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  #31  
Old 01-05-2014
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Re: Through-Hulls

Brian, it sounds like you advocate that the hole in the liner and the core is not a bad thing. You suggest that the seacock, shown in your picture, be mounted to the hull material. Thus, it may be necessary to enlarge the hole in the liner. I was thinking that water will stand in that hole and then the seacock would be standing in the water.
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Re: Through-Hulls

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Originally Posted by gbgreen59 View Post
Brian, it sounds like you advocate that the hole in the liner and the core is not a bad thing. You suggest that the seacock, shown in your picture, be mounted to the hull material. Thus, it may be necessary to enlarge the hole in the liner. I was thinking that water will stand in that hole and then the seacock would be standing in the water.
If the liner is as solid as the hull and not flexible you could do as you plan I guess. If it is not solid I wouldn't do it that way. The seacock shouldn't be in standing water in any case as it should have a thick (ideally fiberglass) backing plate.

Here are a few links that might help:

http://www.pbase.com/mainecruising/seacock_primer

http://www.pbase.com/mainecruising/replacing_thruhulls

http://www.pbase.com/mainecruising/backing_blocks

The last link shows a good method of installing a proper seacock without the bolts penetrating the hull.
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Last edited by mitiempo; 01-05-2014 at 08:41 PM.
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  #33  
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Re: Through-Hulls

I was hoping that you'd tell me that the valve assembly was a sink drain, then I'd say it was a factory install. Because it's a foot pump valve, it's possible it was installed later unless someone can say Beneteau installed foot pumps on all or most of their boats. Does the foot pump valve install look the same as the sink valve install?

Here's my guess? The pump valve is a factory install. Why? The installation looks like it belongs there and is cleanly done, it looks very similar to the valve install that's above and to the right of the foot pump valve, and the valve parts look like they might be European.

While I don't advocate a thru-hull/ball valve combination, you could easily replace the existing fitting with a Groco combi thru-hull and valve, without doing any cutting for a flange, but make sure you have a backing plate.

However, any good thru-hull, and Groco makes a good one, as does Perko, will be using Composition Bronze (AKA 85-5-5-5) which is malleable, and the weakest point is thin walled and notched; and when the threads are exposed like that the fitting can easily bend and crack when hit a few times. Also, my guess from your lock nut dimensions is most likely for a small 3/4" thru-hull, possibly a 1".

If you can afford it and want the safest seacock, I'd always go with a proper seacock like the Groco US made BV series or the Perko PLB(?) series. They're not cheap, but (I know this next statement will cause some discussion) this type of seacock is far stronger and safer than the alternatives. While I think that the Groco flange is stronger than the thru-hull/valve combination, it basic weakness is the same, it's thin walled, notched (the threads are exposed) and the material is soft.

I think Hopcar sells both. Look at the "proper seacock" picture you submitted there's nothing like it for peace of mind.

Fair winds,

Jed
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Re: Through-Hulls

The inside diameter of the intakes (head and galley) are 1/2". Both drains are 3/4". Then, I also pulled the intake for the engine cooling water. It is a 3/4" through hull. I will likely use G-10 discs as the plate and bring it up just proud of the hull liner. Then fill in the gaps and make the flush with the inner liner. Then water will not stand in those pits that are currently there. I will be using the recommended manufacturers (Groco or Perko). Good stuff from you guys and thanks so much.
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Re: Through-Hulls

Got to get to bed. Will you be cutting the inner tub, is the hole big enough to insert a backing pate to accommodate a flange or areyou going to use the thru-hull/valve combination?

Fair winds,

Jed
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Re: Through-Hulls

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Originally Posted by Watercolor View Post
Katsailor,

Just a few thoughts for you to consider regarding Forespar's Marelon seacocks.

First, Forespar calls Marelon a “polymer composite” and a 21st century material. The fact is Marelon is simply a Forespar trade name for Dupont Zytel 70G13L – BK 13% glass-filled carbon blacked 6/6 nylon (that’s not carbon fiber). The nylon 6/6 resin used in Marelon has been around for over 70 years. And the 70G13L – BK can be purchased by anyone. It’s an off the shelf material, nothing exotic.

It has a tensile strength (TS) of 17,000psi and a flexural modulus (FM) of 750,000psi. Both these values are measured “Dry as Molded” (DAM). The DAM measurement is important to remember, especially with nylon. Nylon is great in rode because in water it looses strength and elongates.

(Blah, blah, blah. Snipped for brevity)

There’s a lot more to be said. But I’ll stop here for now

This post is full of impressive factoids and numbers, but I feel that it's alarmism at it's finest.

1st- Marelon through-hulls and seacocks meet ABYC standards. ABYC is a widely accepted, reasonably safe standard to adhere to.

2nd- If you stow a 15lb. alternator, or a heavy toolbox next to a seacock, then you get what you deserve. "Stow for sea" is simply good seamanship. I never stow anything heavy or sharp near any of my through-hulls.

Everything "degrades". It's called entropy. Marelon is not perfect, nor entirely maintenance-free. It merely offers an alternative to metal hull penetrations, while presenting its own set of issues. An owner may prefer "plastic" maintenance issues vs. "metal" maintenance issues. It is however, perfectly safe and acceptable for most recreational sailing that people do.

Watercolor, you're obviously some kind of engineer. You carry what I call "the burden of knowledge". All of the facts you presented are perfectly true...and mostly unnecessary. Your burden of knowledge forces you to take the extreme, mil-spec/aerospace-industry view of everything.

There's nothing wrong with that per se, but it's expensive and often unnecessary, and simply frightens less knowledgeable people for no good reason.

Don't let "perfect" be the enemy of "good".
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Re: Through-Hulls

One reason I love forums is the diversity of information. Don Casey in "This Old Boat" also speaks well of Marelon.

What opions are there on having the cut-out in the liner and hull for all thru-hulls? It seems that water should not be allowed to stand anywhere, and water will stand in the cut-outs that are shown in my pictures.

I really appreciate al of the inforamation.
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Re: Through-Hulls

Quote:
Originally Posted by gbgreen59 View Post
One reason I love forums is the diversity of information. Don Casey in "This Old Boat" also speaks well of Marelon.

What opions are there on having the cut-out in the liner and hull for all thru-hulls? It seems that water should not be allowed to stand anywhere, and water will stand in the cut-outs that are shown in my pictures.

I really appreciate al of the inforamation.
Your situation is unique to my experience (I surely don't claim to know everything!).

In my experience, a cabin fiberglass liner is not a structural, load-bearing piece...at least, not at all points. It's mainly a cosmetic feature meant to hide the raw, fiberglass hull interior, and something to mold cabin furniture and fixtures into.

So, your through-hulls should be in cut-outs, and compressed directly against the hull, not compressed against the cabin liner. Now, what to do about the standing water? I'm not exactly sure what to do about that. Are you sure the gap between the hull and liner doesn't drain to the bilge? Perhaps there's a way to create a path to the bilge, between the hull and liner?

All of my through-hulls are in large voids in the cabin liner, directly on the hull, and way down low, near the bilge so I do not experience your problem.
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  #39  
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Re: Through-Hulls

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Originally Posted by BubbleheadMd View Post
This post is full of impressive factoids and numbers, but I feel that it's alarmism at it's finest.
And it should be a bit alarmist in my opinion. Marelon has some issues. The handles can break on the smaller ones for one thing. Being composed of a modified nylon they do absorb water over time. They also require more frequent maintenance than good 85-5-5-5 bronze seacocks such as Groco's.

This post from MaineSail is an interesting read.
Strength of Seacocks, Are Yours Strong Enough? - SailboatOwners.com

I'll stick to bronze.
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  #40  
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Re: Through-Hulls

@BubbleheadMd: Interesting information on the hull liner. Makes good sense. The liner helps make things look nice and tidy, but also makes it more difficult to access wiring/plumbing, etc. I will check on the drainage through the core. My thought now is to make the liner opening larger so a wrench can easily get to the flange nut. Current installation makes it impossible to get a normal wrench on the flange nut. I had to cut all the fittings with a Dremel Tool to get the thru-hulls off. Hence, perfectly good thru-hulls were destroyed.
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