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Old 11-04-2019, 01:39 PM   #1
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Fiberglassing an older hull

This question for me is purely hypothetical though others might benefit from the discussion. My boat is 50 years old and has a fiberglass over wood hull original build. The hull is in amazing shape. Everything was gutted below deck, all tanks, engine, everything taken out, the inside of the hull was washed, every area inspected for wood damage, and then the bottom third repainted with an epoxy paint to preserve the wood later on down the line from water damage. A few small soft spots around through the hulls were repaired.

While this refit was underway I came across a 1972 Grand Bank that was in amazing shape and I almost purchased it. I do know that all wood boats are a labour of love scenario. The work is endless. But the hull on initial inspection, not a survey, looked in decent shape, based on an interior inspection. Now for the sake of the argument, lets assume the hull is in amazing shape.

Rather than deal with the work involved in the long term with an all wooden hull, why can't the exterior of the hull be finished professionally.

The one disadvantage to a refinished hull would be added weight. But given the amount of work concerning wooden hulls and based on my experience with my 50 year old hull, wouldn't the owner be better off glassing the hull? Since almost no one does this, there must be something I am missing.

So what's the scoop, I guess a wooden scoop covered with fiberglass.

I have linked this before, but thought I'd throw it in as to why I have thought about fiberglassing the hull as the boat owner in the video does continual repairs on his hull:

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Old 11-04-2019, 01:57 PM   #2
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Years ago, when there were many more wood boats, several yards around the country did fiberglass over wood hulls. Especially commercial fishing boats. But it's expensive. A proper job is not just one layer of cloth, but a fiberglass thickness of near what a regular fiberglass hull would be.

If water gets in, the wood rots, just like cored boats. Cracks in the fiberglass means water can get in. Changing rotted planks means removing the fiberglass. Back when we had wood preservers that actually worked, pre-EPA, it was better to treat the wood. My current wood boat was treated with a now illegal treatment in the 1960s and still shows no sign of rot in the hull. But the wood is considered hazardous waste.

Another point on planking, planks are an important part of hull strength. When we had big trees and good lumber, a plank ran from the stem to the stern without splices.
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Old 11-04-2019, 02:11 PM   #3
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The fiberglass on my boat is thin, less than a quarter inch thick, yet the hull has held up. In fact I was surprised at how thin the glass was. I am guessing the original builder was also concerned about weight and cost.
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Old 11-04-2019, 06:00 PM   #4
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It's certainly more common on work boats. Lots of Chesapeake bay oyster / crab boats are glassed over wood. The really slick trick is 2 layers of bi-axial cloth with West system or other epoxy. The boatyard where I get my work done, has done this numerous times. They start by sand blasting the bottom clean. This not only removes the paint, but roughs up the surface for better adhesion. Obviously they check all the wood and survey fasteners. As the wood will be covered, and new fasteners are stainless steel screws. When they are ready to cover the hull, they wet it out first with West system and then apply the first layer. After it has gotten tack free but not cured, they to the second layer. The idea is to have the wet out, first layer, and second layer cure together as one. I'm told the epoxy sticks much better to the wood and makes the hull much stronger than fiberglass. The strength and rigidity is amazing after only these 2 layers.

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Old 11-04-2019, 07:01 PM   #5
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Alan Vaitses did lots of FG covering of both yachts and commerical fishing boats at his yard in Mattapoisett, Ma in the 60's and 70's. He wrote the boat on it,literally. He used matt and polyester resin but would staple the first layer while it was still "green". Often these boats floated higher on their lines due to the layers of glass. I can't remember the number of layers he used but it seemed to work well.
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Old 11-04-2019, 07:15 PM   #6
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Generally the kiss of death on a timber boat , especially something like ours as glues and resins do not take well to the timbers used.
Its usually done in a last ditch effort to squeeze some more years from her.
Inside skin is not glassed, planks move, glass does not and delaminates, water gets behind it and the end is nigh.

Different story if its an actual strip planked boat that was designed to be glassed inside and out making a sandwich.
Timber used here is generally western red cedar, balsa or Kiri, epoxy resins used and waffer thin glass,built light.
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Old 11-04-2019, 07:16 PM   #7
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Not sure if this stuff is still available but I always thought it was an interesting product-

http://seemanncomposites.com/cflex.htm

The down side as I understood it was the fairing once glassed...

"C-flex is an excellent solution for preserving the life and character of vintage wooden boats, because it can be attached on a wooden hull to create a stronger and more durable hull structure. The C-Flex is applied to the prepared hull with an Elastomeric Adhesive, which creates a strong but flexible interface between the wood and the exterior fiberglass. The hull is then laminated with additional layers of reinforcements to the desired strength level."
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Old 11-04-2019, 07:24 PM   #8
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My Rose was built in the 50ís out of cypress, it was c-flexed in the 70ís. Sheís still stong as the day those trees grew today. No rot, no soft spots. As anything if done right itís bullet proof
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Old 11-04-2019, 07:33 PM   #9
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Quote:
Originally Posted by Simi 60 View Post
Generally the kiss of death on a timber boat , especially something like ours as glues and resins do not take well to the timbers used.
Its usually done in a last ditch effort to squeeze some more years from her.
Inside skin is not glassed, planks move, glass does not and delaminates, water gets behind it and the end is nigh.

Different story if its an actual strip planked boat that was designed to be glassed inside and out making a sandwich.
Timber used here is generally western red cedar, balsa or Kiri, epoxy resins used and waffer thin glass,built light.
This. Last resort to keep it afloat a few more years.
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Old 11-05-2019, 09:03 PM   #10
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You can get the book by Alan Vaitses at Amazon. Some wooden boats with really nice interiors had low hours on the engine and been designed too poorly or worked too hard. Vaitsesí method solved that problem. If I remember correctly, it was three layers of Fiberglas, then staples 4Ē on center. Then another 3 layers of mat or cloth, canít remember which. If you are serious get the book.
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Old 11-05-2019, 09:09 PM   #11
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And just want to add why you donít see it anymore. In the 1980ís and late 1970ís there were a lot of nice old bots in yards that would sink if you put them in the water, but they had fine lines and you could get them cheap. Now you go to any yard and there are no old wooden boats, but lots of Fiberglas hulls that wonít sink and are cheap.
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Old 11-05-2019, 09:57 PM   #12
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Glassing or should I say re-glassing a glass over wood boat should be non-problematic. If the glass is firmly attached adhesion re the new glass should adhere well.

But considering the weight and strength of both materials would be recommended.
However the resin contracts as it cures and that may give problems.

There must be something wrong w the old fiberglassing or adding more wouldn’t be on the table. So considering removing the original sheathing should be considered.

Lastly you’re adding a lot of weight to an existing boat and if that boat was already heavy creating a cumbersome overweight boat could happen. Most likely the boat was plenty heavy as a wood boat and became heavier when the first sheathing was applied. It would be a good bet that the original sheathing was put on heavy. So the possibility that an overweight boat will result is high.

Just my rambling thoughts.
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Old 11-06-2019, 01:24 AM   #13
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I have often wondered how well a couple layers of 1/4 plywood applied cold mold style would do?
Using C-flex over a wood hull might give a work boat a number of years longer life but it would be a bunch of work. If you want a yacht type finish it would take a huge amount of work. I have built 3 hulls with C-flex, up to 32 foot, so have some idea of the time needed for fairing and finish work.
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Old 11-06-2019, 01:31 AM   #14
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We did one like that in the local yard here years ago. It was an old planked, long and skinny boat about 60'. Had a bunch of rotten planks which I replaced with house lumber! Then a couple of yard dweebs smeared black tar all over it and pounded on a layer of 1/4 plywood onto it. I refused to take part in that end of it. What a mess! But that's all the owner wanted so that's what he got. IIRC they didn't even glass over it.
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Old 11-06-2019, 07:23 AM   #15
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I owned a wooden boat that was C-flexed over 20 years ago and back then the cost was something like $22k. It showed like a fiberglass boat ,which it essentially was. Contrary to the belief of some, the process doesn't buy a few more years of use, it's basically a new boat. If I remember correctly, it was about 3/8" thick (the glass) & when an old-timer waterman stopped by the house to look at it, I remember him telling me that I could tear out the wood inside and still have the same boat. It was super rigid and the hull never showed any signs of delamination. The only places there was bad wood was where rainwater was allowed to sit, which was in the open part of the boat. I simply dug the bad area out, filled it with fiberglass mud & repainted the patch. The integrity of the boat wasn't compromised at all.
It has since gone back to work like she was intended to be, a commercial working boat plying the local waters. Rot on the non-glassed wood on the inside isn't as much of an issue now since everything is doused with salt water daily.
Attached are pictures showing the outside of the hull and the un-glassed inside 10-12 years after she was C-flexed. The boat will easily go for another 25 years.
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Old 11-06-2019, 08:01 AM   #16
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Quote:
Originally Posted by Simi 60 View Post
Generally the kiss of death on a timber boat , especially something like ours as glues and resins do not take well to the timbers used.
Its usually done in a last ditch effort to squeeze some more years from her.
Inside skin is not glassed, planks move, glass does not and delaminates, water gets behind it and the end is nigh.

Different story if its an actual strip planked boat that was designed to be glassed inside and out making a sandwich.
Timber used here is generally western red cedar, balsa or Kiri, epoxy resins used and waffer thin glass,built light.
Absolutely correct- it creates a bath tub. Fiberglass over wood not original to the vessel makes the vessel uninsurable- I canít think of a market that will offer coverage on such a risk. I know there are boats that have insurance that are glass over wood (post new construction), but many have been represented as glass boats vice their true construction methodology. If there is a claim, and this is discovered, coverage may be rescinded back to policy inception.
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Old 11-06-2019, 08:33 AM   #17
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As others have said glassing over a wood hull not designed to be glassed over is normally just to get a few more years from the hull. Any deck leaks will result in the wooden part of the hull rotting out from the inside. Furthermore, to properly glass a wooden hull you first have to repair all the wood to get rid of any rot. If done right, that step leaves you with a wooden hull in good shape that would likely last longer than the glassed over hull.


Now, as far as the video in the first post. I happen to have some knowledge about that particular person and his boat. His boat has needed quite a few topsides plank repairs because it had deck leaks in the past that caused the topside planks to rot from the inside. As such that boat is likely not representative of other wood boats in terms of the need for planking repairs. That said, that guy is very conscientious and fixes everything as soon as it is noticable. He is also very experienced in all aspects of both wooden and fiberglass boat construction. Of course I am saying that because the guy in the video is me.
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Old 11-06-2019, 10:26 AM   #18
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Say what you want (which isn't always correct), there are lots of Chesapeake bay work boats that are fiberglassed over wood going on 20 years. Course these aren't your delicate Maine built recreational boats from 50+ years ago. The Chesapeake bay work boats such as those pictured in Boomerang's post (very nice Chesapeake bay round stern!) usually have 2 to 3" bottom planks and are built to carry thousands of pounds of oysters. Totally different from the delicate wood boats of a bygone era. The other big difference is that these boats are used 200+ days per year, often in conditions most of us wouldn't go out in.

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Old 11-06-2019, 10:32 AM   #19
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Boom,
Love you’r old boat and picture #2
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Old 11-06-2019, 10:57 AM   #20
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A couple thoughts

1. As long as you are glassing over clean dry wood it should be ok. Anything you glass over is now in it for the long or short haul. Water, bacteria, etc are now untreatable and will not dry out. Start clean and dry.

2. DO NOT use stainless screws, most importantly below the waterline. Silicon bronze is the recommended screw below the waterline. The explanation is longer than I care to type.

The engineering in the world of composites is currently off the charts, spurred mostly by the transportation and renewable energy sectors. Epoxies and glass, kevlar, carbon, and more is better than it has ever been. More expensive too. A simple glass with a simple resin will seal the boat as long as flexing cracks do not open up the sealing surfaces. How stiff is that boat or how flexible is the lay up? How inflexible is the lay up?

Is the amount of time and money much less than just keeping up with the bad wood from time to time?
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