How good are the original plastic through-hull from 1984.

[light24bulbs]

My new to me 1984 Ericson 30+ has all original plastic through-hulls. They all seem to operate perfectly, given that they've been excercised regularly, and don't seem to leak.

Does anyone have anything horrific to say about this safety-critical part of the boat?

Forgive me if this has already been asked, I searched but it's a struggle.

 

[Loren Beach]

If you have the OEM "RC Marine" labels on them, faded... those were the composite thuhulls that EY used thru the 80's, including our '88 model.
Great for their time, but if they bind, at some point the handle may break off, leaving you with no way to open or close the ball valve. Our valves all had the RC Marine labels on them, but sometime in the early 90's Forespar bought up the rights and started to produce them. By the mid 90's ForeSpar had improved the valve body and made them stronger. We changed out all of ours for the newer ones in about '95 or so. Working fine still, but even they can stiffen if not operated regularly.

BTW, they are not "plastic" anymore than your hull is. They are a fiber reinforced material, i.e. a composite like our hulls. I point that out because there are lots of cast plastic resin valves on the market, and none are intended for below-the-waterline use, ever. I have some small ones on the factory manifold for our two water tanks.

If you ever have one that does break a handle, it would be good replace it with the newer Forespar version, or another competitor composite valve, or a bronze sea cock.
I do continue to like the composite valves because I do have to worry about corrosion from stray currents.

If you put the phrase "RC Marine" into the search box, you will have quite list of threads to peruse.

 

[Frank Langer]

Forespar used to have a bit of a monopoly on these composite parts. Recently a new company in New Zealand called TruDesign is producing a better product. It's worth doing your homework before you decide.
Frank

 

[Nick J]

I'm in the process replacing the original Marlon thru hulls under the sink with true design. No question the true design is a better product.... But the original Marlon thru hull and valves were in great condition. It was the PVC 90 and plywood backing plates that needed replacement and I figured if I'm going that far, I might as well replace them with something better. If the backing plates were good and you don't have pvc connections, I would keep them.

 

[Kenneth K]

Does anyone have anything horrific to say about this safety-critical part of the boat?

Here's a prior post that highlights some info about the old RC Marine and the newer Forespar valves.

https://ericsonyachts.org/ie/ubs/forespar-mf850-marelon-ball-valves.575/

One problem with this type of valve is a lack of adequate, reinforced fittings that fit them. This is why Ericson used many PVC fittings. PVC can crack easily and shouldn't be used below the waterline.

 

[Loren Beach]

One problem with this type of valve is a lack of adequate, reinforced fittings that fit them. This is why Ericson used many PVC fittings. PVC can crack easily and shouldn't be used below the waterline.

You are correct about the old RC Marine valve line, Just to keep the record straight, the (then) "new series" from ForeSpar solved that problem with their own tail pieces, straight, or any 90 degree direction that is needed. Our new ones, installed in the 90's, all have a fitting on each one appropriate to the direction needed for the hose.

 

[Kenneth K]

New, newer, newest....

I was using the term "newer" to describe the Forespar MF850 series ball valves in comparison to the original RC marine valves.

I wonder if Loren is referring to Forespar's Series 93 valves, which have a square body held together with four screws. Forespar's website says Series 93 valves are not sold at retail, only to manufacturers as OEM equipment.

The MF850 valve line is still available at most boating parts shops. Forespar's selection of tailpieces, however, is significantly smaller than what is typically available in PVC and metal pipe fittings.

 

[Loren Beach]

I wonder if Loren is referring to Forespar's Series 93 valves, which have a square body held together with four screws. Forespar's website says Series 93 valves are not sold at retail, only to manufacturers as OEM equipment.

Yes. "Series 93."
It's available from chandler's and boatyards. Their rationale, way back, in doing this was that the proprietary thread angle for the thruhull was different than the others on the market and they were concerned about ignorant owners trying to mix n match stuff.
Actually, I have heard that it's a Buttress thread, but cannot be sure of that. Ours were installed at a yard and the base and thruhull were sealed in place with thickened epoxy; and then the outside flange was ground off smooth. Combined with the new backing plate inside, this should outlast the rest of the boat.