Wondering about accuracy of descriptions. i.e.Fiberglass or Canvas?

Nutkin

Canoodler
I've been perusing craigslist and note a number of "old" "Vintage" "antique" wooden canoes. Many of them indicate fiberglass as the exterior. I'm wondering if the seller is just assuming it's fiberglass or if old wooden/canvas canoes are routinely glassed and painted.

I noted in one of Ferdy's photos he was removing glass from a wood canoe, so I suppose it happens, but is it common?

Besides being heretical, is there a reason not to use glass instead of canvas on a restoration? (Don't worry, I'm not considering it, I just want to be informed)
 
Hi Nutkin--

There has been much discussion regarding fiberglass and ribbed canoes in the past... if you want some detail, you can use the "search" function above, but the long-story-short is that fiberglass tends to destroy a canoe that was originally canvassed, unless you can make the interior plastic as well... and if you do that, you may not be able to restore the canoe in the future.

Canvas permits the wood to breathe. Fiberglass holds moisture inside the canoe, against the wood, and the wood will be inclined to rot. It's possible to keep a glassed boat functioning well, but more care must be taken to dry the interior and store sufficiently. Delamination of the fiberglass is also a problem--- but if it pops off, so much the easier to restore with canvas.

There are way-too-many glassed canoes out there... seemed like a good idea in the '50s to replace canvas with fiberglass... but this is how we learned that glass isn't the way to go. So, those canoes in the ads may very well be glassed... or the seller may be thinking the canvas is glass because filler has done its job and covered the weave in the canvas. If buying a canoe from a distance, it's good to get pictures that help determine the presence of fiberglass.

There's a lot of discussion of fiberglass removal, too. Sometimes you get a good boat for a reasonable price, if you don't mind the work. And you'll be saving a canoe.

Kathy
 
I'm generally in favor of replacing canvas with canvas and removing most owner-applied fiberglassing jobs and replacing them with canvas, but some of the above info is a bit sketchy.

The problems and deterioration that have been assigned to fiberglassed rib and plank canoes aren't as much problems with the glass itself as they are with the application. Fiberglassing one of these hulls is a tricky job (much more so than glassing the outside of a strip canoe) and very few of them are done properly or even with the proper materials, often resulting in eventual problems that can be quite serious. If you're buying a fiberglassed canoe and it was glassed by the owner, there seems to be about a 95% chance that it wasn't done very well and should come off and be replaced with canvas.

You most certainly don't need to make the interior "plastic as well" for one of these fiberglassed boats to have a long and useful life. That's just not true. You do need to avoid situations where it sits for extended periods with water inside of it (which is also a pretty darned good idea with a canvas-covered hull as well, as water-soaking lifts varnish and damages the wood). You also want to avoid rocky situations where you might crack planks or break ribs, as replacing them is a lot tougher when you can't pop off the cover to fix them.

I'd really like to see people back off on the whole "wood breathability" thing, because most of it is bunk. It's a double-edged sword at best. The unsealed back sides of the ribs and planks on a wood/canvas canoe are constantly soaking up water and then drying out. On a fence post, we would call this "weathering" and its long term effect is to severely dry out the wood, making it measurably lighter, substantially more brittle and actually shrinking it dimensionally. We've all seen plenty of this on old wooden canoe bodies where big gaps have formed between the planks. Folks think that they can take one of these dried-out hulls, dunk it in a swimming pool for a week or so and everything will get rehydrated and be hunky-dory. In reality, it's just not going to happen and what effect it does have will be short-lived.

A proper epoxy/fiberglass job will actually seal the back sides of the wood better than any other material you can put on it, followed by tar. As long as you maintain the varnished interior well, so that it's not a constant water entry point, the canoe will be less likely to pick up weathering moisture and/or lose the natural moisture and resilience that it comes with over time because you've stopped the soaking/drying/soaking /drying cycles that aren't very good for any piece of wood, especially one with a fancy varnish job on the other side. Rot needs three ingredients to happen: Food (that's the wood fiber and we obviously can't get rid of it) reasonably warm temperatures (provided by mother nature) and moisture. The only one of these that we have much chance of eliminating (or at least controlling) is moisture.

Wood/canvas canoes rely heavily on the natural moisture and rot resistance of the cedar parts to survive this and do it pretty well. Some folks even soak the cedar outside with linseed oil to enhance these properties, though certain studies from the Forest Products Lab have indicated that it just adds more food to the mix. On the other hand, a fiberglassed canoe where bad materials, lack of care or poor workmanshp are trapping moisture pockets against the wood due to delamination, breaks in the skin, etc. can be a veritable rot factory. Thus, it's absolutely critical that the fiberglassing job use premium boatbuilding resins and materials and be well above the typical backyard builder skill level if it's going to last. As far as I can tell though, there aren't any rot-proof wooden canoes out there of any construction and it's much more a matter of how you take care of it than what's covering it. Be advised though, that most non-factory fiberglassing jobs should be removed and it's not a fun job. Even some factory glassing may have some problems and when it comes down to fixing it up and getting back in good shape, canvas is nearly always going to be your best bet.

This is my 38 year-old 16' Old Town guide. The exterior skin is one and a half layers of six-ounce fiberglass and WEST epoxy resin. If anyone can tell me when I can expect it to self-destruct, I'm all ears. At the moment though, it seems to be aging more gracefully than I am. :D
 

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Thanks for your thoughtful, thorough reply, Todd. It's the answer I'll be referring folks to, whenever this question comes up.
 
Besides being heretical, is there a reason not to use glass instead of canvas on a restoration? (Don't worry, I'm not considering it, I just want to be informed)

The single biggest disadvantage of glass vs. canvas is weight.
Even a good (oxymoron)fiber-glassing will add a significant amount of weight.
That said, the canoe becomes pretty bomb-proof.
You can pretend you are in a Ram-X and charge through shallow rapids without any concerns.
The need for boat skills is greatly diminished by the rock hard finish.

Having paddled and owned glassed canoes I can also say that they paddle more nicely than glass, Kevlar or Royalex canoes.
They are quiet in the water and still have the lines of the original canoe, the aesthetic from inside the canoe is still that of a wooden canoe......

However, they do not have the same "feel" under the paddle. The extra weight sucks some of the life out of the boat. And on the chance that they are damaged, they are much harder to repair.
I think you hit the nail on the head when you described glass as heretical.

BTW, I agree with Todd about the whole rot issue. I have seen far more rotten canvassed canoes than damage done by rot due to a glass job. I think that is an unsubstantiated myth perpetuated by those of us that loath glass over wooden canoes...myself included.:D
 
But weight is again one of those application issues. If done properly, the canoe will weigh about the same or a little bit less with the composite covering. Back when Old Town built both canvas and composite skins, the composite skinned canoe was usually a couple pounds lighter on the exact same wooden hull. Mine came in similarly. Most of the home-application jobs are overweight, and mostly because the folks doing them just haven't had much, or any, experience with fiberglass. Combine that with the fact that overweight fiberglass tends to be brittle and have a poor strength-to-weight ratio and you have more problems waiting to happen. The gold mine is to find one that's REALLY overweight, because it usually means that they actually glassed over the old canvas. It greatly simplifies the removal process.:)

As for durability, I'm not convinced that a fiberglass skin is that much tougher. My background is composites (initially for sculpture, then whitewater kayaks and wood/composite canoes and boats). I always assumed that they were drastically tougher for rock encounters. Then one day I picked up a piece of discarded, filled canoe canvas and pulled it really hard over the tip of a great big gutter nail, just to see how easily it would cut/tear or whatever. Compared to the relatively thin fiberglass skin that wooden composite canoes get, I don't believe the canvas was really any less durable. I was impressed! You could certainly build up a very thick, super-tough fiberglass skin if you really wanted to, but then you're going to start paying the weight penalty. If you want similar weight, you're going to end up with fairly similar durability.

Resin is harder than canvas filler and will generally abrade less from rock encounters. Fiberglass cloth will usually have higher tensile (tear) strength than cotton canvas. On the other hand, fiberglass has very little give. When over-stressed, it will either abrade away or fracture and break/tear. Cotton canvas has a much higher ability to give and stretch a bit without breaking or tearing. Neither material will increase impact strength because the outside skin is put in compression during an impact and doesn't do much of anything to reinforce the structure. So there are all sorts of different types of strength and various materials will exhibit differing amounts of them in different situations. Real world durability is a matter of how those differing strengths match up to the typical stresses that you put on the boat as you use it. There really isn't a clear structural winner or loser when you start looking at the durability, combined with the ability to survive the wet/dry cycles and other considerations discussed earlier. Each has some advantages and some disadvantages.

In my opinion, the thing that tends to put canvas on top is that it can be replaced as often as needed without really disturbing the wooden hull and without having to become a fiberglassing wizard to guarantee a good result. It also rides better.....There really is something about the feel and sound of the water against a canvas skin that is different and seems to fit the environment and the experience just a little bit better. I'm not exactly sure what it is, but it's there.
 
Back when Old Town built both canvas and composite skins, the composite skinned canoe was usually a couple pounds lighter on the exact same wooden hull.

The Old Town Canoe Company catalogs from 1967 to 1974 listed a 15 foot canoe covered with a light canvas known as the Lightweight model that weighed 58 pounds. The identical canoe with "polypropylene fiber reinforced plastic" (a.k.a. fiberglass) covering was known as the Trapper model and weighed 55 pounds. The same one with a Dacron covering was known as the Featherweight model and weighed 46 pounds.

Benson
 
What weight canvas did they use?

The standard canvas specifications were number eight for regular canoes and number ten for the fifty pound / lightweight models. This is shown at http://www.wcha.org/catalogs/old-town/specific.gif but this paragraph became less specific in the 1954 and later catalogs. My guess is that they continued with number ten in the 1960s. I am not a betting man but Fitz's comment about being under 60 pounds seems about right.

Benson
 
The Old Town Canoe Company catalogs from 1967 to 1974 listed a 15 foot canoe covered with a light canvas known as the Lightweight model that weighed 58 pounds. The identical canoe with "polypropylene fiber reinforced plastic" (a.k.a. fiberglass) covering was known as the Trapper model and weighed 55 pounds. The same one with a Dacron covering was known as the Featherweight model and weighed 46 pounds.

Benson

Benson,
I am under the impression that the glass covered canoes were not identical to the equivalent wood and canvas models. I recall that the ribs and the planking were not as thick as the standard models.
Am I mistaken about this?:confused:
The French have an expression---compare a cow to a cow....;)
 
Yes, you are mistaken. The thinner ribs and planks were used on models like the Lightweight series (Lightweight - canvas, Trapper - composite, Featherweight - Dacron) to save weight and had nothing to do with the covering material. The reason for this is that other than slightly increased abrasion resistance, a fiberglass outside covering adds no more strength to the canoe than any other covering. It can't, because the typical stresses that the canoe gets (rocks pushing inward from the outside, bottom bouncing in big waves, etc.) tend to put the outer skin in compression. Higher tensile strength only makes a significant strength contribution when it's put in tension, not compression (pulled apart, rather than being pushed together). The outer skin on any rib and plank canoe is basically just an abrasion and water barrier.

The only strength contribution that a fiberglass outer skin would add to one of these canoes would be a situation where you get into the boat and jump up and down (which most folks tend to avoid doing for a number of reasons). As you come down on the boat, the force, pushing from the inside toward the outside, would tend to put the outer skin in tension - where its lack of stretch and high tensile strength could start to make a serious contribution to the hull's ability to resist and survive the stress. So.....if you plan on jumping from a cliff into your canoe on a regular basis, by all means cover it with fiberglass (Kevlar would be even better for those really high cliffs) :D
 
Am I mistaken about this?

Yes, my understanding is that the Lightweight, Trapper, and Featherweight models all used identical wood as Todd mentioned. The only difference was that the Trappers which were to be covered with clear fiberglass had square headed tacks instead of round ones because they looked better. This probably didn't make a significant difference in the weight or durability. All of the other standard wooden models (Otca, Molitor, Guide, etc.) typically had thicker ribs and planking. It was a source of great annoyance to some employees that the saw kerf was larger than the Lightweight's planking. More than half of the wood was lost in cutting it. The page from the 1971 catalog attached below specifies '5/16" by 2 1/4" white cedar ribs (1/4" inch thick on Lightweight)' and '5/32" (1/8" on Lightweight) red cedar planking' if you want more details. This page also has a description of the layers in their fiberglass canoes including a balsa wood core with the thickest "woven roving" layer on the inside of the canoe where it can provide the most strength as Todd has described.

Benson
 

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Benson,

This is an interesting statement, do you know if “polypropylene” was commonly used to reference fiberglass back then?
If I remember correctly, polypropylene has properties similar to kevar and is nothing like glass.

"polypropylene fiber reinforced plastic" (a.k.a. fiberglass) covering


And this one is also interesting, OT didn’t use band saw for resawing??

“saw kerf was larger than the Lightweight's planking.”

Dan
 
Please excuse my lack of clarity. There are many different fabrics available for composite construction which are often referred to generically as fiberglass. Polyproplyene is a synthetic fiber that can be woven and used like fiberglass although the chemical structures are completely different. It provides the best clarity for the planking display on 'natural' or un-painted canoes. More information is available at http://www.oneoceankayaks.com/Abrasion.htm and other sources. The first Trapper model was described in the 1967 catalog as being covered with "polypropylene fiber reinforced plastic" but this was changed to simply "reinforced plastic" in the 1968 to 1976 ones. It became "plastic fabric" in 1977 and then "fiberglass cloth" starting in 1978.

Old Town did use a band saw for resawing but it was over eight feet tall with a blade that was several inches wide and was described as having a kerf of at least 1/8 inch. I never measured it personally.

Benson
 
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The polypropylene cloth they were using is most likely pretty close to the one Benson linked to or this one (there are a couple different types):
http://www.defender.com/product.jsp?path=-1|10918|16458|309346&id=16128

Its properties are somewhat different from fiberglass, but how they stack up against each other depends upon the specific application and which strengths or weaknesses of each product come into play when used for that application. In general, the polypro fibers will be somewhat more abrasion resistant (tempered by the fact that the resin saturating the cloth will be the same and the resin itself also has to withstand the abrasion). Polypro also has greater elongation (stretches and/or flexes more without breaking) and ounce for ounce, it has higher tensile (tear) strength. This may or may not matter a lot, since fiberglass is available in a lot more weaves and weights, so the same raw cloth weight might not be used. Some of these non-glass fabrics also swell a bit when saturated, sucking up more resin than glass would, so even if the cloth is lighter, the finished laminate may not be.

In both cases (fiberglass and polypropylene) any severe impact will most likely break the wooden hull. The poly may fracture but hold together, where the glass might fracture and break apart or split - but you're still kind of screwed either way and your boat will be going in for some serious repairs.

The things that still make fiberglass the most common composite cloth are reasonably low cost, availability in many different forms, and its rigidity. If you try to make an entire boat from polypropylene cloth (or dynel, Xynole or most of the other synthetics) the result would be extremely flexible - to the point of being floppy. Glass, on the other hand can provide a mix of decent strength and some flex, but enough rigidity for the boat to hold its shape.

On a rib & plank canoe, the rigidity is already provided by the wooden ribs and gunwale structure, and the outer skin does virtually nothing to change or increase this rigidity. Since we aren't needing rigidity from the skin, we can choose a cloth that might have a bit more of something we do need than fiberglass offers - in this case, abrasion resistance. If we used the same polypro cloth inside and out on a stripper canoe with no ribs, the cloth would most likely flex so much that the wooden core would break. If we get clever and decide to start mixing layers of fiberglass and polypro to try to get the best aspects of both, they usually delaminate due to their very different flex/elongation characteristics. So you have to pick your cloth type carefully for a specific application to get what's most important for that construction.

Polypropylene and Kevlar aren't really all that similar. Kevlar is more like "fiberglass on steroids" with higher tensile strength and abrasion resistance, but it still maintains good rigidity and you can build an entire boat from it - if you can afford it. The reason it's so expensive is that, unlike glass and the various plastic fibers, it doesn't melt from heat. In order to make yarns from it, the material has to be "melted" with acid. This is very hard on the machinery and a rather hazardous process. Don't look for the price of Kevlar to ever come down much.
 
Interesting discussion. I asked because I've layed up samples of most of the fabrics mentioned, as I was considering polypro for use on a stripper I was building.

With Todd's input, I decided to just stick with glass, but in the samples they were very different.

Over 1/8" kerf on a large BS, I didn't realize it was that much. I have a 36" Moak at home, but it only has a 1" wide blade and I'm not sure what the kerf is. (haven't run it yet, waiting for a phase converter)

Dan
 
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