question repairing transducer penetrations in alloy transom

[rob woods]

i had a fish finder fitted today - there was a communication gap @ the shop and the transducer was mounted directly on a strake and within a couple of inches of the exhaust  I'm not at all optimistic that this is going to work well (down-scanning raymarine), being so close to the exhaust, and although I'll give it a whirl i'm pretty sure I'm going to need to move it ... but - I don't want to run the cable from the current penetration all the way across and down, and I'm not keen on having unsightly and unused penetrations sitting on the back of my pristine hull anyway -

what's the best way to "blank" the holes in an aluminium southern jet hull (one of the holes is 20mm or so with a big cable gland in it now that doesn't properly tighten around the cable because they cut the hole larger than the connector on the cable to be able to route it through the hull)?

[mohawk]

This any help ?
http://www.nzjetboating.com/yabbse/index.php?topic=24760.msg186335#msg186335

[Paul]

Any welder worth their stuff can close up a hole.  I'd suggest placing a small block of copper on the inside of the hole, and the ali filler rod will 'cast' against the copper (think heatsink) - then just grind & polish off the outside.

[PM]

steel works as well

[jetdesign]

If the hull is painted the repair will be substantial
Alloy conducts heat at an alarming rate
There is also the shrinkage from welding to account for
If the transom plate is relatively thin (<3mm) a considerable amount of distortion is inevitable

[PM]

If the transom plate is relatively thin (<3mm) a considerable amount of distortion is inevitable

Who makes a major structural part of the hull out of thin material?

[jetdesign]

Without knowing the boat in the original post I am trying to cover all bases
All the boats I have worked on and indeed repaired lately have used <3mm for their top side parts
I do not personally use less than 3mm plate for my transoms but I do not feel I need to discourage others from trying this

[rob woods]

yes orange paint on aluminium southern jet - see the transducer ... right on a strake .... and right next to the exhaust?

 

 

[Paul]

Something else that maybe a factor for sensor position, is the water temp measurement.

Reading some of the online stuff, the fish sometimes are attracted to temperature changes, so the temp reading graph can be used.  This is fine on an out***rd, however, with a jet with the bucket half-down (for trolling\slow speeds), the warm exhaust water is redirected forwards onto the sensor and screws up your temp measurement (- well it did with my Navman).  Maybe moving the sensor further outboard would help, but that then looses depth measuring capacity at lower speeds.

[heemi.v8]

could machine a nice piece to go in there with a bolt then use an oversized washer on the back and tighten up. i can do a drawing if you like

[Jeff B]

Just stick another skin fitting there like the 2 below it?
Or make a rectangular blanking plate that is held in place by the 2 skin fittings.
That part of your transom should be about 5mm thick. 3mm is too thin there.