Depth Sounder Questions

[mikep.]

I am gearing up to drop my first boat in the water finally. Being completely new to boating and on a smaller lake, I was thinking about a depth sounder. I understand that there are two different mounting options for the transducer. I am looking for any input or advice on either. I wanted to get one that that could be mounted in the dash. I will probably have it in a pod this year, but wanted to redo the dash next year anyway.

Thanks in advance.

 

[Texasmark]

Re: Depth Sounder Questions

Hummingbird and Lowrance make them and have been around for years. Directions come with the units.

 

[Philster]

Re: Depth Sounder Questions

Through-hull transponders are good when there is no wood as a core material, but I've see it work anyway.

I believe transom mounts, because they shoot right into the water, are always best, but if your fiberglass boat has no wood as a core material, through-hull is acceptable.

 

[mikep.]

Re: Depth Sounder Questions

Where is the normal place to mount the through hull ones? Is the engine compartment acceptable? My boat is fiberglass, besides the keel strip, there would be no other wood to pass through. I saw a hawkeye that I liked. Anyone running one?

 

[haulnazz15]

Re: Depth Sounder Questions

I would go with the transom-mount type as well. Humminbird and Hawkeye both make a unit for $100 or so, but I prefer the look of the Humminbird myself. The Hawkeye buttons seem less durable to me, but again, it's personal preference.

 

[Philster]

Re: Depth Sounder Questions

Where is the normal place to mount the through hull ones? Is the engine compartment acceptable? My boat is fiberglass, besides the keel strip, there would be no other wood to pass through. I saw a hawkeye that I liked. Anyone running one?

The bilge area is preferable, which is essentially the bottom of most engine compartments.

 

[UncleWillie]

Re: Depth Sounder Questions

The through hull mounting always sound like a really neat and clean idea. Except....

You need to mount the transducer on a piece of hull that is guaranteed to still be in the water at speed.
This generally means right next to the keel and just forward of the transom.
On a small single engine I/O Boat that may mean pulling the engine to get access to the mounting location.
The transom mount starts looking better all the time.

A factory installation happens before they install the engine.
Twin Engines usually have that area accessible.
Outboards avoid the issue altogether.

How are you powered?

 

[mikep.]

Re: Depth Sounder Questions

I have a 18.5 foot rinker with a single 4.3l i/o setup. There is a factory swim platform that is part of the body. The transom has an angle to it except in the center where the gimbal area is. My concern is mounting it too close to the prop.

 

[kahuna123]

Re: Depth Sounder Questions

Hummingchicken and Lowrent are good a Kmart and Wallyworld and will probably be all you need. If you think that any depth finder is going to save you from running aground they won't. By the time they tell you its too skinny its too late. Its not radar. It read whats under the boat. And running it reads what 20ft behind the boat. If you want the finder to work at speed it needs to have clean water in front of it. In other words no turbulence no air bubbles. For what you are doing a transom mount is probably fine. Just make sure its not behind a strake. Mounted in the hull means it will never get wiped out by anything in the water. Your trailer bunk. Or someone trying to use it as a step. But, it needs to be mounted correctly to work right and you cant have a cored hull half full of water

 

[mikep.]

Re: Depth Sounder Questions

Hummingchicken and Lowrent are good a Kmart and Wallyworld and will probably be all you need. If you think that any depth finder is going to save you from running aground they won't. By the time they tell you its too skinny its too late. Its not radar. It read whats under the boat. And running it reads what 20ft behind the boat. If you want the finder to work at speed it needs to have clean water in front of it. In other words no turbulence no air bubbles. For what you are doing a transom mount is probably fine. Just make sure its not behind a strake. Mounted in the hull means it will never get wiped out by anything in the water. Your trailer bunk. Or someone trying to use it as a step. But, it needs to be mounted correctly to work right and you cant have a cored hull half full of water

I realize that it isnt really designed to keep me from hitting something, especially at speed. But I wanted it more for peace of mind and to familiarize myself with the lake.

 

[kahuna123]

Re: Depth Sounder Questions

And yes it will give a reading if you are at idle or moving very slow that will give you an idea of how safe you are or start showing a trend of getting too shallow to be safe. It will show you deep and shallow. The point I was trying to make is if you are running and all of a sudden its showing too shallow its too late.

 

[UncleWillie]

Re: Depth Sounder Questions

I have a 18.5 foot rinker with a single 4.3l i/o setup. There is a factory swim platform that is part of the body. The transom has an angle to it except in the center where the gimbal area is. My concern is mounting it too close to the prop.

Mounting it low and close to center is fine.
With an I/O, the prop is so far behind the Transom that it does not become an issue.
The issue is with outboards mounted between hull extensions.
A transducer mounted to the hull extension ends up right next to the prop.

It needs to be in clean flowing water with nothing below or directly next to it.
What's behind it is not a concern.

 

[Pez Vela]

Re: Depth Sounder Questions

I understand that there are two different mounting options for the transducer.

Three: Thru-hull (requires a hole in the hull bottom), Shoot-thru-the-hull (mounted inside the hull and the sonar impulses must "shoot-thru" the hull material, so cored bottoms are out), and last, transom mount, as the name implies. As with everything in rigging a boat, gaining access to a desired mounting location is often a deal breaker. You really need to understand your own hull configuration, because some hulls do not lend themselves to a "clean" transom mount.

 

[mikep.]

Re: Depth Sounder Questions

Mounting it low and close to center is fine.
With an I/O, the prop is so far behind the Transom that it does not become an issue.
The issue is with outboards mounted between hull extensions.
A transducer mounted to the hull extension ends up right next to the prop.

It needs to be in clean flowing water with nothing below or directly next to it.
What's behind it is not a concern.

That makes sense.
Is there anything besides the obvious to do/not do, when it comes to drilling through the transom?

 

[UncleWillie]

Re: Depth Sounder Questions

Put tape flags on the drill bits as a depth stop.
There is no sense in drilling any deeper than the screws.
Do not drill all the way through the transom if the screws are not going to come out the other side and fill the holes up.
You will just end up with a hole on the inside of the transom that will leaks water into the wood of the transom core.
If you do end up drilling all the way through, be sure to seal the inside holes when you are finished.