Depth finder
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Hi John
Yes to your question, I use both. My 1986 Catalina 27 came with a thru hull but when I installed new electronics last year in purchased a chartplotter with a in hull transducer. For my purposes both work equally well and I am happy to have one or the other as a back-up. I am not sure what the question is your asking? As Stu would ask, " a little more details please" Good luck, Jack
Yes to your question, I use both. My 1986 Catalina 27 came with a thru hull but when I installed new electronics last year in purchased a chartplotter with a in hull transducer. For my purposes both work equally well and I am happy to have one or the other as a back-up. I am not sure what the question is your asking? As Stu would ask, " a little more details please" Good luck, Jack
Why am I asking?
I recently purchased a "good old boat" (Hunter 27) that doesn't have a depth finder and the lake I sail in is pretty low this time of year. There are places where the depth is questionable for a boat with 4 1/2 ft draft so I tend to stay away from the shoreline. I would feel more comfortable if I had some idea of the depth. I don't plan to haul out anytime soon, so I thought an in-hull transducer may be the way to go, at least until I take her out next year.
I recently purchased a "good old boat" (Hunter 27) that doesn't have a depth finder and the lake I sail in is pretty low this time of year. There are places where the depth is questionable for a boat with 4 1/2 ft draft so I tend to stay away from the shoreline. I would feel more comfortable if I had some idea of the depth. I don't plan to haul out anytime soon, so I thought an in-hull transducer may be the way to go, at least until I take her out next year.
In-hull vs. Thru-hull
Hi John - It sounds like an in-hull transducer would be a good solution for you, mostly because of it's relative ease in installation. You can expect roughly a 10-20% decrease in range - not normally a problem for most sailors. Best, Trevor
Hi John - It sounds like an in-hull transducer would be a good solution for you, mostly because of it's relative ease in installation. You can expect roughly a 10-20% decrease in range - not normally a problem for most sailors. Best, Trevor
thanks
You are right Trevor, the range isn't an issue. It's either really deep or really shallow. I don't care if it's deep but when it sharts getting shallow, I pay attention...
You are right Trevor, the range isn't an issue. It's either really deep or really shallow. I don't care if it's deep but when it sharts getting shallow, I pay attention...
John, I used a transom mount transducer
mounted on a skeg at the stern of Bietzpadlin. Some folks want the transducers near the front of the boat but I figure if the water at the stern is six feet deep and the bottom is flat according to the fishfinder display then the water out infront is probably about six feet too. Anyway I don't have a hole in the boat for the transducer and don't have a lump on the inside to trip on.
mounted on a skeg at the stern of Bietzpadlin. Some folks want the transducers near the front of the boat but I figure if the water at the stern is six feet deep and the bottom is flat according to the fishfinder display then the water out infront is probably about six feet too. Anyway I don't have a hole in the boat for the transducer and don't have a lump on the inside to trip on.
Check the archives here for information.
There are hundreds of posts on this very topic. Make sure your hull is straight glass (no wood, no foam, no air bubbles) or it won't shoot through.
There are hundreds of posts on this very topic. Make sure your hull is straight glass (no wood, no foam, no air bubbles) or it won't shoot through.
Hi John, we have both an in-hull transducer...
(bedded into a hole drilled through the hull) installed at the factory and a through hull type that lays in a bed of sealant inside the boat where there is solid fiberglass for the depth signal to penetrate. Many of the transducers used today come from the same manufacturer. The trouble with having two on the same boat is the potential for signal conflict. Where the signal bands overlap one or the other devices can give you a false reading. Given the choice I would go with the through hull type because it eliminates the need for drilling holes in your boat. Terry
(bedded into a hole drilled through the hull) installed at the factory and a through hull type that lays in a bed of sealant inside the boat where there is solid fiberglass for the depth signal to penetrate. Many of the transducers used today come from the same manufacturer. The trouble with having two on the same boat is the potential for signal conflict. Where the signal bands overlap one or the other devices can give you a false reading. Given the choice I would go with the through hull type because it eliminates the need for drilling holes in your boat. Terry
No potential Leaks
I would think long and hard about cutting a hole in the bottom of my boat. My knotmeter hole scares me a little. I have pulled out the paddlewheel to clean it and was amazed at the amount of water that comes through the hole before I plug it with a wooden cone. If that plastic housing ever fails the boat will sink unless measures are taken immediately. Some through hulls are mandatory for the engine cooling and head. But I'd never cut a hole for a depthsounder. The risk/benefit ratio is too large.
I would think long and hard about cutting a hole in the bottom of my boat. My knotmeter hole scares me a little. I have pulled out the paddlewheel to clean it and was amazed at the amount of water that comes through the hole before I plug it with a wooden cone. If that plastic housing ever fails the boat will sink unless measures are taken immediately. Some through hulls are mandatory for the engine cooling and head. But I'd never cut a hole for a depthsounder. The risk/benefit ratio is too large.
Shoot thru the hull
I cut out the bottom of a small plastic bucket and use silly putty a.k.a. play dough to temporary "glue" it to the bottom of the boat. Filled the bucket with water and use that to locate the best spot to place the transducer. I put the thing as far forward as possible. I really don't care how deep the water is or at what depth my boat just past. It's how shallow and what depth to set the anchor from the bow that I care. Once I got the best spot, I epoxied the transducer to that spot. Make sure there is no air bubble between the face and the hull. It works.
I cut out the bottom of a small plastic bucket and use silly putty a.k.a. play dough to temporary "glue" it to the bottom of the boat. Filled the bucket with water and use that to locate the best spot to place the transducer. I put the thing as far forward as possible. I really don't care how deep the water is or at what depth my boat just past. It's how shallow and what depth to set the anchor from the bow that I care. Once I got the best spot, I epoxied the transducer to that spot. Make sure there is no air bubble between the face and the hull. It works.
EEEnglieesh verry strang lauquage
jimq26's correction to Terry's in-hull vs through hull Another way to look at it: in-hull means it's embedded IN the hull, which requires a HOLE in the hull through-hull means it shoots its signal THROUGH the hull and DOESN'T need a HOLE Kleer enuf? Seriously, basic terminology IS important. Through hull is usually expected to mean built into the hull with a HOLE In-hull is usually expected to mean inside the boat with NO hole
jimq26's correction to Terry's in-hull vs through hull Another way to look at it: in-hull means it's embedded IN the hull, which requires a HOLE in the hull through-hull means it shoots its signal THROUGH the hull and DOESN'T need a HOLE Kleer enuf? Seriously, basic terminology IS important. Through hull is usually expected to mean built into the hull with a HOLE In-hull is usually expected to mean inside the boat with NO hole
I get a kick out of ross
You put the transducer as far forward as possible because.... They now have forward looking sonar because.... You want to know what you are getting in to, not what you have passed. An example...you are coming into a reef area. With your info from behind, you WILL be on the reef before you know it. With the info from in front, as soon as trpouble appears, you might be able to avoid it. We had one on the front (where it should be, unless you go in reverse all the time) and there were dozens of times it kept us on the ICW vs. in the mud or rocks. Not that we couldn't steer straight, or try to, but sunken logs happen and sand moves. I bet that sub that hit rocks off Hawaii a few years ago wishes they had their sonar on. Can you imagine the scene...Captain, we've hit rocks...Impossible, our rear sonar shows 3000 feet so we couldn't have hit rocks...What's the front sonar read...Nothing Captain, it's smashed up in the crash
You put the transducer as far forward as possible because.... They now have forward looking sonar because.... You want to know what you are getting in to, not what you have passed. An example...you are coming into a reef area. With your info from behind, you WILL be on the reef before you know it. With the info from in front, as soon as trpouble appears, you might be able to avoid it. We had one on the front (where it should be, unless you go in reverse all the time) and there were dozens of times it kept us on the ICW vs. in the mud or rocks. Not that we couldn't steer straight, or try to, but sunken logs happen and sand moves. I bet that sub that hit rocks off Hawaii a few years ago wishes they had their sonar on. Can you imagine the scene...Captain, we've hit rocks...Impossible, our rear sonar shows 3000 feet so we couldn't have hit rocks...What's the front sonar read...Nothing Captain, it's smashed up in the crash
Dept finder
I got an "In-Hull" P-79 transducer from Raymarine. Their website covers the advantanges and disadvantages of this type of transducer quite well: "In-Hull Transducers In-hull (a.k.a. shoot-through) transducers are epoxied directly to the inside of the hull. These are only used in fiberglass hulls. In-hulls will not work with wooden aluminum, wood, or steel hulls, or in foam sandwich or hulls that have air pockets. Any wood, metal, or foam reinforcement must be removed from the inside of the hull. With an in-hull transducer, the signal is transmitted and received through the hull of the boat. As a result, there is considerable loss of sonar performance. In other words, you won’t be able to read as deep or detect fish as well with an in-hull transducer as with one that’s transom mounted or thru-hull mounted. Fiberglass hulls are often reinforced in places for added strength. These cored areas contain balsa wood or structural foam, which are poor sound conductors. The transducer will need to be located where the fiberglass is solid and there are no air bubbles trapped in the fiberglass resin. You’ll also want to make sure that there is no coring, flotation material, or dead air space sandwiched between the inside skin and the outer skin of the hull. ADVANTAGES: No holes drilled in hull Excellent high speed performance No obstructions in the water Low maintenance DISADVANTAGES: Reduced maximum depth reading reduced fish detection Can only be used with fiberglass hulls "
I got an "In-Hull" P-79 transducer from Raymarine. Their website covers the advantanges and disadvantages of this type of transducer quite well: "In-Hull Transducers In-hull (a.k.a. shoot-through) transducers are epoxied directly to the inside of the hull. These are only used in fiberglass hulls. In-hulls will not work with wooden aluminum, wood, or steel hulls, or in foam sandwich or hulls that have air pockets. Any wood, metal, or foam reinforcement must be removed from the inside of the hull. With an in-hull transducer, the signal is transmitted and received through the hull of the boat. As a result, there is considerable loss of sonar performance. In other words, you won’t be able to read as deep or detect fish as well with an in-hull transducer as with one that’s transom mounted or thru-hull mounted. Fiberglass hulls are often reinforced in places for added strength. These cored areas contain balsa wood or structural foam, which are poor sound conductors. The transducer will need to be located where the fiberglass is solid and there are no air bubbles trapped in the fiberglass resin. You’ll also want to make sure that there is no coring, flotation material, or dead air space sandwiched between the inside skin and the outer skin of the hull. ADVANTAGES: No holes drilled in hull Excellent high speed performance No obstructions in the water Low maintenance DISADVANTAGES: Reduced maximum depth reading reduced fish detection Can only be used with fiberglass hulls "
Tom h, You have a fine imagination but
you lack knowledge. My Apelco fishfinder keeps me off the rocks around Garrett Island while we travel forward. That's about the only place on the Chesapeake bay to find any rocks. At the south end of Garrett Island there is a reef that rises from 60 feet of water to 9 feet in about a hundred yards. With my fish finder I can "see" the change in the slope well before I get there. When I clear the top and read 9 feet I can "see" the slope down to the 20 feet on the west side of the reef. It is but TEN feet from the transducer to the forward edge of my keel and I doubt that ten feet is enough distance for even you to turn away from danger.
you lack knowledge. My Apelco fishfinder keeps me off the rocks around Garrett Island while we travel forward. That's about the only place on the Chesapeake bay to find any rocks. At the south end of Garrett Island there is a reef that rises from 60 feet of water to 9 feet in about a hundred yards. With my fish finder I can "see" the change in the slope well before I get there. When I clear the top and read 9 feet I can "see" the slope down to the 20 feet on the west side of the reef. It is but TEN feet from the transducer to the forward edge of my keel and I doubt that ten feet is enough distance for even you to turn away from danger.
I'd like to have two
I agree with Ross that at normal speeds 10' won't make much if any difference. BUT whhen I am poking around in an anchorage it would be nice to know how deep it's at the front of the boat. Why you might ask. Well often in lakes and small anchorages I will drop the anchor and then tie to a tree on shore. I approach shore bow first because I want to protect my rudder also if I see that 15' from shore the water is 3' deep I won't go any closer and dig the keel into the bottom. I guess some sort of toggle switch to read from one transducer or the other . I was once in the keys reading 45' on the depthsounder and looked over the side to see coral just beneath the surface. Stupid luck saved the day. But in that situation a bow mounted depth sounder would have made no difference. Isolated coral heads coming up out of the depth are a real hazard. But if we had been heading toward the head there would not have been enough time to dodge. After that near miss I knew that being in deeper water didn't mean that it was time to relax.
I agree with Ross that at normal speeds 10' won't make much if any difference. BUT whhen I am poking around in an anchorage it would be nice to know how deep it's at the front of the boat. Why you might ask. Well often in lakes and small anchorages I will drop the anchor and then tie to a tree on shore. I approach shore bow first because I want to protect my rudder also if I see that 15' from shore the water is 3' deep I won't go any closer and dig the keel into the bottom. I guess some sort of toggle switch to read from one transducer or the other . I was once in the keys reading 45' on the depthsounder and looked over the side to see coral just beneath the surface. Stupid luck saved the day. But in that situation a bow mounted depth sounder would have made no difference. Isolated coral heads coming up out of the depth are a real hazard. But if we had been heading toward the head there would not have been enough time to dodge. After that near miss I knew that being in deeper water didn't mean that it was time to relax.
Inside mount is fine.
John: Our Hunter 31 had the original transducer mounting inside the hull and it worked fine. When we changed to a new system we had the transducer mounted with a thru hull fitting. There is no difference and you can do it without pulling the boat. The mfg should have direction on how to to this to their specs. If they do not recommend this method, then you may want to find a mfg. that approves of this method.
John: Our Hunter 31 had the original transducer mounting inside the hull and it worked fine. When we changed to a new system we had the transducer mounted with a thru hull fitting. There is no difference and you can do it without pulling the boat. The mfg should have direction on how to to this to their specs. If they do not recommend this method, then you may want to find a mfg. that approves of this method.
Great responses
I really appreciate the amount of response I got on this issue. I liked the idea of an in hull (as in shoot thru) vs. drilling another hole in the boat. Sounds like the consensus is the shoot thru works fine if installed properly. I was going to also get a knotmeter in the spring, but that would also be a hole in the boat. Now I think I'll just go with the "shoot thru" transducer for the depth finder and a GPS as a speed indicator. I guess I may be a little paranoid about thru hulls, but like the man said: "Just because you're paranoid doesn't mean there's NOT someone out to get you." Also, I've become more sensitive to this issue because the old, neglected looking Cal 25 across the way from me has been slowly sinking for 3-4 months now. Every couple of weeks the owners visit the boat to bail it out again. It seems to sink a couple of inches a week. Apparently they are unable to find the leak. Bummer. Thanks for your advice everyone. John
I really appreciate the amount of response I got on this issue. I liked the idea of an in hull (as in shoot thru) vs. drilling another hole in the boat. Sounds like the consensus is the shoot thru works fine if installed properly. I was going to also get a knotmeter in the spring, but that would also be a hole in the boat. Now I think I'll just go with the "shoot thru" transducer for the depth finder and a GPS as a speed indicator. I guess I may be a little paranoid about thru hulls, but like the man said: "Just because you're paranoid doesn't mean there's NOT someone out to get you." Also, I've become more sensitive to this issue because the old, neglected looking Cal 25 across the way from me has been slowly sinking for 3-4 months now. Every couple of weeks the owners visit the boat to bail it out again. It seems to sink a couple of inches a week. Apparently they are unable to find the leak. Bummer. Thanks for your advice everyone. John
This firm made knotmeters that shot thru the hull
SM-3/3A & SM-4/4A Knotmeters - go to their web site and look up the manuals for those two items. I bought one 4 years ago, and it has worked just great. The best thing - no holes to drill. You could always check out the chandleries on line. I heard that one of the big boys (think it was TacTic) was taking over the knotmeter end of it.
SM-3/3A & SM-4/4A Knotmeters - go to their web site and look up the manuals for those two items. I bought one 4 years ago, and it has worked just great. The best thing - no holes to drill. You could always check out the chandleries on line. I heard that one of the big boys (think it was TacTic) was taking over the knotmeter end of it.
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