Does anyone recognize this aluminium through hull design

[mstopo]

Hello,

longtime reader, first post here. I bought a 24 year old custom aluminium sailing yacht built by the french Meta yard. There's not a lot of documentation available and the yard (which still exists) isn't forthcoming with information, so I'm kind of lost with the through hull design for the log and depth transducers this boat is equipped with. I want to modernise electronics and sensors hardware, hence the question.

I've never seen it before. Does anyone recognize it?

Thanks for any pointers!

Regards
Markus

[DotDun]

It looks like a blank plug in a housing where a retractable depth/speed/temp transducer resides.

[mstopo]

Yes, I'm sorry the question wasn't clear enough.

I'm wondering about how the sensor housing is attached to the hull. The housing seems to be embedded in some kind of sealant (yellow, I didn't poke it, so I don't know what material it is, but I guess it is semi-rigid), which in turn is locked inside a cylinder which has a screwed-on cover-ring. I presume the ring compresses the sealant (yellow) and causes a water-tight embedding of the housing.

Since the housing (white) has the wrong diameter for new sensors, I need to replace the part the housing is embedded in.

Regards
Markus

[Boatyarddog]

Raymarine,
Here's a link. http://www.raymarine.com/view/?id=14...nid=8&col=1482
Transducer tubes, stuffing tubes
You'll probably have to change out the old style to the new profile.
Nothing new about that.
Hope that's helpful.


Sent from SV Cloud Duster

[noelex 77]

Welcome to the forum Markus and congratulations on the boat.

In the early days of electronics, transducers were only available in bronze. These cannot be used on aluminium hulls. I think the complicated arrangement that has been fitted to your boat is designed to isolate a bronze transducer from the hull.

A thick aluminium ring has been welded to the hull and tapped. Bolted onto this with the six stainless steel bolts is a plastic ring. A bronze transducer can then be fitted to the plastic ring and is not in electrical contact with the hull. It looks a very good and well thought out system.

With modern plastic transducers it is unnecessary, as these can be bolted directly to the hull. At some stage a plastic transducer has been fitted so the complicated system is therefore overkill, but it still does have some potential advantages. It allows the transducer to fire directly downward and also means the transducer can be fitted flush or slightly indented into the hull (too much will create turbulence). This means any lifting straps used by a travel lift will not put any pressure on the transducer itself.

I would retain the system. If using a plastic transducer you can replace the plastic plate with an aluminium one. This would be easy to fabricate and stronger than a plastic one.

[GordMay]

Greetings and welcome aboard the CF, Markus.

[mstopo]

Thanks guys for the welcome and thanks noelex 77 for the detailed technical response.

I wasn't planning to replace the configuration because I too think it's quite good.

So, I need to find a new insulator component (the cylindrical yellow part inside the alu-tube which holds the transducer housing), because new transducers have a larger diameter. I also don't know if the component would survive removal and drilling a larger hole into it. So I like to be prepared and have it ready in case it can't be reused.

Any idea what material this might be made of and where I could source it?

Thanks again!
Best Regards
Markus

[northwestsailor]

Hi Markus, I also have a Meta hull. My old transducer was imbedded in epoxy so when I decided to change the old technology out, it required a lot of work. Needless to say it did come out and a new transducer with a sleeve was installed. PM me if you need more details.

[Terra Nova]

In your case I would get a pro to remove the existing fitting for modification or replacement by a marine oriented machine shop.

[Stuarth44]

looks like b and g, it isthe plug as someone said for depth or spped impeller

[noelex 77]

This diagram should make it clearer. This is how I think the system was designed to work, but with a plastic top plate to provide isolation.

The hole around the bottom of the transducer might need some fairing to reduce turbulence this could be done with some Sikaflex, but the main watertight seal is between the transducer and the top plate.

[mstopo]

Thanks noelex77 for taking the time to make a drawing. I'm not 100% sure this is how it is set up. Based on my observations (purely from the inside, I didn't have a chance to look at the through-hull from the water side yet) I made one of my own:

Based on what northwestsailor told me in our private conversation, the insulator is epoxied into the collar. I assume the transducer housing is in turn epoxied into the insulator. I might be wrong on both accounts. The whole assembly is mounted perpendicularly to the hull, so the transducer exits the hull at a 90 degree angle.

I guess the main question now is what material the insulator is made of. And if I'm able to manufacture one with the correct dimensions to fit new transducers myself.

Regards
Markus