Installing transducer in Hunter 216

[Ed_S]

I'd like to install a depth through hull transducer in my Hunter 216

Background: The 216 hull is composed of plastic outer, foam core and fiberglass inner.
An in-hull transducer will not work though the foam core based on tests and input from Hawkeye.
Hawkeye recommends the transducer be installed 6" forward of the centerboard but the floor steps up
and is quite thick to install the transducer.

Two questions I would appreciate input on:
Can I mount the transducer aft of the centerboard without significant turbulence interference?
What precautions do I need to take to seal the foam core to ensure that I do not cause
leaking between layers of the hull after drilling for the transducer?

Thanks for taking the time to read this and any insight you can provide

 

[CloudDiver]

I don't think that the installed transducer will protrude enough from the hull surface to cause any kind of turbulence. The recommendation on installing forward of the CB pretty much has to do with being centerline and at the lowest point. Someone correct me if I'm wrong, but I doubt hydrodynamics behind the CB would effect the signal and return. I've seen many, including in my own hull, transducers mounted left or right of center because that's the easiest area to access.
The foam in the core should be non-reactive to adhesives, i.e. it won't dissolve in epoxy or polyester resin, or an adhesive/sealer like 3M 4200. You should be fine drilling the appropriate mounting hole, sand away the bottom paint around the flange profile, and mounting with the recommended adhesive/sealer. If I wanted to be 100% sure I would never get leakage that wet the core material, I'd overbore the mounting hole by 1/4", then fill it with epoxy resin slightly thickened with microfibers. Then re-drill the hole to the correct mounting size leaving you with a nice collar of solid epoxy that seals off the core material. This is somewhat more labor intensive, over-engineering at its best, but also saves you the step of sanding the bottom paint away from the flange.

 

[Ken Cross]

The speed of water has no bearing on transducer performance because you are looking at the speed of sound through water (much faster than through air) compared with the speed of the water traveling near the transducer. The thing you would want to avoid is air introduced into the water. That's not likely at the speeds I travel. Even some air wouldn't be a problem. Some sounders work on speedboats at 50 kts. My boat has the transducer at the bow and a fish finder transducer near the stern. both places work well.

Ken

 

[Crazy Dave Condon]

AS you said, this is a composite plastic reinforced with construction style foam for structural integrity and flotation. However, as a dealer, I would not install thru hulls for many reasons to first include a good addhension to the hull material and that includes 5200 as well. Then there is the thought of damaging the foam as well. Now I may be wrong but I would tend to think that this would be a question for posting in the smaller hunter section with attention to 216 owners and one I would ask is CHUCKWAYNE to get in on this. I am not sure if he ever installed a thru hull style.

Not sure if a puck style on the transom would work.

 

[Ed_S]

AS you said, this is a composite plastic reinforced with construction style foam for structural integrity and flotation. However, as a dealer, I would not install thru hulls for many reasons to first include a good addhension to the hull material and that includes 5200 as well. Then there is the thought of damaging the foam as well. Now I may be wrong but I would tend to think that this would be a question for posting in the smaller hunter section with attention to 216 owners and one I would ask is CHUCKWAYNE to get in on this. I am not sure if he ever installed a thru hull style.

Not sure if a puck style on the transom would work.

Thank you for your input. I will follow up with CHUCKWAYNE

 

[Ed_S]

Top

Quote:
Originally Posted by Crazy Dave Condon
AS you said, this is a composite plastic reinforced with construction style foam for structural integrity and flotation. However, as a dealer, I would not install thru hulls for many reasons to first include a good addhension to the hull material and that includes 5200 as well. Then there is the thought of damaging the foam as well. Now I may be wrong but I would tend to think that this would be a question for posting in the smaller hunter section with attention to 216 owners and one I would ask is CHUCKWAYNE to get in on this. I am not sure if he ever installed a thru hull style.

Not sure if a puck style on the transom would work.

Thank you for your input. I will follow up with CHUCKWAYNE

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[Chief RA]

ED_S: It will cost you little to test an inside mount system in your boat. Take the transducer and put it in toilet bowl ring wax inside the hull bottom and test it. Move it to several places to test. You can also use a zip lock bag of water and press the transducer firmly down on it while in a bottom spot. I expect it will work fine. Do not forgo this test just because someone thinks it won't work!
Merry Christmas, Chief

PS: Transducer mounting on the transom of a sailboat usually will not work well as the transom lifts out of the water a lot.

 

[Jackdaw]

ED_S: It will cost you little to test an inside mount system in your boat. Take the transducer and put it in toilet bowl ring wax inside the hull bottom and test it. Move it to several places to test. You can also use a zip lock bag of water and press the transducer firmly down on it while in a bottom spot. I expect it will work fine. Do not forgo this test just because someone thinks it won't work!
Merry Christmas, Chief

Chief,

That trick only works on a solid glass hull. The 216 is cored.

 

[Chief RA]

Jackdaw: I know, but I would try it anyway as it cost little or nothing to try. Many of todays sonars produce so much power that it may work fine. It will depend on styrofoam core thickness and if it attenuates the signal too much. My current fishfinder is so powerful it can detect crabs crawling on the bottom! Don't forget, I have sonar experience and education, so trust my 50 years in the field. Chief

 

[Ed_S]

Jackdaw: I know, but I would try it anyway as it cost little or nothing to try. Many of todays sonars produce so much power that it may work fine. It will depend on styrofoam core thickness and if it attenuates the signal too much. My current fishfinder is so powerful it can detect crabs crawling on the bottom! Don't forget, I have sonar experience and education, so trust my 50 years in the field. Chief

I have tested the Hawkeye in hull transducer in several places in the hull with petroleum jelly between the transducer and hull as Hawkeye recommended. The transducer is not strong enough to transmit through the hull. This why I'm considering the through hull transducer.

 

[Chief RA]

OK, I would CONSIDER only cutting through the inner liner and remove the core. Test both materials with silicone to be sure of no reaction and probably will not be. Inject a layer of silicone if needed for strength increase behind the outer layer. Use toilet bowl wax and fill rest of hole area with it. Press the transducer firmly into it. Now it should transmit fine through just one layer with or without the silicone. Trying to help so you won't have to cut a hole all the way through. Also wise to get feedback from the man Dave suggested as well. Have a beautiful Christmas day! Chief

 

[Chief RA]

Last resort, consider transom mounting even if it has its limitations. You could place it on an underwater extension if necessary to get it low enough.
I have never used petroleum jelly as a transmission medium so would feel more confidence in wax or bag of water for hull tests to insure no air bubbles.
Still trying! Chief

 

[Joe2954]

Does the foam core extend the entire length? On a mac26c the aft locker floor was single layer fiberglas. I had good luck epoxying a flat spot then sticking the transducer to it first with plumbers putty then later with rtv.
If you press down hard enough with any substance, the sound transmissions are not dampened much over the short distance.

 

[Jackdaw]

Jackdaw: I know, but I would try it anyway as it cost little or nothing to try. Many of todays sonars produce so much power that it may work fine. It will depend on styrofoam core thickness and if it attenuates the signal too much. My current fishfinder is so powerful it can detect crabs crawling on the bottom! Don't forget, I have sonar experience and education, so trust my 50 years in the field. Chief

Chief,

It does not surprise me at all that the OP failed to get the sonar to work thru the cored hull.

As you know, sonar waves are tuned to radiate well through their intended medium, water, typically at 50-200kHz. This ability to radiate has to due with the density and compressability of water, or any material with similar characteristics. Too dense, it reflects. Not dense enough however, it is severely attenuated. Fiberglass has a very similar density to water, so that works. The bottom reflects, that the desired effect. But air and foam and very soft wood attenuate the signals to the point that the device is ineffective.

 

[Chief RA]

Jackdaw: I know these things as well but it is best to just try. The alternative is a lot of work and worry. This all depends on what substance was used for core. Thats the major factor here. All I wanted to get him to try is the best transfer media test he could to be SURE he could not transmit through it. I indeed am not convinced that I could not get a signal through the substance were I to get a chance to test. Any method he can use, to me, would be better than cutting through the hull! Just offering alternative avenues. Chief

 

[Crazy Dave Condon]

Unless you have owned what I referred to the plastic boats, you will understand my concerns. Chief, this is a different material and has its drawbacks. This is not cored nor is it glass. I introduced these boats and again sold the most. I simply go back to experience.

In addition, a fixed thru hull could also eventually cause the hull to crack which I have seen as well with a thru hull.

 

[Chief RA]

Crazy Dave & ED: I didn't recommend a through hull either. I am aware it is a different plastic boat but earlier reports said it had a core with 2 ply. With one ply and no core it should be easier to penetrate the sonar signal through it somewhere in that hull. Vaseline is NOT dense enough to make a good temporary transfer media to test locations for using a transducer. I much prefer a ziplock bag of water with someome watching for signals on the screen. This can't be effectively done unless the boat is in the water.
Dave, what sonar transducer is effective for this boat? It is conceivable that this perticular sonar unit does not produce a strong enough signal for this material.
Chief.

 

[Jackdaw]

Dave,

While you are correct it is not technically cored (even though Hunter described it that way); it would be more correctly described as a laminate as the inner and outer materials are different. But it has the same effect as traditional core between glass; it is structural foam sandwiched between fiberglass and APC (BASF Luran S). But in any case there is no way an accoustic sonar transducer can shoot through that foam.

 

[Rick Webb]

For What it is Worth

1. Vaseline does work not only as a temporary method but semi permanent one as well, one glob on mine lasted years to hold the puck. I could get depths of up to 30' after that who cares?

2. I would not put ANY additional holes in one of these hulls, including a hole for the display unit. I would try to make a bracket that fastens to the lower gudgeon and hang the puck off the transom.

3. Do you really need a depth meter? Mark your paddle in 6" increments if your curious how deep the water is. I do not think depth is an issue until your in less than twelve " of water and then you just get out and push. Mine depth meter I think works but the sun beat it up so much I can't read it so I have not replaced it. Our area is pretty clean sand, I know other areas I would not be as inclined to do the same thing.

Just another perspective to muddy up the options.

 

[Chief RA]

30' is not considered to be an adequate depth for max reading! If I were you I would sure keep using that Vaseline! Chief