Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-06-2010, 19:35   #16
Registered User
 
rustypirate's Avatar

Join Date: Nov 2008
Location: Largo, Florida
Boat: Bruce Roberts Offshore 38
Posts: 268
Images: 10
I think we are getting a little off track here with regard to the seacocks. The original question was about replacing a transducer, not a plumbing through-hull.

There are lots of options, but I personally would not install any plastic or marelon fitting without a steel reinforcing tube welded into the hull to protect the fitting from accidental damage from inside. The tube should be long enough to protect the hight of the internal fitting while still allowing the proper retaining nut to thread on securely. These tubes can be perpendicular to the hull surface, or installed vertically to compensate for hull angles.

The profile of the transducer on the outside is relatively low and not terribly inclined to damage unless you ground on rocks or coral, or if you run into something else solid like ice. Damage to the outside can be prevented by adding protective gaurds that extend about an inch or so on the outside of the hull near the transducer.

As for installing bronze or stainless through hulls for plumbing, I personally would not and I have been told by people whose authority on such things I trust.

Likewise I will bow to Mr. Swain's many years of experience with designing and building steel boats about this, and if he says that it is a non-issue, then I would take that as his personal experience in the matter, and worthy of consideration.
__________________

__________________
Some people are like a slinky...

Not really good for anything, but fun to push down the stairs.
rustypirate is offline   Reply With Quote
Old 02-06-2010, 19:36   #17
Registered User
 
SabreKai's Avatar

Join Date: Sep 2008
Location: Toronto, Canada on Lake Ontario
Boat: Roberts Offshore 38
Posts: 1,287
Images: 5
Deepfrz, guess you left your sense of humor at home today. It was meant in jest. If you have ever seen Babylon 5, you would understand the reference.

Brent, what filler did you use when doing the weld?


Sabre
__________________

__________________
SabreKai
SV Sabre Dance, Roberts Offshore 38
http://sabredancing.wordpress.com/
SabreKai is offline   Reply With Quote
Old 02-06-2010, 19:48   #18
Senior Cruiser

Cruisers Forum Supporter

Join Date: Nov 2005
Location: Out there doin' it
Boat: 47' Olympic Adventure
Posts: 2,635
Quote:
Originally Posted by rustypirate View Post
I think we are getting a little off track here with regard to the seacocks. The original question was about replacing a transducer, not a plumbing through-hull.
Actually the OP said transducer AND through-hull.

Quote:
Originally Posted by perchance View Post
What do commercial and military vessels use for thru hulls? I'm sure it ain't plastic.
No, it's pipe welded to the hull - we call 'em "skin-valves", but "nipple" seems to be the local term. Dunno what the metal is - sorry.
__________________
Lodesman is offline   Reply With Quote
Old 02-06-2010, 19:50   #19
Registered User
 
nitpik's Avatar

Join Date: Feb 2010
Location: Canada, North Channel of Lake Huron
Boat: 41' Colvin Gaff-rigged Schooner
Posts: 222
Send a message via Yahoo to nitpik Send a message via Skype™ to nitpik
My vote is for plastic for the depth transducer, but not for the thru-hull fittings. I just replaced my transducer by welding a mild steel pipe through the hull plating, fairing it on the outside, and inserting the transducer from below with suitable caulking. This also gives me the security of having a cap available to screw onto the pipe section in the event of catastrophic failure, thus sealing the hole effectively. Several depth sounder manufacturers recommend using plastic transducers on a steel hull, and bronze on a wood hull.
Because you have a steel hull, you have the distinct advantage of being able to weld in galvanized standpipes for all your through hulls, and T-ing the seacocks off of these pipes. Very secure, plus, if you have a separate, smaller pipe to screw down into the standpipe, YOU CAN REMOVE YOUR SEACOCKS ANY TIME FOR SERVICING, without shipping so much as a drop of water. Also, if you get up at 3am to discover the floorboards awash due to failure of a seacock, you can quickly seal off all water ingress, then inspect/repair/replace the seacock at your leisure.
There are some negatives attached to owning a steel hull ......... might as well take advantage of the positives!
__________________
Some days you step in it ............... some days you don't.
nitpik is offline   Reply With Quote
Old 02-06-2010, 19:54   #20
Registered User
 
nitpik's Avatar

Join Date: Feb 2010
Location: Canada, North Channel of Lake Huron
Boat: 41' Colvin Gaff-rigged Schooner
Posts: 222
Send a message via Yahoo to nitpik Send a message via Skype™ to nitpik
ps., when attaching stainless steel to mild steel under water, it is apparently the welds that can cause you grief. From the research I have done, consensus of opinion seems to be - your hull is made of mild steel, the fittings welded to it should also be mild steel. Don't introduce different metals to one another unnecessarily.
__________________
Some days you step in it ............... some days you don't.
nitpik is offline   Reply With Quote
Old 02-06-2010, 20:00   #21
Moderator
 
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
Transducer on Boracay...

To mount the depth sounder on Boracay I had a fitting custom machined up from solid steel stock to fit the Raymarine ST40 transducer.

I then paid a professional welder heaps of cash to enlarge the hole and to weld the fitting in place.

As it was made from lots of nice thick steel they did prewarm before welding with multiple weld runs. No worries at all.

Of course now I lust after one of those new sidescan sonars. Just have to see if I win the lottery.
__________________
Rust never sleeps
Boracay Blog.
Boracay is offline   Reply With Quote
Old 03-06-2010, 02:32   #22
Senior Cruiser
 
idpnd's Avatar

Cruisers Forum Supporter

Join Date: Sep 2007
Location: Almerķa, ES
Boat: Chiquita 46 - Libertalia
Posts: 1,551
Lots of learned opinions, and they all differ, good!

Quote:
Originally Posted by Lodesman View Post
Actually the OP said transducer AND through-hull.
Sorry probably too stupid to express self properly - my through-hull I meant the fitting the transducer is stuffed into!

Although in my uneducated opinion it is essentially the same issue (steel hull material compatibility)

Quote:
Originally Posted by Brent Swain View Post
I recently removed a plastic thru hull from a steel boat by lightly kicking it. Scary. Any piece of gear shifting a bit could easily do that.
That's what happened here, hence not too keen on plastic. Well I was pulling it to test for robustness rather than kicking it. Didn't offer much resistance I might add

Quote:
Originally Posted by nitpik View Post
Because you have a steel hull, you have the distinct advantage of being able to weld in galvanized standpipes for all your through hulls, and T-ing the seacocks off of these pipes.
I know, I know.. met the boat's architect he was on and on about that, of course its the optimal solution. Saving up for that!
__________________
sv Libertalia
idpnd is offline   Reply With Quote
Old 03-06-2010, 15:48   #23
Registered User

Join Date: Jun 2009
Location: STX and Portland, until refit finished
Boat: 1999 Steel (Tom Collin's design)
Posts: 371
Quote:
Originally Posted by nitpik View Post
My vote is for plastic for the depth transducer, but not for the thru-hull fittings. I just replaced my transducer by welding a mild steel pipe through the hull plating, fairing it on the outside, and inserting the transducer from below with suitable caulking. This also gives me the security of having a cap available to screw onto the pipe section in the event of catastrophic failure, thus sealing the hole effectively. Several depth sounder manufacturers recommend using plastic transducers on a steel hull, and bronze on a wood hull.
Because you have a steel hull, you have the distinct advantage of being able to weld in galvanized standpipes for all your through hulls, and T-ing the seacocks off of these pipes. Very secure, plus, if you have a separate, smaller pipe to screw down into the standpipe, YOU CAN REMOVE YOUR SEACOCKS ANY TIME FOR SERVICING, without shipping so much as a drop of water. Also, if you get up at 3am to discover the floorboards awash due to failure of a seacock, you can quickly seal off all water ingress, then inspect/repair/replace the seacock at your leisure.
There are some negatives attached to owning a steel hull ......... might as well take advantage of the positives!
Can you describe this arrangement to allow yourself to replace the seacock with ease better? I can't seem to picture it in my head.

Thank you
__________________
ViribusUnitis is offline   Reply With Quote
Old 03-06-2010, 16:03   #24
CF Adviser

Cruisers Forum Supporter

Join Date: Aug 2009
Boat: Custom Van De Stadt 47 Samoa
Posts: 3,744
I just had a bit of a bad experience with Forespar marleon. I have an aluminum hull and plastic (marleon) is really the only option. After 12 years I just went thru and replaced all (5) our seacocks because a couple had gotten so stiff they were not really closable anymore. So we went thru and 5 new ones and got them all bedded in and relaunched and one was leaking right thru the valve body - defective and non-repairable.

I looked closely at the other 4 new seacocks and its obvious their quality control/consistency is not very high since the tolerances were quite different piece to piece. But for an aluminum hull these are really all we can use. We have aluminum stand pipes with flanges (not threads) that match the flange on the marleon seacocks. So the seacocks bolt down on these aluminum flanges with a compression gasket. I think this is preferred to the threaded pipe approach, because the threads can corrode invisibly inside the seacock and the pipe possibly snap off below the seacock (bad!).

We rehauled and replaced the defective one and relaunched and finally got everything ok.
__________________
estarzinger is offline   Reply With Quote
Old 03-06-2010, 20:07   #25
Registered User
 
nitpik's Avatar

Join Date: Feb 2010
Location: Canada, North Channel of Lake Huron
Boat: 41' Colvin Gaff-rigged Schooner
Posts: 222
Send a message via Yahoo to nitpik Send a message via Skype™ to nitpik
ViribusUnitis - standpipe

If a picture is worth a thousand words, and if I can get a picture attached to this post, then I might be able to explain better. The first picture attempts to show the basic standpipe arrangement:

In the second picture, the standpipe end cap is unscrewed, and a smaller diameter pipe (the plug) is inserted down into the standpipe and screwed into a threaded receiver at the bottom. Now no water can enter the system, so you can dismantle the standpipe at your leisure. I have three such standpipes, all within easy reach in the engine room. If all hell should break loose on a dark night in the middle of the Atlantic, it is comforting to know that I can insert the plugs quite quickly and stop the flow of water, even if I can't immediately see what is leaking. Then, when my heart rate has returned to normal, I can take my time looking for the problem. This system has also proven handy when I have frozen the boat in during the winter, since there is not even an eighth of an inch of water inside the bottom of the pipe. With the seacock attached directly to the hull, there would still be some water in there to freeze, even with the seacock shut off.
Hope this makes sense ....... David
(second picture in next post)
__________________
Some days you step in it ............... some days you don't.
nitpik is offline   Reply With Quote
Old 03-06-2010, 20:09   #26
Registered User
 
nitpik's Avatar

Join Date: Feb 2010
Location: Canada, North Channel of Lake Huron
Boat: 41' Colvin Gaff-rigged Schooner
Posts: 222
Send a message via Yahoo to nitpik Send a message via Skype™ to nitpik
Here's how the plug works:
__________________
Some days you step in it ............... some days you don't.
nitpik is offline   Reply With Quote
Old 03-06-2010, 20:10   #27
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Quote:
I looked closely at the other 4 new seacocks and its obvious their quality control/consistency is not very high since the tolerances were quite different piece to piece.
That's discouraging.
__________________
DeepFrz is offline   Reply With Quote
Old 03-06-2010, 20:11   #28
Registered User
 
nitpik's Avatar

Join Date: Feb 2010
Location: Canada, North Channel of Lake Huron
Boat: 41' Colvin Gaff-rigged Schooner
Posts: 222
Send a message via Yahoo to nitpik Send a message via Skype™ to nitpik
Final note - you can have multiple seacocks T'd off the same standpipe, perhaps reducing the number of through-hulls.
__________________
Some days you step in it ............... some days you don't.
nitpik is offline   Reply With Quote
Old 03-06-2010, 20:21   #29
Registered User
 
nitpik's Avatar

Join Date: Feb 2010
Location: Canada, North Channel of Lake Huron
Boat: 41' Colvin Gaff-rigged Schooner
Posts: 222
Send a message via Yahoo to nitpik Send a message via Skype™ to nitpik
Estarzinger - is it possible (next time you replace seacocks!) to modify your standpipes a little? A solid and strong plastic coupling between the standpipe and the seacock would accomplish two things:
1. the seacock is now isolated electrically from the standpipe, reducing risk of corrosion, and
2. This would allow you to use ANY seacock, including bronze, stainless, etc. - your choice
__________________
Some days you step in it ............... some days you don't.
nitpik is offline   Reply With Quote
Old 03-06-2010, 20:31   #30
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
David, you don't want to use bronze in an aluminum boat. Kanter nickel plates anything bronze on their boats.
__________________

__________________
DeepFrz is offline   Reply With Quote
Reply

Tags
steel hull, thru 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
Hull material nylarlathotep General Sailing Forum 50 01-06-2015 13:57
Hull material in Catamarans freetime Multihull Sailboats 69 27-04-2009 08:31
Hull material tolly Multihull Sailboats 7 22-10-2008 08:42
steel hull boat prices? RRR Monohull Sailboats 7 25-09-2008 17:03
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 00:20.


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.