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Old 07-24-2021, 07:35 PM   #1
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FG Over Wood Stability

Considering that the job is done by a knowledgeable professional, when wood boats are glassed over, how stabile are they in the long run? Does the glass remove the majority of the risk of rot from the outside in? And if replanking is always a possibility, how is it done without making the hull look like a patchwork quilt?
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Old 07-24-2021, 07:50 PM   #2
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are you upgrading to a wood boat?
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Old 07-24-2021, 07:59 PM   #3
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It makes the boat heavier if the fiberglass is thick enough to do any good. So a glassed over wood boat rides like a bigger, deeper boat. It also uses more fuel. It was popular with commercial fishing boats to extend their life and save a lot of maintenance. I did several boats in the 35-60' range in the 1970s.
Back then we still had wood preservatives that worked and they were applied to the normally wet areas of the bilge. If not preserved, leaks had to be stopped, otherwise the hull would rot. Better, bigger boats worth the money got their bilge areas glassed, too. Just not as thick as the outer hull. Properly done, a glassed over wood boat has the potential to last a long time.
It's also important to fiberglass the decks and cabin tops. I ran the cloth up the cabin and bulwarks a couple inches so the decks were like a bowl and kept water from coming thru the overhead. Windless, cleats, etc. were removed and when reinstalled, the bolt holes were sealed with fiberglass. Fish holds were foam insulated and fiberglassed. Everything I did was epoxy resin.
There use to be a product called C-Flex. It was cloth with a solid fiberglass rod every few inches. I used it where there was no planking or on new builds with just bulkheads and frames because it helps keep a smooth hull form.
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Old 07-24-2021, 08:32 PM   #4
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Quote:
Originally Posted by toocoys View Post
Considering that the job is done by a knowledgeable professional, when wood boats are glassed over, how stabile are they in the long run? Does the glass remove the majority of the risk of rot from the outside in? And if replanking is always a possibility, how is it done without making the hull look like a patchwork quilt?
Fiberglass is used to add structural strength not to prevent rot.
Permeability to water depends on the resin used, not fiberglass. As an example fiberglass with polyester resin is permeable to water, epoxy resin is not.

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Old 07-24-2021, 09:43 PM   #5
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Wood boats often get what is known as 'west system bottoms' to properly renew wetted hull. However, wood boats are typically repaired with wood by wooden boat shops to as new condition. No one I have ever spoken with during my antique and classic boating and repair years would ever encapsulate existing wood because unless the wood can be made absolutely dry and waterproof, rot will actually accelerate. Not a good idea unless it's new boat construction. You may want to contact wooden boat restoration shops to discuss this in detail as there are specific products and techniques available to provide penetrating sealer.
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Old 07-24-2021, 10:26 PM   #6
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You might want to read “Covering Wooden Boats with Fiberglass” by Allan Vaitses. It’s available at used book stores if you do a web search.
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Old 07-24-2021, 10:45 PM   #7
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Here is an article I found, link at the bottom:

Is it OK to put fiberglass over wood or not?
There are two dimensions to this question. The first is whether or not to glass over wood
in new construction. The second is whether or not to glass over wood on an old boat.
The first is a common practice in stitch and glue construction. The second is not as
common but is sometimes used to extend the life of some older boats that have structural
problems.
The normal procedure in stitch and glue construction is to glass over all the seams of the
boat with fiberglass and epoxy. Then the exterior of the boat is often sheathed in
fiberglass. There is nothing wrong with this. The normal technique in stitch and glue
construction is to coat all of the wood in epoxy, which effectively completely seals the
wood. This stabilizes the wood and under normal conditions prevents water penetrating
the wood. If the boat is given normal maintenance and given an occasional new coat of
epoxy the boat will last indefinitely and the wood will remain stable. The problem arises
when the wood is penetrated for whatever reason and water expands the wood, and rot
spores begin to grow. Then the wood never dries out because the moisture is trapped in
the wood. Eventually rot will spread throughout the boat and destroy the wood.
However, if the boat is properly constructed and maintained, this rarely occurs and
thousands of boats have been built using this technique. It is not just used for dinghies
and canoes either. Some large boats, up to the thirty foot range, have been built using
stitch and glue. It is a proven and effective method of boat building. (in fact I have built
a boat using this technique, and I was a skeptic.)
So, what about older boats that were originally built using traditional wood boat building
methods? There are thousands of existing boats built of wood that are nearing the end of
their life due to various reasons, or that have serious structural problems. Often in cases
like these the cost of rebuilding the boat using the same method as the original is very
expensive, sometimes prohibitive. So the question is, how can I save this old boat? One
technique is to simply fiberglass over the wood hull of the boat, essentially sealing out
the water and adding the structural strength of the fiberglass to the hull. But this has its
downside.
On an old boat the wood in the boat is wet. Because of the damp, rot has probably
infected the wood even though the boat looks sound and is seaworthy. Sealing the wood
then traps the moisture and the rot spores. The boat then rots from the inside and the rot
is generally not evident until you are left with a fiberglass shell and no structural
integrity.
Certainly you can dry out the boat to a great extent, but that causes the wood to shrink,
often leaving large gaps between the planking and seams. These can be filled with epoxy
NEW BOATBUILDERS
HOME PAGE
paste or wood powder and epoxy filler. The seams can then be glassed over with
fiberglass and resin. However, if you seal only one side of the wood, it will still absorb
moisture from the air. It will still expand and contract. If fiberglass is bonded to the
wood eventually the bond will weaken and the glass will disconnect from the hull.
Some people advocate a mechanical connection as well as the chemical bond. This is
usually achieved by stapling the fiberglass cloth to the wood after applying the resin.
When everything sets, the glass is not only chemically bonded to the wood but
mechanically bonded as well. Those who use this method claim it stabilizes the glass and
keeps it from delaminating from the wood.
So, should you or shouldn’t you? Some claim that if the boat is no longer structurally
sound and the cost of restoring it is prohibitive, then this is a good technique to get a few
more years out of the boat. Others believe this is a perfectly acceptable solution for any
wood boat regardless of condition. I have even seen fiberglass sheathing on new Navy
wooden minesweepers.
My own personal belief is that the only times that fiberglass sheathing is an acceptable
practice is for new boats that are completely coated with epoxy or some other resin that
seals the wood, and when there is no other way to save an old boat that is going to be far
to costly to restore. I believe that coating any other wooden boat with fiberglass is just
inviting disaster and will accelerate the aging of the boat.
There are other experienced, knowledgeable people who disagree. They believe that if
done properly, making sure to get a good mechanical and chemical bond between the
wood and the glass, the boat will last longer and rot will not occur.
Unfortunately, this is one of those subjects that does not have a definitive answer.
Experiences vary from builder to builder and boat to boat. There does not seem to be a
consensus opinion on this. What a person needs to do is weight the cost versus how much
longer the boat would last. In other words do a cost/benefit analysis. If you can get a few
more years out of an old boat then it may be worth it.
Glen-L on how to fiberglass wood. http://www.glen-l.com/methods/how-to-fg.html
eHow How to fiberglass wood. http://www.ehow.com/how_4473981_fibe...-overwood.html
Boat Building. Stitch and Glue http://www.common-sense-boats.com/boat_building.htm
Devlin on Stitch and Glue construction. http://www.devlinboat.com/stitchandglue.htm
Wikipedia Stitch and Glue construction. http://en.wikipedia.org/wiki/Stitch_and_glue

https://newboatbuilders.com/docs/fiberglassoverwood.pdf
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Old 07-25-2021, 01:28 AM   #8
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It makes the boat heavier if the fiberglass is thick enough to do any good. So a glassed over wood boat rides like a bigger, deeper boat. It also uses more fuel. It was popular with commercial fishing boats to extend their life and save a lot of maintenance. I did several boats in the 35-60' range in the 1970s.
Back then we still had wood preservatives that worked and they were applied to the normally wet areas of the bilge. If not preserved, leaks had to be stopped, otherwise the hull would rot. Better, bigger boats worth the money got their bilge areas glassed, too. Just not as thick as the outer hull. Properly done, a glassed over wood boat has the potential to last a long time.
It's also important to fiberglass the decks and cabin tops. I ran the cloth up the cabin and bulwarks a couple inches so the decks were like a bowl and kept water from coming thru the overhead. Windless, cleats, etc. were removed and when reinstalled, the bolt holes were sealed with fiberglass. Fish holds were foam insulated and fiberglassed. Everything I did was epoxy resin.
There use to be a product called C-Flex. It was cloth with a solid fiberglass rod every few inches. I used it where there was no planking or on new builds with just bulkheads and frames because it helps keep a smooth hull form.
As of a couple of years ago C-flex was still being made by Seaman Fiberglass. They had written material telling how it could be used to glass over old wood boats. A lot of work and tough to get a good pleasure boat finish. Not too hard to get a work boat finish. I have built 3 all glass boats from 21 to 36 foot using C-Flex.
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Old 07-25-2021, 05:54 AM   #9
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are you upgrading to a wood boat?

I can't deny that I wouldn't enjoy a wood boat, and often wondered about this type of technique. What prompted this post was this boat. It's under a covered slip two docks from our boat. When they originally brought it in they had crews working on it for a while getting it cleaned up and stuff. I've looked at the listing for months and months and months and the price has gone down and down and down. I always dismissed it as a "never gonna happen because I can't maintain a wooden boat" type of thing, but yesterday I actually read the description and noticed it was 'fiberglass over wood'. I don't think FG was around in 1960 so this is clearly a job that was done later in the boats life.

I was just kind of curious as to the characteristics to see if it was even possible to be interested in it. Ever since I had the '67 Chris Craft I've been a sucker for an old boat. They just have much more character than modern boats.
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Old 07-25-2021, 07:50 AM   #10
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…When they originally brought it in they had crews working on it for a while getting it cleaned up and stuff. I've looked at the listing for months and months and months and the price has gone down and down and down...
Nice looking boat for sure. Maybe the price reductions are a function of the construction and age which affects the insurability? Given she’s 61 years old and with the insurance market as it is.
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Old 07-25-2021, 07:57 AM   #11
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Nice looking boat for sure. Maybe the price reductions are a function of the construction and age which affects the insurability? Given she’s 61 years old and with the insurance market as it is.

That would be my guess because it's definitely not in any state of disrepair. It's been for sale for at least a year if not longer. I can't remember exactly when it was brought in.
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Old 07-25-2021, 08:30 AM   #12
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That’s a beautiful boat that has had a mountain of money poured in to it. It’s a steal at 45k. No interest.
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Old 07-26-2021, 01:06 PM   #13
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Originally Posted by Lepke View Post
It makes the boat heavier if the fiberglass is thick enough to do any good. So a glassed over wood boat rides like a bigger, deeper boat. It also uses more fuel. It was popular with commercial fishing boats to extend their life and save a lot of maintenance. I did several boats in the 35-60' range in the 1970s.
Back then we still had wood preservatives that worked and they were applied to the normally wet areas of the bilge. If not preserved, leaks had to be stopped, otherwise the hull would rot. Better, bigger boats worth the money got their bilge areas glassed, too. Just not as thick as the outer hull. Properly done, a glassed over wood boat has the potential to last a long time.
It's also important to fiberglass the decks and cabin tops. I ran the cloth up the cabin and bulwarks a couple inches so the decks were like a bowl and kept water from coming thru the overhead. Windless, cleats, etc. were removed and when reinstalled, the bolt holes were sealed with fiberglass. Fish holds were foam insulated and fiberglassed. Everything I did was epoxy resin.
There use to be a product called C-Flex. It was cloth with a solid fiberglass rod every few inches. I used it where there was no planking or on new builds with just bulkheads and frames because it helps keep a smooth hull form.


What you need to do is avoid fresh water in the bilges in contact with the wood hull. In my old, wooden boat I have never seen wood in contact with salt-water rot but I have seen plenty of wood damaged by rain water.

Glassing the bilges and stopping all fresh water leaks should do the trick. I would even consider adding rock salt to the bilges to keep them salty.
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Old 07-26-2021, 03:58 PM   #14
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Glassing the bilges and stopping all fresh water leaks should do the trick.
easier said than done. I don't think that its possible to do on an older wood boat.
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Old 07-27-2021, 07:52 AM   #15
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Glassing a traditional, plank on frame, wooden hull should be a last ditch effort to get a few more years out of a boat. It's a poor long term solution for many reasons (traps in fresh water, promotes rot, adds weight, and prevents the flexing a wood boat needs for strength).

I've only seen it done on workboats to get a couple more years use out of a hull.
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Old 07-27-2021, 08:01 AM   #16
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Glassing a traditional, plank on frame, wooden hull should be a last ditch effort to get a few more years out of a boat. It's a poor long term solution for many reasons (traps in fresh water, promotes rot, adds weight, and prevents the flexing a wood boat needs for strength).

I've only seen it done on workboats to get a couple more years use out of a hull.
I agree, but as usual I am sure there are exceptions.

Many hulls are very poor candidates as sometimes the most critical/structural areas are the most deteriorated.

If you get into rebuilding/reinforcing those, the project becomes large enough to just renew like original.......maybe.
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Old 07-27-2021, 09:02 AM   #17
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What you need to do is avoid fresh water in the bilges in contact with the wood hull. In my old, wooden boat I have never seen wood in contact with salt-water rot but I have seen plenty of wood damaged by rain water.

Glassing the bilges and stopping all fresh water leaks should do the trick. I would even consider adding rock salt to the bilges to keep them salty.
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easier said than done. I don't think that its possible to do on an older wood boat.
A few years ago, we were in a boat yard in Ireland and the yard owners owned a wooden trawler that they had converted to personal use. The boat was built in 1943 at a boat builder that is still in business after 100+ years. The owners had done some work on the boat but I don't know how much, and she was pretty outside and in the pilot house...

The problem was the deck leaked badly. Down below was a mold fest. They had fiberglassed the deck but it had delaminated. I don't know if the deck wood was original, one would not think so on a fishing boat over 70 years old, but that fiberglass was pulling up from the deck. The leaks were mainly down the hull sides from what we could tell with our limited time on the boat. It was raining, the boat was loaded with mold, and we did not want to stay down below too long.

I think of that boat frequently and wonder what has happened to her.

Later,
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Old 07-27-2021, 11:18 AM   #18
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There was a video in OffCenterHarbor.com (sorry, it is a pay-site, but excellent). Where an old wooden lobster boat is glassed: hull and decks.

The reason they did this was because it was iron-fastened and could not be properly repaired. Glassing was the only way to preserve it.

FWIW, the boat was acquired and repaired by Erik Blake, a highly experienced marine carpenter and founder of the site who said he plans to use it "the rest of his life".

https://www.offcenterharbor.com/vide...life-charlena/

Keeping fresh water out is absolutely necessary.
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Old 07-30-2021, 04:30 PM   #19
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Almost impossible to keep fresh and salt water segregated

Keeping the fresh water separated from the salt would be impossible in practical boating. Ocean waves while it is raining for example.
I spent 30 years in Alaska repairing wood commercial fishing boats, many of which are still in use today. The one that I am certain about is a 60's Seattle Marine 32' Salmon boat built with 1-1/8" yellow cedar. It was my own. I can't honestly explain why I decided to glass her over, but pounding cotton between the planks every season is as good as any. The boats are out of the water for 8 months a year and they shrink. It was common to see 1/8" openings between the planks in spring. The norm was to run a hose into the hull and flood it. The planks would expand and seal (mostly) and you re- packed the rest. Not being an experienced fiberglasser, I covered the hull with a quality epoxy and cloth. With the complicated structure and equipment installed. I had no way to even begin to cover the inside, In one season, the planks split the surprisingly strong epoxy/cloth layer along many of the "cotton" lines. I decided to saw out all of the lines and go back to stuffing cotton. The boat looked bright and shiny, but that was short lived. Eventually, the fiberglass layer started delaminating, probably due to the seasonal expansion/contraction of the wood. So, my recommendation is Don't mess with the planks on a wood boat. Pay what it costs to have bad planks replaced and you will be good for a long time. Paint over wood is cheaper and lasts as long as anything else. Epoxy is for plastic boats, combining them is begging for problems as numerous builders learned in the transition. Leaks in a plastic boat are ever so easy to fix. Just try to find and fix a leak that got into the 10% of a boat that was built with wood stringers, etc during the seventies and eighties. Even worse, try to fix a Balsa cored boat that leaked. It's a nightmare.
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Old 07-30-2021, 05:04 PM   #20
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Boatbuilding company over here has done a few timber trawlers now
All quad and triax glass using epoxy resins
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