Transducer replacement

[Anonymous]

We have a 33' long aluminum research vessel that was built in 1994 and is getting refurbished in the next year. We have a Furuno FCV 1200BB sonar that is still using the original transducers from 1994: 88Khz (CA88F-126H) & 200Khz (CA200B-8B). The existing transducers were mounted on the transom with custom aluminum brackets in 1994. I am trying to decide whether to replace the transducers and if so with what and how they should be mounted. I was hoping that there are newer transducers that might provide better resolution of targets at depth.

We do not really use this system to look at fish much. We mostly use this system to look at the depth of man-made items within the water column of Crater Lake. Either instruments that we have hanging underneath the boat on a winch or items on moorings anchored to the bottom of the lake. The lake is almost 2000 feet deep (the deepest in the US) so we have to be able to look deep. For example, we may deploy a rope mooring in 2000 feet of water that has a series of 20 temperature sensors, floats, anchors, chain, etc. and we need to be able to look at the mooring in detail to see if part of the mooring tangled on the way down. So spatial resolution is important to us at depth. We also use it in shallower water at times (hence the 200 KHz).

Having good clarity while underway is not super important for us because we are usually just drifting when using the Furuno. So, the transom mounts have not been a real big problem. However, this is our chance to change the mounting of the transducers if we want to as the boat will be out of the water at a boat builder for the project.

My main questions are:
-should i stay with 88 & 200 KHz
-what wattage is best for our application
-what beam angle
-will changing to in-hull mounting significantly change the output of the transducers when we are not moving

 

[C-Bass]

Good morning Scott,

I read through your post and it sounds like an interesting project. I could not imagine working in a more pristine place than Crater Lake. I have a couple follow up questions, you mentioned that you are using a CA88f-126H.

1.) Do know if there is a BT-5 booster box installed that allows the sounder to output 5kw?
2.) As you mentioned spacial awareness is important for the project, with reference to how you use the sounder on average is vertical resolution more important that horizontal resolution?
3.) When dropping temp. sensors on a rope, at what distance are the sensors separated on average? How large are the sensors?
4.) With your current transducer line up, have you noticed a difficult time seeing the rope and sensors or other items attached to the rope on the screen when deployed? When deploying the temperature sensors, is the rope dropped straight down, does the scope angle of the rope change over time when deploying?
5.) Items that you have anchored to the bottom of the lake on a mooring do the float above the bottom or do the just stick up from the bottom? If either scenario how far do they float or stick up from the bottom?

Thank you for taking the time to answer these questions, they will help narrow down the list of possible replacement transducers to find a nice fit for your needs and how you use the product.

 

[Anonymous]

Thanks for getting back to me. Here are answers to your questions.

1) We do NOT have a booster box. We originally had an FCV-1000 and upgraded several years ago to the 1200 black box. Did not realize a booster box was an option for the 1200.

2) vertical resolution is definitely more important than horizontal.

3) Distances between items on a mooring are variable but the past examples I can think of are glass floats (approx 16" diameter) that are only 1-2 feet from a set of shackles and those only 1 foot from a temperature sensor (12" long plastic tube). In that type of situation, the entire set of stuff just blends all together into one big return. Not the end of the world, but would not hurt to see separation on the returns in that instance.

4) See #3 above. Usually the mooring is straight up and down. Often do not see the rope itself as a return but that is ok. Also use wire-rope (3/16") for lowering instruments and stuff and can see the wire rope more easily, espeically when it gets some scope.

5) Most of the items on the bottom are anchored and only stick up out of the sediment 12 inches or so.

Thanks much!

 

[C-Bass]

Good afternoon Scott,

I recently sent you a PM for contact outside this forum. Please get in touch with me per the message.

Kind Regards,