Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 16-07-2015, 03:19   #1
Registered User

Join Date: Sep 2011
Location: Jervis Bay NSW Australia
Boat: Adams 45 Steel Masthead Cutter
Posts: 97
Images: 8
Steel Hull Skin Fittings?

Did a bit of a search for this topic before posting - apologies if one exists already!

I am replacing my skin fittings on my steel hull cutter. It originally had mild steel stand pipes welded in place - onto the 5mm mild steel plate hull. Its about 30 years old.

Not terribly comfortable with them as a couple have thinned out too much.

My research indicates that 316 Stainless skin fittings are OK above or at waterline - correctly installed to eliminate metal incompatibility - but, can I use them below the waterline?

Advice on type would be appreciated.

Aussie Monty
__________________

__________________
Aussie Monty is offline   Reply With Quote
Old 16-07-2015, 11:20   #2
Senior Cruiser

Cruisers Forum Supporter

Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 1,708
Re: Steel Hull Skin Fittings?

No. 316 is fine for salt water above the waterline. In salt water below the waterline it will pit. The more it pits, the faster pit get bigger. I believe 317 is what you want. Good lick finding it at a reasonable cost. I would just replace the pipes with mild steel schedule 80 - thicker walls. Or schedule 40 and wait for the next 30 years.
__________________

__________________
Lepke is offline   Reply With Quote
Old 16-07-2015, 11:34   #3
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,369
Re: Steel Hull Skin Fittings?

I'd stick with steel stand pipes if you can find a good welder for that. But I'm not that steel boat knowledgeable.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 16-07-2015, 19:43   #4
Registered User

Join Date: Mar 2009
Location: Australia, Central Coast.
Boat: Boden 36 Triple chine long keel steel, named Nekeyah
Posts: 777
Re: Steel Hull Skin Fittings?

I know that the conventional wisdom is no stainless below the waterline. Our steel boat has had stainless prop shaft and rudder pintles for 25 yrs no problems.
A few years ago I had a machine shop turn up a thick walled stainless stub threaded to take a stainless seacock. This stub is welded to the hull plating.
I have expected to see pitting, and inspect it at each slipping, but so far no problems with stub or seacock. Must be around five years now.
Our head outlet is done differently. Four stainless bolts through the hull and with their heads welded. A marelon (sp?)flanged stub is retained against the inside of the hull by a suitably drilled stainless plate which is held down by the four studs. There is a gasket between the flat head of the stub and the hull. There is also a gasket and sealant between the plate and the hull. I have checked it once in 25 years and it was as good as the day it was installed.
These are the only two through hulls in the boat. The cockpit drains above waterline, and the sink runs into the cockpit drains. The engine and toilet share a seacock with a valve at the toilet so that the engine cannot suck air back on a long run.

Regards,
Richard.
__________________
boden36 is offline   Reply With Quote
Old 17-07-2015, 03:03   #5
Registered User

Join Date: Sep 2011
Location: Jervis Bay NSW Australia
Boat: Adams 45 Steel Masthead Cutter
Posts: 97
Images: 8
Re: Steel Hull Skin Fittings?

Boden 36 states the obvious...replacing with mild steel, thicker walled, seal well with good finish and it should outlast me! I am in fact a boilermaker by trade so am confident i can install without issue....just that my shipwrighting skills are developing!

Thanks all for thoughts so far.

Aussie Monty
__________________
Aussie Monty is offline   Reply With Quote
Old 17-07-2015, 03:42   #6
Registered User

Join Date: Mar 2009
Location: Australia, Central Coast.
Boat: Boden 36 Triple chine long keel steel, named Nekeyah
Posts: 777
Re: Steel Hull Skin Fittings?

Aussie, what you suggest will work well, but it was not what I meant. I used 316 stainless to make the pipe stub and welded it to the hull plate with appropriate rods.

Regards,
Richard.
__________________
boden36 is offline   Reply With Quote
Old 17-07-2015, 03:50   #7
Registered User

Join Date: Sep 2011
Location: Jervis Bay NSW Australia
Boat: Adams 45 Steel Masthead Cutter
Posts: 97
Images: 8
Re: Steel Hull Skin Fittings?

Quote:
Originally Posted by boden36 View Post
Aussie, what you suggest will work well, but it was not what I meant. I used 316 stainless to make the pipe stub and welded it to the hull plate with appropriate rods.

Regards,
Richard.
Apologies for the misunderstanding Boden36. Indeed this clarifies another solution that I was eyeing off. Can I simply use stainless 316 tube/standpipes directly welded to mild steel hull and be either be free off, or avoid, metal incompatibility issues?

Aussie Monty
__________________
Aussie Monty is offline   Reply With Quote
Old 17-07-2015, 03:52   #8
Registered User

Join Date: Mar 2009
Location: Australia, Central Coast.
Boat: Boden 36 Triple chine long keel steel, named Nekeyah
Posts: 777
Re: Steel Hull Skin Fittings?

A lot of people say you can't, but it has worked for me so far. Used at least 10mm wall thickness.

Regards,
Richard.
__________________
boden36 is offline   Reply With Quote
Old 19-07-2015, 01:05   #9
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,458
Images: 69
Re: Steel Hull Skin Fittings?

If the original stuff lasted 30 years, I'd be reluctant to try a different material, with unknown galvanic consequences.


Our steel boat had mild steel stand pipes too. Any rust happened from the inside, and was easily seen, cleaned up and painted.
__________________
44'cruisingcat is offline   Reply With Quote
Old 20-07-2015, 02:27   #10
Registered User

Join Date: Apr 2007
Location: Australia
Boat: Island Packet 40
Posts: 1,376
Images: 7
Re: Steel Hull Skin Fittings?

Quote:
Apologies for the misunderstanding Boden36. Indeed this clarifies another solution that I was eyeing off. Can I simply use stainless 316 tube/standpipes directly welded to mild steel hull and be either be free off, or avoid, metal incompatibility issues?
I have a mix of both mild steel and 316 stainless all welded into the hull plate and have not had any corrosion problems with either of them. The boat was launched in 1987.
__________________
RaymondR is offline   Reply With Quote
Old 20-07-2015, 02:43   #11
Registered User
 
stillbuilding's Avatar

Join Date: Jan 2008
Location: Hong Kong
Boat: Custom Freya 20m
Posts: 961
Re: Steel Hull Skin Fittings?

Always had 316 SS, but always heavy gauge and professionally welded on nipples. No problem. Almost impossible to find Duplex anyway. I could not bring myself to use weld-in mild steel. Can see that well painted it could be ok though. Probably does not matter if well blasted and painted.


Sent from my iPhone using Cruisers Sailing Forum
__________________
stillbuilding is offline   Reply With Quote
Old 20-07-2015, 04:57   #12
Registered User
 
Hartleycruiser's Avatar

Join Date: Mar 2011
Location: Darwin Australia
Boat: Jeanneau 45.2
Posts: 41
Re: Steel Hull Skin Fittings?

Aussie Monty

The problems people have encountered seem to be with the cast skin fittings, they may have some impurities in the casting and are therefore not up to being under water .
__________________

__________________
Hartleycruiser is offline   Reply With Quote
Reply

Tags
steel hull, steel, hull

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
Source of Quality Skin Fittings/Through Hulls in Australia GILow Construction, Maintenance & Refit 9 16-07-2015 03:35
440: Replacing Skin Fittings And Ball-valves The Boat's 5 Years Old. Lagoon4us Lagoon Catamarans 115 15-02-2015 00:42
Skin care - what is the best way of keeping your skin clean while cruising? Eyeback Health, Safety & Related Gear 16 03-11-2013 09:15
Skin fittings ii337 Construction, Maintenance & Refit 2 19-08-2013 10:43
Skin Fittings in a Ferro Hull Steve Kidson Construction, Maintenance & Refit 4 27-03-2006 02:15



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 05:26.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.