Removing/replacing stock tranducer on a Sundeck 220 (2010)

[Jdr01930]

I got a new GPS with sounder (Garmin 546s), and have pretty much decided my best would be to replace the stock thru hull transducer. From what I can tell, only thing I will lose by removing stock 'ducer is depth reading on the system tach, which will be a little obsolete anyway.

The transducer is accessed in the engine compartment, just in front to the engine.
It's a little out of my arms reach, so I'll have to contort/hang a bit or see if my son get get down there.

Question: How hard is it to remove the stock transducer? Looks like you just loosen the nut, but then I'm guessing there will be some sealant holding it in. Any tips for how to deal with that and get it out? I assume people have done this, or is this not a good path to take?

This boat spends all season in salt water, so transom mount 'ducer might not be ideal. I considered a shoot thru hull, but I kinda like the thought of getting water temp. And also the hole is already there so might as well use it. My understanding is I'd want to disable the stock one anyway, as two 'ducers will interfere with each other.

Any thoughts? I am far from an expert in transducers and any advice appreciated....

I'm thinking this is what I want?:
Airmar P319
https://buy.garmin.com/shop/shop.do?pID=15166
It says it's good for 0-7 degree dead rise. Anyone know if that's about right for that part of the Sundeck 220 hull?

 

[Henry Boyd]

First off the transducer may be functionally what you want, just not the specific one. Your proposed transducer is for a 0-7 degree deadrise hull. Your boat has a 21 degree deadrise. Deadrise is the angle from horizontal of the hull at the transom. So you would need a 20 +/- degree transducer so that the sonar beam would be pointed down.

The installation of the transducer is deceptive. Yes, the big nut 'holds' it in, but it really only holds it in until the half a tube of adhesive caulk that Sea Ray beds the transducer with cures. Getting the thing out is best done on the idea of destructive removal. When we had ours done, it took the installer quite a while to bash the old one out.

The other thought that is worth pursuing is that you may not need a new transducer. Airmar seems to make most of them now anyways, the only difference being frequency. You might do a little research on what you have already, it may be compatible with the new GPS. So all you'd have to do is swap the wires. Or rather disconnect the transducer from the Smartcraft harness and run wire to the GPS. I don't have any Garmin stuff, do they need an intermediary device between the transducer and display head?

In either event you should consider connecting the GPS to the SC1000 tach via NMEA 0183 and then you will get depth back. I'm not familiar with the System Tach, but I think connecting it to the GPS will also give you fuel mileage data as well.

If you decide to have this installed for you and don't want to get the dealer involved, you might contact Voyager Marine in Essex. They have installed a lot of stuff for me and my friends over the years and always do a good job.

Henry

 

[Jdr01930]

Thanks Henry.
I know my deadrise is 21 degrees at the stern, but I was thinking it was less where the 'ducer hole is.
However now that I think about it I doubt it's that much less as that steepness is carried forward quite a bit. Will measure before buying anything to be sure...

I think I'll try working with the stock transducer first though, based on the info/suggestions you provided. My main desire with this new device was GPS. I got sonar on bit of a whim as it was not that much more expensive, so I don't "need" to have it working immediately. I'll probably play around with the wiring a bit this summer when time permits, then wait till next year to replace the 'ducer if it's deemed worthwhile. I'm launching Saturday so time is running out (for transducer replacement)!

I talked to the guys at Seatronics a few days ago, as they are very close to where I live. Did not talk to Voyager but might do so. Seatronics was going to be way expensive, but at the time I was talking about having them install and wire a transom mount one, and most of the labor was routing of cables through the hull etc.

So my thinking right now is to experiment with the factory 'ducer, and if it doesn't work out deal with replacing it for next year.

 

[Alex F]

Why not just add the new transducer and leave the existing one in place? That's exactly what I did on my 320DA and it worked like a charm. I'm all for system redundancy and backups, and having 2nd transducer is a huge plus, IMO. Why break what's working if you just need some additional functionality?

 

[spfortjohn]

Why not just add the new transducer and leave the existing one in place? That's exactly what I did on my 320DA and it worked like a charm. I'm all for system redundancy and backups, and having 2nd transducer is a huge plus, IMO. Why break what's working if you just need some additional functionality?

That is what I would do and interface the GPS with the speed through nema

 

[Henry Boyd]

The concern is that two transducers operating on the same frequency could corrupt each others signal processing.

Henry

 

[Alex F]

I agree with Henry, but this is why preliminary homework is necessary. I'd verify the frequency of both ducers and make the final decision. Usually, there are few choices, so it can be done. Mine work just fine and I never saw any sign of signal conflict.

 

[Lazy Daze]

Alex... more for my own curiosity than anything else... how close are the two ducers to each other?

JDR... concerning deadrise... as you move forward the deadrise increases. All the way up at the bow it could be something like 60*. From the transom to where you would mount the ducer, the deadrise is likely exactly the same... or close enough as makes no difference. But, if anything, it would be slightly higher, not lower.

 

[Alex F]

Alex... more for my own curiosity than anything else... how close are the two ducers to each other?...

Here you go, Dennis (this is from my 320DA. New ducer is B60-20 and old one, if I recall, was P19):

 

[saopm]

I was looking to do the same so I contacted Airmar a while back. Your existing transducer is not going to work with your new Garmin unit because it is looking for an analog signal whereas the existing transducer is putting out a digital signal for the Smart Craft set up.

 

[docofthebay]

I replaced my transducer this year because it always lost a reading when moving more than a few miles per hour. It was the flush mount type that Alex shows in his picture. I called airmar and they said it is not uncommon for the flush mounts to do this when moving as a small microscopic layer of air bubbles can track backwards from the bow and interfere with transmission and reception. They recommended the thru hull replacement that extended down an inch below the hull and had the fairing block to hold it there and cut water resistance. Jim here at BOE fixed me right up with the recommended one.
It really was tough to get the old one out due to the bedding material. Once out, it wasn't hard to cut the fairing block to the proper angle ( with a table saw) and reinstall with new 5200 caulk. Works great now!!

 

[Jdr01930]

Just want to add a bit of info about transducer and dead rise that became apparent after taking a closer look, in case anyone comes across this in a search:

On this boat, the transducer is dead center on the keel, shooting straight down, so effectively the dead rise is 0.