Mounting transducer on aluminum boat

Discussion in 'Boat Repair Help' started by Jimmy Don, Apr 15, 2007.

  1. Jimmy Don

    Jimmy Don Member

    Messages:
    166
    State:
    Arkansas
    How is the best way to mount my transducer to the transom of my aluminum boat? I really don't want to put holes in the boat below the water line.

    I was looking at mounting plates on the Cabelas web page that allows you to keep all holes in the boat above the water level, but the idea of paying 30 bucks for an 18"X12" piece of plastic just doesn't appeal to me.

    I was wondering if anyone has any ideas for a cheaper mounting plate.
     
  2. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    What I'm doing to the rear of both pontoons is to weld some aluminum stock whether its 2x2 tubing or 4 Channel from the bottom of the toon to the top.
    I can mount the transducer to it and use the channel or tubing for a wire chase .
     

  3. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Work up a rig that'll clamp to the transom like a trolling motor. You could even use the remnance from an old transom mounted trolling motor.

    Just one idea.
     
  4. ShilohRed

    ShilohRed New Member

    Messages:
    4,339
    State:
    West Tn
    I have mine mounted on a 1" thick piece of marine plastic that way I can move it as many times Is I need to and theres not a hole anywhere near the water line of the boat. It only has 2 bolts near the top holding it on.
    Works great.
    Pete
     
  5. Chrisingeorgia

    Chrisingeorgia New Member

    Messages:
    113
    State:
    NY
    Make sure you don't use a metal mounting bracket for your transducer, it can cause electrolysis problems and eat a hole right through the aluminum. I learned the hard way.
     
  6. Mr.T

    Mr.T New Member

    Messages:
    2,553
    State:
    MO
    Holes below the water line really aren't a big deal if you take the time to seal them properly with silicone.

    The advantage of the big plastic board from Cabelas is that you can re-position your transducer until you find the sweet spot without making any new holes in the transom. You could buy a nylon cutting board at Wally-world and probably get the same functionality for less money.

    I like Mark's idea of welding a piece of channel stock - he's doing it on a pontoon, but it'd work on a regular boat just as well. A 12 or 18 inch piece mounted along the bottom of the boat would be great - you could move the transducer around all you want pretty easily.
     
  7. 223Smitty

    223Smitty New Member

    Messages:
    478
    State:
    Indiana
    Find a scrap of treated lumber & rip yourself a piece about 1" X 1.5"
    Mount your transducer to it & use a C-clamp to hold it on the transom once you're in the water. Use a thin scrap of wood under the clamp inside the boat to protect that surface if needed.

    Smitty
     
  8. DANZIG

    DANZIG New Member

    Messages:
    6,672
    State:
    West Virginia
    I have been pondering the same.
    Mark (as Usual)prob. has the "right way" to do it. Considered the C clamp idea as I will need to remove the whole finder frequently for transport. Looked at the same mounting plates in the catalog but came to the same conclusion, too many bucks for some plastic.

    Now my thinking is runnning more along the lines of using a "slice" from a cheap plastic cutting board. Maybe epoxy it on with bolt heads facing the stern and attaching the Trans with nuts.

    Being as it is yard sale season, an old cutting board should be cheap and easy.
     
  9. fishhook

    fishhook New Member

    Messages:
    658
    State:
    Willow Woo
    I mounted mine right on the transom. I glued a piece of plywood on the inside where the transducer was going to mount so I could use stainless screws and put marine glue on the threads before I screwed them in. I've mounted several transducers this way on aluminum boats and never had a leak. On my pontoon that I used to have I had a block of aluminum welded on the back bottom edge of the pontoon which I drilled and tapped to mount the transducer so I suppose you could do the same thing with a boat.
     
  10. Wabash River Bear

    Wabash River Bear New Member

    Messages:
    3,019
    State:
    Indiana
    You can also epoxy the transducer to the floor inside your boat. This is offered as an option to mounting on most transducers from the manufacturer. Check your installation guide, it will give you the details.
     
  11. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    I aint skeered of putting holes in boats below the waterline.
    Next time you venture around the backside of your boat check out those big dog gone bolts that go all the way through her rear that hold the muscle on.

    A little 5200 or good silicone caulking under the washers is usually plenty to seal a hole with a bolt running through it in aluminum.
    If it were a wood transom I'd do it a little different.
    but the rail or flat stock is definately the way to go. You build adjustability into your transducer.


    As far as epoxying a transducer down. They dont work very well trying to shoot through aluminum or wood. There are however transducers for some units that are available and will shoot through aluminum. I would save my money though.
     
  12. DANZIG

    DANZIG New Member

    Messages:
    6,672
    State:
    West Virginia
    "I aint skeered of putting holes in boats below the waterline."

    For me, it is a question of maybe having to remove the trans-d some time. Get a new unit, whatever.. then you have holes to plug. Why not just avoid that problem all together?

    As for the big holes, That's why I got the 18 footer so cheap. Water got in around the mounting bolt holes and rotted the transom.
    To be fair, I have learned that the Arrow Glass factory did not exactly build these holes the right way. Longevity of the craft was not in their program.
     
  13. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    It aint just Arrow Glass Company. Shoddy work particularly in the rigging of boats is often their downfall. Just as bad is the floor installation and stringers.
    For some reason boat companies think a chopper gun and polyester resin prevents rot. The reality of it is it invites rot. If a rod holder, cleat, or railing isnt installed properly it can destroy a boat in a matter of a few years.

    Alot of people have the idea that an aluminum boat solves this problem. Aluminum boats come with a whole different set of problems of its own.
    They get to the point they are unreapirable by conventional methods.
    Electrolosis most often is caused by a poor electrical installation. (very common in even in high priced boats) The boat consumes itself.

    The proper way to penetrate a transom with wood in it is to drill the hole oversized by about a 3/8" Fill the hole with thickend epoxy then drill your actual size hole through the epoxy. That epoxy thickend plug aint coming out ever. Rot may creep from somewhere else but it wont originate from there.

    Alot of people dont know that fiberglass rots. You can look in the bilge of some fiberglass boats. You'll see these dark lines on the glass like tar or oil is dripping or running along the glass.
    Water causes this. Water gains access to the glass strands and runs the glass strands eventually saturating the glass to the point hydraulics will force the ooze out somewhere else. Its called wicking.
    If you are boat shopping and see any evidence of this inside the bilge RUN not walk from it. It aint worth it if they give it to you. The best place for it is in the local dump.
    The only known cure is a lengthy process (months) just to dry it out and expensive to correct.

    Contrary to mass marketing tactics by boat manufacturers I do believe without question that wood is the best building material for boats especially with today's advancements in epoxy systems and paints. The only reason fiberglass and aluminum have done so well in the market is because they are not labor intensive to build. The profit margins are higher and the boats are more affordable to more people. It doesn't make them better boats.

    There are numerous 100 year old and older wood boats being restored or have been restored. They have managed to survive all those years often times sitting in water.
    Last year Wooden Boat Magazine had a feature article on a wooden sailing ship built in 1895 being restored in California from the keel up. The C.A. Thayer.

    http://www.techprose.com/Samples/SFMaritime/thayermoreinfo.htm


    These are pictures of the restoration. Those ceiling timbers are awesome.
    http://www.bay-ship.com/thayer_index.html