Survey Survey Survey

[Ralph Johnstone]

Yesterday, @Plymouth Sailor sailor discussed the perils of having holes in the bottom of our boats.

At the risk of offending @Plymouth Sailor , I'd like to narrow the question down a little and simply ask:

Are your through hulls ABYC approved and flanged as shown on the left or not flanged as shown on the right hand side as shown below. Perhaps mention if they are factory installed or not.

Taken from Marine How To with big thank you to Maine Sail for his excellent display and photographic skills.

I think we all know the perils of the NPS / NPT valve through hull and if not, this MARINE HOW TO article tells you everything you'd want to know as well as a few things you may not want to know.

Seacock & Thru-Hull Primer - Marine How To

These are called Thru-Hulls This item is called a thru-hull or sometimes a mushroom-head or even a skin fitting. They are straight threaded (NPS thread) so they can be cut to the correct length, for your hulls thickness, and then be

marinehowto.com

 

[Ralph Johnstone]

All not flanged and factory installed in 1998 NPS through hulls.

 

[Davidasailor26]

Beneteau OEM not-flanged through hulls here.

Being Beneteau they might be brass too. I know the older Beneteau ones were; I don’t know about newer ones.

 

[dmax]

O'Day originals were not flanged, all replaced with flanged ones with new backing plates. Eliminated the macerator through hull and paddle-wheel speed sensor so only 3 holes in the bottom of my boat now

 

[FastOlson]

My '88 boat was built by Ericson. They were using all Marelon thru hulls at the time. That was good; altho they were screwing Marelon ball valves on the top, which is not as strong. That said, Marelon is a fiber-reinforced product and is intrinsically strong.
In the 90's we changed them all out for the then-new Forespar 93 series of Marelon, built as true sea cocks on heavy flanged bases. Ours are all "sealed" in epoxy. Still working fine.

Whether bronze or Marelon, one important factor is that the valve body be one piece. IIRC from Maine Sail's article, the ABYC standard was ability to withstand a 200# side load. Example cited was a heavy tool box being thrown against the valve when a boat rolls.
Strictly IMHO, those Forespar sea cocks would withstand a demented assault with a sledge hammer... !

Anyhow, check 'em often, work the handles, have no hoses over 20 years old, MAX. and double clamp.
Then you sleep better at night, on the off watch, until the boat takes a hit from a sneaky cross sea!

 

[sailcapt340]

If I could add. My 2000 340 are not flanged either. Still working smoothly and solid to the hull.
I totally agree with Fastolson, check them often and exercise those handles regularly! It‘s you best defense against a potential problem.
And if can add another word of caution….don’t get heavy handed with the grease. I did and it led to a completely stuck (in the open position) thru hull. I couldn’t move that handle for all the money in the world.
Finally after my winter haul out, I was able to apply heat from a heat gun and melt the grease out of the fitting. Now it’s the easiest to open and close thru hull I have on the boat.
I don’t know why I used to much grease that year but I did.
Now I’m very light on the grease!
A word of advice to all.

 

[Rick D]

Not flanged. Original 1994; just replaced one. I will probably do them all next haul. No, I don't exercise them as often as I should. BTW, the major manufacturers would probably take exception to this construct not being ABYC compliant. I know Hunter tested them and they were in compliance with ABYC side loading. FWIW.

 

[Tally Ho]

1988 O’Day 322, not flanged….yet.
Only 3 valves.

Greg

 

[jaysweet]

I replaced 3 of the 5 with Groco flanged seacocks, as described in this thread:

Thru-hull replacement and hull thickness

Hi folks. I'm trying to refit our 2005 Hunter 306 after it's been sitting on land for 3 1/2 years. I just cleaned up quite a few gallons of grungy bilge water, and I noticed that 2 or 3 thru-hulls which were wet for that long have plywood backing disks which are not in good shape. They were...

forums.sailboatowners.com

After 2 years, I'm glad to say that the new thruhulls and seacocks are holding up just fine. (Some questions were raised in the thread about polyester resin sticking to the Groco backing plates.)

The backing plates have also been painted with gelcoat since then (and yes, I did use hose clamps: this was an in-progress picture).

The remaining two are on the head sink and galley sink, which have appallingly bad access, so I'll have to get pretty far ahead on my project list before they rise to the top.

 

[dLj]

Are your through hulls ABYC approved and flanged as shown on the left or not flanged as shown on the right hand side as shown below. Perhaps mention if they are factory installed or not.

I really must clarify this - the wording of this sentence implies (not saying that's what you intended) that non-flanged installations are not ABYC approved and that the approved ABYC installation are flanged. That is not the case. ABYC H-27 "SEACOCKS, THRU-HULL FITTINGS, AND DRAIN PLUGS" recognizes both geometries and both can be ABYC approved.

The loading requirement states that the seacock be capable of withstanding a static load test as defined in H-27. (there are numerous other requirements but this is the one that the flanged set-up vs non-flanged set-up really focuses on - seems to me.)

27.22 STATIC LOAD TEST

27.22.1 There shall be no evidence of physical failure of a simulated installation of an assembly of a thru-hull fitting and seacock when a 500 lb (227 kg) load is applied to the end of the hose or pipe fitting used to connect the seacock to the boat system. The assembly is to be made in accordance with the manufacturer's instructions and the test load is to be held for a period of 30 sec (see FIGURE 1).

27.22.2 A combination seacock/thru-hull fitting is to be tested in the as-received condition. A seacock marked for use with a specific thru-hull fitting is to be tested with that fitting. A thru-hull fitting marked for use with a specific seacock is to be tested with that seacock. If the seacock (or fitting) is marked for use with both nonmetallic and metallic thru-hull fittings (or seacocks), the test is to be conducted using the weakest material. A seacock not marked for use with a specific thru-hull fitting(s) is to be tested with a bronze fitting and a thru-hull fitting not marked for use with a specific seacock(s) is to be tested with a bronze seacock. A test conducted on a sample of the smallest seacock of a series of seacocks, or the longest thru-hull fitting of a series of thru-hull fittings, of the same design is to be accepted as representing the series, providing the constructions are basically identical and the wall thicknesses are directly proportionate to the sizes. If, because of changes in wall thickness or differences in construction, the smallest seacock or longest fitting may not be the weakest assembly, tests on individual sizes may be necessary.

27.22.3 For the test, the thru-hull fitting/seacock assembly is to be installed in accordance with the manufacturer's instructions.

27.22.4 The hull test section in which the seacock assembly is mounted is to be secured to a rigid test fixture so that a 500 lb (227 kg) load can be applied to the seacock assembly. The load is to be applied at a controlled rate of 12 in/min through a straight hose fitting so that the load is applied 90° to the axis through the bore of the thru-hull fitting and valve.

dj

 

[Ward H]

My C30 came with marelon thru hulls with older Forespar in-line valves screwed on. After reading an article, probably on marinehowto.com, about how those older valves would leak if the handle broke, I installed new thru hulls with Forespars newest in-line valves that resolved that problem.
Last year I installed a new Forespar OEM Series 93 thru hull and flanged valve for AC intake. It feels so much more secure when operating it I'll be replacing all the others next spring.

 

[Ralph Johnstone]

I really must clarify this - the wording of this sentence implies (not saying that's what you intended) that non-flanged installations are not ABYC approved and that the approved ABYC installation are flanged.

My primary concern dealt with mis-matched threads on the thru-hull to seacock joint.

ABYC 27.6.1.3 Threads used in seacock installations shall be compatible (eg. NPT to NPT, NPS to NPS).

If the valve assembly is flanged, it's almost assured to have an NPS inlet thread.
Mushroom headed thru-hulls, to my knowledge, are invariably NPS and are sold with an NPS nut. When I see that nut, it means just grab an NPT valve, screw it on, and you're good to go. That's where I believe the problem lies. Or actually, more like here below:

Courtesy of Marine How To

You now have an assembly guaranteed to fail ABYC 27.22.4 in addition to having mis-matched threads which violates ABYC 27.6.1.3

Additionally, I'm not to keen on having an exposed section of NPS threaded pipe subject to sea water corrosion on the I.D. and wide open to the boat interior on the O.D. In his Marine How To article on thru-hull fittings, @Maine Sail did the research for me and concluded that the wall thickness at the root of a 1" dia, thru-hull is 1.54 mm. or just under 1/16".

My cooling raw water inlet to my engine is 1/2" dia. Any guesses as to the thickness of that thru hull at the thread root .

I do not want my first line of defence against sea water ingress to be less than 1/16" thick bronze and no upstream valve. Given a proper thru-hull installation as shown below:

Courtesy of Marine How To

................ you are protected even if the NPS thru-hull should corrode away due to extreme stray current.

The more I look at NPS threads mismatched to NPT threads with less than 1/16" thickness at the thread root, the more determined I become to change out all of my old thru-hulls to proper flanged installations .................... next year !

Already half hauled earlier in the spring for zincs and inspection.

 

[BAD ORCA]

I have an 1980 Peter Canning Mariner36. They used bronze, flanged taper cone seacocks on nine of my eleven thru hulls. For some reason the 1.5" head discharge was just a thru hull with a threaded nut and some sealant, no backing plate or glass reinforcment. Replaced it with a Spartan Marine taper cone. All the taper cone seacocks were Wilcox Crittendon flanged, and then they added about 3/8" thickness of woven roving over the base of each seacock.

The engine raw water thru hull was similar to the head discharge seacock but had about 1/2" of fiberglass and roving covering the base of the thru-hull. Unfortunately they were the two that needed replacing the most. Took me two days to cut out and prep the engine raw water thru hull. Im guessing they wanted it low profile or because its just off the centerline where that thru-hull comes into the boat at a wierd angle?

Fixed that with a Groco flanged base and a screw on valve with a 0.75" thick G-10 base bedded in epoxy and milled fibers. I think it might outlast the boat.

 

[Ralph Johnstone]

I think it might outlast the boat.

Let's see the archaeologists figure THAT one out 500 years from now when they find what remains of your boat at the bottom of the sea.