Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 25-07-2008, 15:46   #1
Registered User
cburger's Avatar

Join Date: May 2006
Location: Nyack, NY
Boat: Westsail 32
Posts: 1,502
Images: 1
Seacock Backer Donut

My raw water intake's seacock (Grocco) has a rotten wooden backer donut that has to be replaced. I would like thoughts on whether I need to remove the exterior bronze through hull and inspect the hull in this area then re-bed as part of the repair or considering that the fitting has never leaked can I get away with just removing the seacock from the nipple and fabricate a new wooden donut and reassemble? (Think I know what the answer is going to be). Also some reccomendations on what species of wood (Teak) solid or plywood?

Thanks All!!

cburger is offline   Reply With Quote
Old 25-07-2008, 18:34   #2
Eternal Member
Chief Engineer's Avatar

Join Date: Aug 2006
Location: North of Baltimore
Boat: Ericson 27 & 18' Herrmann Catboat
Posts: 3,798
Take the whole thing out. Clean surfaces inside and out. Use marine grade plywood.

Since you are working on a hole in the bottom of your boat it is prudent not to do the job 1/2 way

Chief Engineer is offline   Reply With Quote
Old 25-07-2008, 18:58   #3
Moderator Emeritus
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
What's the worst that could happen? It might!

With backing plate bad you don't have a solid foundation to fix this problem. Marine plywood is just fine and easier and stronger.
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote
Old 25-07-2008, 18:59   #4
Boracay's Avatar

Cruisers Forum Supporter

Join Date: Feb 2004
Location: Pelican Bay, Great Sandy National Park
Boat: Steel Roberts Offshore 44
Posts: 5,175
Images: 18
If using plywood...

First I recommend cleaning the area with an appropriate degreaser (follow instructions, make sure there is plenty of ventilation), then abrade roughly all places that might be glued.

The ideal would be to make up a replacement "doughnut" using layers of fibreglass mat and epoxy resin, and then to glue this in place using epoxy glue. If it is possible to do this "in situ" (drilling holes after the resin has set ), even better.

If using ply I suggest cutting the piece to size, drilling all holes and chamfering the edges then saturating all end grain with epoxy resin thinned 10%. Then continue to saturate the rest of the ply, then the end grain again. After the epoxy has set and all solvent has evaporated sand lightly and coat again with straight epoxy resin. Glue in place with excess glue and clean up with a spatula. Redrill all small holes.
Rust never sleeps
Boracay Blog.
Boracay is offline   Reply With Quote
Old 25-07-2008, 19:13   #5

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 12,077
I second the thought of using something that can't rot to make the new donut. Even if that means filled epoxy, which would be sufficient all by itself.

I don't see any "must" to remove the whole thruhull, but this would be a good opportunity to inspect the whole thing, and removing it, or making sure it didn't need removal and was solidly fixed, would be a prudent thing at this time. The fact that the donut has gone bad indicates moisture, and that's never a good sign.
hellosailor is offline   Reply With Quote
Old 26-07-2008, 06:34   #6
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Santa Cruz
Boat: Boatless Again
Posts: 3,720
Because you will have a hell of a time getting the valve and the nut off the thru-hull, just take a small angle grinder and grind off the flange on the outside of the boat and drive the remains into the boat. Then replace with all new--the fittings are not that expensive.
donradcliffe is offline   Reply With Quote
Old 26-07-2008, 11:09   #7
Marine Service Provider
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 2,868
Feel Free

Feel Free to read these articles on seacocks and take away any info you like..

Seacock & Thru-Hull Primer/Pre Information

Mismatched threads be careful:

Replacing Thru-Hulls and Seacocks

Fiberglass Backing Blocks:
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 26-07-2008, 16:05   #8
Senior Cruiser
Roy M's Avatar

Cruisers Forum Supporter

Join Date: Feb 2007
Location: Southwestern Yacht Club, San Diego, CA
Boat: Searunner 40 trimaran, WILDERNESS
Posts: 2,925
Images: 4
Since the primary function of the "doughnut" is to spread the loading around the perimeter of the hole, you can do another option: Assuming you can extract the "doughnut" without challenging the watertight integrity, use aforementioned hole saw to cut two new doughnuts, each one half the thickness of the original, or better yet, one larger than the original. Cut the doughnuts in half and thoroughly seal all surfaces with epoxy. Insert the first, wider doughnut in two halves around the throughhull base, using 3M 5200, followed by the second, smaller pair, rotated ninety degrees, also using 5200 as the bedding adhesive. You can then screw through the upper doughnut into the lower, not penetrating the hull. The following day, when the 5200 has set up, tighten down on the throughhull nut until it is secure against the top doughnut. You can remove the screws and fill with 5200 if you wish.

Roy M is offline   Reply With Quote

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Open or closed seacock Chief Engineer Engines and Propulsion Systems 45 11-06-2008 07:45
Seacock = Wet/Dry???? alexleclainche Plumbing Systems and Fixtures 14 28-01-2008 10:52
seacock/Thru hull problem anglooff Plumbing Systems and Fixtures 12 08-01-2008 12:59
Marelon seacock 1.5in Forespar EngNate Classifieds Archive 3 27-07-2007 06:00
toilet hose seacock connection seafox Construction, Maintenance & Refit 12 02-09-2005 06:32

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:16.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.