PiranhaMax question

Wonk · #1 06-25-2007, 05:28 PM

I purchased a Humingbird Piranhamax 215 to put on my new Hobie Outback. I did the "test" as suggested in the install manual by firing up the FF with the transducer outside the boat over a known bottom to get a base reading. I then used petroleum jelly inside the hull to check if the place I wanted to permanently mount the transducer would give the same reading. I did this testing in my pool and would float the yak over pool toys on the bottom to simulate a little structure. Although this was a very shallow water test (4' deep max) it seemed to give good results. I "glued" the transducer to the hull with a healthy application of 100% clear silicon (bathroom/kitchen caulk). When I took the yak to the river, it gives inconsistent readings as in going from a depth reading (say 18') to 0 feet, bouncing back and forth.

I also had the sensitivity set to maximum to get a "picture" of the bottom. If set at minimum it would not show a bottom line.

Have I screwed up the transducer install or possibly a bad location or is the hull material or the silicon my problem?? Any help would be apreciated.

PerryC · #2 06-25-2007, 08:39 PM

Heya,
Offhand, I would guess the transducer install. The only hulls I know of that have problems if they're not prepped right are the older malibu kayaks like the eXtreme with the foam in the hull. Most all other brands without foam do pretty good as long as the place where you install it is under the waterline where water is constantly against the hull to get a signal through.

If it were me, I might take the transducer off and scrape away any remaining silicone from it. I would try the vaseline again, and if all was good with that, I would clean the vaseline off the area where I test mounted the transducer/puck at, and I would remount it. I would try a different adhesive like Marine Goop though. I'm not an adhesive expert, but I used Goop more than a few times with good results. If you want, try that and please let us know how it works out for you, Good Luck,
Perry

Wonk · #3 06-25-2007, 10:41 PM

Thanks for the reply. I did a little research on the Hummingbird website and they recommend to NOT use silicon as it gives inconsisitent readings. I guess I proved them right. I asked a local boat supply place about Goop and they didn't carry it but said they had silicon. I assumed that is what the Goop was. That's what I get for assuming. I am going to remove the transducer tommorrow along with all the silicon and try again. What type of material exactly is Goop and is it removeable? Hummingbird recomends a slow set 2 part epoxy. I didn't really want to use that as I figured it would be much more permanent (in case I screwed up or it wouldn't work right).

Tarpon guy · #4 06-26-2007, 07:19 AM

Howdy,

These guys know a lot more than me, but I have found Marine Goop and Plumber's Goop at Home Depot.

Good fishing to ya!

PerryC · #5 06-26-2007, 04:30 PM

Wonk,
Marine Goop is a silicone for marine use. Even with that in mind, when I use it to glue down a puck I use a certain method that works for me. I find a mounting area that is flat so I can use a thin layer to secure the puck, and I find one that point straight down or as much as possible. Then I sand the area with 80 grit, and wipe it down with alcohol afterwards to get any residue off. I use a new tube of Goop so I'm sure it's fresh and has the least amount of air bubbles in it. I wipe down the puck with alcohol and run a continuos ribbon of goop on the bottom of the puck so the bottom is covered. Then I go to my spot I' going to mount it. I press it down and rotate it (about 1/8 turn) clockwise into it's final resting position in one smooth motion. While still applying downward pressure on it, I either put a 3-4lb weight on it so it won't lift up and draw air under it, or I'll duct tape it down then put a weight on it.

A few things to consider are you want as thin of a layer of goop that you can get away with. Second is the signal for your fish finder can't travel through air. If you have alot of bubbles in the goop, of say the puck is 3 inches around, and you have a small spot the size of a quarter with goop on it, that small spot is the only place the fish finder will get a signal from. Hope this helps,
PerryC.

Wonk · #6 06-26-2007, 05:34 PM

Thanks for the help guys. I looked for Goop tonight and only found Plumbers Goop. It said it shouldn't be used on polyethylene??? I reattached the transducer with epoxy tonight and am not feeling great about it. I am afraid it may have a lot of real tiny bubbles in it. I will have to wait until the next time I can get on the water to check it out. Does anyone know how hard it is to remove epoxy if it still doesn't give satisfactory results??

PerryC · #7 06-26-2007, 06:50 PM

Wonk,
Some of the goops sold under the "Amazing Marine Goop" brand will say they shouldn't be used on polyethylene. The brand I use made by eclectic products inc. also contains some of the same solvents such as toluene, but has no warning about polyethylene. How different are the two brands in reality? I dunno.

Some folks also use 3M 5200 Marine Adhesive for puck installs and swear by it, others use a product called Lexel and swear by it, then the epoxy crowd uses epoxy and swears by it. I have used 3M 5200 on my first kayak and never had a problem with it, then I switched to marine goop to try it and I have never had a problem with it either. A few friends though have had to remount their pucks because they got bubbles in it the first time around. I have never used epoxy or Lexel. However, I may try the Lexel on my next install just to try it. I have heard it's really good for having very few bubbles in it which is a big plus.

Below is photos of 3M 5200 Adhesive, Lexel and the tube of marine goop I use.

I'm not sure of the best way to remove epoxy. Maybe you can just pop it loose?

Perry

Tarpon guy · #8 06-26-2007, 08:08 PM

I had trouble finding Marine Goop the time I used Plumber's Goop. I tried it on a small spot overnight. It looked good in the morning so I did the install and it's been ok for a few months.

Robert · #9 06-26-2007, 09:48 PM

Marine Goop, Plumber's Goop, or Household Goop I have used them all and they all work just fine for gluing your transducer to the inside of your hull. Just follow the way Perry described and you will be good to go. Epoxy did not work worth a

for me! It delaminated from my hull the first time I went out.

Not only that it was a mess getting it off of the transducer afterwards. Once I did get the epoxy off I glued the transducer down with Goop and it worked perfectly for me for 2 years. I sold my kayak to a guy and as far as I know it is still working fine.

Robert

Wonk · #10 06-26-2007, 10:15 PM

Thanks all. I am going to try to hit the river tommorrow for a better test, maybe try to catch a few more stripe bass. I did put the yak back in the pool tonight and when I floated it over the steps, the FF gave me a reading of 8'. The pool is only 4' deep?????. This is why I am leary of my second attempt. If this doesn't pan out I am going to try the Goop or maybe the Lexel. I actually have a tube of the Lexan at home but it's a little old. I may try to find a little flatter spot on the inside of the hull too. Where I have been putting it has a slight curve and this may be some of the problem.