bilge water and transducers

[bones774]

I am new to boating and very novice question.
I want to install a new depth finder , searches on this board tell me that transducers need to be in water to work, yet everything else I read says "NO" to standing water in bilge, bad for boat.
So is the bilge supposed to be wet or dry? even when my bilge pump turns on it doesn't pump out all the water.
Thanks

 

[Dave1251]

Re: bilge water and transducers

The boat has to be in the water for the transducers to work. Place the thru hull transducer in the bilge in an area that does not have standing water after the bilge pump has run.

 

[Rocky_Road]

Re: bilge water and transducers

I am new to boating and very novice question.
I want to install a new depth finder , searches on this board tell me that transducers need to be in water to work, yet everything else I read says "NO" to standing water in bilge, bad for boat.
So is the bilge supposed to be wet or dry? even when my bilge pump turns on it doesn't pump out all the water.
Thanks

Bottom line is that the depth finder's transducer will work the best when properly transom mounted...but many use the bilge floor mounting option for a 'cleaner' installation, and to avoid drilling any holes into their transoms. I used a factory option suction cup for my transom install, which allows me to use my depth finder in either of my boats.

When properly glued to the bilge floor, the transducer will work fine for most people...and there is no need for any water to be around the transducer. You need to keep the bilge as dry as possible, for all of the obvious reasons!

Here is a shot of my suction mount...which has stayed in perfect place for all of this season, and works fine even at WOT:

Happy boating!

 

[bones774]

Re: bilge water and transducers

I don't think my bilge is ever 100% dry. Is that wrong. My bilge pump is really not that far back in bilge area and always has remaining water, should i be concerned?
Thanks

 

[83Evinrude]

Re: bilge water and transducers

Water in the bilge or dry won't matter to a through the hull mounted transducer at all.

I mounted my Humminbird through the hull. To test the location they have you put water in the bilge over the top of the transducer and weight it down with a sandbag. You need a single thickness location (no air or foam), test it then clean and glue it down. Works fine on my boat, no outside holes or cables.

The transducer is glued down with epoxy, and is in complete contact with the inside of the hull. It won't matter whether the bilge is dry or wet. Just test the location first to make sure the transducer can get through the hull ok.

 

[dingbat]

Re: bilge water and transducers

For optimum performance a shot thru transducer should be submerged in some type of liquid to improve the acoustics of the unit.
They make special fluid filled enclosures to mounted to the bottom of the hull that you fill with caster oil or propylene glycol.

 

[Rocky_Road]

Re: bilge water and transducers

I don't think my bilge is ever 100% dry. Is that wrong. My bilge pump is really not that far back in bilge area and always has remaining water, should i be concerned?
Thanks

If a boat is used on a regular basis, there is probably some water in the bilge even after the drain plug is pulled. I wouldn't be concerned that it isn't 100% dry. Mine isn't...and it is a fairly new rig!

Happy boating!

 

[83Evinrude]

Re: bilge water and transducers

For optimum performance a shot thru transducer should be submerged in some type of liquid to improve the acoustics of the unit.

Not sure why, if mounted correctly the transducer has a thin layer of epoxy filling any gaps between it and the hull so I'm not sure where the water would be to help it.

When a boat with a transom mounted transducer is on plane, only the face of the transducer is in water. You have to use a good location for a through hull transducer, and it needs to be glued down properly. If the desired location is tested first there won't be any surprises when its mounted.

Here is the manual for a Humminbird 610/610P depth sounder.
http://store.humminbird.com/media/document/hdr610.pdf
No mention about water being needed for a through hull transducer except for testing the install location. The water takes the place of the epoxy during the test.

 

[180Fisherman]

Re: bilge water and transducers

Interesting. I had always assumed that thru-hull transducers required a hole to be drilled with an external piece to the transducer. Never knew you just glued them down to the inside of the hull.

 

[dingbat]

Re: bilge water and transducers

Not sure why, if mounted correctly the transducer has a thin layer of epoxy filling any gaps between it and the hull so I'm not sure where the water would be to help it.

When a boat with a transom mounted transducer is on plane, only the face of the transducer is in water. You have to use a good location for a through hull transducer, and it needs to be glued down properly. If the desired location is tested first there won't be any surprises when its mounted.

Here is the manual for a Humminbird 610/610P depth sounder.
http://store.humminbird.com/media/document/hdr610.pdf
No mention about water being needed for a through hull transducer except for testing the install location. The water takes the place of the epoxy during the test.

In order for your transducer to work properly it must be perpendicular (conventional transducers are not to be mounted on anything more than a 10 degree deadrise) to the water. On mid to high performance applications this is typically done by mounting a tank to the bottom of the boat and hanging the transducer at the desired angle inside the tank. The sound is transmitted from the transdcuer to the hull via fluid with very little, if any, lose of signal.

To make up for the deadrise on an epoxy mount you will have to compensate by using a thick layer of epoxy on one side of the transducer which will greatly decrease the transducers performance. You are effectively putting a pair of ear muffs on your transducer.

Deadrise Angle
Be sure the transducer you have chosen is designed for your
boat?s degree of deadrise angle (see Figures 2 and 3).
Never use adhesive to fill gaps between the transducer and the hull since
this will greatly reduce the transducer?s performance (see Figures
2 and 4).

http://airmartechnology.com/uploads/installguide/17-010-01.pdf

 

[Ohioriver]

Re: bilge water and transducers

Interesting. I had always assumed that thru-hull transducers required a hole to be drilled with an external piece to the transducer. Never knew you just glued them down to the inside of the hull.

There are thru-hull transducers which you refer to, and shoot-thru hull transducers which they are refering to.

 

[Capt'n Chris]

Re: bilge water and transducers

Transducer type nomenclature:

Transom-mounted transducer: Transducer is externally mounted to the transom whereby the face of the transducer makes contact with the water. Typically, these are the most effective, the easiest to service, to adjust for an optimum sounding, easily replaceable and; of course, the most popular.

"Shoot-thru-the-hull-transducer: Transducer is mounted inside of the hull, usually in a bilge, sump or keel, permanently adhered to the hull or contained in a liquid reservoir. The sonar ping emitted from the transducer must penetrate a solid unblemished hull material to effectively record a sounding. The transducer has no contact with the water outside of the boat. These generally are installed to avoid having to drill holes in a transom below the waterline, for protection, and in most instances, will reduce the effectiveness of the sounding. Compromises are made in regards to eliminating a speed wheel, if equipped, recording water temperature and a reduction in sounding performance. This transducer is usually fixed with a bonding material and cannot be adjusted, serviced or changed without the likelihood of destroying it during removal.

Through-hull: Transducer is permanently installed in a "through-hull" hole whereby the face of the transducer is in contact with the water on the bottom side of the boat. It is usually faired to the deadrise so the its beam is parallel to the surface of the water. This transducer is fixed and cannot be adjusted. These are the most permanent of all types of transducers.

Captain Chris
SternMate?