OK, I'll be the first to admit it...I'm stoopid...I've never needed to install a depth finder before, and the product descriptions of the transducer are confusing me. There's a transom mount, an in hull, and a thru hull. The in hull model mentions "gluing," and it seems like they are saying it is glued to the **inside** of the hull? Huh? I thought all depth finders needed a thru hull fitting, but there is nothing clear about this on the sites I've looked at. As far as the use, I really need this thing to navigate the channel from my dock out to the Trent River in New Bern, NC...I don't need to map the bottom of an ocean trench. And I understand various transducers do better at various depth ranges, so it's a good idea to know what you are buying so you get the one for the application...and I need something that is best at shallower depths. This'll be used on my Cat 22. If someone has the time to educate me or give me a link to a site where I can learn about this, I'd really appreciate it. Thanks, Eric
Depth sounder (finder) transducers types?
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Inside works fine ...
The inside hull transducers work just fine on solid FG hulls (like Catalinas). The transducer sends sound through the water and listens for the echo. They will work just fine though FG too (not quite as well as a through hull transducer). Mine works to about 300' or so. All you need is a spot to glue it. Don't use silicone or any flexible caulk, use epoxy or something else that will get hard when it sets up. (Silicone absorbs some of the sound and reduces the performance). Fill a freezer bag with water and set the transducer on the bag against the hull to test before you glue it in.
The inside hull transducers work just fine on solid FG hulls (like Catalinas). The transducer sends sound through the water and listens for the echo. They will work just fine though FG too (not quite as well as a through hull transducer). Mine works to about 300' or so. All you need is a spot to glue it. Don't use silicone or any flexible caulk, use epoxy or something else that will get hard when it sets up. (Silicone absorbs some of the sound and reduces the performance). Fill a freezer bag with water and set the transducer on the bag against the hull to test before you glue it in.
Avoid transom hung
You want your transducer as close as possible to centerline. This will reduce the effect of heeling. I found on my last boat that a transom hung doesn't work well because on one tack it will come out of the water because it has to be so far from center. Good luck, Jim
You want your transducer as close as possible to centerline. This will reduce the effect of heeling. I found on my last boat that a transom hung doesn't work well because on one tack it will come out of the water because it has to be so far from center. Good luck, Jim
How about mineral oil?
Thanks for the info guys. I did finally run down some info on the Cat 22 SA site, and one interesting possibility was mentioned involving epoxying a PVC pipe to the hull, filling the bottom with mineral oil, and placing the transducer into that. If for no other reason than curiosity, i'm trying to get ahold of the guy who made that post to find out how he kept the transducer from shifting around. However, I have another follow on question. When the boat is heeled, even if the transducer is dead center in the hull, aren't you now reading depth at an angle, which will be greater than true depth? Eric
Thanks for the info guys. I did finally run down some info on the Cat 22 SA site, and one interesting possibility was mentioned involving epoxying a PVC pipe to the hull, filling the bottom with mineral oil, and placing the transducer into that. If for no other reason than curiosity, i'm trying to get ahold of the guy who made that post to find out how he kept the transducer from shifting around. However, I have another follow on question. When the boat is heeled, even if the transducer is dead center in the hull, aren't you now reading depth at an angle, which will be greater than true depth? Eric
Oil wells ...
The PVC tube filled with oil is a way to trick a through hull transducer into thinking its in the water. The well has a plate at the top that the transducer mounts to. The plate seals the well so the oil doesn't slosh out when the boat heels. Yes, when the boat is heeled you get a slightly false reading. Its the Cosine of the heel angle. At 15 degrees heel you only have 96.6% of the depths
Not a problem at normal sailing angles.
The PVC tube filled with oil is a way to trick a through hull transducer into thinking its in the water. The well has a plate at the top that the transducer mounts to. The plate seals the well so the oil doesn't slosh out when the boat heels. Yes, when the boat is heeled you get a slightly false reading. Its the Cosine of the heel angle. At 15 degrees heel you only have 96.6% of the depths
Not a problem at normal sailing angles.I'm liking this oil idea
Moody, I'm trying to visualize how this works. I take a short piece of narrow ID PVC pipe and use silicon to bed the outside bottom of the pipe to the inside bottom of the hull as close to the centerline as possible. Then I take an end cap, drill it to allow me to pass the transducer thru, then seal the drilled hole with silicone so that the transducer will ride right at the bottom of the tube. Then I add mineral oil to the tube, put on the transducer-cap assembly so the the transducer is well immersed in the oil, and put a dot of silicone at the cap-tube join just to secure the cap, but still allow me to twist it off should I need to access the transducer. Does that sound like a good way to go? Eric
Moody, I'm trying to visualize how this works. I take a short piece of narrow ID PVC pipe and use silicon to bed the outside bottom of the pipe to the inside bottom of the hull as close to the centerline as possible. Then I take an end cap, drill it to allow me to pass the transducer thru, then seal the drilled hole with silicone so that the transducer will ride right at the bottom of the tube. Then I add mineral oil to the tube, put on the transducer-cap assembly so the the transducer is well immersed in the oil, and put a dot of silicone at the cap-tube join just to secure the cap, but still allow me to twist it off should I need to access the transducer. Does that sound like a good way to go? Eric
toilet wax
I use toilet wax and it works perfect. Just push the ducer into it, try to squeeze all the air bubbles out, level it and forget it. If the location is worthless (like over your keel) just pull it out and try another location. Just 99 cents and you will always have some sticky wax on board to plug any holes or post notes. Now if I can just get my paddle wheel sensor to work I'll know how fast my wax ring is flying
I use toilet wax and it works perfect. Just push the ducer into it, try to squeeze all the air bubbles out, level it and forget it. If the location is worthless (like over your keel) just pull it out and try another location. Just 99 cents and you will always have some sticky wax on board to plug any holes or post notes. Now if I can just get my paddle wheel sensor to work I'll know how fast my wax ring is flying
Re: Oil Wells ...
You have the right idea. The well on my boat is thick wall pipe, 6" O.D. or so. It is bonded to the hull under the v-berth. It has to be sealed well and the stiffer the better. Epoxy does a good job and can be removed if you ever need to. (Just heat it with a torch) The transducer mounts through a piece of 3/4" ply and the plywood disk has 6 screws that hold it to the edge of the pipe. Silicone is used as a gasket. When the old echo sounder died. I changed over to a internal puck type transducer since I've had good luck with them on other boats. Unless you already have a through hull type transducer, I wouldn't go to the trouble of building an oil well mount. The puck type transducers work fine and are much less work to install. Standard Horizon makes this one: DST55A In-Hull with Well Housing If your fish finder comes with a transom mount transducer, it can be used in the oil well type mount also.
You have the right idea. The well on my boat is thick wall pipe, 6" O.D. or so. It is bonded to the hull under the v-berth. It has to be sealed well and the stiffer the better. Epoxy does a good job and can be removed if you ever need to. (Just heat it with a torch) The transducer mounts through a piece of 3/4" ply and the plywood disk has 6 screws that hold it to the edge of the pipe. Silicone is used as a gasket. When the old echo sounder died. I changed over to a internal puck type transducer since I've had good luck with them on other boats. Unless you already have a through hull type transducer, I wouldn't go to the trouble of building an oil well mount. The puck type transducers work fine and are much less work to install. Standard Horizon makes this one: DST55A In-Hull with Well Housing If your fish finder comes with a transom mount transducer, it can be used in the oil well type mount also.
Eric, Don't use Silicone
Eric, don't use silicone, The seal between the PVC pipe and hull will be gone in about 2 weeks. Then you'll have a bilge with mineral oil in it and silicone worms floating around in that. Use thickened epoxy. Silicone needs to be compressed between two surfaces. Silicone just doesn't belong on a boat. I'll go put on the flame resistant suit now. Dan
Eric, don't use silicone, The seal between the PVC pipe and hull will be gone in about 2 weeks. Then you'll have a bilge with mineral oil in it and silicone worms floating around in that. Use thickened epoxy. Silicone needs to be compressed between two surfaces. Silicone just doesn't belong on a boat. I'll go put on the flame resistant suit now. Dan
A vote for silicon by itself.
I’m not sure I understand the advice not to just bed the transducer in silicone. If a flexible adhesive is detrimental to performance, how is that different than a water, or oil medium? Water and oil seem pretty flexible. As for my actual experience, I put a blob of silicone inside the hull of my old C25, and pushed the transducer in. I estimate it reduced the maximum depth range by about 30%. I think that is pretty typical of any inside the hull mounting. My own feeling is that the oil well setup is a needless complexity to accomplish similiar results.
I’m not sure I understand the advice not to just bed the transducer in silicone. If a flexible adhesive is detrimental to performance, how is that different than a water, or oil medium? Water and oil seem pretty flexible. As for my actual experience, I put a blob of silicone inside the hull of my old C25, and pushed the transducer in. I estimate it reduced the maximum depth range by about 30%. I think that is pretty typical of any inside the hull mounting. My own feeling is that the oil well setup is a needless complexity to accomplish similiar results.
You're right, Jon
Jon, from my perspective, I think you are right. In fact, I have seen posts on other sites about transducer mounting that have supported silicone, epoxy, wax, oil wells, and in fact, one fellow who had a transducer just lying in a puddle of water in the bottom of a fishing boat. Frankly, the interest I have in the oil well is simply one of "Hmmm. That's kinda neat." But from what I've read, I agree it is not necessary. And I want to thank everyone who responded to this thread and helped educate me on this topic. I do appreciate it. Eric
Jon, from my perspective, I think you are right. In fact, I have seen posts on other sites about transducer mounting that have supported silicone, epoxy, wax, oil wells, and in fact, one fellow who had a transducer just lying in a puddle of water in the bottom of a fishing boat. Frankly, the interest I have in the oil well is simply one of "Hmmm. That's kinda neat." But from what I've read, I agree it is not necessary. And I want to thank everyone who responded to this thread and helped educate me on this topic. I do appreciate it. Eric
you dont need a finder
I sail my 30 catalina all over that area and the only places we need to steer clear of, have crab traps. If you are sailig up the trent, stay close to the channel. and watch out for tree stumps and old pilings.Oh and the 29 alpha red marker on the other side of the twin bridges.
I sail my 30 catalina all over that area and the only places we need to steer clear of, have crab traps. If you are sailig up the trent, stay close to the channel. and watch out for tree stumps and old pilings.Oh and the 29 alpha red marker on the other side of the twin bridges.
Hey, Cole...
...thanks for the info. Sometime I'd like to talk with you as I am new to this area. Being new is one of the reasons I want a depth finder. That, PLUS, I am parked all the way back up at the head end of Plantation Channel, and frankly, I thought that sounder might well pay for itself just to get me acquainted with any "low spots" in there. Eric
...thanks for the info. Sometime I'd like to talk with you as I am new to this area. Being new is one of the reasons I want a depth finder. That, PLUS, I am parked all the way back up at the head end of Plantation Channel, and frankly, I thought that sounder might well pay for itself just to get me acquainted with any "low spots" in there. Eric
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