I've read where you can mount the transducer in the bilge of a sailboat. I have a Mac 25 and was wondering if the lower end Hummingbird units would work. I mainly want it for depth and temp, but will drop a line or two when there is no wind. Any help would be appreciated. Thanks, Mac
Fish Finder
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If you are going to shot through the hull you need a place that is solid glass with no voids or air between layers. You could not shot through your water ballast area. Once you find the area build a dam (Cardboard taped to the glass works) around the place you want the transducer to mount and fill the area with something that will not allow air. I read you can put the transducer in a bag of water, but I did not get good readings this way. Vaseline worked for me, I have also read about marine grease, but never had it handy. After you have a good test with the location it is time to permanently mount it. Take down the dam and sand the area to clean. Put up another dam and mix glass resin, hold the transducer in the resin until it sets, it is faster than you think so get it held to the bottom and hold it there using the wire to hold it down. Once it feels solid let it cure overnight and test again.
Good luck.
Good luck.
Perhaps not exactly the bilge, especially if it has a keel or ballast under it but it is correct that in SOME boats a depth sounder transducer can be attached inside the hull and provide good readings. The reason I mention some boats is because if the hull is of a cored construction or has trapped air bubles in the chosen location it will not work. Also the mounting of the transducer requires there is no air trapped between the puck and the hull. The low end hummingbirds can work just fine as the transducer can shoot through the hull to get accurate readings but do not expect accurate temperature readings with the sensor being inside the boat. I would suggest you locate the puck as close to the centerline as possible but in a flat spot away from the keel. A flat spot is recommended so the transducer shoots straight down. If no good spot is available ahead of the keel perhaps there may be one on the stern. I would do a trial installation to make sure the spot works. Make a pool of water and immerse the puck or use play clay and attach puck to the hull. Once satisfied the spot is the correct one then you may create a pool of epoxy and set the puck in it and allow to dry. As a final note determine the height distance from the waterline to the puck as the sounder instrument will only read from the puck to the bottom and that differential distance will need to be added back when talking about water depth. Also remember that a depth sounder is a navigation aid. It is mostly used to compare charted depths with actual depths but it will not guarantee that you will not run aground.
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I have used the water in a baggie method and it worked well for me. Just move it around till you get a good steady reading. Measure the actual depth with a lead line to make sure you are getting a good accurate reading. Don't expect the temp. to be extremely accurate. Some one like Ross can probably give you the skinny on how conductive fiberglass is, and what you can expect, but I don't have a clue.
I have used the water in a baggie method and it worked well for me. Just move it around till you get a good steady reading. Measure the actual depth with a lead line to make sure you are getting a good accurate reading. Don't expect the temp. to be extremely accurate. Some one like Ross can probably give you the skinny on how conductive fiberglass is, and what you can expect, but I don't have a clue.
Again, this board comes through! Thanks everyone, I will try it on under the cockpit, it seems fairly flat there and away from the swing keel. One more thing, you say to use epoxy, that will be forever. Can I use silicone?
I mounted the transducer of an Eagle SeaCharter 642c iGPS in my forward locker. Used the epoxy that Lowrance sells. Works fine, though the constant clicking of the depth sounder can be annoying. I turn it off at night and just use the gps to ensure we don't drag the anchor.
Humminbird Rocks
On a US27 I had a 100SX Humminbird unit that worked great epoxied to the inside of the hull. Trade in the transducer that comes with the unit for the hockey puck one (might be just $20) as that works and lasts longer and is made for that use.
On a US27 I had a 100SX Humminbird unit that worked great epoxied to the inside of the hull. Trade in the transducer that comes with the unit for the hockey puck one (might be just $20) as that works and lasts longer and is made for that use.
Better spot than under the cockpit is under the forward settee in the starboard side, if you dont want permanent then use the wax toilet ring, that's what I use, no problems in over 2years now. The temperature sensor won't work very well, the hull is a good insulator, if you want temp you will probably have to hang it off the transom.
The PO mounted the transducer under the threshold that leads to the head. He cut a 3'' hole and resined it on the hull forward of the keel. He covered the hole with a round plate. Looks nice and is really the perfect spot. He also mounted the through hull speedometer sender there.
Yes you can. It is more difficult to get the puck level, and more difficult to insure that there are no air bubbles, but it can be done.
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