I've finally decided to go offshore with my 21' that I've been using exclusively for river diving. I have a Garmin 240 fishfinder on my boat which I think will be inadequate for locating ledges and wrecks. I've seen the Interphase Probe work, which is a forward looking sonar, and am considering purchasing that. I was on a diveboat that used the Interphase and when coming to a wreck this thing painted a beautiful picture of the wreck, you could even see the tower and crowsnest. There are fishfinders available that project a 3D picture that are also interesting but if anyone of you have any suggestions I'm all ears. Since electronics are so expensive I would like to purchase once and for all.
Sonar or bottomfinder for finding dive sites
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matt_unique
Guest
Sonar is of course heads and tails over fish finder/bottom finders. I priced them once and it was over $1000 for the cheapest model as I can recall. A nice fish finder is under $300 of course.
Radar would be a priority for me if I had the choice.
Good luck with your research.
--Matt
Radar would be a priority for me if I had the choice.
Good luck with your research.
--Matt
AFAIK, fishfinders are SONAR. How do you differentiate the two?
I used an older Hummingbird 3D Wide for years and it is much easier to find larger bottom structure, but the older single frequency model wasnt real good at finding smaller objects like ships. One issue with all 3D sonar including the Interphase models is that you have a very large transducer that you have to keep in clean water when moving and it must stay fairly level to work well. This can be difficult on smaller boats at any speed over a slow idle. I havent used the new 3D models, but they do have a lot of good new features including connecting to your GPS, which can be very handy when trying to pinpoint something youve already passed over. Until you get up into the high end and expensive Interphase models I dont know of any that let you pick the frequency you want to scan with.
You may or may not be happy with your Garmin for what youre wanting to do not knowing which transducer you have (8deg 20deg) but the lack of dual frequency on it will make it a little difficult to identify hard from soft objects.
You may or may not be happy with your Garmin for what youre wanting to do not knowing which transducer you have (8deg 20deg) but the lack of dual frequency on it will make it a little difficult to identify hard from soft objects.
Yes fishfinders use SONAR, but typically a SONAR will have additional features like multi frequency, zoom capabilities, and even adjustable power along with gain.Chuck Tribolet:
The difference is in the price.
Its true that they are both sonar. Typical fishfinders only look straight down from the transom, but the Interphase looks forward several hundred feet, so if you have GPS numbers on a particular wreck or ledge, you should be able to detect it well in advance in being over top of it. Some models of Interphase also have the ability to integrate GPS numbers into the Interphase screen. The Interphase can run split screen showing directly under the transom, as well as looking forward at the same time. Based upon this feature you should be able to see the object in advance and watch it come directly under the transom. Typical fishfinders only look straight down, with a narrow beam, and its easy to miss the object unless you are giving the fishfinder your undevided attention. Typical fishfinders don't have gain adjustment until you get in the more pricey models, and without the gain control its hard to analyze the bottom to determine if you are looking at live bottom, a ledge, or a wreck. One thing I've learned with fishfinders is there is a fine line between too much gain and too little gain. Having the gain too high gives an unreal analysis of the bottom, over amplifing what you are looking at, in other words you think you are looking a ledge with several feet of releif, but when you make a recon dive you find only humps on the bottom with no releif. The Interphase is even being used by search a recovery teams to find drowning victims. With the Interphase you can rotate in a 360 degree circle and hopefully spot what you are looking for and then manuver straight too the object. With a typical fishfinder you would have to set up a search grid and not find the object until you run directly over it, if you are lucky enough to do so.
matt_unique
Guest
Chuck Tribolet:
Technically yes of course, but what you see on the bottom from a fish finder is nothing compared to what you would see with even a basic side scan sonar unit. I have a decent Raytheon fish finder that shows bottom topography but it could not distinguish a wreck from a ledge - not enough detail. It's like the difference between an old Atari video game compared to the fancy systems kids use now a days - the detail is incredible.
--Matt
Ron_Bahrain
New
We have recently installed an Interphase Colour Twinscope on our club dive boat. It is a lot more complicated than the 3D unit that we had previously but the Twinscopes ability to scan such a wide area more than justifies the change and the additional cost. If you can afford it I recommend the Twinscope as the horizontal scanning mode is excellent for locating a wreck from a good distance off and then once you have lined yourself up on it switching to the vertical scanning mode allows you to position yourself over it fairly easiily. If you do opt to go down this route then you might however want to just confirm that you are comfortable with the size of the transducer on your 21ft boat as it is consideraly larger than the fishfinder ones.
Ron
Ron
Ron,
Ive wondered how sensitive the Twinscope transducer is to bubbles if its not in totally clean water flow. Do you find certain speeds that it doesnt like to give a clear image, or do you only use it at displacement speeds?
Ive wondered how sensitive the Twinscope transducer is to bubbles if its not in totally clean water flow. Do you find certain speeds that it doesnt like to give a clear image, or do you only use it at displacement speeds?
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.
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.
