Bronze thru hull transducer

[Robl]

I get that this is not ideal due to electrolysis however I can't find a plastic housing through hull for my HDS10. Do any of you run bronze thru hulls? This is a freshwater boat with no ac power. Better yet anyone know of a plastic thru hull that does 50/200khz and 455/800khz?

[Supersport18]

http://www.imarineusa.com/AirmarP319-DT ... AtU48P8HAQ

[barkleydave]

Nice find!
You may also use the bronze: most our boats have bronze engine thru hulls. They must be isolated from the hull. A piece of mylar or similar insulating material on both sides works well.

FYI: Just for the record: There is and will always be confusion regarding our aluminum boats and galvanic corrosion. AC power is not a major factor in this process. DC power leakage (which is also in all AC circuits) needs to be filtered out by a Galvanic Isolator or Galvanic Transformer. Also even with NO DC leakage galvanic corrosion is a natural process of disimular metals sheading electrons to protect the more noble metal. Aluminum becomes the Anode and the bronze fitting becomes the cathode. The Anode become sacrificial. I personally use an additional Mag. anode I hang over the side at the slip. It adds additional protection from other "dirty" boats that may be moored near me.

Safe Boating,
dave

AC leakage is the dangerous only .65 amp of ac can kill someone!

[Robl]

I already own the bronze through hull that does what I want, so that would be easiest. Isolating with Mylar, just a ring or larger? It has a plastic fairing that goes on the outside of the hull that will isolate. What about where it passes through the hull? Should I do something there as well?

That plastic through hull will not do the frequencies im after, thanks though.

[barkleydave]

must not touch hull. Oversize hole and bed with 3m 5200

[bcassedy]

2nd Dave's comment.

3M's 5200, being viscus by nature, can allow lateral movement if there is that. And an oversize hole could allow for that making contact by the transducer to the hull a (remote!) possibility. You could prevent that by finding a rubber O-ring that would fit over the transducer's body BUT fit inside the oversize hole so that it becomes something of a grommet w/o flanges. When you tighten up the holddown nut the 2 gaskets, coated with 5200 will squeaze that 5200 in and around the grommented hole. The "grommet" will keep the transducer body from making any contact. Won't matter if the O-ring (grommet) is as thick as the hull material: The 5200 will fill in the space. Use it (5200) liberally).
This is a depiction of what I mean:

[barkleydave]

That surely would help. I did one several years ago on mine. First I coated the portion of transducer that went through hull. Let is cure for 24 hrs. then LIBERLY APPLIED and applied to hull both sides and the insolation plates and let sit for a a few hours to start a cure then snugged them tight. Been 10 years now and no continuity. Once 5200 cures it is tough stuff!

safe boating,

dave

[jralbert]

Be aware, as hinted just above, that 5200 is almost forever. I once saw a piece naming a solvent but I've forgotten it's name. There's a sealant, 4200, I think, that holds and seals just as well but is more flexible and much easier to cut free.

[Robl]

Thanks for the info guys!

I have 4200 fast cure for the job because I lack confidence in a modern electronic lasting a long time. The o-ring trick is a great idea. I was thinking of using liquid electrical tape where it passes through the hull but that's a much better idea.