Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 25-07-2011, 12:18   #1
Registered User

Join Date: Sep 2010
Posts: 844
Images: 1
Testing a Steel Hull for Defects . . .

Threadmates,

I am considering buying a steel hulled boat and am wondering how I can get a sense of the worthiness of the hull. The boat was constructed in 1980 and is sitting at anchor.

The owner is selling at a discount, so I am sure that he will not want to take it out of the water unless I am willing to pay to haul her out, and there may not be a crane able to lift her where she is now located.

Is there any reliable way to test for defects while she is in the water? Any old sailor's tricks that might be useful?

Lastly, I'll probably have to make a judgement on the hull myself since the boat is in a relatively remote area.

Any help that anyone could provide would be greatly appreciated.

Regards to all,

G2L
__________________

__________________
Gone2long is offline   Reply With Quote
Old 25-07-2011, 12:49   #2
Registered User

Join Date: Nov 2010
Location: Lafayette, Louisiana
Boat: Ketch, Hardin 45
Posts: 440
Images: 6
Re: Testing a Steel Hull for Defects ...

1. By striking the hull with a chipping hammer... If the hammer goes through the skin or puts a deep dent in the skin. It is not for you.
2. Electronic thickness gauge. Using the stated thickness of the metal as a guide, you can determine if the skin has be reduced in thickness due to either rust chasing or pitting out where you can't get to the interior of the hull. Or reduced by electrolysis.
But the boat needs to be hauled out for testing of the hull below the water line. And that is the buyers problem.
__________________

__________________
boasun is offline   Reply With Quote
Old 25-07-2011, 13:27   #3
Writing Full-Time Since 2014
 
thinwater's Avatar

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 4,337
Re: Testing a Steel Hull for Defects ...

Quote:
Originally Posted by boasun View Post
1. By striking the hull with a chipping hammer... If the hammer goes through the skin or puts a deep dent in the skin. It is not for you.
2. Electronic thickness gauge. Using the stated thickness of the metal as a guide, you can determine if the skin has be reduced in thickness due to either rust chasing or pitting out where you can't get to the interior of the hull. Or reduced by electrolysis.
But the boat needs to be hauled out for testing of the hull below the water line. And that is the buyers problem.
UT testing can be done in the water, but access is less; you are limited to what you can reach. Hauled is much better.

If the paint is not very tight, it is required to blast off everything that is loose. The more layers, the more trouble getting go numbers can be.

However, UT testing will miss pitting smaller that than the transducer head (anything smaller than ~ 3/16-inch is often missed). There is no substitue for a good visual internals and external exam. UT is for measuring general thickness, not detailed condition.

Hammer testing is very valuable, but it looks brutal and scares owners. It's really quite safe.
__________________
Gear Testing--Engineering--Sailing

Writing full-time since 2014.
Bookstore:http://sail-delmarva.blogspot.com/20...ook-store.html
thinwater is offline   Reply With Quote
Old 25-07-2011, 16:26   #4
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
Plans, builder's certificate, records, visual inspection...

If you can look at the plans or contact the designer then you can check what the scantlings for the hull and deck should be. If there is a builder's certificate it may list the plate and frame thickness for the hull and deck. Looking at the boat sitting in the water check that it sits level and on its marks. A few people standing on the toerail may be of interest.

The owner may have records showing how frequently the anodes have been replaced and when this was last done.

There may be photographs that show the hull below the waterline with some detail together with the condition of the rudder and the propeller.

Much can be gained from a visual inspection. Rust spots on the outside of the hull above the waterline and the external surface of the deck may only be cosmetic but would need to be checked carefully. An internal inspection, particularly along frames, stringers and bulkheads and all visible welds can also be very informative. Attention may need to be paid to the internal wiring, particularly the state of any automatic bilge pump and switch. The presence of any pools of internal water should also be noted. The type and condition of all through hulls, seacocks hoses and clamps should be checked and assessed as to their suitability.

These are the items that come to mind for a steel boat. There are a multitude of items on all boats that need to be checked as part of the "due diligence" of boat buying.

Based on the above it is wise to draw up an operating budget for the boat.

If, after assessing the above items the boat is still attractive then engaging the services of a surveyor experienced with steel boats is essential.
__________________
Rust never sleeps
Boracay Blog.
Boracay is offline   Reply With Quote
Old 26-07-2011, 06:04   #5
Registered User

Join Date: Sep 2010
Posts: 844
Images: 1
Thanks Boracay, Boasun, Thinwater

Quote:
Originally Posted by Boracay View Post
If you can look at the plans or contact the designer then you can check what the scantlings for the hull and deck should be. If there is a builder's certificate it may list the plate and frame thickness for the hull and deck. Looking at the boat sitting in the water check that it sits level and on its marks. A few people standing on the toerail may be of interest.

The owner may have records showing how frequently the anodes have been replaced and when this was last done.

There may be photographs that show the hull below the waterline with some detail together with the condition of the rudder and the propeller.

Much can be gained from a visual inspection. Rust spots on the outside of the hull above the waterline and the external surface of the deck may only be cosmetic but would need to be checked carefully. An internal inspection, particularly along frames, stringers and bulkheads and all visible welds can also be very informative. Attention may need to be paid to the internal wiring, particularly the state of any automatic bilge pump and switch. The presence of any pools of internal water should also be noted. The type and condition of all through hulls, seacocks hoses and clamps should be checked and assessed as to their suitability.

These are the items that come to mind for a steel boat. There are a multitude of items on all boats that need to be checked as part of the "due diligence" of boat buying.

Based on the above it is wise to draw up an operating budget for the boat.

If, after assessing the above items the boat is still attractive then engaging the services of a surveyor experienced with steel boats is essential.
Helpful suggestions from all of you. Will start with a visual and a hammer, then go from there if conditions warrant it. Was thinking that the hammer idea can also work underwater as a rough indicator, used with a pair of fins, snorkle and mask, given that the underwater growh is not too obtrusive.

Thanks again to all,

G2L
__________________
Gone2long is offline   Reply With Quote
Old 26-07-2011, 06:35   #6
Registered User
 
Artif's Avatar

Join Date: Jan 2011
Posts: 261
Re: Thanks Boracay, Boasun, Thinwater

Quote:
Originally Posted by Gone2long View Post
Was thinking that the hammer idea can also work underwater as a rough indicator, used with a pair of fins, snorkle and mask, given that the underwater growh is not too obtrusive.

Thanks again to all,

G2L

Be very careful using a hammer underwater, hitting a thin spot could be expensive, if you put it through the hull.
__________________
Artif is offline   Reply With Quote
Old 26-07-2011, 07:02   #7
Registered User

Join Date: Sep 2010
Posts: 844
Images: 1
Re: Thanks Boracay, Boasun, Thinwater

Quote:
Originally Posted by Artif View Post
Be very careful using a hammer underwater, hitting a thin spot could be expensive, if you put it through the hull.

A couple of taps top side should clue me as to how hard I might want to to knock on the bottom (if ya know what I mean. : )

Thanks for the advice,

G2L
__________________
Gone2long is offline   Reply With Quote
Old 26-07-2011, 07:12   #8
Registered User
 
Gnwceleste42's Avatar

Join Date: Jul 2011
Posts: 4
Some higher end ultrasound gauges will read steel from epoxy for exact reading and not stripping. Definitely haul unless you understand the full potential costs of blasting to white steel and epoxy as well as some spot welding etc.as part of your investment
__________________
Gnwceleste42 is offline   Reply With Quote
Old 26-07-2011, 17:00   #9
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
No hammer, screwdriver...

I strongly advise against using a hammer or screwdriver to check a steel hull, particularly below the waterline.

If you believe this to be necessary then the boat may not be a good candidate for purchase.
__________________
Rust never sleeps
Boracay Blog.
Boracay is offline   Reply With Quote
Old 26-07-2011, 17:34   #10
Senior Cruiser
 
Jacko's Avatar

Cruisers Forum Supporter

Join Date: Mar 2011
Location: Far North Queensland Australia
Boat: John Pugh / Currawong 48/OAL
Posts: 188
Re: Testing a Steel Hull for Defects . . .

Gone2long A very simple starting point !! If you can dive on the boat and check the Anodes if they are gone ( eaten away to nothing left ) I suggest that you be gone !!! There is every chance that you will have major repairs to do also if there is rust around the water line this is an area that will show that there is no anode protection so head for home and find another boat to look at Cheers Jacko
__________________
Jacko is offline   Reply With Quote
Old 26-07-2011, 19:26   #11
Writing Full-Time Since 2014
 
thinwater's Avatar

Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 4,337
Re: No hammer, screwdriver...

Quote:
Originally Posted by Boracay View Post
I strongly advise against using a hammer or screwdriver to check a steel hull, particularly below the waterline.

If you believe this to be necessary then the boat may not be a good candidate for purchase.
In truth, this is mostly true. You will need to re-paint. Mostly it is a method for use where there is more corrosion than most boat purchasers would accept.

Where it is useful is in areas where UT testing gives inconclusive results; sometimes there are areas where it is very difficult to get clean echos and the reverse side is not easily accessible.

(I've done UT inspections on thousands of oil tanks, many tankers, and a few smaller boats.)
__________________
Gear Testing--Engineering--Sailing

Writing full-time since 2014.
Bookstore:http://sail-delmarva.blogspot.com/20...ook-store.html
thinwater is offline   Reply With Quote
Old 27-07-2011, 16:48   #12
Registered User
 
lorenzo b's Avatar

Join Date: May 2009
Location: Panama
Boat: Steel trawler 63' Eileen Farrell
Posts: 961
Re: Testing a Steel Hull for Defects . . .

Are we talking about a sailboat with compound curves or a work boat with hard chimes and flat steel?
Do you like to weld?

Bad news; you need a new bottom
Good news; you get a new bottom
__________________
lorenzo b is offline   Reply With Quote
Old 28-07-2011, 08:43   #13
Registered User

Join Date: Sep 2010
Posts: 844
Images: 1
Jacko, Thinwater, Boracay et all ...

... More good tips. Appreciate them.

I am looking at two steel boats and one cement one. More on the cement in another thread.

As per the question by one of our thread mates above, the boats are single chine steel sailboats, not unlike Boracay's Roberts 44.

Don't know how to weld, but learning may be in my future. : )

Regards to all,

G2L
__________________
Gone2long is offline   Reply With Quote
Old 28-07-2011, 10:07   #14
Registered User
 
lorenzo b's Avatar

Join Date: May 2009
Location: Panama
Boat: Steel trawler 63' Eileen Farrell
Posts: 961
Re: Testing a Steel Hull for Defects . . .

If they are sailboats, I would not worry too much, they do not get the abuse and neglect of a workboat.
__________________
lorenzo b is offline   Reply With Quote
Old 28-07-2011, 11:49   #15
Registered User
 
rustypirate's Avatar

Join Date: Nov 2008
Location: Largo, Florida
Boat: Bruce Roberts Offshore 38
Posts: 268
Images: 10
Re: Testing a Steel Hull for Defects . . .

The first thing you will need to do is perform an internal inspection.
Most steel sailboats will rust from the inside out. the rust will occur wherever the water can pool along stringers and ribs inside the hull with plenty of oxygen available.
Make sure that you can get eyeballs on as much of the internal surface of the hull and deck as possible. If any paint appears loose or flaking, then a hammer test is a good verification. I recommend a rubber mallet for this as it will not chip the paint unless it was flaking off anyway, and you can apply a firm enough hit to shake loose any flaking rust if it is there.

Make sure that you check areas that will get extra wet like anchor lockers and deck accessed storage.

Check the zinc annodes to ensure that no stray current may be causing corrosion.

If the boat cannot be hauled out, dive on it to examine the undersides. DO NOT use a chipping hammer for this as the potiential for punching a hole through a thin sopt can make a leak which if untreated will sink the boat.

Some things I have seen are bulges in the paing on the topsides caused by rust swelling underneath. Fiberglass patches over rusted out steel to stop pin-hole leaks.
__________________

__________________
Some people are like a slinky...

Not really good for anything, but fun to push down the stairs.
rustypirate is offline   Reply With Quote
Reply

Tags
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
Fiberglass vs Steel Hulls larryb Monohull Sailboats 24 21-08-2016 00:31
Steel Boats and Welding SaltyMonkey Monohull Sailboats 634 04-05-2013 02:54
For Sale: Steel Sail Boat blanche Classifieds Archive 5 16-08-2011 15:13
Hull Thickness Too Thin ? I Paid the Deposit - Oops or Not ? cilrath Construction, Maintenance & Refit 22 03-08-2011 20:09
Hartog 36' Steel Hull KenH Monohull Sailboats 7 15-07-2011 17:53



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 21:57.


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.