information

[GREG OLSON]

Pat,you have to keep in mind that the alignment of the ducers is a function of the quality and consistancy of the piezo elements in the potting compound.That is why the true "made for sidescan" transducers are so expensive.The best you can hope for in the future is to call the mfg and ask what the tolerance is that they use to align the elements and then quantify the total amount of error that is possible.By doing this , software can be designed to partially overcome the out of phase problem.


oh and by the way, the EG&G system was mine but sold in june to me Gerald Buchanen of Pike Lake, Mn.


He currently has it up for sale

• Great Lakes Shipwreck Message Board

[Patrick]

Re: information

Greg,


Thanks for the information ... seriously.


I'm just following Dan's plans and making some minor modifications along the way. I guess we are assuming that the manufacturer (in this case Lowrance) has some type of consistency or quality control in their manufacturing process. Making that assumption, it would be best to keep the transducers square.


I'll try to give Lowrance a call over the next week and see if I can get any information on the alignment.


I'm sure that this seems like a crazy idea to you since you have the real thing. But, it is keeping me busy during the rainy days (seems like every day) that we are experiencing in Alaska this summer.


Most of the others on the list are trying to start from the ground up. In my case, I have about 7 weeks left of the boating season before the snow falls (heavily). After living here for over a year, I have gotten some general information on the location of several wrecks (from 1904 to several years ago). They are located in waters from 20' to 175'.


Out vis is not that good in te summer due to a combination of plankton bloom as well as glcial run-off. I went 40 miles last week to find that 1904 wreck and had to abandon that idea when I saw the color of the water as I got closer to the end of the bay (near a glacier). It was a grey/green color (due to the high amount of glacial silt). Vis was less than 6" ... not even worth getting wet. Plan "B" (always have a plan "B" up here) was to go fishing. I can't complain about getting 3 silver salmon in an hour.


A friend was able to locate a "fish processor" using his Interphase (not sure of the model) Fish Finder ... the one that looks down and across similar to a radar. It helped that he knew the location of the wreck before it sank too.


Couple of questions, if you do not mind on the EG&G ...


How far off the bottom do you normally tow the fish. How deep can you expect the fish to swim at normal tow speeds when the cable is 175' long? What type of power do you need for that system?


Thanks,


Patrick

[Patrick]

Re: information

Greg,


In reference to the alignment of the transducers you mentioned that it would create a phase problem. It seems that they will pulse at the same time ... so it would not be a phase problem as much as it would effect the fan.


In other words, if the transducers are pulsing at the same time you do not have a phase problem However, if the transducers are not exactly aligned (not pointing in the exact direction) it would distort the image and if they are not grossly out of alignment the distortion would be minimal.


Your thoughts?


Also, why are you selling your sidescans for so much less than your friend? You are asking $4500 and he is asking $9500 (if I recall correctly).


How did you land up with three sidescans?


Thanks,


Patrick