Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 16-01-2022, 05:28   #1
Registered User

Join Date: Jul 2012
Posts: 20
Thru Hull vs Hole Size

Replacing cockpit drain thru hulls. These are just below the water line. Removed old plastic 1 1/2" hose thru hulls with same but SS. Just noted the new thru hull has almost a 1/2" play inside the thru hull "hole". I could tighten the thru hull nut real good and just use a good blob of 4200 but it doesn't feel right. Any proven suggestions - backing plate with correct hole size, filling and re-drilling, some type of bushing?
commander500 is offline   Reply With Quote
Old 16-01-2022, 05:45   #2
Senior Cruiser
 
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 46,380
Images: 241
Re: Thru Hull vs Hole Size

See Rod Collins' excellent tutorials at https://marinehowto.com/
Including:
Seacock & Thru-Hull Primer ➥ https://marinehowto.com/seacock-thru-hull-primer/
Replacing Thru-Hulls and Seacocks ➥ https://marinehowto.com/replacing-th...-and-seacocks/
Seacock Backing Plates https://marinehowto.com/seacock-backing-plates/
and much more ...
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 16-01-2022, 06:17   #3
Moderator
 
Pete7's Avatar

Cruisers Forum Supporter

Join Date: Aug 2009
Location: Solent, England
Boat: Moody 31
Posts: 16,263
Images: 14
Re: Thru Hull vs Hole Size

Not a good use for stainless steel, choose bronze or plastic to avoid crevice corrosion.

You might consider going up to 2" with new pipes etc rather than try and fill in the wholes, particularly for cockpit drains.

Pete
Pete7 is offline   Reply With Quote
Old 16-01-2022, 09:30   #4
Moderator
 
tkeithlu's Avatar

Cruisers Forum Supporter

Join Date: Feb 2012
Location: Carrabelle, Florida
Boat: Fiberglas shattering 44' steel trawler
Posts: 5,121
Re: Thru Hull vs Hole Size

If you've got a good grip on the hull with the mushroom and the backing nut, you're fine with the 3M 5200 solution. If in doubt, use a backing plate with right sized hole and decide whether to glue it in place or through bolt it.
__________________
Never let anything mechanical know that you are in a hurry.
tkeithlu is offline   Reply With Quote
Old 16-01-2022, 10:10   #5
Registered User
 
Cadence's Avatar

Join Date: Dec 2008
Location: SC
Boat: None,build the one shown of glass, had many from 6' to 48'.
Posts: 10,210
Re: Thru Hull vs Hole Size

Get the correct size for the existing holes, not in SS. 1/2" is a lot of play for one below the WL.
Cadence is offline   Reply With Quote
Old 16-01-2022, 10:24   #6
Do… or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 13,093
Re: Thru Hull vs Hole Size

If the hull is fiberglass, then either upgrade to a larger size fitting (preferred) and use either a reducer or upgrade hose too.

I also agree that you should go to bronze (Rod Collins info, use Groco flanged adapters etc.)

For steel boat, stainless steel makes sense. You can buy the Groco hardware in stainless as well or just weld.
__________________
May the Force be with you!

s/v Jedi is offline   Reply With Quote
Old 16-01-2022, 10:32   #7
Registered User
 
Cheechako's Avatar

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 24,575
Re: Thru Hull vs Hole Size

Quote:
Originally Posted by Cadence View Post
Get the correct size for the existing holes, not in SS. 1/2" is a lot of play for one below the WL.
Yeah, something wrong there....
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 16-01-2022, 12:30   #8
Registered User

Join Date: Sep 2016
Location: West Palm/Kent Island
Boat: Ted Brewer Pilothouse 40
Posts: 13
Re: Thru Hull vs Hole Size

All good answers above. Purchase a bronze thru hull in that fits your hole snugly and 5200 in then adjust the plumbing to it accordingly.
Delaware is offline   Reply With Quote
Old 16-01-2022, 13:49   #9
Registered User

Join Date: Dec 2011
Posts: 1,487
Re: Thru Hull vs Hole Size

If you have a solid glass layup hull you can grind out the area and install a proper multi-layered hull patch and redrill the hole for your new thru-hulls. If you have a cored hull probably not.
jmschmidt is offline   Reply With Quote
Old 16-01-2022, 14:02   #10
Registered User

Join Date: Nov 2016
Location: Sarnia ON
Boat: S2 9.1
Posts: 242
Re: Thru Hull vs Hole Size

Do the hoses lead from essentially thru hull type fittings in your cockpit sole?

2 inch is a pretty standard size for cockpit drains. I would check the fittings in the cockpit to see if they are undersized for the hole as well. If so replace every thing with 2 inch.
Gary Mc is offline   Reply With Quote
Old 16-01-2022, 15:56   #11
Registered User

Join Date: Jul 2012
Posts: 20
Re: Thru Hull vs Hole Size

Appreciate all feedback. About SS under WL, I guess true. With cockpit drains I believe size matters. I will study going up to 2".

Again, thanks to all. Great advice each one. Good to have other's perspective and experience.
commander500 is offline   Reply With Quote
Old 17-01-2022, 08:38   #12
Registered User
 
Celestialsailor's Avatar

Join Date: Nov 2006
Location: Back in Northern California working on the Ranch
Boat: Pearson 365 Sloop Westsail 28 and 14ft.Whitehall pulling skiff.
Posts: 9,423
Images: 5
Re: Thru Hull vs Hole Size

There is absolutely no reason to use 5200. 4200 works just fine and is removable. There is very little water pressure at the seal of a thru-hull.
__________________
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming: Wow - what a ride!"
Celestialsailor is offline   Reply With Quote
Old 17-01-2022, 09:13   #13
Do… or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 13,093
Re: Thru Hull vs Hole Size

I actually prefer a polysulfide sealant for thru hull fittings. Now that 3M 101 is gone, LifeCaulk is one I know and use.
__________________
May the Force be with you!

s/v Jedi is offline   Reply With Quote
Reply

Tags
hull, size, thru hull

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
filling hole with epoxy - no access to back of hole. mikebikeboy Monohull Sailboats 31 29-09-2020 08:31
Reducing hole size for thru hull finefurn Construction, Maintenance & Refit 48 28-02-2017 23:42
Exhaust: Thru Hull? Not Thru Hull? steel Powered Boats 12 18-10-2012 21:14
How Large is Hole Diameter for Thru-Hull ? erict Plumbing Systems and Fixtures 0 31-08-2011 10:49
Hole drilling for thru hull transducer. Orrjames Our Community 5 24-06-2011 05:13

Advertise Here


All times are GMT -7. The time now is 17:47.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.