32XX: Advantages in-hull or thru-hull transducers for chartplotters?-gctid404686

[Guest]

I do not understand the +/- of these two types of transducers. Is a thru-hull type going to be more consistent and reliable than an in-hull version given the hull construction of the 32's?

This would be for something like a Garmin 441s (though I'm open to suggestions on a different model/brand at the lower price range as well) or the like and used in salt water. Does it merit drilling the hole in the hull? I'm not that much of a fisherman, so accurate depth readings would be the emphasis if that plays. Your comments appreciated, Dean

[mmichellich]

Why does a chartplotter need a transducer. Chartplotters need a gps??

[Guest]

mmichellich wrote:
Why does a chartplotter need a transducer. Chartplotters need a gps??

If I'm misstating it , sorry. I mean a GPS with depthsounder.

[Guest]

I'd be really interested in hearing what everyone thinks as well. We're about to purchase a new sounder/gps plotter and would like to avoid pulling the boat from the water if possible. I haven't heard much about the in-hull's but i haven't heard anything negative.

[Guest]

For what is worth... I have two through hull ducers. One original, one i had installed expensivley with the fairing block, done professionally to go with a garmin unit, temp, depth and paddle for speed over water. This failed transducer failed out of warranty, and i never replaced it due to the expense involved. Plus the water paddle style really should not be used in salt water due to growth that you cannot keep up with. So recently I again upgraded to a new Garmin for the bridge and it came with a small dual freq transducer. I tried "shooting" itthrough various points in the hull, being cognisant of keeping it a distance from the original through hull, but couldnt get a relaiable signal. Finally I strapped it with cabke ties to an aluminum flat stock bar, and fashioned it to hang over the support below the diamond plate in the bilge. My bilge water never has oil or contaminants, simlly a small amount of seawater/freshwater below the stripping pump. This has worked exceptionally during this summer. I keep an eye on it when down there, but have found no reason to not leave it in place. If you use or need a absorber sock in the bilge, i would keep an eye on it so that you are not preventing in to move or move the sounder.

[SomeSailor]

A true thru-hull has the advantage of not having to deal with the insulation properties the fiberglass will introduce. For a simple depth finder, this isn't a problem. If you're looking for fish, I would opt for a through hull. Also... with the Airmar units, the paddle wheels are removable in the water so marine growth is not a problem.

[ksanders]

SomeSailor wrote:
Also... with the Airmar units, the paddle wheels are removable in the water so marine growth is not a problem.

Mike, I cant wait to clean my paddle wheels. :arr

Pull the unit out, and it'll be water everywhere. I have the plugs for the transducers next to them already but am still too nervous to give it a try.

[SomeSailor]

I almost sank my 2859 over one of those. We were stored on the hard at Dagmars (dry stack marina) and unbeknownst to us, the lift driver inadvertently sat the boat down on the transducer after a trip we made. He realized his mistake just after it touched and repositioned the boat. His visual inspection looked good so he thought no harm, no foul.

I went out a few days later and didn't check the bilge after startup and launch and some hours later was surprised with a foot or more of water in the bilge. It cost me a starter and a new gimbal bearing (that I had replaced only days earlier), but learned as lesson that day.

As far as the water coming in... it's a small amount and under hardly any pressure. With my Airmar, they provide a dummy plug (no wheel), you can install while you have the paddle wheel out. DC plug or a gob of beeswax would work as well.

[Uncle_Bob]

An electronic guru told me using a through-the-hull rather than a through hull was like driving through a puddle. In spite of that, I plunked my through-the-hull in a blob of silicone near the water pick-up for the head (in the cave) and hit bottom over 1000' with well defined fish reflections under 500'. The factory Bayliner through-the-hull is forward of the engine but the cave worked. I was warned that silicone breaks down and epoxy is better and sure enough a few years later the sounder quit so I scraped off the silicone and used epoxy. It still works fine 20 years later.

[Guest]

While I have your guy's eyes on this, I will post a photo tonight of what I have for transducers. I have one of each- in hull and thru hull. Neither are consitent readers and seem to screw up (a depth value I know is incorrect or flashing indicating loss of signal at a depth that this should not occur like in Quartermaster at Vashon) which is why I'm trying to purchase a new one immediately. I called Hylebos and they had a cancellation so I pulled it this morning and want to get back in middle of next week. I obviously need to do a thru hull now if I'm going that route. I'd like it to be as good as possible, but fish is really secondary for me at this time (subject to change as soon as I pick a path).

Given EVERYTHING that goes up to the flybridge on the 32's routes through the chase adjacent to the lower helm, has anyone tried a different routing of transducer or other wiring to avoid possible signal interference ? Or given it's shielded cable it's not usually a consideration? The manual on the existing units says to avoid such routing. I've pulled the transducer cable back, and routed it externally on the boat to test, but now I"m on the hard so too little, too late for such testing. Just thought I'd ask while I'm at it- Dean

[Guest]

why not mount it on the transom... some of the units I have looked at require this application.

[Guest]

I have the Airmar P79 shoot thru transducer onboard, and it works great. I get a clear picture to 500+' at speeds from a slow crawl to WOT (about 24 knots). I didn't want to haul the boat to replace an existing thru-hull, so I researched the shoot-thru option and went in that direction. I get excellent bottom definition, including suspended fish and structure.

No regrets.

[Guest]

In theory, a thru-hull in a clean stream of water will provide the best picture... in practice, shoot-thru, thru-hull and transom-mount transducers all perform very similarly. The main thing is they need a clean, unobstructed view of the water... for a shoot-thru, this means mounting it only above solid fiberglass. For all types, this means mounting it as far away from anything which causes cavitation ahead of the transducer, like a step, chines, prop pockets, etc.

For simplicity's sake, I always use a transom-mount and get good performance.

I'd recommend the Lowrance HDS for a starter unit (yet quite powerful) or a Simrad NSS or NSE for a high-end. They're all extremely easy to use, fast, and have great sounders, broadband radar which cannot be beat for close-in performance, etc. The transducer which comes in the packages (HST-WSBL) provides more than adequate performance - I don't fish, I use it solely as a depth finder/sonar, but it works very well.

[Guest]

Pull the unit out, and it'll be water everywhere. I have the plugs for the transducers next to them already but am still too nervous to give it a try.

Piece of cake Kevin. The water pressure is only a few PSI (if that) at the thru-hull. It's more of a burble than a fire hose...You'll have plenty of time to install the plug before anything bad happens.

Multiply your draft (at the thru-hull) by .4331 to calculate the PSI. Example: Draft 3' = PSi 1.3 (rounded up). A baby could do it.

[mmichellich]

Our 47 came from the factory with a hocky puck Lorance depth transducer installed with a worthless digital depth meter. I had a bronze through hull installed just in front of the stbd engine. I have a commercial grade Furuno depth sounder installed with the bronze through hull. It will read to 1000-1200 feet. I purchased a factory rebuilt Lorance depth sounder to replace the digital meter on the bridge. This was a cheaper version of the Lorance but had a large power out. With the hocky puck glued to the hull inside with 3M5200 (from the factory) the bridge Lorance reads reliably to 600 or more feet, 800 if the bottom is rock. If you can find the right spot to install a transducer inside, it should work just fine.

On our old 38 I wanted a good quality depth sounder and did not want to haul the boat for a through hull transducer so I installed the sounder head and placed the transducer at the bottom of the keel which always had a bit of water in it that the bilge pump would not remove. I blocked it in position with a couple of diving weights and it worked perfect for the 5 plus years we owned our 38. The transducer was a good quality bronze through hull transducer but just laid on the bottom of the keel with a bit of water over it. Over the years it ended up having all kinds of bilge stuff over the face including oil, etc. and it always worked.