Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 28-08-2015, 12:44   #1
Registered User
 
zboss's Avatar

Join Date: Sep 2011
Location: On a boat
Boat: Cabo Rico 38
Posts: 3,427
Fiberglassing in hole in thick hull.

Hello,

I am moving two through hull's further up on our hull and when we take then out we will leave two holes. Our hull is about 1.75 inches thick layup at that location. They used both fiberglass chop and cloth.

Obviously, if I followed the directions from West Systems I would need to grind out a sloped area three feet across. That's insane!

I was thinking about epoxying in a plug the total thickness and then grinding down both sides so I only needed to grind an area about 6 to 8 inches in diameter.

Opinions?
__________________

__________________
zboss is offline   Reply With Quote
Old 28-08-2015, 13:38   #2
Moderator
 
Don C L's Avatar

Join Date: Sep 2014
Location: Channel Islands, CA
Boat: 1962 Columbia 29 MK 1 #37
Posts: 4,399
Images: 35
Re: Fiberglassing in hole in thick hull.

Having done this once years ago I can only offer what worked for me. But I think the question is how much does that hole compromise the strength of the hull at that point? The through-hull does to some extent create a weak point in the hull. If you strike something at the through-hull vs. somewhere else how much more likely are you to cause a breach in the hull? Ideally you repair the hull to the extent that the hole now is covered in a way that equals the strength of any other corresponding part of the hull, or better. Hence the directions from West System I am guessing. However that does seem to me to be overkill too. In my own case I roughed up an area on the inside about a foot and a half wide (I did not take off layers of glass.) I layered up cloth with each layer about a half inch wider than the previous until I had a patch of about 1/2 to 3/4 inch which was the about the thickness of the hull at that point (much thinner than yours, it was a Columbia 24!) On the outside I filled the hole with epoxy putty and put two layers over it and faired it in. It was as bit of a bulge on the inside, yes, and it did seem like overkill too. It probably was, but I didn't think about it again. I never struck the patch so I don't know how it would have fared, but it sure seemed strong to me, and through-hulls are usually in places that don't get struck. Recently I removed the head and didn't have time to fill the hole so I just capped the through-hulls. That was a lot easier but not exactly permanent. I hope we hear from some fiberglass experts from West and/or Cabo Rico!
__________________

__________________
DL
Pythagoras
1962 Columbia 29 MKI #37
Don C L is offline   Reply With Quote
Old 28-08-2015, 13:49   #3
Marine Service Provider
 
Scott Berg's Avatar

Join Date: Jul 2011
Location: Aboard
Boat: Seaton 60' Ketch
Posts: 959
Re: Fiberglassing in hole in thick hull.

12 - 1 bevel would be about 20" and that sounds rightDo you have the layup schedule from the builder? Much better to match it for flex and strength.


Sent from my iPad using Cruisers Sailing Forum
__________________
Scott Berg
WAĜLSS
SV CHARDONNAY
Scott Berg is offline   Reply With Quote
Old 28-08-2015, 13:54   #4
Resin Head
 
minaret's Avatar

Cruisers Forum Supporter

Join Date: Aug 2007
Location: Seattle WA
Boat: Nauticat
Posts: 7,201
Images: 52
Re: Fiberglassing in hole in thick hull.

Quote:
Originally Posted by zboss View Post
Hello,

I am moving two through hull's further up on our hull and when we take then out we will leave two holes. Our hull is about 1.75 inches thick layup at that location. They used both fiberglass chop and cloth.

Obviously, if I followed the directions from West Systems I would need to grind out a sloped area three feet across. That's insane!

I was thinking about epoxying in a plug the total thickness and then grinding down both sides so I only needed to grind an area about 6 to 8 inches in diameter.

Opinions?

Done it that way many many times. Buy a piece of G10 and laminate it together to make your plug. Then grind and glass exterior, grinding at least 1/8" material off and laminating with 2-3 1708. Then slap a fat patch on the interior too. Fair exterior, barrier coat, and paint to match.
__________________
O you who turn the wheel and look to windward,

Consider Phlebas, who was once handsome and tall as you.
minaret is offline   Reply With Quote
Old 28-08-2015, 14:22   #5
Senior Cruiser
 
Jim Cate's Avatar

Cruisers Forum Supporter

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 11,467
Re: Fiberglassing in hole in thick hull.

Perhaps I'm naive, but these holes have been in the boat since launching. They were "plugged" by the skin fitting, but not much strengthened. Now he has removed the skin fitting and needs to keep the water out. The hull is no weaker than it has ever been.

I find it hard to justify making a big deal out of this. Grinding a small bevel area on both sides, glass over the inside with a couple of layers, fill the hole with epoxy mish-mash and do a good job of glassing over the outside, then bog and fair. Waterproof and at least as strong as it has been all its life.

But I am not a pro...

Jim
Edit: Seems that Minaret and I were typing at the same time. And he IS a pro... I'd take his advice over mine any day!!
__________________
Jim and Ann s/v Insatiable II , lying Port Cygnet, Tasmania once again
Jim Cate is online now   Reply With Quote
Old 28-08-2015, 14:26   #6
Moderator
 
Don C L's Avatar

Join Date: Sep 2014
Location: Channel Islands, CA
Boat: 1962 Columbia 29 MK 1 #37
Posts: 4,399
Images: 35
Re: Fiberglassing in hole in thick hull.

Quote:
Originally Posted by Jim Cate View Post
Perhaps I'm naive, but these holes have been in the boat since launching. They were "plugged" by the skin fitting, but not much strengthened. Now he has removed the skin fitting and needs to keep the water out. The hull is no weaker than it has ever been.

I find it hard to justify making a big deal out of this. Grinding a small bevel area on both sides, glass over the inside with a couple of layers, fill the hole with epoxy mish-mash and do a good job of glassing over the outside, then bog and fair. Waterproof and at least as strong as it has been all its life.

But I am not a pro...

Jim
That's what I was thinking too, and then someone said, "if you hit that with a hammer as hard as any other place on the boat, will it leak?" So then, doubting my initial impulses, my patch started growing and growing...
__________________
DL
Pythagoras
1962 Columbia 29 MKI #37
Don C L is offline   Reply With Quote
Old 28-08-2015, 14:52   #7
Registered User
 
zboss's Avatar

Join Date: Sep 2011
Location: On a boat
Boat: Cabo Rico 38
Posts: 3,427
Re: Fiberglassing in hole in thick hull.

The old "holes" are on the stern quarter of the vessel where the stern slopes back onwards, so unless I'm backing into something or maybe broadsiding something, then I think the likelihood of them getting hit are slip. But your advise is well taken.

I think I'm also comfortable with both Mineret's and Jim's advice.
__________________
zboss is offline   Reply With Quote
Old 28-08-2015, 14:53   #8
Registered User
 
Impetuous too's Avatar

Join Date: Feb 2015
Location: Bristol, UK
Boat: Alajuela 38
Posts: 33
Images: 3
Re: Fiberglassing in hole in thick hull.

Don't regret going pretty overkill on ours, particularly the under water holes. We dished out both sides -in just over an inch of hull we went to about a foot across. A short cut we went with for a low risk spot was to glass a couple of ever increasing circles on the outside and fill in some of the inside with mish mash and epoxy. We probably put between twenty and thirty layers on each patch but in the grand scheme of things it was easy to do amongst other jobs so didn't take too long. Once we were pretty even we filled with thickened epoxy then awl-fair to get our shape back and long boards with guide coat.

Getting the cracks in the gellcoat out... Now that's another matter! It was a lot of work but we've no worries. All the best!
__________________
Ruth and Duncan,
Alajuela 38
www.impetuoustoo.blogspot.com
Impetuous too is offline   Reply With Quote
Old 28-08-2015, 15:15   #9
RDW
Registered User

Join Date: Dec 2009
Location: Lexington, Kentucky
Boat: Morris 1996 46' Lexington
Posts: 378
Re: Fiberglassing in hole in thick hull.

Take any suggestions. I give here with a large grain of salt
I did see a need video once. they did all the work from the inside. They placed a Pap plastic barrier over the outside with some sort of support. From the inside. They sprayed on a layer of jelcoat. They took some sort of routing tool and beveled out the center. A small amount. Then they applied there approximately N fiberglass from the inside. Upon removing the outside support. All they need to do was above the Jelcoat.

Again my only experience is watching the video. It did look like an excellent repair.
Best of luck.
rdw
__________________
RDW is offline   Reply With Quote
Old 28-08-2015, 16:17   #10
Registered User
 
zboss's Avatar

Join Date: Sep 2011
Location: On a boat
Boat: Cabo Rico 38
Posts: 3,427
Re: Fiberglassing in hole in thick hull.

I saw that gelcoat trick as well. They basically put plastic on the outside and taped over it then sprayed the gelcoat on and followed it the layup.
__________________
zboss is offline   Reply With Quote
Old 28-08-2015, 16:23   #11
Registered User

Join Date: Nov 2012
Location: French Polynesia
Boat: Allied 39
Posts: 470
Re: Fiberglassing in hole in thick hull.

Quote:
Originally Posted by Jim Cate View Post
Perhaps I'm naive, but these holes have been in the boat since launching. They were "plugged" by the skin fitting, but not much strengthened. Now he has removed the skin fitting and needs to keep the water out. The hull is no weaker than it has ever been.



I find it hard to justify making a big deal out of this. Grinding a small bevel area on both sides, glass over the inside with a couple of layers, fill the hole with epoxy mish-mash and do a good job of glassing over the outside, then bog and fair. Waterproof and at least as strong as it has been all its life.



But I am not a pro...



Jim

Edit: Seems that Minaret and I were typing at the same time. And he IS a pro... I'd take his advice over mine any day!!

Jim. Greetings

That is just what we did when we needed to patch a transducer hole. Ground it out to about 5 inches slapped in some epoxy and 6 layers biaxial cloth and then bogged over the area that wasn't totally filled in. Again our old hull is pretty thick.

Cheers

Chuck


Sent from my iPad using Cruisers Sailing Forum
__________________
www.jacarandajourney.com
chouliha is offline   Reply With Quote
Old 28-08-2015, 17:08   #12
Bailing as fast as I can.
 
GILow's Avatar

Join Date: Sep 2008
Location: Adelaide, South Australia
Boat: Swanson 42
Posts: 3,585
Fiberglassing in hole in thick hull.

I asked a pro from our yard to do this for us at our first slipping. Our hull is over 2 inches thick, nearer 2.5 for most of the holes that needed to be plugged.

He had a collection of premade fibreglass disks of the same size as the through hull holes. He packed these disks in to make up the bulk of the filling then did the bevel thing with the outer layers.

Have not sunk yet.

Edit. On rereading minarets post I wonder if what I thought were fibreglass disks were actually the g10 laminate minaret mentions. I will ask the yard guy when I see him next. Anyway, they were precut disks of some slightly off white material.

Sent from my iPad using Cruisers Sailing Forum
__________________
Very funny Scotty, now beam down my clothes.
http://www.swansonsailor.id.au
GILow is offline   Reply With Quote
Old 28-08-2015, 17:27   #13
Resin Head
 
minaret's Avatar

Cruisers Forum Supporter

Join Date: Aug 2007
Location: Seattle WA
Boat: Nauticat
Posts: 7,201
Images: 52
Re: Fiberglassing in hole in thick hull.

Quote:
Originally Posted by GILow View Post
I asked a pro from our yard to do this for us at our first slipping. Our hull is over 2 inches thick, nearer 2.5 for most of the holes that needed to be plugged.

He had a collection of premade fibreglass disks of the same size as the through hull holes. He packed these disks in to make up the bulk of the filling then did the bevel thing with the outer layers.

Have not sunk yet.

Edit. On rereading minarets post I wonder if what I thought were fibreglass disks were actually the g10 laminate minaret mentions. I will ask the yard guy when I see him next. Anyway, they were precut disks of some slightly off white material.

Sent from my iPad using Cruisers Sailing Forum

Nah, I do what your guy did. Just don't expect others to have fiberglass flat stock scraps of varying thickness lying around.
__________________
O you who turn the wheel and look to windward,

Consider Phlebas, who was once handsome and tall as you.
minaret is offline   Reply With Quote
Old 28-08-2015, 17:49   #14
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,371
Re: Fiberglassing in hole in thick hull.

Quote:
Originally Posted by Jim Cate View Post
Perhaps I'm naive, but these holes have been in the boat since launching. They were "plugged" by the skin fitting, but not much strengthened. Now he has removed the skin fitting and needs to keep the water out. The hull is no weaker than it has ever been.

I find it hard to justify making a big deal out of this. Grinding a small bevel area on both sides, glass over the inside with a couple of layers, fill the hole with epoxy mish-mash and do a good job of glassing over the outside, then bog and fair. Waterproof and at least as strong as it has been all its life.

But I am not a pro...

Jim
Edit: Seems that Minaret and I were typing at the same time. And he IS a pro... I'd take his advice over mine any day!!
I'm with Jim on this one. I'd plug the hole and grind both sides to put maybe 1/4" + of glass layup on each side and call it a day. Use the plugs you core out of the hole for the new location for the plug!
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 28-08-2015, 19:09   #15
RDW
Registered User

Join Date: Dec 2009
Location: Lexington, Kentucky
Boat: Morris 1996 46' Lexington
Posts: 378
Re: Fiberglassing in hole in thick hull.

Use the plugs you core out of the hole for the new location for the plug! __________________
Excellent thinking
rdw
__________________

__________________
RDW is offline   Reply With Quote
Reply

Tags
fiberglass, 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
The Fear of Fiberglassing sarafina The Sailor's Confessional 48 11-11-2012 11:38
How thick is your hull? stevensuf Construction, Maintenance & Refit 36 19-06-2012 13:18
Fiberglassing-in Ballast - What to Use ? KJson Construction, Maintenance & Refit 14 28-12-2010 16:30
Fiberglassing wood masts San Juan Sailor Construction, Maintenance & Refit 22 08-10-2008 21:29
Fiberglassing wooden boats.... never monday Construction, Maintenance & Refit 22 27-12-2005 07:18



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 15:16.


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.