"the other tru hull"-my transducers

[njlarry]

The recent sad thread about a sinking has made me think about my 30+ year old "factory original" speed and depth transducers. The seacocks have all been replaced.
How robust are these plastic transducer mountings? Other than looking for leaks can they be inspected without damaging them. I am considering removing them and glassing over the holes although I realize that would be a major project.
Hope all stay safe and water tight.

 

[JamesG161]

This is my thought on the boat sinking possibility that triggered many thoughts for all of us. I have "plastic" ones also.

But....
On all of my thru hulls I have Bronze ferrules which hold the plastic to the hull and makes the outside seal. Since the plastic is only under stress by the sea cock "open/close" movements and minimal due water pressure, I would inspect the plastic with bright light magnifier on the top edges ( in the direction of sea cock handle movement) for tiny cracks. No cracks... normally no problems.

IMHO the problem is the metal ferrule corrosion that would be sudden failure and a big hole.

I was thinking that I would comment on the "sinking thread" since one of his sea cocks had been recently changed, but felt it was premature.

Two things might have happened to that sea cock.
1) over tightening of the sea cock installation, spitting a plastic fitting.
2) Rapid galvanic corrosion by mismatching sea cock valve metal with ferrule thru hull metal, which would lead to ferrule failure. ( most likely the failure if any new sea cock failed)

Most people don't think of installing a Stainless Steel sea cock on a bronze ferrule, but this the reason I have zinc anode on my SS shaft and Bronze propeller.

So...
I do a hose, clamps, plastic thru hull, sea cocks and etc. "close" inspection annually.
Jim...

PS: I inspected my ferrules when out of water about a year ago. No problems.

 

[Chris & Lenore]

The recent sad thread about a sinking has made me think about my 30+ year old "factory original" speed and depth transducers. The seacocks have all been replaced.
How robust are these plastic transducer mountings? Other than looking for leaks can they be inspected without damaging them. I am considering removing them and glassing over the holes although I realize that would be a major project.
Hope all stay safe and water tight.

I have exactly the same "anxiety" - two old SR Mariner transducers. Both unused now and both in an almost impossible place to reach if they did fail.

I plan to remove them and glass in the holes. This is not a difficult task and there are many "how to" and video articles available. It is a bit of a PITA but you will sleep better if you do it.

FWIW the only failure of a plastic transducer mount I have encountered was on a friends 20 foot trailerable. We were anchored off Pensacola Beach this past June (BEER cruise) when Eric yelled out that he was sinking! We pulled him into shore so he couldn't actually sink (benefit of a trailerable), bailed him out and investigated.

Turned out his depth transducer had popped out of the thruhull fitting. And the reason was that instead of a stainless bolt retaining it, the DPO used a twist tie. When the twist tie rusted off the transducer popped out and the boat started to fill. Ten minutes later and Eric would have been off the boat and enjoying beer at one if the local bars (while his boat sank).

Goes to show that a lot of factors can be responsible to a sinking..

Chris

 

[repawn]

Having read this forum post I decided to take a look at my transducer as well - pretty sure it was the cause of my recent leaks - the boat is out of the water for the season so I figured now is the time. Well, taking a look under the boat it didn't look like the transducer was that bad - inside the transducer goes through the cabin sole - then through some wood (can't get under to see) then through the hull. I unscrewed the hand tightened transducer nut - it went easily - then I put a tiny bit of weight on the whole assembly - the trasnducer just slid right down - would have went through the hull if I hadn't left the nut ont he end - I am guessing no sealant or whatever had been there has been gone forever - this is an old datamarine system - can't purchase the sender any longer. I thing I will inspect for any fiberglass damage and then re-install - probably use 3m 4200 or 4000 - I also have some lifecalk - I would like to use the depth gauge - if only for anchoring in the future.

 

[Chris & Lenore]

Having read this forum post I decided to take a look at my transducer as well - pretty sure it was the cause of my recent leaks - the boat is out of the water for the season so I figured now is the time. Well, taking a look under the boat it didn't look like the transducer was that bad - inside the transducer goes through the cabin sole - then through some wood (can't get under to see) then through the hull. I unscrewed the hand tightened transducer nut - it went easily - then I put a tiny bit of weight on the whole assembly - the trasnducer just slid right down - would have went through the hull if I hadn't left the nut ont he end - I am guessing no sealant or whatever had been there has been gone forever - this is an old datamarine system - can't purchase the sender any longer. I thing I will inspect for any fiberglass damage and then re-install - probably use 3m 4200 or 4000 - I also have some lifecalk - I would like to use the depth gauge - if only for anchoring in the future.

A friend of mine glassed in the holes but still wanted the depth sounder. He epoxied the old fitting to the inside of the hull, filled it half full with mineral oil and inserted the transducer. It now shoots through the hull an d worked as well as it did before.
Food for thought...

Chris

 

[njlarry]

Having read this forum post I decided to take a look at my transducer as well - pretty sure it was the cause of my recent leaks - the boat is out of the water for the season so I figured now is the time. Well, taking a look under the boat it didn't look like the transducer was that bad - inside the transducer goes through the cabin sole - then through some wood (can't get under to see) then through the hull. I unscrewed the hand tightened transducer nut - it went easily - then I put a tiny bit of weight on the whole assembly - the trasnducer just slid right down - would have went through the hull if I hadn't left the nut ont he end - I am guessing no sealant or whatever had been there has been gone forever - this is an old datamarine system - can't purchase the sender any longer. I thing I will inspect for any fiberglass damage and then re-install - probably use 3m 4200 or 4000 - I also have some lifecalk - I would like to use the depth gauge - if only for anchoring in the future.

Glad you found it. My choice sealant/caulk would also be Lifecaulk or 291. 4200 might be overkill? Beyond the caulk, what should our concern be with the older plastic fittings?
Chris, using the old fitting to mount inside the hull is a great idea.
I guess another question I have is, since the original plastic fittings have been universally trusted to remain water tight on millions of boats, why do the manufactures not make a similar plastic plug designed to peranantly fill the hole left after removing the transducer?