REMOVING old equipment forward facing sonar

[Traderjoe]

I have a old mechanical device in the bilge and it is part of the hull. I would like to remove it. Can I take it out safely without expecting leaks?

Aloha and Mahalo!

Joe

 

[twistedtree]

Is it above the waterline? Probably not, in which case you will probably sink the boat. And once removed, I expect you would want to patch over the opening in the hull surface, in which case it's probably a good job for your next haul out.

 

[slowgoesit]

What the heck IS it?!?

 

[RT Firefly]

Greetings,
Messrs. T & s. YES! What the heck is that???

 

[twistedtree]

I think the OP's assessment is correct that it's a raise/lower sonar. The pictures show the lift mechanism and the sonar tube.


Here is a current model Furuno searchlight sonar from inside the boat.

 

[RT Firefly]

Greetings,
Mr. tt. I don't see where the OP mentioned WHAT the device was but it may well be what you describe.

 

[twistedtree]

Greetings,
Mr. tt. I don't see where the OP mentioned WHAT the device was but it may well be what you describe.

The subject line mentions forward facing sonar.

 

[RT Firefly]

Greetings,
Mr. tt.m You're absolutely correct! My humblest apologies, kind sir.

 

[Traderjoe]

Can I unbolt it and get rid of it?

 

[twistedtree]

Can I unbolt it and get rid of it?

See reply #2 above. The tube coming up from the hull is likely open to the ocean. If you unbolt and separate the flange, sea water will flood in, assuming that flange is below the waterline.

 

[STB]

I strongly recommend against most anyone doing this in water. Given what it's, it would seem to leave a hole below the water line with all of the obvious risks.

Having said that, I have done similar in water. And the water can be manageable. Even a 3/4" thru hull near the watering won't sink a boat fast and the flow can be mostly stopped with a hand or foot on the inside or a plug or plunger or wax putty from inside or out.

If I, with due consideration to the risks, decided to remove it in water. I'd replace it with a thru hull if large enough or a 316 stainless bolt, otherwise. If I did it with a bolt or thru hull I didn't want, I'd take it out and do the fiberglass work at the next haul out.

The basic idea would be to have the bolt or thru hull ready. Remove the device with the assistance of a diver and control the water flow with a plunger or otherwise from the inside until ready. Let a diver goop the thru hull or bolt with 5200, pound on the hull with a pipe so I could remove the plunger, and let the diver push it thru and hold it in place while I got it started from the inside. If I needed to make the hole larger, for example for a larger thru hull, I'd use an air drill (, but have also seen it done with battery drills). The diver is done and just on standby once it is started as it can be held from the inside after that point.

If installing a thru hull, I'd fill it with wax plug paste first, so once it is in, it won't leak. Then, after tightening, I'd knock it out with a dowel and cap it off. From there a bolt can be cut off.

If concerned about a round bolt head underwater...remember zincs have thru bolts.

To mitigate risk, one wants a good and experienced diver or two, and a good or experienced helper or two. As much as possible, plan with them, let then do the work, and stay thoughtful, calm, and ready to manage things as needed if something comes up. A trash pump is never a bad idea, etc.

Again, I am reqlly not suggesting that one do this. Just that people make choices and some might choose to do this, including.me under some circumstances. There is obvious risk.

 

[twistedtree]

I don't know anything about the particular sonar/lift in this boat, but if it's anything like the Furuno or Wesmar sonars that I have seen, the stand pipe (Furuno calls it a retraction tube because the sonar head retracts into it when not in use) is anywhere from a 4" to 8" pipe, the bottom of which is wide open to the sea. Mine is 8" is diameter and you REALLY don't want to open that up with the boat in the water. Even a 4" tube would be very risky to do in the water, and I just don't see any reason to risk it when you can wait for a haul out. Or is there some really compelling reason to remove it now?



If the plan is to abandon the sonar and retraction tube, then the opening in the hull should be glassed over in the same thickness as the hull. That's definitely an out-of-the-water operation.


Now all that said, it's possible that the top of the retraction tube is above the water line. That's actually the preferred installation method, but is often not possible. But if it is above the water line then the sonar could be removed from the tube and the tube top capped off with a plate fabricated to fit.

 

[boomerang]

It's very hard to tell what you have from the pictures. The retractable sonars I'm familiar with have the sonar housing separate from the sonar transducer so the housing can be mounted in the hull and then the transducer and hoist added later. There should be a blanking plate used for service that gets bolted in place after the equipment is removed. It looks to me that yours comes apart at the flange just under the hoist motor. Your tube does stand pretty tall but I would be damn sure it's above the waterline before removing the bolts!

 

[boomerang]

The blanking/service plate isn't in the picture (it's normally stored close by the sonar) but it would bolt to the hi-hat in place of the sonar. Look around your boat and see if you have a plate.
This particular sonar is bigger than yours by a mile but 2 of the boats have a much smaller Wesmar & a Furuno and it's the same setup with a plate for servicing.