Completed Fish ... Almost

[Patrick]

[img]../images/Completed_fish1x.jpg[/img]


The photo above is of Garrett holding the fish. It is approximately 31" long. There are a couple of minor things left, but for all practical purposes, the fish is ready to go for a swim this weekend.


I attached the 3 fish sections together by using screws. In between the sections are solid stock. It is so strong that it feels like one piece.


I'll post a report on the results late this weekend.


In the meantime, if anyone has any questions ... ask.


Patrick

[Jan]

Re: Completed Fish ... Almost

Patrick,


Looks good.


I am very curious how it behaves in water.


Regards, Jan

[bob]

Re: Completed Fish ... Almost

Patrick,


Looks great! I have to tell you how much I appreiciate all of your work.


Yeah, I have been dealing with a lot of theory, but at some point, I'll be asking you questions when it comes time to build the fish!!!


One idea I saw on a commercial fish that you might consider.. they had 'breakaway fins' I'm not sure how to do this, but I bet we would all be happier losing some delrin than an array!


(Perhaps something for you to work on over those long winter months!!)


Good luck this weekend! (post pics!)


-Bob

[Patrick]

Re: Completed Fish ... Almost

Bob,


I've seen the fish on the internet that you are talking about with the break-away fins. I would think that the fins are independent of one another and basically ride on a track or groove inside the body.


I thought that was a pretty neat idea also. I have some thoughts on this if you get to the point where you are ready to design the fish body.


If I ever figure out what the hell you guys are talking about, and build a more sophisticated SSS, I would do the prototype in PVC (much cheaper). If the results were good, I would then invest in a stainless fish.


If you did not go stainless, then I would definitely go Delrin over PVC.


Patrick

[Jan]

Re: Completed Fish ... Almost

Patrick,


Any major disadvantages for PVC over Delrin or is it more "looks" ?


I can machine PVC with my "wood cutting" (do not know english word) machines, suppose can do same with Delrin ?


Regards, Jan

[Patrick]

Re: Completed Fish ... Almost

Jan,


Both PVC and Delrin are easy to work with. Delrin does collapse (see past post on making the tail section) where PVC does not. PVC is at least 1/3 the cost of Delrin. Delrin is much stronger and is very chip resistant. To give you an idea on how tough this stuff is ... we dulled a router bit, ruined a brand new table saw blade (after very few cuts), broke a small drill bit drilling into it, and broke a stainless steel screw backing it out. PVC can be glued easily also. Delrin is almost impervious to any type of chemical.


I presently live in Alaska and my concern was using PVC in cold water. I did not want to hit something on the bottom and have the fish crack or shatter.


If I end up making the transducers, etc. for the SSS the list is discussing now I would make the prototype fish out of PVC to test the electronics. I would only take it in a known area with a sandy bottom. If it produced outstanding results (like Sture's SSS), then I would invest is a stainless steel fish. I think it would be worth the investment for the security.


I only have $160 worth of transducers in my fish. You can build the whole thing (cable, attachments, transducers, etc.) for around $300 (does not include fish finder) if you make it out of PVC. Add another $100 for Delrin. For the electronics I have now (don't expect them to be even near the quality of Sture's), Delrin is as high as I will go.


Based on my prior conversations with Dan Fountain, I thought that I would just go with the Delrin and only have to make it once. Also, I should note that I have enough Delrin (already cut) to make at least another fish. I also have enough PVC for two of them. I have spare sections made just in case something gets busted.


I began this project about two months before the SSS list began. Dan's unit seemed pretty easy for me to make because it did not require much electronics background. Right now, you guys have me lost.


I'm more than happy to answer any questions you might have. You and a couple others are doing all of the thinking right now while I watch and try to learn something. I'm not asking any questions now, because it would slow you guys down. I'm saving them for when I have to start putting stuff together (hehehe).


When you start putting the transducers together, do you have a digital camera so you can send photos to the list? It will save you a lot of typing!!


Patrick

[Patrick]

Re: Completed Fish ... Almost

Jan,


Almost forgot, my Delrin was done on a metal lathe. However, I would think that if you could machine PVC on a wood lathe, you could machine Delrin on it.


Your tools will just get dull a little faster.


Patrick

[Jan]

Re: Completed Fish ... Almost

Patrick,


First of all please post any question you have.


It might bring us on new ideas, or expose errors in our thinking.


Thats why we are on this forum.


Do not worry about electronics.


The moment we have something that works, all schematics,board layouts, PIC programs etc will be posted.


There will be enough people on the forum that will help you with building it or programming your PIC's.


I do not own a digital camera, and since I just ordered a new PIC Basic compiler I have no money left anymore (hehe)


Expensive compiler.. but very very nice.. )




Regards, Jan

[Charles]

Re: Completed Fish ... Almost

Hi,


I have a JWFisher Pulse 12 boat towable metal detector. The fish is the same dimensions as the one used for their SSS. The pulse 12 is made of PVC. The data sheet for the SSS says PVC, epoxy, and stainless. I'm not sure where the stainless is since I haven't seen but only pictures. If anyone would think that it would be helpful, I would be happy to take many detailed pics of the fish and provide dimensions. The endcaps are removeable and one has lead weight in it. I bought it used in non-working condition and I haven't restored it yet. But I'm happy with the purchase if for no other reason than to see how they made the towfish. As I have ordered towtec boards, I may wish to duplicate it for that alone. If you are interested let me know. It would be a few days before I could help as I just had gall bladder surgery and I'm not moving around too good yet and next week I'm scheduled to go to NY on business.


Thanks,


Charles

• JWFishers homepage

[Patrick]

Re: Completed Fish ... Almost

Charles,


I would be interested in seeing the photos. Maybe some shots on how they connected the pieces together, how they mounted the "insides", etc.


Thanks,


Patrick

[Patrick]

Re: Test Run of the Fish

Our plan on Saturday was to test the "fish" and the X-16 paper graph.


After we got to the site of a known wreck I noticed that I did not pack the power cable to the X-16. Fortunately, we were able to hook it into my LCD fishfinder, a Lowrance 350A.


After attaching the cables together, we dropped the fish in the water. We were unable to get any return signal from the "fish". After some limited troubleshooting, we were able to eliminate the fishfinder (350A) and the cable. Since there are not that many parts to the system (the fish only has some cable in it and four fishfinder transducers), we can only assume that it is in the wiring. We'll perform a bench test on the "fish" on Monday and hopefully be able to correct what ever is wrong.


If we are able to solve the problem, we will take it back out during the week.


The "fish" did swim quite well in the water and when being towed. We did not have to add any additional weight to it. I did have some extra lead that I could have attached to the bottom of the tow plate if it was needed.


I'll post a follow-up when we figure out what went wrong.


Patrick

[Jan]

Re: Test Run of the Fish

Patrick,


Sorry to see your problems.


When you benchmark your transducers make sure they are in water.


In my depthsounder manual they specificly warn not to switch depthsounder on when transducer is not in water.


Regards, Jan

[Patrick]

Re: Test Run of the Fish

Looks like the problem (lack of any signal) we encounted on Saturday's trial run of the "fish" was a short in the cable.


The problem has been resolved (only lost 3 inches of cable) and we plan on testing the unit again on Thursday.


Hopefully, everything will go well and I'll be able to provide some results late Thursday evening (Alaska time).


On a side note ... what happended to all of the traffic on the list? Did everyone die?


Patrick

[bob]

Re: Test Run of the Fish

Still alive here!


I will be away next week, but want to get prices for piezos before I go...


-Bob

[gordon buchanan]

Re: Completed Fish ... Almost

seeking info on what you will be using for your units in the boat for data acquistion unit or also called the control unit..and thermal printer? I am new at this. Want to build a low cost freshwater towfish with pvc. Don't know where to start with the units on the boat and the types of cable I need etc. Can you help me? Did Sture and Dan Fountain help you. Tried to send you 2 emails tonight but don't know if they went thru. Can you buy used control units?