Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 19-10-2018, 07:13   #1
Registered User

Join Date: Oct 2013
Posts: 13
Bronze Through Hulls and Seacocks in Steel Boat

I know that many of you are going to talk about the ease of welding a threaded pipe to the boat and that in many places in the world this is the preferred method. But please, I would just like to hear opinions about this particular set up that we are planning and what your thoughts are about it. I believe everything is isolated correctly and that there are no issues with this but I'd love to hear what everyone has to say.


The backing plate would be installed to the seacock before install, with polysulfide using the bronze fasteners. The hole in the hull will be drilled about 1/8" larger than the OD of the through-hull. I hope my drawing meets everyone's artistic standards.


OK...Give it to me straight Doc.
Attached Thumbnails
Click image for larger version

Name:	20181019_090124.jpg
Views:	274
Size:	381.7 KB
ID:	179237  
__________________

strongmonty is offline   Reply With Quote
Old 19-10-2018, 07:35   #2
Senior Cruiser
 
Sailmonkey's Avatar

Cruisers Forum Supporter

Join Date: Sep 2009
Location: Houston
Boat: '76 Allied Seawind II, 32'
Posts: 6,532
Re: Bronze Through Hulls and Seacocks in Steel Boat

Ummmm. Marelon.

The bronze is an awful idea, there is still a current path seeing as you’re immersed in electrolyte.
__________________

Sailmonkey is offline   Reply With Quote
Old 19-10-2018, 08:00   #3
Registered User

Join Date: Oct 2013
Posts: 13
Re: Bronze Through Hulls and Seacocks in Steel Boat

Thank you for the reply but I am specifically interested in bronze. We purchased this boat a year ago and this was done on our boat for the last 15 years with no corrosion problems. I have also heard from others who have not had any problems as long as things are correctly isolated (if only I had quizzed them further when I had the chance!). Unfortunately, it was not installed strong enough; it had no backing plate. We are replacing all our seacocks and removing half of them during this refit.

Marelon was considered but it is not going to work for us so we are interested only in people who have specific success in using bronze fittings with a metal hull.

Thanks.
strongmonty is offline   Reply With Quote
Old 19-10-2018, 08:19   #4
Registered User

Join Date: May 2008
Posts: 2,180
Re: Bronze Through Hulls and Seacocks in Steel Boat

Out of interest, why did you decide against Marelon?
CarlF is offline   Reply With Quote
Old 19-10-2018, 08:46   #5
Registered User

Join Date: Jun 2010
Location: Easton, MD
Boat: Catalina 22 Capri, 15' Catboat, Bristol 35.5
Posts: 1,712
Re: Bronze Through Hulls and Seacocks in Steel Boat

Quote:
Originally Posted by strongmonty View Post
I know that many of you are going to talk about the ease of welding a threaded pipe to the boat and that in many places in the world this is the preferred method. But please, I would just like to hear opinions about this particular set up that we are planning and what your thoughts are about it. I believe everything is isolated correctly and that there are no issues with this but I'd love to hear what everyone has to say.


The backing plate would be installed to the seacock before install, with polysulfide using the bronze fasteners. The hole in the hull will be drilled about 1/8" larger than the OD of the through-hull. I hope my drawing meets everyone's artistic standards.


OK...Give it to me straight Doc.
You can use G10 for the backing plate. A really good how to is here: https://marinehowto.com/seacock-backing-plates/
kmacdonald is offline   Reply With Quote
Old 19-10-2018, 09:37   #6
Registered User

Join Date: Oct 2013
Posts: 13
Re: Bronze Through Hulls and Seacocks in Steel Boat

Thank you kmacdonald for the link. I had found that site and had written it off as it was for GRP boats but looking at it again, I see they used the backing plate idea that was basically the same as ours (but with an even better idea for the bolts!).
CarlF, we aren't going to use marelon (although we really wanted to!) Because we are setting the boat up for high latitude sailing and plan to be hanging around Tierra del Fuego a bit. Lots of rocks around there and many places still have very bad charts. Were we to hit a rock there, we will feel much more comfortable hitting a bronze mushroom as opposed to a marelon. Many people claim them to be of equal strength, but if you look at their stats, there is a strength difference of almost 50% (I think I'm remembering that number correctly). In most people's case that is probably not an issue to be concerned with but for us that difference could make the difference.
Anyone have any thoughts on our isolation?
strongmonty is offline   Reply With Quote
Old 19-10-2018, 09:45   #7
Registered User

Join Date: May 2014
Location: Houston, TX
Boat: Catana 471
Posts: 76
Re: Bronze Through Hulls and Seacocks in Steel Boat

Quote:
Originally Posted by kmacdonald View Post
You can use G10 for the backing plate. A really good how to is here: https://marinehowto.com/seacock-backing-plates/
After Maine Sail wrote this article, Groco took the (excellent) idea and put it into production. They're designed obviously to fit Groco's flanged seacocks and flanged adapters, but I believe I saw somewhere that they can also be used with Apollo seacocks (same bolt pattern apparently). https://www.groco.net/products/valve...backing-blocks
Jetx is offline   Reply With Quote
Old 19-10-2018, 10:08   #8
Registered User

Join Date: Oct 2012
Location: Seattle
Boat: Tayana Mariner 36
Posts: 99
Re: Bronze Through Hulls and Seacocks in Steel Boat

Bronze sea valves on steel hulls is the norm for commercial / milspec vessels.
(Anyone that says its a bad idea has no idea what they are talking about...but that's often the norm on these forums.)
Typically steel hulls have a flanged steel spool piece welded to the hull. The valve is then fastened to the spool piece with appropriate gasket. Often waster pieces are installed as reassurance against corrosion.
bauer965 is offline   Reply With Quote
Old 19-10-2018, 10:12   #9
Registered User
 
Davidhoy's Avatar

Join Date: Jul 2016
Location: Fort Lauderdale
Boat: Morgan 462
Posts: 792
Re: Bronze Through Hulls and Seacocks in Steel Boat

Have you considered a sea chest instead of individual through hills? Gives you great safety, if you have the space for it.
__________________
Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.” – Mark Twain
Davidhoy is offline   Reply With Quote
Old 19-10-2018, 10:19   #10
Registered User

Cruisers Forum Supporter

Join Date: May 2011
Location: Miami Florida
Boat: Ellis Flybridge 28
Posts: 3,401
Re: Bronze Through Hulls and Seacocks in Steel Boat

Quote:
Originally Posted by Jetx View Post
After Maine Sail wrote this article, Groco took the (excellent) idea and put it into production. They're designed obviously to fit Groco's flanged seacocks and flanged adapters, but I believe I saw somewhere that they can also be used with Apollo seacocks (same bolt pattern apparently). https://www.groco.net/products/valve...backing-blocks
JetX beat me to it. He is absolutely right.
I really like Groco products and wouldn’t hesitate to use either their imported seacocks or their American made seacocks. Apollo Seacocks are equally as good. I believe they were the first to come out with a ball valve flanged seacock. I had Apollo seacocks on my boat for 28 years with no maintenance and no failures.

The Groco backing blocks took Maine Sail’s idea and went him one better. They have metal threads for the bolts to screw into. I highly recommend them.
__________________
Retired from Hopkins-Carter Marine Supplies
HopCar is offline   Reply With Quote
Old 19-10-2018, 11:07   #11
Registered User
 
mvmojo's Avatar

Join Date: Mar 2018
Boat: Robt Beebe Passagemaker 49-10 in steel
Posts: 115
Re: Bronze Through Hulls and Seacocks in Steel Boat

We have a sea chest on MOJO for all intake water. Steel welded threaded pipes on the side of the sea chest with bronze ball valves. The sea chest opening (maybe 10" x 10") has a bronze grill over it. 18 yrs w/out any corrosion. Head thru hulls are welded threaded SS pipe w/bronze valves. Curious why you're not going with welded thru hulls - nothing to break in a grounding since no external protrusions from the hull.
mvmojo is offline   Reply With Quote
Old 19-10-2018, 19:15   #12
Registered User

Join Date: Mar 2009
Location: Australia, Central Coast.
Boat: Boden 36 Triple chine long keel steel, named Nekeyah
Posts: 823
Re: Bronze Through Hulls and Seacocks in Steel Boat

Gilbert Klingel's steel boat building book has a good diagram of this setup if you can get a copy of it.
I think you would do better just machining a stainless stub and welding it into the hull with the appropriate electrode. This is what we do and seems pretty bullet proof.


Regards,
Richard.
boden36 is offline   Reply With Quote
Old 19-10-2018, 19:25   #13
Registered User

Join Date: Oct 2015
Posts: 942
Re: Bronze Through Hulls and Seacocks in Steel Boat

I am not going to try to convince you for or against bronze. Certainly if done right, there is nothing wrong with it. BUT... The design you have drawn has a flaw that to me is very serious.

Once mounted... how can you remove the valve?????

I know, I know... you do not expect to ever have to. But you will.
billknny is offline   Reply With Quote
Old 19-10-2018, 23:54   #14
Registered User

Join Date: Nov 2009
Boat: Tayana 37 Pilot House
Posts: 30
Re: Bronze Through Hulls and Seacocks in Steel Boat

The Groco full-flow flanged seacock can be serviced w/their kit, consisting of a new ball & teflon seals, w/o removal from the hull.

On the subject of protecting the external face of the thru-hull fitting, I think I recall seeing steel hull commercial fishing boats with a donut ring made from solid round stock welded onto the exterior of the hull around each thru-hull.
Taipe is offline   Reply With Quote
Old 20-10-2018, 23:41   #15
Registered User
 
Fore and Aft's Avatar

Join Date: Jan 2015
Location: Gympie
Boat: Volkscruiser
Posts: 336
Re: Bronze Through Hulls and Seacocks in Steel Boat

I surveyed a steel yacht last Wednesday that had been built in 1990. All the through hulls and seacocks were bronze and there was zero signs of any corrosion around the fittings on the hull. There was no backing plates, just the bronze nut fitting tightly against the inside of the hull.
The boat had been home built and the current owner had no idea why the skin fittings had been done like that.
Cheers
__________________

Fore and Aft is offline   Reply With Quote
Reply

Tags
boat, hull, steel

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
Bronze chainplates silicone bronze or aluminum bronze Eastward ho 24 Deck hardware: Rigging, Sails & Hoisting 33 24-01-2018 20:50
Corrosion on bronze through-hulls? Peregrine1983 Monohull Sailboats 13 31-07-2017 12:22
Bronze or Stainless Steel Thru-Hulls ? Hampus Plumbing Systems and Fixtures 17 11-02-2010 14:39
Replacing through hulls and seacocks Fotoman Construction, Maintenance & Refit 2 20-04-2009 19:54
Bronze through hull transducer for steel boat ? ribbony Construction, Maintenance & Refit 3 06-05-2008 13:44



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 00:58.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.