Ron:

back in 1996, on my 1993 330DA, my thru hull ducer quit in June. Al Gore's internet was still in it's infantile state, so getting a replacement was a bit of challenge back then, and we were going on trip down the ICW....inside all the way.....to Cape May. As you know, you MUST know the depth there. Anyway, the local shop had one of those 'in hull' hockey pucks in stock, so I bought and installed it. That thing worked great for the next four years. It's probably still working now.

That's only my experience........and YMMV....but it sure worked well for me.

 

I think it mainly depends on the placement. As long as your selected location is good solid fiberglass, there's no reason it should be any less effective. I've seen it stated that they have an advantage in that there is no additional turbulence created by the external puck.

Personally, I installed an Airmar P-79 (mid-grade model) to use with my Garmin FF and it holds just as well at all speeds as the OEM Lowrance DF.

 

ok, that sounds good so far. do you guys remember how it is mounted? does it use adhesive? must it be mounted in a bone dry portion of the bilge? to be honest i'm dreading fishing wires up from the bilge to the flybridge - i guess i could just attach to the existing wires and pull up (or down). anyone familiar with this unit?

http://store.humminbird.com/humminbird-products/depth-sounders/hdr-610-p/prod406480-1P.html

seems pretty inexpensive - does that mean you get what you pay for?

ps: dom, did you make the trip to cape may ALL THE WAY ON THE INSIDE!??!!?? were there any points you had to get out and walk??

 

From memory, and remember, I'm old, you first put the 'puck' in a baggy filled with water, plug it in and then test around the bilge floor for good readings. The directions will give you the tips/tricks I'm sure. The one I had came with an adhesive, probably water based and that's why they have you test it in a baggy filled with water.

Running the wire to the helm area is always the worst part! Using the old wire as a drag is a good way to do it. Just add an extra string to the new wire so that you will then leave a drag for future use.

ps: dom, did you make the trip to cape may ALL THE WAY ON THE INSIDE!??!!?? were there any points you had to get out and walk??.....

That was our first trip down there....and it was 'challenging' at many times. We did see, and funny 'you' should ask....I have the still pics home some where...again, before the internet and digital cameras.....a 340DB that ran aground. He must have run aground at high tide (the worst) because his boat was completely out of the water. His crew were actually sitting on lounge chairs around the boat....probably a mutiny..

 

The housing mounts directly to the bilge - seems they change adhesive recommendations regularly so you'll have to verify that with the model you get. You then fill the 'cup' with a fluid - again it has changed several times over the years but I think they're recommending anti-freeze now.

It does not have to be in a 'clean' spot -in fact it might give better performance in a normally wet spot. But you will need to have it clean and dry for the initial installation (gluing) obviously.

I'm not familiar with Hummingbird's transducers, but most mfgs use ones made by Airmar. You will find a wealth of info on their website - www.airmar.com

 

I’ve installed two of these in previous boats and both worked great. The downside is all you can get through the hull is depth – no speed and no water temperature, unless you want temp inside the bilge.

Because they operate using sonar, air is a problem for the transducer. You must select a spot on the hull that is not cored and has solid fiberglass. Likewise, the epoxy you use can not have air bubbles in the mix.

To locate the spot what I did was put about 6” of water in the bilge, set the puck in position under water and hold it down in place with some old barbell weights while going for a test drive.

 

In-hull ducers lose about 30% of their useful range but they don't lose any clarity (in Fishfinder applications). Otherwise they are great. All the advice above is good. Those Humminbird units work fine. There are LOTS of options, this HB unit is probably the least expensive approach.

 

There is usually a choice of wide and narrow angle transducers. Wide angle would be wise choice for epoxy installation.

 

Why :huh:

 

Jim, I have the Garmin 430x. I also have the in hull dual beam transducer. With this plotter do I have to get the GSD-21 sounder module or just get a different cordset to hook the transducer to the plotter? Garmin isn't very clear on this in the manual.

OOOPS, sorry Rondds I don't mean to highjack with this question it just popped into my head while reading this thread...

 

hey riverrat - IMO, there's no such thing as a hijack - it's just more information added to the till! besides, i've gotten great info so far - my questions have been answered swiftly and efficiently from my great fellow SR owners, as is the norm. thanks to all for the responses.

 

Riverrat,

'Transducers' are made up of a piezo-electric crystal that is suspended in a plastic block. In the case of a through hull the crystal is orientated to compensate for the deadrise angle of the hull. Basically you buy the through hull that matches your deadrise.

Becuase the actual mounting location of an in hull transducer may not be known until the moment of installation, and the published deadrise angle is of the exterior of the hull (the angle inside may be different), in hull transducers have to be a one size fits all. They are set up with the crystal being straight, but the housing being adjustable. Case in point the Raymarine / Airmar P-79 where the housing is designed to be turn to point the transducer in the correct direction after the inside angle has been determined at the location of installation.

As for the comment about wide angle beam vs narrow angle, I seem to recall that for the same wave frequency a narrow beam would provide a stronger signal and thus provide a better peek at deep water when shooting through an inch or so of fiberglass.

Henry

 

Might be prudent to clarify, there are 2 different 'philosophies' when referring to in-hull transducer mounting.

1. Some transducers, such as the P79 mentioned several times in this thread are specifically designed to be mounted in a bilge and actually sit in a 'cup' of fluid. These have markings on the cup that allow you to mount them properly with respect to various angles (deadrise) so that the puck is basically level. The actual fluid recommended varies and correlates to the type of adhesive used (which varies as well).

2. Another method is to just epoxy a transducer directly to the inside of the hull. In this case, you can use other types of transducers such as thru-hull or transom mounts. You just have to make sure your epoxy is mixed and spread well so that it does not have air pockets (bubbles). Because the puck is usually mounted at an angle, this method can produce less accurate results - more so as the water gets deeper.

Edit: Apologies to Henry for restating some of his post - just trying to be clear.

 

No need to apologize, I should have mentioned the liquid bath. That by the way can be a source of endless irritation if the adhesion/seal is less than perfect as one of the liquids used is mineral oil.......

Henry

 

The SR depth guage in my 38 is next to worthless as displayed on the Smartcraft, erratic readings all the time. I have been considering installing the RM fish finder/sounder module that will interface with the E120 display. Will this work in a thru hull (actually I mean in-hull...sorry) configuration. Anyone done this on a newer SR, seems they have a liner in the engine bay and not sure where to place the transducer.

I'm thinking about getting a RM radar from Jim and if I can install the fish finder/sounder without poking a hole in the hull, may get this as well for a nice summer DIY project. Don't really care about the signal loss as we boat in the gulf and rarely see more than 30' depth.

Thanks,

Mike