bushing below the waterline

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HBY
Posts: 2
Joined: Tue Jan 01, 2019 8:13 am

bushing below the waterline

Post by HBY » Tue Jan 22, 2019 10:30 am

Hi.

I bought a Albin Ballad that need alot attention and the first thing I was planing to do with the boat is change the bushing below the waterline. Now I wonder where I can buy new ones, I can see that the bushing is cone shaped and sunken in the hull so how do I measure the bushing so I get the correct size?

Thankful for a quick response

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prjacobs
Posts: 225
Joined: Fri Oct 12, 2012 4:06 pm

Re: bushing below the waterline

Post by prjacobs » Tue Jan 22, 2019 6:14 pm

Hi,
Welcome to the Ballad Forum, and congratulations on your new boat.
I did a similar job on my Ballad. The original thru-hulls are called "flush" thru-hulls, as opposed to surface mount ones. When I removed mine I found the replacement fittings had a different shape so the fibreglass had to be ground out to fit the new ones. One way to get around this would be use surface mount thru-hulls, and fill the old chamfer with thickened epoxy.
As to dimensions: you can measure the size of the actual hole in the fitting to get the size. They are generally in inches ... a 1/2inch is listed as a 500, a 3/4 inch as 750, a 1 inch as 1000, and 1 1/4" inch as 1250. check out this web page for a chart of all the sizes.
You'll probably want to replace the old sea cocks. The ones on my boat were badly corroded, and one thump from a hammer snapped them off ... not a good situation.
Here is a good article on the whole process.
These are pictures of my new thru-hulls installation.

Hope this helps!
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prjacobs
Posts: 225
Joined: Fri Oct 12, 2012 4:06 pm

Re: bushing below the waterline

Post by prjacobs » Tue Jan 22, 2019 8:44 pm

Here is some more about thru-hull installation. This is what I did. Most of my method was copied from here, except for the way the backing plate-to-seacock studs were installed.

I wanted to install flush mount thru-hulls, but the original fittings had a very narrow lip compared to the replacements, so I had to grind the holes out for them to fit. This made the holes too large so, after wrapping it in tape, I coated the head of the thru-hull with thickened epoxy, pushed it up into the hole until it was flush, and put a brace under to hold it while the epoxy cured.
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Rather than using wood, I made fibreglass backing plates about 3/4" thick and ground the backs to roughly match the curve in the hull. The seacocks are bolted to them using bronze flat head machine screws, countersunk into the back of the backing plate, rather than going right through the hull. This is an acceptable alternate method covered in Groco's installation instructions. The holes for the machine screws are drilled under-size and threaded to match the machine screw threads. Then the machine screws are threaded into the backing plate and tightened, leaving three studs protruding through the plate for attaching the seacock. The thru-hull, threaded and tightened into the seacock, makes a strong sandwich with the hull/backing plate in between.
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HBY
Posts: 2
Joined: Tue Jan 01, 2019 8:13 am

Re: bushing below the waterline

Post by HBY » Mon Jan 28, 2019 3:45 pm

Thanks you so much for all the tips. You have been most helpful and I have orded new bushing.

Regards Rickard

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