Just replaced thru-hulls on my Gulf 32 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 04-25-2011
bwindrope's Avatar
Break, curse, fix, repeat
 
Join Date: Feb 2007
Location: Bainbridge Island, WA
Posts: 267
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 8
bwindrope is on a distinguished road
Just replaced thru-hulls on my Gulf 32

For anyone with genuine interest or just morbid fascination, I just posted a story on my boat blog about replacing thru-hulls on my Gulf 32. I tried to post a lot of pictures to clarify the process and outcomes, and let me just say it was a major PIA, but completely worthwhile. They were glassed in, flush head thru-hulls, just to make it more fun!!!

To see about my experience go to: Stories of Aeolus- Our Gulf 32 Pilothouse: Replaced Thru-Hulls and Seacocks-Down the rabbit hole

Feel free to contact me if you have any questions. I'm just adding my experience to the library of others who have done, or will do, this project.
__________________
Aeolus
Gulf 32
Bainbridge Island, WA

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #2  
Old 04-25-2011
mitiempo's Avatar
Senior Member
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,069
Thanks: 0
Thanked 68 Times in 59 Posts
Rep Power: 7
mitiempo will become famous soon enough mitiempo will become famous soon enough
Looks good but plywood doesn't make a great backer - long term it gets soggy. Fiberglass backers would be a first rate choice. As done here Replacing Thru-Hulls and Seacocks Photo Gallery by Compass Marine at pbase.com
I will be using fiberglass when I replace mine at haulout time.
__________________
Brian
Living aboard in Victoria Harbour
Reply With Quote Share with Facebook
  #3  
Old 04-25-2011
Tim R.'s Avatar
Senior Member
 
Join Date: Mar 2003
Location: Portland, Maine
Posts: 1,541
Thanks: 1
Thanked 27 Times in 26 Posts
Rep Power: 12
Tim R. is on a distinguished road
And hopefully Maine Sail will have some pre-made FG blanks available soon.
__________________
Tim R.
Out cruising
1997 Caliber 40LRC

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

-----------------------------------------------------
Reply With Quote Share with Facebook
  #4  
Old 04-25-2011
bwindrope's Avatar
Break, curse, fix, repeat
 
Join Date: Feb 2007
Location: Bainbridge Island, WA
Posts: 267
Thanks: 0
Thanked 2 Times in 2 Posts
Rep Power: 8
bwindrope is on a distinguished road
Maine Sail has great information, including the use of fiberglass blocks, and I do not doubt their effectiveness. However, there are trade offs. Making or buying the fiberglass was far more expensive than the 3/4" plywood. As for rigidity and structure, the plywood is equal in useful strength to the fiberglass, meaning, they are both absolutely solid and rigid for the purpose. And finally, as for longevity and strength, I have a boat that is 23 years old with untreated plywood in various places, including the old 1/4 inch puny backing blocks, and none of it showed any signs of significant decay.

Fully encasing the new 3/4 inch backing blocks with epoxy will provide them with all the longevity I would ever need or expect, and in 20 years time I will likely want to replace them and the thru-hulls again anyway. Another reason for using 4200 and not 5200.

So I would never argue against using fiberglass, at all, it is obviously great, but I believe a solid epoxy covered plywood block will fill all the same purposes except immortality, and I don't expect that anyway.
__________________
Aeolus
Gulf 32
Bainbridge Island, WA

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Share with Facebook
  #5  
Old 04-25-2011
mitiempo's Avatar
Senior Member
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,069
Thanks: 0
Thanked 68 Times in 59 Posts
Rep Power: 7
mitiempo will become famous soon enough mitiempo will become famous soon enough
If properly epoxied and epoxied to the hull plywood is probably a fair substitute for fiberglass. Fiberglass is easy to make, can be purchased, or can be obtained as offcuts/waste from a builder.
My job lets me see many boats' bilges and I can't recall wood backing blocks that were not soft and punky with age.
__________________
Brian
Living aboard in Victoria Harbour
Reply With Quote Share with Facebook
  #6  
Old 04-25-2011
Junior Member
 
Join Date: Jan 2011
Location: Texas
Posts: 5
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Goblinfog is on a distinguished road
I'm in the mist of redoing mine, but I'm using Densetec Marine Board instead of wood or fiberglass backing. Does anyone see a problem with 5200 and compatability with the marine board? Hope this doesn't bother the thread.
Reply With Quote Share with Facebook
  #7  
Old 04-25-2011
mitiempo's Avatar
Senior Member
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,069
Thanks: 0
Thanked 68 Times in 59 Posts
Rep Power: 7
mitiempo will become famous soon enough mitiempo will become famous soon enough
My feeling is that the backer should be permanently attached to the hull. Easy to do with fiberglass or plywood using thickened epoxy.
I'm not sure about the Densetec but I don't think many sealants will stick to it and I'm certain epoxy will not.
__________________
Brian
Living aboard in Victoria Harbour
Reply With Quote Share with Facebook
  #8  
Old 04-25-2011
casey1999's Avatar
Senior Member
 
Join Date: Oct 2010
Location: HI
Posts: 2,829
Thanks: 4
Thanked 17 Times in 17 Posts
Rep Power: 4
casey1999 is on a distinguished road
Quote:
Originally Posted by treilley View Post
And hopefully Maine Sail will have some pre-made FG blanks available soon.
You answered my question- that would be great. I have barely enough time to work on my boat, making back plates would eat up all my time.
Reply With Quote Share with Facebook
  #9  
Old 04-25-2011
mitiempo's Avatar
Senior Member
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,069
Thanks: 0
Thanked 68 Times in 59 Posts
Rep Power: 7
mitiempo will become famous soon enough mitiempo will become famous soon enough
McMaster Carr sells fiberglass panels in many sizes and grades - up to G10 which is epoxy. It is expensive but you don't need much for a few through hulls.

As I said earlier, builders may have offcuts.
__________________
Brian
Living aboard in Victoria Harbour
Reply With Quote Share with Facebook
  #10  
Old 04-25-2011
eherlihy's Avatar
Learning the HARD way...
 
Join Date: Jan 2007
Location: Boston Area
Posts: 3,458
Thanks: 107
Thanked 56 Times in 55 Posts
Rep Power: 8
eherlihy will become famous soon enough
Quote:
Originally Posted by bwindrope View Post
As for rigidity and structure, the plywood is equal in useful strength to the fiberglass, meaning, they are both absolutely solid and rigid for the purpose. And finally, as for longevity and strength, I have a boat that is 23 years old with untreated plywood in various places, including the old 1/4 inch puny backing blocks, and none of it showed any signs of significant decay.
I would disagree with this...

Here is a picture of the sink drain through hull that was on my '87 O'day 35:


I removed it because I noticed several small cracks in the bottom paint around the fitting. After I removed it I saw evidence that this through hull had been replaced at least twice (Black unknown sealant, which had been covered with White 5200). I presume that the reason for the earlier replacement was galvanic corrosion, and explained why the bonding wire (visible on the left) was not attached to this fitting. I also found that the genius that installed the latest through hull, put the NPS thread of the through hull into the NPT thread of the seacock...


The ˝" marine plywood backing plate, however, had been mushed down by the nut and allowing the through hull fitting to wobble slightly, thus causing the little cracks. While the plywood had not decayed, it did not support the compressive load that it was subjected to from the through hull fitting and the flange nut. It was definitely weaker than what I used to address the problem. Had I left this, I believe that I would have soon had a leak around the through hull, through the plywood. I believe that it would also have invited osmotic blistering around the through hull.

Because it was relatively new, I re-used the seacock, and the through hull, but added a flange adapter, which adapts from NPS to NPT.

I installed a new backing block made from 3/8" thick G10 (GP03) fiberglass cut into a 6" circle. You can buy a 36" x 6" sheet ready made for less than $25 here. You could make 6 of them from one sheet, and your cost/per would be $5... I could have purchased the same material in ˝" thickness for less than $50, but a friend gave me the 3/8" scrap that he had for free!

Because 3/8" is thinner than ˝", I had to cut some of the threads off of the through hull. Because through hulls use NPS thread, you can easily do this. Just remember to put the flange nut on before you cut. Use the flange nut as a guide while cutting, and to help clean the threads after the cut is complete.

I used black 4200 to seal around the flange fitting, and you can almost see that the bonding wire has been reattached.

Here is the result;
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Which shrouds/stays get replaced first? northoceanbeach Gear & Maintenance 15 03-30-2010 08:08 PM
Impeller replaced, but did I screw up? countrygent5201 Gear & Maintenance 17 02-24-2010 06:50 PM
Swing Keel Hardware Replaced CHOCKfullOnuts222 Gear & Maintenance 0 04-13-2009 11:36 AM
Replaced Keel Bolts? A Red Flag? gnsail Boat Review and Purchase Forum 14 01-06-2008 02:40 PM
Cutlass Bearing needs to be replaced on a boat Im looking at saurav16 Boat Review and Purchase Forum 3 04-14-2007 11:28 AM


All times are GMT -4. The time now is 07:25 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.