I have a Hunter 34 with a fin keel. Anyone give me an idea as to which transducer would be better an in hull or thru hull? Also where would be the best location?
Thru hull or in hull transducer
- Thread starter Hans Baart
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They say you can silicone a transducer to the inside of your hull and the beam will go right through and read correctly so long as there are no air bubbles in the silicone. Some transducers work better than others with this method. A way to test is to fill a zip lock with water, grease up both sides and set it up like you are doing an ultrasound. If it works like that you can likely silicone it in place. If you epoxy it, it will be difficult to remove. But more permanent if that's what you want.
I think I would mount mine as far forward as possible, just try to aim it straight down(perpindicular with the seabed).
How to..
Installing the transducer in the hull works best if the hull is not cored.
I used a thru hull z transducer inside the hull.
Step 1: cut the bottom out of a large plastic cup.
Step 2: Tape the cup to the inside of the hull where you want to install the transducer.
Step 3. Squeeze a large amount of silicone into the cup.
Step 4. Place Transducer into the silicone.
Step 5. Tape transducer to the cup to steady it.
Much easier than installing a thru hull. It worked fine for years like this.
Installing the transducer in the hull works best if the hull is not cored.
I used a thru hull z transducer inside the hull.
Step 1: cut the bottom out of a large plastic cup.
Step 2: Tape the cup to the inside of the hull where you want to install the transducer.
Step 3. Squeeze a large amount of silicone into the cup.
Step 4. Place Transducer into the silicone.
Step 5. Tape transducer to the cup to steady it.
Much easier than installing a thru hull. It worked fine for years like this.
I have both - a factory installed through-hull Standard Horizon and an Eagle Chartplotter/Fishfinder with the transducer epoxied to the hull. Both seem to work fine and return similar depths. Speed is another matter as the factory Standard horizon paddle wheel seems to show a lot of variablility.
A couple of boats ago, I used an in-hull transducer puck with good results. While many suggest using epoxy, I decided to use silicone in the event I wanted to move the puck at some future date. I think an in-hull will work best on a solid fiberglass hull. I first tried to pick a spot a bit forward of the keel to get a clear shot at the bottom. I then sanded the inside of the hull to create a very smooth mounting location. Using modeling clay, I made circle a bit wider than the diameter of the puck on the mounting spot. Filled the circle with silicone, then sort of mashed it down and around with the back of a plastic spoon to get any ambient air bubbles out. Seated the puck and hit start. Was still working when I sold that boat 5 years later.
I have an Eagle fish finder/depth finder. What I did and it works perfectly is to set the transducer into the wax from a plumber's wax ring. I worked the wax with my hands into a glob the size of a donut. Then I pressed the wax against the inside of the hull then forced the transducer into the wax. I didn't believe it until I did it and it works great. Best of all there are no holes through the bottom of the boat. The only catch is my transducer transmit the water temperature. With this setup the temperature that is transmitted is the temperature of the inside bottom of the boat not the water temp.
Not sure
I have no first hand experience with this. My understanding is that the air in the coring material would prevent good signal transduction.
The eagle instructions said it wouldn't work through a cored hull, but I think (and I'm not 100% on this) that it did say that you could mount it against the outer hull if you wanted to take out some of the core material. Personally, I wouldn't try that, but your mileage might vary.
In hull installations for depth meter transducers definitely will not work through cored hulls. They have long been around (or the idea of installing them inside the hull has). Years ago they used to install them inside of a housing that held liquid, but modern through hulls are said to shoot through up to an inch and a half of solid fiberglass as long as there is no core and no bubbles in the lamination. And you also have to set it in silicone or epoxy as mentioned above with no bubbles.
If you have a cored material in the hull, it is not advisable to remove the core and then put in the transducer inside the hull because the thickness of the fiberglass is too thin. You would first have to build up a solid fiberglass lamination on top of the lower hull skin which lies beneath the core material. Same goes for a through hull installation in a cored hull. It is best to take a hole saw and cut through the upper fiberglass skin and through the core material, but not the lower fiberglass skin. Then you put alternating areas of glass and resin until it gets to the thickness of the entire cored hull. You can see from the bottom where the pilot drill hole was first drilled and use it as a spot to drill the new hole with a hole saw the exact size of the through hull transducer that you intend to use if a through hull installation. If you use a through hull type installation DO NOT USE SILICONE or 3M 5200. You want to use a polysulfide caulk such as Boat Life's Life Calk, or 3M's 101 (not an adhesive type caulk). And silicone is not recommended under the waterline.
The location of a through hull should be as far forward as possible and closest to the keel line (right on, if possible). That way you can expect similar readings on either point of heeling. You also have to consider the inside location. You want it hidden and not sitting where you walk. If it is a through hull install, then you want to be able to get at it to examine the water integrity of the installation. I have installed hundreds of through hull transducers and never had one leak (if done properly). So, I am not afraid to use through hulls. Also, if you install it through the hull, it doesn't stand so proud on the inside of the hull (it has a lower profile) and there is no risk of toppling it over if something hits it (though that is usually not the case if you epoxy it in place - you just cannot remove easily or without destroying it).
If you have a cored material in the hull, it is not advisable to remove the core and then put in the transducer inside the hull because the thickness of the fiberglass is too thin. You would first have to build up a solid fiberglass lamination on top of the lower hull skin which lies beneath the core material. Same goes for a through hull installation in a cored hull. It is best to take a hole saw and cut through the upper fiberglass skin and through the core material, but not the lower fiberglass skin. Then you put alternating areas of glass and resin until it gets to the thickness of the entire cored hull. You can see from the bottom where the pilot drill hole was first drilled and use it as a spot to drill the new hole with a hole saw the exact size of the through hull transducer that you intend to use if a through hull installation. If you use a through hull type installation DO NOT USE SILICONE or 3M 5200. You want to use a polysulfide caulk such as Boat Life's Life Calk, or 3M's 101 (not an adhesive type caulk). And silicone is not recommended under the waterline.
The location of a through hull should be as far forward as possible and closest to the keel line (right on, if possible). That way you can expect similar readings on either point of heeling. You also have to consider the inside location. You want it hidden and not sitting where you walk. If it is a through hull install, then you want to be able to get at it to examine the water integrity of the installation. I have installed hundreds of through hull transducers and never had one leak (if done properly). So, I am not afraid to use through hulls. Also, if you install it through the hull, it doesn't stand so proud on the inside of the hull (it has a lower profile) and there is no risk of toppling it over if something hits it (though that is usually not the case if you epoxy it in place - you just cannot remove easily or without destroying it).
Hans...
My H34 has the DF transducer mounted through the hull on the centerline ahead of the keel. It gives you about a fraction of a second warning advantage over any other location just before you run aground.
There is a Beckson access port above them in the v-berth cabin sole, about six inches forward of the bulkhead/door frame.
As pointed out, a internal silicone mounting would be one less hole thru the hull to worry about.
My H34 has the DF transducer mounted through the hull on the centerline ahead of the keel. It gives you about a fraction of a second warning advantage over any other location just before you run aground.
There is a Beckson access port above them in the v-berth cabin sole, about six inches forward of the bulkhead/door frame.
As pointed out, a internal silicone mounting would be one less hole thru the hull to worry about.
Personally mount them through the hull. Its no big deal to do it. 2" hole saw and some 5200 and a plywood backer and your good as gold. Now...for those of you who insist on mounting a depth transducer infront of your keel, let me ask you a question. i have a 38 foot sloop. It is aprox. 10 feet from the bow to the leading edge of the keel. Can you stop your boat in 10 feet if you pick up a submerged object? My boat has a displacement of 20,000 lbs. I know I can't. Bottom line, mount it where it is easiest to get to for maintaince and emergencies. Also there are alot of new transducers that are tri-ducers with speed, depth and temp all in the same hole.
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