89 mid cabin black water thru hull

[mrrudely]

If I have to pull the boat out of the water to fix my trim tab leak I want to replace
the blackwater thru hull at the same time
does anyone know the specs for this?
probably easiest if I replace it with the same kind
thx
rr

[prowlersfish]

Contact Bob at Beacon Marine, he may have what you need. best to call.

Beacon Marine Supply © 2024
Forks Township, PA and Columbia, PA
bob at beaconmarinesupply dot com
609-713-4602

[Scott67]

If I have to pull the boat out of the water to fix my trim tab leak I want to replace
the blackwater thru hull at the same time
does anyone know the specs for this?
probably easiest if I replace it with the same kind
thx
rr

I went with the following Groco ball valve. So, much easier to maintain, easy to change out if needed. Additionally, now would be a good time to replace the backing plate as well. I went with epoxy board as you can see.

Thru hull.jpg (31.53 KiB) Viewed 2765 times

[mrrudely]

thank you
just a few questions
what model number and size valve?
was the old backing plate easy to remove?
how thick is the new backing plate and how is it secured to the hull?
any thoughts on forespar marelon?
thx
rr

[Scott67]

thank you
just a few questions
what model number and size valve?
was the old backing plate easy to remove?
how thick is the new backing plate and how is it secured to the hull?
any thoughts on forespar marelon?
thx
rr

mrrudely,
I will verify size and number today and revert. I suspect it was a 3/4" valve, but let me be sure.

Old backing plate was rotten and not too difficult to remove with a flat scrapper and some coercion.

New backing plate is 1/2" thick G10 epoxy board and it's adhered to the sanded hull by slightly thickened epoxy.

I'm kinda old school when it comes to valve materials, Marelon fittings have their place, but not on my boat's thru-hulls. The valve 's handles seem to be the weakest link in their design, unless they improved them over the years. Again, nothing wrong with them in my opinion for this installation, but I just prefer good old fashion bronze.

[mrrudely]

thx

I have given it some thought and I agree with you, no marelon.

I am curious about the backing plate
The current valve seems as if it was bolted to the backing plate before it was installed,
when I turn one of the nuts the bolt turns with it. (probably a flat head machine screw)
I will probably have to grind off the thru hull to get this apart.

Groco makes a backing plate with threaded inserts so you would bolt from the top.
Is it better to do it the way you did?

Also, is the backing plate supposed to be attached to the hull so that it will never separate? Hence the epoxy?

rr

[Scott67]

thx

I have given it some thought and I agree with you, no marelon.

I am curious about the backing plate
The current valve seems as if it was bolted to the backing plate before it was installed,
when I turn one of the nuts the bolt turns with it. (probably a flat head machine screw)
I will probably have to grind off the thru hull to get this apart.

Groco makes a backing plate with threaded inserts so you would bolt from the top.
Is it better to do it the way you did?

Also, is the backing plate supposed to be attached to the hull so that it will never separate? Hence the epoxy?

rr

A lot (not all) of backing plates are assembled that way, bolted from the back before install. That's the way I did mine, except I epoxied them in and over the flat head slotted machine bolts to keep them from turning...ever! The other, less popular way would be to countersink longer screws from under and into the hull like the shaft log and epoxy over them to conform with the hull. Personally, I don't like extra non-necessary holes in my hull.

You're right! Groco does make a mounting flange/plate with the inserts that would work just as well. I already had the G10 material and wanted to use it as a backing plate and using their flange and a backing plate would create and extra joint (and quite frankly additional cost) that I wasn't fond of doing. I would also submit that because of the non-cored, solid glass hull bottom we have come to appreciate on the Trojans, if you chose to use the Groco backing plate, there would certainly be no need to use an additional one.

Regarding the backing plate attachment to the hull, it's really a personal preference. As the old saying goes, there is usually more than one right way to do things and this would be one of them. Since I was using epoxy board (which will never have to be replaced) and I was epoxying the bolts to it, what the hell, may as well epoxy it to the hull. It's certainly not required, in fact, a lot of folks would advocate to use 5200 and they would be right as well. Up to you really, but my wife would tell you that he builds things "to the nines", when "twos" would be just fine. Guilty as charged!
That being said, I modified all my through hulls in the same fashion

Also, the part number of the valve I used for the waste thru-hull is: IBV-750 3/4" NPT Bronze Inline Valve

[mrrudely]

can't thank you enough
the plan is to do the trim tabs, the transducer, and the blackwater thru hull