Anyone ever had the trailer bunk get in your way when mounting a transducer?

Discussion in 'Fish Finder Review and Study' started by Big Dav, Apr 22, 2008.

  1. Big Dav

    Big Dav New Member

    Messages:
    1,016
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    Southwest
    I had seen a few commercial "spacer or mounting plates" on-line. I figured one would be easy enough to make if I could find the material. I started thinking about this after talking with Pete (ShilohRed) and he mentioned in a PM that he used a plate on his transom. Thanks for the info and help Pete. Much appreciated.

    I needed to get the transducer for my Humminbird 997c farther away for the motor than the trailer bunk was going to allow me to do. I posted in the SI User group and the fine folks from Humminbird recommended using a spacer of some type to get the transducer far enough back to miss the bunk. A side effect (According to Humminbird) is that this also may help with higher speed operation by getting the transducer back in cleaner (less turbulent) water.

    I needed a spacer of at least 1 &1/2 inches to get back far enough to clear the bunk. I was told on the message board that some have used spacers as thick as 4 inches.:eek:oooh: I could not find a commercial spacer any thicker than 3/4", so back to making one myself. I did a little searching out of necessity and came up with a product called HDPE (High Density Polyethylene). It is also called by the brand names of StarBoard and / or Seaboard.

    I made the spacer tonight and I am getting ready to mount it to the transom. Once I get it mounted I will take a few pictures of the spacer and how / where it is mounted.
    The HDPE was very easy to work using standard wood working tools. Cut with a miter saw or table saw and machine the edges with a small hand router to round the edges (yep same one that cut through the end of my thumb several days ago:crazy:). Sanded smooth, drilled a few holes to mount and it was ready to mount to the boat.
    I will be attaching it to the transom using 3M 5200 and 316 grade stainless steel #10 screws. In order for the 5200 to have a chance of slightly sticking to the HDPE. The surface must be roughed by sanding, then heat treated with some source of flame. Better directions on doing that can be found with a quick Google search "gluing HDPE or Gluing StarBoard together".
    This is probably old information to a lot but hopefully it will be helpful to someone else.:big_smile:

    I just need to figure out if the spacer needs to be flush with the bottom of the transom, (At least that is what I am thinking) or if it needs to be stepped up a small amount from the bottom edge of the transom.

    Here are a couple pics of the spacer block. The second picture is of the intake screens that I also need to space back from so they would not interfere with the SI transducer.:crazy:

    Thanks
    David
     

    Attached Files:

  2. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    Either move the winch upright at the front of the trailer back if it's not welded in place or put a spacer on it.
    There isn't any need for the bunk to extend past the transom.
     

  3. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    I'd throw my 2 cents in with Mark on this one. My bunks come to the exact edge of the transom. There is no need for them to extend 2 inches past the end of the transom as there is nothing there to support. The transducer comes right up to the bunk, about 1/2 to 3/4 inch clearance.
     
  4. Bill in SC

    Bill in SC New Member

    Messages:
    4,451
    State:
    South Caro
    I agree with mark and AwShucks.
    BB in SC
     
  5. Big Dav

    Big Dav New Member

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    Well that would be easier.:smile2: I guess the five minutes I spent making the spacer and the 10 minutes I spent typing the post aren't too much wasted time.:smile2::embarassed: I was just going to do a plate like Pete was talking about in case i needed to move the transducer around. After talking with the guys on the SI board, I got on the spacer suggestion.
    I can move the winch support back and I have done that on another boat in the past but not for the same purpose as this (to get a little weight off the trailer tongue). It just did not enter my pitiful little mind to do that this time. :eek:oooh::crazy::roll_eyes::embarassed::sad2:
    As usual, I stressed over a little thing and completely overlooked a simple solution. I will hold off on mounting the transducer until I can get to the water with it.

    Thanks guys for the replies and thanks JW for the PM.:0a31:
     
  6. Big Dav

    Big Dav New Member

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    1,016
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    :0a13::0a14::0a15::005::roll_eyes:Anyone need a nice 6" x 4" x 1.5" white paper weight.:smile2: Cheap! :wink: I guess I could always use it as a wheel chock.
     
  7. Big Dav

    Big Dav New Member

    Messages:
    1,016
    State:
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    OK, After some much needed sleep I went back to the SI users board and tried to figure out why he suggested a spacer. I mentioned it in my original post. So the SI transducer would be clear of the three stainless steel mesh screens on the livewell fill pumps. He was concerned they would be in the way of the SI transducer and would block or interfere with it. They stick off the back by almost 2 inches and are below the transducer.

    Does this spacer idea still seem as stupid now?:confused2::smile2::eek:oooh: Any of the other folks out there with an SI unit have any problem or similar situation?

    Also there is the comment he made about the spacer getting the SI transducer back into cleaner (less turbulent water) for better performance at speed. Which I have read is a problem on a lot of aluminum boats. Any input on this?

    So I guess he had more reasons that just helping me get around the bunk. The screens were my concern when I originally asked on the SI board.

    I don't want to mount this goofy looking brick on the back of my boat if it is not necessary. :0a36::0a31:
    Thanks in advance,
    David
     

    Attached Files:

  8. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    Dont know if I would call it a spacer as much as I would call it a backer but on an aluminum boat I wouldnt mount a transducer directly to the hull.
    Block outside and a block inside if possible.
    With a little backyard engineering you could come up with something that would make moving the transducer around a piece of cake.
    Hmmm maybe something with a dovetail slot?
     
  9. SkipEye

    SkipEye Well-Known Member

    Messages:
    7,525
    State:
    Winfield, MO
    Name:
    Darryl
    My bunks extended 3.5 inches past the transom. The boat was tongue heavy anyway so I just moved the winch back 3 inches. The boat is still FULLY supported by the bunks. Problem solved. I did mount my transducers to Marine StarBoard but that was just to allow moving them if required without new holes in the boat.
     
  10. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    If moving the weight of the boat forward or backward on the trailer has a detrimental effect on weight transfer, most trailers still have an axle.
    You can shift that too.:eek:oooh:
    No guarantee that it was right in the first place. Trailers are pretty generic. Boats aren't necessarily generic.