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[tomtomterrific]

Ahoy again,

I'm installing new Radar and MFD, replacing the old speedo and depth sounder.

Q - Would you remove the old through hulls?

How big of a DIY is it? I've done fiberglass work before but nothing as critical as a hull repair.

Cheers,
Cap't Tom

[km1125]

I would only remove them if you have something else to put in their place. Won't you need a transducer for depth info?

[SplashyLady]

Check the frequency of the new and old sounders. Maybe the old ones are compatible with the new equipment, and save yourself a lot of time and money. If it's the same manufacturer, sometimes the plugs will match. If it's different, you can often just splice the coax cable (something like a BNC connector) and the new sounder will work with the old 'ducer. Lots of 'ducers are either around 50-80KHz (deep water) or around 200KHz (shallow water), or both (dual frequency). The old transducer will work with a new unit if the frequencies are close. HOWEVER (there's always a catch!). Newer sounders using CHIRP or side-scan require specialized 'ducers and older models usually won't work with the new technology.

Good luck!

[Tireless]

Unless they are in the way of your new installation or are leaking, I would just leave them in. Lots of boats out there with old installations in their hulls. I would also consider what SplashyLady says, you never know, but there is a thing called "designed obsolescence" and you will find that the old will not mix with the new very well. That's how these tech companies make their money. I am currently looking to refit my boat with a new MFD and I am running into the same thing with the sonar and radar. Good luck...

[Viper]

What system are you installing?

I don't recall what the '86 Riviera had for a hull...cored, solid glass? This would help my decision on whether I would remove the old ducers. If it's a cored hull, I would definitely remove the old ducers. Cored or not, if there are any signs they have been leaking, remove them.

[Sadey]

Our boat had all Raymarine and we replaced with same. We had to purchase an ITC5 to use the old speed and depth ducer on the new Ray MFD. We also had a new chirp installed to take advantage of the MFDs capabilities. Overkill yes and cool factor high. If we had not used the old ducers we would have left them in place and zip tied the wires. No need to cause a problem where there isn’t one. The thought process was the hole might not be the same size for the new ducer so for minimal cost redundancy was added.

[tomtomterrific]

Thanks everyone -

The old speedo and depth sounder units are mid 80's vintage and the old radar was Raytheon (pre RayMarine) probably also mid 80's vintage - no sign of leaks.

The new sounder is a transom mount. No new holes or reusing the old hole. Sounds like the consensus would be tidy up the old wiring and leave the old units in place!

Much appreciated!

[tomschauer]

Hey Tom, a transom mount transducer on an inboard boat is pretty useless unless you are barely moving. It will see the bubbles and such from the propwash and give you crazy readings. The transducer always needs to be forward of the props.

[Viper]

Qr Bbpost Hey Tom, a transom mount transducer on an inboard boat is pretty useless unless you are barely moving. It will see the bubbles and such from the propwash and give you crazy readings. The transducer always needs to be forward of the props.

+1

[tomtomterrific]

I took tomschauers advice and got a through hull transducer. The old ducer has a 2-1/2" diameter at the edges of the flange. My new unit requires a 3-1/8" hole. My plan is to cut the 3-1/8" hole from outside the hull by going straight through the existing ducer, with the hole saw outside the existing 2-1/2" flange, with the old unit inplacew ehile I do this.. (it's very difficult to access it from the bilge to remove) Appreciate your thoughts and feedback. Is this a good idea? Thanks, Tom