I hooked my fishfinder transponder to the end of a boat hook and stuck it down into the water with the sound shooting forward. I could easily detect the seawall 35' away and a floating dock 150' away. With a little practice I think that it will be able to detect a coral head or sandbar in front of the boat..before it hits the boat. Sure it is not forward scan sonar but at $76 it is a lot cheaper. It is supposed to have a 600' range which is plenty of distance to avoid hitting a reef or isolated coral head. The visual display was a mess except for showing fish under the dock. I need a back up depth sounder anyway so dual purpose to look forward is a bonus.
Proof of concept Fishfinder to look forward
- Thread starter MoonSailer
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Be careful! I have friends that grounded on a log at their keel. The sounder forward of the keel showed 6 feet. Depending upon orientation the transducer will look where it is pointed but it won't show depth of obstruction. You may need two systems one for depth and one for distance to obstructions. Then you will need to learn to interprete the results.
My fear is isolated coral heads!!!! I was once in the keys in 40' of water and looked over the side to see that I had just missed a coral head a couple of feet below the surface!!! I envison using the fishfinder mounted on a pole sticking 5' below the surface with the transponder pointing forward. This is all mounted at the bow or maybe the wife holding it while standing at the bow. Anything less than 5' deep will show up and I draw 4.5'. Actually the sound makes a cone so at a distance should pick up things more than 5' deep. Of course the regular depth sounder will be pinging away to let me know the depth beneath the keel. Another option I might explore is mounting the transponder inside the bow looking forward at 45 degree angle. The depth sounder transponder is now about midship. No warning at all for a sudden change in depth!!!!
Moonsailor,
I have two transducers for one display on my old Macgregor 26S. The forward one was mounted inside a PVC tube filled with anti-freeze with a screwed on cap. The PVC tube was epoxied to the inside of the hull. The transducer tilted forward about 45 degrees. I have a switch at the display to select forward or stern transducer. I found that at higher angle, the display goes nuts as it can't really detect sound wave echo from above water. The transducer seems to have a cone about 20-30 degrees.
I don't use that for sailing just for anchoring near shore. Georgian bay shoreline is full of rocks. Going at very slow speed (<0.5 kt) thru narrow channel to anchorage is pretty scary.
I no longer own the boat but the contraption worked for me.
I have two transducers for one display on my old Macgregor 26S. The forward one was mounted inside a PVC tube filled with anti-freeze with a screwed on cap. The PVC tube was epoxied to the inside of the hull. The transducer tilted forward about 45 degrees. I have a switch at the display to select forward or stern transducer. I found that at higher angle, the display goes nuts as it can't really detect sound wave echo from above water. The transducer seems to have a cone about 20-30 degrees.
I don't use that for sailing just for anchoring near shore. Georgian bay shoreline is full of rocks. Going at very slow speed (<0.5 kt) thru narrow channel to anchorage is pretty scary.
I no longer own the boat but the contraption worked for me.
I like this idea..
it's true that the you won't get any readings if it's tilted too upright, as the sound won't bounce off anything and come back... until there's something there!!! That's why it works with the seawall!
So if I understand this correctly, you get no readable display until you are in danger of hitting something? Sounds like a pretty good deal to me..
cup
it's true that the you won't get any readings if it's tilted too upright, as the sound won't bounce off anything and come back... until there's something there!!! That's why it works with the seawall!
So if I understand this correctly, you get no readable display until you are in danger of hitting something? Sounds like a pretty good deal to me..
cup
- Jan 22, 2008
- 519
Re: I like this idea..
so lets take it one step further in concept. Lets say you mount a forward looking transducer with a digital numeric readout, (as well as your standard downward to determine depth). You are in a race and the sailboat ahead of you... should show up on your digital display when it comes into range and within the cone of registry... correct? If so, this and the next generation would allow you to pivot/rotate the 'sonar' so that you can read not only the boat dead ahead of you but other boats ahead and to one side, or even behind you to determine a 'distance off' from your boat, and determine if you are gaining on him or them gaining on you. Simply aliging him/her with a shroud or other fixed object on your boat and tracking whether the boat falls behind or moves ahead is easier, but I'm talking about the science of sonar electronics here and trying to advance the utility. If the display were graphic, could you use it to sail through a reef approach. The channel (looking forward) should look further away to the fishfinder, than the coral heads to each side.... yes??? what say you mateys?
so lets take it one step further in concept. Lets say you mount a forward looking transducer with a digital numeric readout, (as well as your standard downward to determine depth). You are in a race and the sailboat ahead of you... should show up on your digital display when it comes into range and within the cone of registry... correct? If so, this and the next generation would allow you to pivot/rotate the 'sonar' so that you can read not only the boat dead ahead of you but other boats ahead and to one side, or even behind you to determine a 'distance off' from your boat, and determine if you are gaining on him or them gaining on you. Simply aliging him/her with a shroud or other fixed object on your boat and tracking whether the boat falls behind or moves ahead is easier, but I'm talking about the science of sonar electronics here and trying to advance the utility. If the display were graphic, could you use it to sail through a reef approach. The channel (looking forward) should look further away to the fishfinder, than the coral heads to each side.... yes??? what say you mateys?
Well, that's basically what the forward looking sonars do...they have two transducers with one pointing forward and one pointing down. The difference is that they know how to combine both signals to paint the bottom floor. I do believe though that the ones that can "find a channel" are much more expensive. Most are 2D and show you the side view (as if you were 300 yards away to the beam and looking at your boat/bottom from under water) which is what is most used so you can see the bottom sloping up, however, to find the channel, you need a front view 2D, or a 3D display. A front view will not show the bottom sloping up.
I think that you could build a "sonar dome" that would allow you to control the position of the transducer remotely. The key would be to having a riser inside the boat that came up well above the WL and allowed the cables and 3 axis maneuvering controls to be less complicated by not requiring complex seals.
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