Is it possible to see what you are about to go aground on before you reach it? Its nice to know whats under the keel but in these thin waters I'm much more interested in what's ahead of it. Has anyone got something that works in around 12ft of water?
- Status
Sure, it's on my web site
and pictures are there of the transucer too. Mine sees ahead, 1200' (that's right, twelve Hundred) and down 800'. (not that you care about that part) These puppies are made buy Interphase. WM has them in their catalog but I found the best price and purchased from http://www.vitmarine.com/index.html. Say hi to Everette for me. Patrick, you just can't get away from me. How's your motor running?
and pictures are there of the transucer too. Mine sees ahead, 1200' (that's right, twelve Hundred) and down 800'. (not that you care about that part) These puppies are made buy Interphase. WM has them in their catalog but I found the best price and purchased from http://www.vitmarine.com/index.html. Say hi to Everette for me. Patrick, you just can't get away from me. How's your motor running?
I Tested Most Makes
I took part in a test of most makes for a popular UK boating magazine. Whilst they all claimed great ranges, we discovered that, in reality, they can only "see" forward for about three times the current depth under the boat. This seems reasonable because reflections from a sloping underwater sea bed will be quite weak with most of the energy being reflected upwards and onwards, thus setting the limit. Considering depths likely to be of interest, viz. 15 feet, the max forward range was about 45 feet. At 6 knots the warning was only 4.4 seconds before grounding occurred. We felt they would be more effective if one was approaching a rock wall from deeper water where the advance warning could be of value. Also they might detect a partially submerged container - provided it was floating dead square on to your approach.
I took part in a test of most makes for a popular UK boating magazine. Whilst they all claimed great ranges, we discovered that, in reality, they can only "see" forward for about three times the current depth under the boat. This seems reasonable because reflections from a sloping underwater sea bed will be quite weak with most of the energy being reflected upwards and onwards, thus setting the limit. Considering depths likely to be of interest, viz. 15 feet, the max forward range was about 45 feet. At 6 knots the warning was only 4.4 seconds before grounding occurred. We felt they would be more effective if one was approaching a rock wall from deeper water where the advance warning could be of value. Also they might detect a partially submerged container - provided it was floating dead square on to your approach.
Don' what other brands are out there?
Interphase is claiming a patent because they invented these things. I'm referring to units for recreational boaters. The kind used by Woods Hole is beyond our reach. You're right about the proportionality. You don't get 1200' if it's shallow, but then too, I put on the brakes when the bottom comes up or when looking to drop the anchor. During sea trials last summer, we were impressed. This unit also has a GPS repeater/plotter screen. Neat. Also the scan can be aimed, like lighting up a boogie with radar. A target is lit up brightly in a 15 degree cone, ahead. And less brightly to 25 degrees. Not bad. And they make another model that sees in all directions. Good for search and rescue.
Interphase is claiming a patent because they invented these things. I'm referring to units for recreational boaters. The kind used by Woods Hole is beyond our reach. You're right about the proportionality. You don't get 1200' if it's shallow, but then too, I put on the brakes when the bottom comes up or when looking to drop the anchor. During sea trials last summer, we were impressed. This unit also has a GPS repeater/plotter screen. Neat. Also the scan can be aimed, like lighting up a boogie with radar. A target is lit up brightly in a 15 degree cone, ahead. And less brightly to 25 degrees. Not bad. And they make another model that sees in all directions. Good for search and rescue.
Performace - Spec' or Experience?
Fred: You advise that your” sees ahead, 1200'”. Is that the result of your actual experience in shallow water - or the manufacturer’s Specified figure? I ask because my (very limited, & perhaps out of date) experience mirrors that posted by Donalex (“they can only "see" forward for about three times the current depth under the boat”). I installed an “earlier” (‘96?) Interphase unit (the cheaper one - NOT the “Twinscope”) which only tested to a maximum of 4 times depth ( with 2x - 3x most common), over sand spoils at between 10 - 25 Ft. Depths. I didn’t participate in any testing over rocky/coral bottoms. The Transducer was mounted about 18" below waterline, and our slowest test speed was ±5 Knots (506 fpm - 8.44 fps). We played with the Range & Gain selections, but may not have achieved the optimal settings. The owner was interested in 10 Kt speed performance (a Sportfisher), and was not a “happy camper” (I think he fired the Captain, over this and other issues). I look forward to your further comments. Regards,
Fred: You advise that your” sees ahead, 1200'”. Is that the result of your actual experience in shallow water - or the manufacturer’s Specified figure? I ask because my (very limited, & perhaps out of date) experience mirrors that posted by Donalex (“they can only "see" forward for about three times the current depth under the boat”). I installed an “earlier” (‘96?) Interphase unit (the cheaper one - NOT the “Twinscope”) which only tested to a maximum of 4 times depth ( with 2x - 3x most common), over sand spoils at between 10 - 25 Ft. Depths. I didn’t participate in any testing over rocky/coral bottoms. The Transducer was mounted about 18" below waterline, and our slowest test speed was ±5 Knots (506 fpm - 8.44 fps). We played with the Range & Gain selections, but may not have achieved the optimal settings. The owner was interested in 10 Kt speed performance (a Sportfisher), and was not a “happy camper” (I think he fired the Captain, over this and other issues). I look forward to your further comments. Regards,
water clarity/quality
Pat, as you know, the waters in the harbor are coffee in the summer and tea in the winter. I can't help but wonder how some of these things will work in our very NOT clear waters? Also, I have doubts about most depth shounders in certain bottom conditions in south Florida. There are areas where the silt is 4-6' deep. I mean it is so bad that you don't realize you are in silt because it is sooo soft and ooozzzy.
Pat, as you know, the waters in the harbor are coffee in the summer and tea in the winter. I can't help but wonder how some of these things will work in our very NOT clear waters? Also, I have doubts about most depth shounders in certain bottom conditions in south Florida. There are areas where the silt is 4-6' deep. I mean it is so bad that you don't realize you are in silt because it is sooo soft and ooozzzy.
Steve, little doubt that in ooze like that, well
forget it. The laws of physics still apply. I've been in some of those waters, like sneaking out of the back of Key West. In mucky water, any sounder is handicapped. And thermoclines still block their vision. (that's what submarines hide under) The transducer on my units have nine 'pingers' other wise known as a phased array. A computer directs the power to each, sequentially, or as directed by the operator. I'm not sure, but I see no reason that the range of these sounders isn't the same as any other brand with the same power. (lots)(You can hear it working when inside the boat) And Gord, that 1200 foot see ahead is the manufacturers effective range. We have not taken the boat over deep water enough to fairly judge what it can see at long range. We will though, but it won't be until later this spring. And yes, it has to be over deep water to see forward 1200'. For what Patrick is asking for, it's just the ticket. Since the day I bought my first sounder, twenty five years ago, I have wanted to see ahead. I don't need to see what I just hit.
forget it. The laws of physics still apply. I've been in some of those waters, like sneaking out of the back of Key West. In mucky water, any sounder is handicapped. And thermoclines still block their vision. (that's what submarines hide under) The transducer on my units have nine 'pingers' other wise known as a phased array. A computer directs the power to each, sequentially, or as directed by the operator. I'm not sure, but I see no reason that the range of these sounders isn't the same as any other brand with the same power. (lots)(You can hear it working when inside the boat) And Gord, that 1200 foot see ahead is the manufacturers effective range. We have not taken the boat over deep water enough to fairly judge what it can see at long range. We will though, but it won't be until later this spring. And yes, it has to be over deep water to see forward 1200'. For what Patrick is asking for, it's just the ticket. Since the day I bought my first sounder, twenty five years ago, I have wanted to see ahead. I don't need to see what I just hit.
- Status