{Stus-List} Leaking Gate? - repair/replace?

Jim Watts jimwatts at shaw.ca
Sun Jun 7 21:29:24 EDT 2009

It sounds like that valve is the only "real" marine valve on the boat. The round-handled ones are gate valves, so called because there is a sliding shutoff gate thingy inside the valve. The leaky one is likely a ball valve, which is similar to a seacock in many ways. Your standard in-line ball valve is usually equipped with tapered thread fittings (NPT - National Pipe Tapered), while a seacock has a straight (NPS) thread on the intake and a NPT thread on the outflow side. 
Real through-hulls have NPS threads so the nut or seacock can be threaded down onto it a far as needed to clamp it tightly to the hull, unlike the finite interference fit of NPT threads. 
Seacocks of that era were usually of the tapered plug style vs the ball valve style as found in modern Marelon fittings and some bronze fittings.

What all this means is you probably have a relatively modern ball valve which is usually replaced instead of repaired. If it can be dismantled fairly easily it may be worthwhile having a look at it. You don't get a huge amount of water in the boat when you pull a fitting if you have a tapered plug handy to pound into the through-hull (or dive on the boat and use an appropriate flip-top drain plug on the outside), but it would probably be a lot less stress doing it out of the water. 

Jim Watts
Paradigm Shift
C&C 35 Mk III
  ----- Original Message ----- 
  From: Nate Flesness 
  To: cnc-list at cnc-list.com 
  Sent: Sunday, June 07, 2009 1:27 PM
  Subject: Re: {Stus-List} Leaking Gate? - repair/replace?

  On my first shakedown cruise of the year (25-30 knots of breeze, 10
  knots - new record hullspeed), I just found a leaky head freshwater
  intake gate? valve on my freshwater 1980 30-1. It is located under the
  sink in the head. I say "gate?" because it has a lever with 2-3" throw,
  unlike any other valve I've seen on my boat (plumbing type round handled
  shutoff valves). The leaky valve is screwed into a thru hull which looks
  to taper from 3/4" at the hull to 1/2" threads which go up into the
  leaky valve.

  The drips are coming from the valve itself, the end opposite the handle,
  which has a 6-sided "nut" fitting. I tried tightening this as tight as I
  dared, made no difference. Boat is now in the water (after a long
  winter), unfortunately a 4 hour drive away. Bilge pump currently keeping
  up with drip drip easily......

  Two questions:

  1. Can anyone tell me what I'll find if I unscrew the valve nut (besides
  a lot of cold Lake Superior coming in)? Is there a chance I can
  grease/tighten this valve and it will fix the leak?
  2.  Anyone know where to find a replacement or improvement?

  Many thanks as always for the shared knowledge on this amazing list,

  "Sarah Jean"
  Conucopia, WI

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