Sonar or bottomfinder for finding dive sites

[robo]

For locating ledges or wrecks where you have the numbers and dont mind zig-zagging around a little, your garmin will work fine.

There are many makes and brands, with different features and power. The interphase was mentioned, and the twinscope, although more expensive than the probe, gives you both horizontal and vertical scanning, which is very trick. There are other searchlight scanning sonars from makers such as furuno and simrad, which are commercial or high end sportfishing sonars, which are very expensive, and great for locating shools of fish.

treasure hunters use side scan sonar, with a towed fish, that gives you a picture of the bottom on each side.

Most folks use conventional sonar, and with a gps or loran and a little practice, will put you on the spots. A high power sonar will also help locate thermoclines, and color will show the density of the bottom structure, and discriminate different species of fish.

Sunlight visibility is a big factor for me in my open boat. i prefer a monochrome transflective screen which I can read from the other end of the boat, and cant read a color display in glare. You need to have color units under a top for visibility IMHO.

My lowrance lcx15mt has the MT screen, gps, and recording sonar, which is super cool. You can record the bottom profile on a SD flash memory card, take it home and look at it on your computer. You can even put your mouse cursor on a ledge and it will give you the coordinates of that location. These units are on closeout at cabelas, and you can get one for around 5 to 6 hundred dollars.

 

[Hank49]

Now it looks like plan B will be the Furuno FCV 600L, any of you have any experience with this fishfinder?

I just bought a fishfinder (Raymarine DS400) because this model and the Furuno 600 were recommended by many on Spearboard, who use it to do what I want to do. So far I've gone to sites that I've dived and hunted and the bottom shows up on the screen pretty much as it looks underwater. It shows very clearly, drop offs and rock outcroppings along those walls. And it's only US$360 with the transom mount transducer. I have a deep V also but it doesn't seem to have a negative affect on the machine. It's also mounted right next to my compass on the center console. It says it should be mounted 3 feet away but I think that's just to cover their butts. I don't think THEY really know how it'll be affected and they say to contact them and report what you find. Hank

 

[pipedope]

I would love to have a SQQ-14 but don't know what the Navy did with them when they decomissioned all the old MSOs.

Best fish and wreck finder I have ever seen.

 

[bhampton]

hey guys I'm brad a scuba instructor from central washington
I own a 16ft zodak with a 50hp honda 4cycle
I also have an interphase phased array forward scanning sonar and a new
Hummingbirs 987c Si sidescan sonar and to tell the truth I have one of thoes flash light sounders which works great under water.
I have been able to run my interphase while up on plane and can easly scan 240 feet infront of my boat accrost a 90 deg arc centered on my bow(only because that is where I put it)if you wish you can go from 90 deg to like 10 deg and steer it from left to right manualy and it will scan accrost that arc where ever you point it.
with the scan set at 240 feet and the detail set low I can navigate around shallow reefs and rocks at night while traveling 20mph.
for the flash light sounder I have a 400Khz model which I like much better than the 200Khz that scuba pro sold and I think places like west marine sell them for like 160us. the 400Khz has les range but much better directivity.
for example you pointing at a wall that is 75 feet ways and you want to locate the end of the wall the 400Khz will give you a better angle to the tip of the wall than the wider beem of the 200Khz, at closer ranger it is possable to determin a ruff profile of an object keeping in mind it is a numaric display only but it is possable.
I have saved dives when we dived down the ancor line only to find sand at 130ft insted of a pretty wreak I came up off the bottom a bit and panned the sonar atound like a flashlight starting on the compass heading I thought the wreak was in and in no time found it just byond visability.
as for the Hummingbird 987cSi
http://webpages.charter.net/bhamptonkc7mrp/
wow is the word.
brad

 

[Chuck Tribolet]

How well does that Humminbird 987c SI work in salt water depths of 80-100'?

 

[lamont]

hey guys I'm brad a scuba instructor from central washington
I own a 16ft zodak with a 50hp honda 4cycle
I also have an interphase phased array forward scanning sonar and a new
Hummingbirs 987c Si sidescan sonar and to tell the truth I have one of thoes flash light sounders which works great under water.
I have been able to run my interphase while up on plane and can easly scan 240 feet infront of my boat accrost a 90 deg arc centered on my bow(only because that is where I put it)if you wish you can go from 90 deg to like 10 deg and steer it from left to right manualy and it will scan accrost that arc where ever you point it.
with the scan set at 240 feet and the detail set low I can navigate around shallow reefs and rocks at night while traveling 20mph.
for the flash light sounder I have a 400Khz model which I like much better than the 200Khz that scuba pro sold and I think places like west marine sell them for like 160us. the 400Khz has les range but much better directivity.
for example you pointing at a wall that is 75 feet ways and you want to locate the end of the wall the 400Khz will give you a better angle to the tip of the wall than the wider beem of the 200Khz, at closer ranger it is possable to determin a ruff profile of an object keeping in mind it is a numaric display only but it is possable.
I have saved dives when we dived down the ancor line only to find sand at 130ft insted of a pretty wreak I came up off the bottom a bit and panned the sonar atound like a flashlight starting on the compass heading I thought the wreak was in and in no time found it just byond visability.
as for the Hummingbird 987cSi
http://webpages.charter.net/bhamptonkc7mrp/
wow is the word.
brad

16 ft zodiac, 50hp motor and humminbird sidescan.... sounds like you own the boat i'm looking to get.

Is your zodiac a RIB or is it a flat-bottom? I've been attracted by the 13-14' flat bottom zodiacs that you can break down and store in a box (i'm still living in an apartment, so storage is an issue), but i don't know how the humminbird would do on them...

 

[Nemrod]

Lamont, I would get the RIB in that size. My Novurania is about 14 feet and it has a V hull using a keel board to hold the fabric in a V. Some use an inflatable kee, like the Achilles I used to ownl. Very few boats actually have a flat bottom. I recommend an RIB in anything over 13/14 feet because the engine and boat are going to be heavy and all the rigging out will begin to take up your diving time. An RIB could be stored on a trailer and of course covered. Most roll up boats do not have a console an I figure the RIB type generally do have some type of fixed steering location. That Hummingbird unit is fairly large, be aware of that, it uses a lot of panel space.
I sure wish we could get some good first hand info on how these work out in salt water/marine at 60-130 feet depths?
N

 

[captain]

The biggest problem with finding offshore structure is knowing where to look to begin with. Just running around hoping to find something is like looking for a needle in a hay stack and will burn a lot of gas. If you know where to start looking almost any type of unit will work. More important in a navigation system and co-ordinates that will put you close enough to find the structure without too much searching.

 

[SeaKing98]

I worked many years doing hydrographic survey, then when I bought m first boat I bought a good high resolution "fishfinder" and turned that feature that draws the fish OFF. A dual freq. model will add the depth you need to get offshore. the high res display will help show the features. I found wrecks , ledges, coral formatiions and fish. Fish show up as returns from the sounders at depths adove the bottom. Cross behind a ship wake and you can see the disturbed water caused by the ship propellor.

Hope this helps.

 

[tribaltim]

I too have a 14' Achilles (zodiac) with a 25hp Suzuki engine and am curious if the hummingbird works in salt water very well?