp change than one immersed in the water. You have to have a solid glass hull for the shoot thru units to work. I prefer it to the transom mounted units, no marine growth, no turbulence and best of all, NO holes in my hull.
 
Xplicitlnck said:
How certain of that are you? That would be very nice but for some reason in thinking I mine is cored. What about from the rubrail up? Is that solid glass to?
Click to expand...

I am very sure that we have solid fibreglass hull The topsides of our boats are balsa cored (all the decks )


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Lots of good information. Racking my brain on what to do. I'll let you guys know as soon as I figure it out
 
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