Installing Garmin GSD20 and In Hull Transducer

[seamegr]

FYI, I am in the process of installing a Garmin GSD20 and the Garmin In-Hull Transducer, which is an Airmar P79. These connect to my GPSMAP276C.<br /><br />I assembled the wiring harness on the bench and tested, then took it to the boat. As per the instructions I put the transducer in a plastic bag filled with water and placed it in my preferred location. In the bilge, slightly to right of centre, right between the front engine stringer and the fuel tank bulkhead. (just enuff room, it's only a 17' boat)<br /><br />I had depth readings right from idle to about 25mph which is as I fast went so there does not seem to be any problem there<br /><br />I only had about a 100' of water to test in. As per the instructions I then stopped and held the transducer over the side of the boat to check accuracy. Taking into account drift and waves, there did not seem to be a big difference. Less than 1 foot. From this I will assume all is well and will permanently install this weekend. <br /><br />Airmar now recommends the base of the transducer mount be secured with GE Silicone II and not with any of the 3M products. The base is filled with mineral oil.<br /><br />This is my first experience with a sonar type device and I was surprised at how loud the clicking is from the transducer. It is extremely audible at idle and below planing speed.<br /><br />Greg

 

[ufm82]

Re: Installing Garmin GSD20 and In Hull Transducer

It said to use silicone? That seems extremely odd to me but I'm not the manufacturer. <br /><br /> I have told people in the past to NOT use silicon because it is not hard and will not transmit the signal properly. That is why all manufacturers will tell you to use a 2-part epoxy to secure the transducer with. It will transmit the ping with little signal loss. <br /><br /> It has been my experience that the higher powered finders are the most noisy, I.E. you can hear the ping, which we hear as a click. I have found that if you are hearing the click, the transducer is not mounted securely and the ping is not being transmitted properly. The X91 I have in my boat right now is a 3,000 watt unit and if I simply laid the transducer in the bilge, I could hear the ping quite clearly. Once I epoxied the unit in place, the clicking sound went away. I have also found that I can hear the pinging from most transom mounted units as well. <br /><br /> Many fisherman will turn off their finders when they actually fish so as not to spook the fish. The click is very audible to them underwater. <br /><br />UFM82

 

[dingbat]

Re: Installing Garmin GSD20 and In Hull Transducer

UFM82,<br />Epoxy is an absolute no, no in this type of installation. It's way to brittle and prone to leaking. <br /><br />Greg S<br />Don't worry about the noise. It will dissipate once you put the transducer in the oil bath..<br />Make sure you use GE silicon II and I'd recommend using castor instead of mineral oil.<br /><br />I installed mine with 3M silicon and used mineral oil as recommended at the time and it began to leak within months of the install. I ended up tearing the whole thing out this spring and reinstalling it with the GE product and switched over to castor oil as is now recommended. It’s been 5 months now and the silicon has yet to show any signs of softening so I hope that resolved the issue. <br /><br />BTW you;ll like that setup. I’m good up to 40 mph and not a bit of noise on the screen.

 

[seamegr]

Re: Installing Garmin GSD20 and In Hull Transducer

UFM82, as you point out the transducer was not secured in any way. Just lying in a baggie full of water. This type of transducer is in 3 pieces. The base which is hollow and silicones to the hull and is the container for the oil. The transducer itself and a locking ring. The transducer face is immersed in oil not attached to the hull.<br /><br />Ding, I'm intrigued about the castor oil. Is it a 2 stroke transducer? Sorry couldn't resist that.<br />Where did you find the info on using it instead of mineral oil? I am a little concerned about the mess either will leave in the bilge in case of a leak. Does it show up in the water like an engine oil leak?<br /><br />Thanks<br /><br />Greg

 

[ufm82]

Re: Installing Garmin GSD20 and In Hull Transducer

Oh, well there you go. I'm ignorant about this 'ducer then. <br /><br /> As Emily LaTella used to say on Saturday Night Live, "Never mind".<br /><br /> I'm intrigued- I'll have to read up on that thing. <br /><br />UFM82

 

[dingbat]

Re: Installing Garmin GSD20 and In Hull Transducer

Airmar recommends mineral oil, castor oil, or propylene glycol but having problems with the installation I decided to do a little investigation of my own. I checked the compatibility charts and found that silicon is a marginal performance in presence of both mineral oil and propylene glycol to which I can certainly attest. Silicon’s performance in the presence of castor oil is rated excellent so it wasn’t that hard to decide which fluid to use on the second go around. <br /><br />As for the mess, the mineral oil is clear and tends to stay in little globules and didn’t disperse like motor oil. Most of it went out the drain when I pulled the plug so I had little mess with the stuff.<br /><br />As for the castor oil I don’t have a clue, I’ve not had to deal with it so far. Knock on wood.<br /> airmar FAQ

 

[seamegr]

Re: Installing Garmin GSD20 and In Hull Transducer

UFM82, "Too much violins on TV"<br />I do miss her.<br /><br />Ding, ok I'm sold, castor oil it is. Thanks for doing the research.<br /><br />The pharmacist sure looked at me funny last night when I asked if they had both castor and mineral oil. Then I told her what it was for. Of course the castor oil is more expensive and comes in smaller containers.<br /><br />Greg