View Full Version : Stopwaters

12-15-2000, 10:27 AM
Can someone please let me know what “stopwaters” are used for? From reading Chapelle’s book, I know how stopwaters are used, but cannot figure out why they are used. Also, how did stopwaters get their name?

Thanks, Bill

12-15-2000, 10:53 AM
Stopwater- a dowel of softwood, inserted in the joints of a boat's backbone structure where the planking crosses the joint. So named because they prevent the joint from leaking.

Not to be flip...if you think about the backbone structure (keel, stem etc) wherever pieces join, in a scarf or other joint that crosses the rabbet (where the plank meets the framing) there is an opening. Even if tightly fitted, and well bedded, it's assumed that joint would leak, so a softwood dowel is fitted in a hole, drilled at the apex line (just what it sounds like, the middle line of the rabbet) perpendicular to the longitudinal direction of the structure. The dowel swells and stops the leak. Stop water.

Difficult to discribe, easy to understand once you see it. Try visiting a boat in frame and ask to see the stopwaters. Best of luck, Jack

Art Read
12-15-2000, 12:52 PM
Bill... I had trouble getting my head around that one too... Jack's comment on the scarf joint being "assumed" to leak, at least eventually, is the operative word here... I'm still leary about the way I did mine. I "think" it's in the right place, and I "hope" I made the diameter large enough... We'll see.

Ian McColgin
12-15-2000, 01:41 PM
On Goblin as she aged the stopwaters became ineffective. I replaced some to doubtful effect, but George Kelly showed me one of Capt Pete's tricks - screw a grease fitting into the joint and seriously pressurize inject some waterpump grease. Pull the fitting out and sail on.

12-16-2000, 06:11 AM
WoW neet trick with the grease fitting hooda thunk it

Dave Fleming
12-18-2000, 06:34 PM
Ayup, Zerk fittings in the way of scarphs or joins is an old trick. As mentioned in thread on Wedge Seaming, old vessels sometimes would have Zerks put around the deadwood and shaft log and just pump away. Grease would ooze out of the most peculiar places but vessel was less wet than before it was done. Seems like once a year at the time it was hauled out for a 'shave and a haircut'.
Capt'n Petes time in working boat yards shows through with that little bit of info.
Wouldn't look too spiffy if done on your New York 50. " I say there fellow what is that slick trailing aft of your boat?" :)

Andrew Craig-Bennett
01-01-2001, 03:37 PM
50% white lead 50% grease in the grease gun. Also highly effective, and I do mean highly effective, in stopping leaks around coachroof coamings, under beadings, etc.

The grease gun has a modified fitting which screws into a small (say 3/16"dia.) hole drilled down to the joint or seam. Pump away until some comes out.

Fine for New York 50's, and probably most of them had the process; it's invisible when done and the finest varnished teak beadings and rails can benefit!

Dave Fleming
01-01-2001, 09:37 PM
Now Andrew, that white lead and grease would have no effect on the finish of Teak or Varnished Teak is good news to me.
Next time I have some troublesome leaks in a coaming or coachroof carlins I know just what to do.
I thankee.

Bear's Oil
01-01-2001, 10:59 PM
#56 WB has a great article on stopwaters. "Profusely illustrated". Author is Ed McClave.

Andrew Craig-Bennett
01-03-2001, 08:54 PM
Dave, the white lead is to stop the grease migrating into the wood. It has not the slightest effect on the finish because it's in contact with the invisible undersides of the highly finished teak coamings, etc.

Works for me!