Sonar or bottomfinder for finding dive sites

[mntdiver]

I haven't used one myself, but have talked to a couple of public safety dive teams that have them and love'm. Less than $2k with GPS chart plotter. Have a look. The Humminbird 987C

http://www.humminbird.com/products.asp?ID=512

 

[Nemrod]

I am new to using fish finders or sonars on my new whaler. I am currently running a Lowrance 332 with dual frequency. It has both 50 hz and 200 hz frequencies for both wide angle and narrow beams. Using it with the spit screen GPS loaded with chart software makes finding most dive sites--the few I have tried---easy. The way I have used it is to use my GPS to locate the exact spot. I then cross over the area several times until I am sure I am painting the ledge or wreck. So far it has abeen a no brainer as long as my GPS coordinates are accurate. These units sell for under 700 dollars. I saw a demo on the side scan Hummingbird as was impressed. Cost is 2000 dollars. it can see to the side, or both sides but not directly under the boat until you switch back to the conventional sonar/ff mode as I understand from the demo. I can see how this would make something like look over at a rock pile or jetty as you cruise along it very interesting.

 

[Ron_Bahrain]

Ron,
Why did you elect to go with the Twinscope versus the Probe. I've been researching and realize the transducer is larger than most fishfinder transducers but my hull has the perfect place for mounting. Because of my hull design I'll need the thru-hull transducer, the transom mount would never work correctly because of hull interferance with my deep V. If anyone is interested, here is the website for Interphase. http://www.interphase-tech.com/ Any of you that are technically profecient and would like to peruse their site, check it out and comment.

The reasons for opting for the Twinscope were firstly the availability of colour which clearly differentiates between the strong return signal that you get off a solid surface such as a wreck and softer substances. The second reason was the amount of water that the Twinscope can search in. You are not just searching directly ahead of you as with the probe but can instead see a full 90 degree arc ahead. It just increases the possibility of finding something new to dive on. There is of course a price penalty for having these features and I am sure that the Probe is also an excellent unit. The club was fortunate enough to have the funds available to go for the Twinscope instead.

Just to also address the question posed in the previous message as well then so far I have only played with the sonar at displacement speeds. The sender has to my mind been mounted too far forward on our dive boat and I anticipate that the unit consequently won't perform particularly well once you go onto the plane.


Ron

 

[lamont]

i want one of these: http://www.questelectronics.com/

 

[Nemrod]

One thing on the Hummingbird unit is that in the side scan mode it has a very limiting depth range but as I understand and was demonstrated at the trade show was that it can switch to a conventional mode and then it has excellent depth capability.
Another thing, I may be wrong, but I have been told that narrow beams are better for locating rocks and wrecks because they respond more to small changes in bottom contour since they see a smaller area where a wide beam tends to average the bottom out. I am not usre how this all works out in real life because I am new to using the things.
I should think that if you have coordinates a decent standard so called fishfinder ought to be able to see a sizeable wreck. My Lowrance spotted the Liberty ship in Destin easily, it stood out clearly and gave a huge echo in part from all the fish but I could see the ship as well. I can see though if you are looking for new features you could cover more area faster with a side scan type unit.

 

[ranger]

I did a little more research on the Interphase by calling their tech support and asking alot of questions. We dive alot of ledges in 70 to 100 feet of water, and according to their tech support the Interphase needs a ratio of 1:4 in relation to bottom structure and water depth to be able to detect change in bottom. In other words, if looking for a 10 foot ledge we would have to be in 40 feet of water for it to be visible to the Interphase. Based upon this info the Interphase will not work for the depths we are diving as the ledges range from 4 to 10 feet of releif. Just thought I would pass this along for the benefit of the rest of the divers. Now it looks like plan B will be the Furuno FCV 600L, any of you have any experience with this fishfinder?

 

[Kim]

I have a slightly tangential question. Does anyone have any knowledge or experience with fully portable sonar/fishfinders? I have seen that they exist, but do they work very well? I am interested in something that could be used from a kayak and will give me an idea of depth plus some indication of bottom topography - fairly rough would do, stuff like large rock outcroppings etc.

 

[ranger]

I don't have any experience with those but I know they are available. One thing I've found out in researching equipment....if the equipment will do as advertised the manufacturer doesn't mind giving out a list of clients that use the equipment. This way you can email and call some of the clients to get feedback from the real world users, not some salesman. I've done this for personal purchases and do this 100% of the time for professional purchases.

 

[Chuck Tribolet]

I have a slightly tangential question. Does anyone have any knowledge or experience with fully portable sonar/fishfinders? I have seen that they exist, but do they work very well? I am interested in something that could be used from a kayak and will give me an idea of depth plus some indication of bottom topography - fairly rough would do, stuff like large rock outcroppings etc.

Ans: it depends.

There's a unit that's been kicking around for a while that looks like
a fllashlight. It will tell you how deep the water is, that's it, won't meet your
requirements. I've seen this unit with several brand names, including a major SCUBA
manufacturer (ScubaPro, I THINK).

On the other hand, Humminbird makes a kit to battery power and clamp on the
transducer that works with most any of their units. I suspect that even with a $120
fish finder it would serve your needs. Here's the transducer mounting kit:
http://www.humminbird.com/retail/ca...tegory_name=Portable+Mounting+Hardware&Page=1
I couldn't find the power kit on their website. I have a buddy that put a motorcycle
gel cell (or maybe AGM) in a small Pelican case to power one.

They also have a couple that are designed to be portable:
10pt: http://www.humminbird.com/products.asp?ID=438
30pt: http://www.humminbird.com/products.asp?ID=479
535 Portable: http://www.humminbird.com/products.asp?ID=478

 

[Bill51]

I’ve used one of the flashlight sonar units a couple times and was surprised at how well they worked. In one case I carried it on my Waverunner to map out some shallows and walls we were looking for and just by reading the depth we knew when we were over the wall. The other time a guy brought one diving with us when we were searching along a wall in low visibility, and we used it tell us how far out from the wall we were. That was pretty cool for maintaining an exact distance from a fixed location during the dive and stay parallel to the wall.