Cruisers Forum
 


Join CruisersForum Today

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 16-04-2019, 03:28   #31
Registered User

Join Date: Feb 2017
Location: Panama, Central America
Boat: CT 49, 1989
Posts: 460
Re: Straight Thread Thru Hull to NPT Valve

Quote:
Originally Posted by a64pilot View Post
I guess Im arguing again, but you cant screw a nut down an NPT thread all the way with no resistance.
An NPT thread is tapered for lack of a better word, Ive cut too many of them on pipe myself.
Embedding bronze studs into a G10 plate is fine, but assumes of course that you have not mounted the plate and can access the backside to counter sink it for the screw heads.
Unless your talking actually tapping the G10 and using actual studs, which I guess would be OK, but Id want the plate to be at least .500 thick myself.
Yes exactly using 'Studs' ie no heads, tapped directly into the G10 backing plates.

But yes, agreed that as you correctly say you need some thickness in the Backing plates to have 'enough meat' to tap into.

But the Backing plates should be 'substaintial' being that their intended purpose in life is to support and distribute the Seacock loads to the hull much more. Ie so they dont get broken off when they are kicked or something falls on them leave a big hole in the hull sinking our boat.

Many just buy bronze bolts and cut the heads off with a hacksaw.

As usual Mainsail has a write up of this https://marinehowto.com/seacock-backing-plates/

Thanks again Mainsail.
__________________

Q Xopa is offline   Reply With Quote
Old 16-04-2019, 04:46   #32
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 24,126
Straight Thread Thru Hull to NPT Valve

Why not counter sink screws from the backside of the G10 plate?
It would have to be stronger, you have the head of the screw to prevent it from being pulled out.

Actually I think I would epoxy in a threaded insert, the greater diameter of the threaded insert is way stronger, yet the stud is still easily removable.

Just read Maine Sails article, he is using 5/8 which has way more meat to hold a stud than 1/4 does.
__________________

a64pilot is offline   Reply With Quote
Old 16-04-2019, 05:19   #33
Registered User

Join Date: Feb 2017
Location: Panama, Central America
Boat: CT 49, 1989
Posts: 460
Re: Straight Thread Thru Hull to NPT Valve

Quote:
Originally Posted by a64pilot View Post
Why not counter sink screws from the backside of the G10 plate?
It would have to be stronger, you have the head of the screw to prevent it from being pulled out.

Actually I think I would epoxy in a threaded insert, the greater diameter of the threaded insert is way stronger, yet the stud is still easily removable.

Just read Maine Sails article, he is using 5/8 which has way more meat to hold a stud than 1/4 does.
Yes sure, that would fine. The only disadantages I could see are that once the backing plate is glued to the hull there is no getting the screws back out if you needed to replace them in the future.
Also I havent looked but can you get countersunk head silicone bronze screws?
To me the best way to do this would be the aircraft way, using a composite potted threaded insert instead of threading directly into the backing plate fibre glass.
But this is probably overkill. Where does it stop?
Peraonally Im just going to thread it into the backing plate fibre glass.
Keeping this all in perspective this is way better than 98% of the boats out there. Most of which dont have issues.
Q Xopa is offline   Reply With Quote
Old 16-04-2019, 05:23   #34
Do or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 9,483
Re: Straight Thread Thru Hull to NPT Valve

Quote:
Originally Posted by a64pilot View Post
Why not counter sink screws from the backside of the G10 plate?
It would have to be stronger, you have the head of the screw to prevent it from being pulled out.

Actually I think I would epoxy in a threaded insert, the greater diameter of the threaded insert is way stronger, yet the stud is still easily removable.

Just read Maine Sails article, he is using 5/8 which has way more meat to hold a stud than 1/4 does.
Its always possible to make something stronger, but for a 3/4 seacock, I feel that tapping 1/4 G10 for a 1/4 machine screw is plenty strong. G10 is much tougher than people think. I dont think that countersinking from the other side makes it stronger as the removal of material eliminates any gain from having the head of the screw behind the plate.

For seacocks 1-1/4 diameter and up I would go to 1/2 G10, which is probably twice the tensile strength of the hull
s/v Jedi is offline   Reply With Quote
Old 16-04-2019, 09:24   #35
Registered User

Cruisers Forum Supporter

Join Date: May 2011
Location: Miami Florida
Boat: Ellis Flybridge 28
Posts: 3,539
Re: Straight Thread Thru Hull to NPT Valve

My gut feeling on this is that 1/4 is too thin unless you bolt through the hull as well.

My choice would be to use the Groco Backing Block. It is 1/2 thick and uses threaded inserts pressed into the back before it is glued down.
https://www.groco.net/products/valve...backing-blocks
__________________
Retired from Hopkins-Carter Marine Supplies
HopCar is offline   Reply With Quote
Old 16-04-2019, 10:14   #36
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 24,126
Re: Straight Thread Thru Hull to NPT Valve

The Groco BB seems good, especially as its ready to go.
However, I wonder what PVC foam is?
a64pilot is offline   Reply With Quote
Old 16-04-2019, 10:42   #37
Registered User

Join Date: Feb 2017
Location: Panama, Central America
Boat: CT 49, 1989
Posts: 460
Re: Straight Thread Thru Hull to NPT Valve

Quote:
Originally Posted by a64pilot View Post
The Groco BB seems good, especially as its ready to go.
However, I wonder what PVC foam is?
Im sure the Groco ones are good as they make quality stuff.
But for half the cost, $30, and twice the thickness of solid fibre glass these might be ok https://dreamgreen.org/order-here/vi...category_id/18 ?
__________________

Q Xopa is offline   Reply With Quote
Reply

Tags
hull, 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
Exhaust: Thru Hull? Not Thru Hull? steel Powered Boats 12 18-10-2012 21:14
NPS vs NPT Thru Hulls Sailorman375 Construction, Maintenance & Refit 4 02-01-2011 08:36
Thru-hull ball valve stuck. will it break? Aquah0lic Construction, Maintenance & Refit 28 13-12-2008 10:35
Thru Hull Valve Rating Question Pete the Cat Plumbing Systems and Fixtures 5 03-11-2008 11:24
thru hull valve replacement Jack Long Plumbing Systems and Fixtures 4 15-09-2008 16:19



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 00:09.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.