Bottom paint buildup on raw water intake through hull...

[TimBSmith]

Greetings to all.

While bottom sanding, took a closer look at every part of the hull. Noted that my raw water intake has several layers of bottom paint on it. The diameter of the intake opening is about 1/4 inches on a 1/2 inch Marlon mushroom through hull. What are some practices for reaming out the reduced intake hole inside the mushroom shaped through hull?

And if you will allow a bonus question. I am using Aquaguard bottom paint consistent with prior owner. I noted some bottom paint on the depth sounding transducer and I put a layer on as well. Now I am wondering if I should sand all the bottom paint off and just use transducer paint? Research says some 200 grit would do it, then repaint with transducer bottom paint? Thoughts?

I will be testing the transducer "as is" tomorrow, though while I am on the hard would like to have it right before getting wet later next week.

Thankful. Stay well.

[Mo]

You will be good with bottom paint on it....will work fine if it (transducer) works.

[roadnsky]

The diameter of the intake opening is about 1/4 inches on a 1/2 inch Marlon mushroom through hull. What are some practices for reaming out the reduced intake hole inside the mushroom shaped through hull?

Tim-
Have you considered going bigger with the Engine intake thru hull.
I did it and the difference between the old, smaller thru hull and the new, larger one is dramatic.

A bit of expense and work but well worth it while you're on the hard IMHO.

[tenders]

I'd be a bit concerned if a buildup of bottom paint is causing you to lose significant diameter in the intake. There is a metal tab or band cast into the inside of the through-hull which allows a tool called a "step wrench" to grab onto when tightening the inner nut. You'll need to adapt your paint-removal technique to respect that band.

But with that in mind, legitimate paint removal techniques include sanding using a thin pipe wrapped in sandpaper, Dremeling, chiseling, drilling, or paint stripper.

[TimBSmith]

Thank you...

After some study and steading nerves, I gently placed the point of my buck knife(the one my boys bought me) on the edge of the inlet hole and applied careful pressure. Years of bottom paint cracked and flaked off. Will take a picture of the bottom of the mushroom inlet head. I did feel the embedded metal ring and was extremely careful to control scraping pressure because of the caution here...

As for my transducer. It is an Airmar transducer. I can hear/feel it making pinging noises from outside the boat resting a finger and ear close to the transducer. So it is getting power and it is transmitting pulses. My Raymarine Tridata depth reads blinking 00.0 so not reading depth which is not surprising on the hard. Thanks Mo, the bottom paint is water based so I have that going for me. I have seen dry land tests using a 4 inch diameter tube that is 3 feet long as has a metal cap at the bottom. Anyone have any experience dry land testing a depth sounding transducer?

Thankful. Happy Father's day to all the dads out there.