Kevlar and or Dynel in duckboat hulls-Voodoo, who do...or, should you do?

R

RLLigman

Well-known member
I received a message with an attachment in the email from another boating website that focused on the subject of the values and virtues, both real and perceived, of use of Kevlar in a hull's lay-up sequence. I seldom post on this website anymore because the subject matter is largely focused on offshore, large hull multi-powerhead powerboats. After reading the entire thread through several times, a couple of the comments by a marine engineer and a chemical engineer were quite interesting. There were repeated comments that mentioned the use of specialty fabrics in specific applications, but then the poster(s) repeatedly never actually stated what those specific applications actually were. It was an interesting discussion that made me on my own materials choices in a recent duckboat refurbish.

Given the physical environment that duckboats are used in: shallow, debris laden water; large river systems with floating and stationary deadheads; as well as the fact that duckboat hulls are frequently grounded (intentionally as well as unintentionally) on flats,gravel, mud, and sand, I thought it might be worthwhile to initiate a broad discussion of lay-up techniques, sequence, and materials in fiberglass and composite laminate duckboat hulls.

So, what materials would you build your custom duckboat hull with and what resin, or resin combination(s) would you use? I'll cap the hypothetical overall hull length at 19' or under.
 

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Yes, this was the comment I found most "telling":

"So if this were a democracy, then the 99% of commenters who said that Kevlar was a selling tool only would have won the argument, and the 1% who actually have some scientific knowledege (darbrikrash) would have lost.

That's a good (and scary) reason to never believe anything you read on the internet." -Thunnus, THT

A re-work of the old woodsman's saying: "You have to know what the woods look like, before you can recognize the unusual!"


This touched on most of the misconceptions surrounding Kevlar applications in small boat construction:

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Quote: Originally Posted by mike carrigan Usually a speciality company. Typically a very small flats boat and the like.
E-glass, perhaps "3610" triaxial has a multi direction strength. KEVLAR doe's not. KEVLAR has a strength at the direct point of impact only, not mutidirectional.
The hull of an offshore fiberglass boat must flex, work in all directions. KEVLAR will not. It's used in part with an offshore hulls structure in some cases. I know of no case that an entire hull is laid up with KEVLAR having to do with an offshrore hull. At least none that I know of.
It doe's not bond well with E-Glass. Allmost all hulls are built with E-Glass. It doe's not "wet out" well at all.
There's a small flats boat that I have allways been very fond that was once a KEVLAR hull. Please understand though, a small Flats boat is for backwater, inland use. Building it very light was paramount for the particular manufacturer of which I speak. Having said that, it was never built for offshore purposes.
KEVLAR is sometimes used in some very specific lam schedules in some particular area of a hull. Varies some from manufacturer to manufacturer that use it. We've used it.
If, for example, you expected someone to shoot at you. You might wish to reinforce a particular area of the hull to reduce the effect of the projectile. KEVLAR would be more resistant to a bullett than E glass. But, a hull bending and working and flexing offshore, KEVLAR is for certain not the choice.
It's light and it's strong and for it's purposes can be quite useful. Those purposes do not include the lamination of an entire offshore hull.
If there's an engineer on site that takes issue with what I'm saying, I invite the disagreement and the corrections to anything I've said that is incorrect. "I think much of what you say is correct. Kevlar is often used as a more effective marketing tool than an engineering tool. There are a couple of minor points to clarify:

- Sea Hunter does lay-up the entire hull using Kevlar. The boats range in size to 40’. Now this does not mean every layer in the laminate is Kevlar, it is not, but one complete skin is, usually the innermost (bilge) side.
- Kevlar is more often used as reinforcing material, for example stringer caps, rather than an entire hull, as you point out.
- Either vinylester or epoxy resin may be used with Kevlar.
- Kevlar skins are commonly mixed with E glass cloth, they bond just fine together.
- It is harder to wet out, but an experienced lamination crew can handle it easily. Vacuum bagging is preferred.
- The Kevlar fabric used in boat laminations is not the same material used in ballistic penetration applications, but it is from the same family (Aramid fiber)
- Kevlar 49 (Dupont) has 10X the stiffness of E glass, with approximately the same weight.
- Kevlar can also be obtained as multi-directional cloth, and can act orthotropically as can E glass. It can handle loads in all directions.

The main advantage to Kevlar is not it’s strength, but it’s stiffness. Stiffness is very different than strength, and for small boat design material strength is not really a factor. Stiffness is. This goes to minimizing panel deflections.

Substituting a layer of Kevlar cloth into a traditional E glass laminate does not really take advantage of the material properties, although it does increase the panel stiffness significantly. It won’t be any lighter, so the although the owner will get better panel stiffness, he doesn’t go any faster or get any better economy as there is no effective weight savings. Not sure he’d notice any benefit.

A properly engineered "start from scratch" hull using Kevlar can show real benefits over a typical E glass hull, as the extra material stiffness will allow the designer to reduce stringer sections, reduce or eliminate longitudinal members, and take material away from other parts of the structure that are not contributing to the vessel stiffness due to the use of the Kevlar skins. This can mean larger interior spaces and lighter weight, higher speeds and better fuel economy, which are advantages the owner can see and use.

This is not something done “by eye” because if you make a mistake, things break as it takes formal engineering training to succeed at this approach. Even with formal training things still break."
Darbrikrash, THT

Of principal note: 1.)Polyester resin is a no-no. 2. Boat building Kevlar (Aramid 49) is not the ballistic laminate. 3.Layers at points of stress, potential impact/crush hull sections, and abrasion areas-as an internal laminate are best uses. 4.Added resin needed to adequately wet-out Kevlar largely offsets any savings. 5. You cannot wet it out to "show" background wood grain, if that is your desire.

What he left-out was that, by orienting the weave at 45 degrees to the previous laminate layer improves both the stiffness of the resulting panel, but also diminishes the degree of penetration and surrounding delamination area should that panel collide with something.

I used to race canoes for a few years. My partner built custom kevlar and carbon/kevlar boats for guys he knew as a sideline. I worked with him, mainly as a pair of extra hands, but it was quite informative, since he had was a dual major engineering degree out of a horrible little podunk college down the road from mine (Michigan). I was quite impressed by how much abuse these hulls could take, as well as their weight. There is a race on the AuSable. It is a mult-day affair that quickly puts its participants in "zombie mode" collisions during the night-time legs are pretty common, as are broken paddles.

Now, on to Dynel.
 
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RL, I have been building big sportfish boats for 36 years. I have been through the kevlar/ carbon thing since the early eighties. These materials have their place, mostly in the aerospace and race boat industry where strong light weight structures are most important. A good composite engineer and builder can build a perfectly strong and functional boat without any of these expensive and somewhat harder to work with materials, and still be somewhat light weight. Modern boat builders use this stuff more for the wow factor than for ultimate top speed like the gofast guys. I have one layer of kevlar hybrid cloth in the bottom of my corecell and glass gator trax look alike mud boat. This is mostly because I had the cloth laying around from a big boat project. I would by no means buy this cloth to save 10 pounds in my boat, Heck my weight varies by that much each winter! My boat is 17 feet long had a dry weight of 175 lbs. My son and I could easily man handle it around. My 23 hp mudbuddy weighs as much as the boat. All of this weight savings can be easily accomplished with good resin control. My boat is all epoxy, I find it easier to build light weight with epoxy than polyester or vinylester as you have more time to squeege out the excess resin, and you can use stitched biax cloths without mat stitched to the back which greatly increases the weight of the layup, and resin used, Vacuum bagging has its place, but a careful glasser can do a very skinny but proper layup on a small boat without it. I vacuum bagged my rub rails mostly to get the cloth to go around the tight radius shapes, not for weight savings. Forget Dynel I know sailboaters still use some of it, but I havn't heard of any serious builders doing so today. I think I posted some pictures of my boat sometime back, you can probably find them by clicking on my avatar. Rich
 
Rich~

I really appreciate your thoughts on this topic - I am from There's No Substitute for Experience School....

Question: Since I am re-building my 'glass Sneakbox at the moment - Do you recommend adding anything to the outside of the hull/ down the midline ? - to protect the surface from the inevitable abrasion from sand on the bottom of Great South Bay. It has never caused a serious problem on any of my boats - and even the "miracle, slick surfaces" concede that sand and shells will wear through any outer coating.

BTW: I like my skeg but otherwise have learned to avoid strakes or runners on my gunning boats.

All the best,

SJS
 
With all do respect to your experience, Rich, your entire post focuses on one aspect of structural Kevlar; its use to produce a lighter hulled boat, capable, as you state, of increased performance. I also recall your previous post regarding shooting through some panels of structural woven Kevlar to determine just how "bullet proof" it really was. As I mentioned in that thread, and do again, structural Kevlar is not the same "beast" as ballistic Kevlar. Your depth of experience doesn't appear to include a broad understanding of the actual full array of the specific structural properties of the composite materials you dismiss.

As I was reading through that THT thread, I kept encountering similar statements regarding perceived weight savings in large and consequently heavy offshore power boat hulls. Would I consider incorporating Kevlar, Carbon Fiber, or Dynel into construction of a layout boat? No, essentially a layout boat is a tub floating stationary in the water, with very little of its design elements involved in any of the broader aspects of boat construction and design beyond floating as a stable platform. Where I would use it is as an interior laminate panel in hull SECTIONs where the hull would be exposed to abrasion and/or potential crush damage, either via repeat grounding,ice breaking duty, or in a collision.

One thing I openly doubt the majority of commercial boat builders focus on: How will this hull perform when things go wrong i.e. how will the boat hull behave when it collides with an object, or when it is taking-on water. Particularly in fiberglass hulled duck boats, is that I see very little focus or effort to protect a hull from the wear and tear of repeated groundings. Case-in-point was the experience the former editor of Great Lakes Angler survived when a vendor delivered his new USCG registered aluminum sport fisherman to their office for use, and a free write-up, as a salmon trolling platform. The crew were trolling in a heavy chop in southern Lake Michigan during summer, when they hung-up a downrigger cable in the propeller. While they were trying to clear the prop with the engine up on tilt, with two guys hanging out over the transom, a wave set quickly swamped the boat. What they did not expect in their newly USCG approved hull was that the boat quickly filled with water as it flowed in through the transom cut-out, sinking out from under the three man crew. That's right, sinking! Two crew members grabbed life jackets from among the resulting flotsam. Dave Mull swam over to a floating cooler and hung-on. The ambient current quickly separated them. Dave was eventually picked-up three hours later by the sport fisherman that had earlier come across and rescued his crew members who managed to stay together, enhancing their visibility. Fishing gear, camera equipment, and personal items were never recovered, although Dave did report he saw the video camera bag intact and floating away post-sinking.

When you have experienced boat performance failure a handful of times following swampings, sinking, and collisions in a variety of commercially produced boats,your focus tends to shift to center on: What does this hull require to perform as well as protect me during use, and how do I maximize its longevity and integrity.
 
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RL at the end of your initial post you asked the question "So what materials would you build your custom duckboat hull with, and what resin or resin combinations would you use?" I answered! Beyond that I am signing off . Rich
 
RL at the end of your initial post you asked the question "So what materials would you build your custom duckboat hull with, and what resin or resin combinations would you use?" I answered! Beyond that I am signing off . Rich
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typical lack of answer from him. It isn't too much work for him to tell us what an expert he is and that he has been building mega sportfish for 107 years, but to help someone out with some specific details is just too much work, apparently. Sadly typical....

Don't feel bad RL, even the site owner can't get Rich to answer simple specific questions:

http://duckboats.net/cgi-bin/forum/gforum.cgi?post=208667;search_string=I%20would%20appreciate%20some%20answers;#208667
 
I've built and worked on a lot of small duck boats. Expenses related to techniques and materials are prohibitive to high-tech duck boats for average guys. Even guys who are good craftsman with experience building things shy away from investing into one-off or risky projects. I know this isn't a new revelation or anything. The investment to maintain a facility and crew along with equipment and materials to build specially engineered/designed duck boats for a niche market is unrealistic.

Would I like to build a duck boat extremely lightweight and durable with the ability to endure impact and abrasion while being unsinkable and offering great performance, yeah... Then it sort of goes around in circles that way while trying to justify costs or considering the needs to execute proper laminates using epoxy/kevlar.

A personal story from some of the boats I've repaired. A guy who makes small one-man duck boats in my area uses carbon fiber. I'm 90% sure he's using epoxy. So the story goes his materials are procured from the company where he works. The company has to watch the material's dates and outdated materials become these small boats. I'm not entirely sure of the construction but I think it's open molds. Most will agree that vacuum bagging parts will give you ideal weight/strength while many experienced builders or managers say kevlar/carbon fiber materials can be laid up traditionally with negligible differences. I've seen/heard a lot of argument about the skills of the people doing the lamination. This could be true/false, I don't join that debate and I realize CF wasn't part of the hulltruth.com discussion either. The noticeable thing on the carbon fiber boats I mentioned is they crack along the cockpit rail from weight flexing it. Having fixed two with the exact same problem it makes me question the materials/techniques. They are light/stiff boats and being made of carbon fiber has people in my area seem somewhat enamored by them. This leads me to believe what the engineering states about materials being best applied for their strengths and avoid using others based on their drawbacks. The data pertaining to these materials isn't much if you can't/don't test it against real use in a duckboat because you cannot predict or envision every potential flaw or situation that will effect the boat. I think if you notice similar problems arise before/during/after a boat's creation and subsequent use that may or may not be definitive proof of the technical data but if you own or work on the boat you'll be keen to solve the problem regardless.

In my opinion there is only one way to know for sure what the performance qualities and costs are to build variations of certain boats and that is to actually do it. The forum debates could go a thousand pages without settling anything but if you made 4-5 different boats and tested them that would be more valuable than ten thousand posts worth of conjecture. In skimming the other forum's thread I kept thinking about one of my Pals who worked for a high-tech F-1 racing team. They would test and modify parts for improving performance in different ways using the highest tech composites and cost was never a concern. They tested many variations and parts were equal to those made for aerospace applications. I often said how sweet would it be to build boats and one-offs so easily. They would spend a month building molds and parts, then never use any of it. A duckboat guy with deep pockets could certainly use the finest composites to build an awesome boat. There is a company down the road from me who would do projects like that start to finish. It's six figures before the decimal point to be sure.
 
There are too many requirements from individuals to build a boat a certain way that by the time you accommodate everyone's needs, you have 100 different models. Just to show some differences in the weight of various kayaks that can be used for duck hunting built with different materials, here is an example.


The Poke Boat


View attachment poke.jpg


For me, carbon fiber is not a good idea as when it hits something, it tends to crack. And I know this boat will bump into objects like rocks and trees. But, for a lake paddler, chances that they will hit something is slim and the carbon fiber may work for them.


Kevlar is 4lbs heavier than the carbon fiber and worth the trade off for me. It is also 6 lbs less than the fiberglass version and worth he extra cost to me. Ask 10 other guys what they would prefer if they were looking at this boat and their reasons for choosing one over the other would be varied.


Hoefgen can tell a similar story where the fiberglass version weighs 65 lbs and the Kevlar version weights I believe 20 lbs less. While weight is one factor, I don't know the sturdiness of the Kevlar verses the fiberglass version. I do have fist hand knowledge of easily puncturing a Kevlar canoe on a Boundary Waters trip. Thank goodness for duct tape.....


For what this is worth.....




Mark W
 
And to throw fuel on the fire, I would build the under 19' duck boat using some of the fiberglass reinforced urethane foam boards available from a few manufacturers (if it is good enough for the Navy on some of their new destroyers and submarines, it is good enough for my small duckboat). Lightweight and strong, this is what I would build my boat out of if cost were no object. Layup with epoxy or vinyl ester resin and high tech fibers bagged in some manner. Or, if cost were really no issue, maybe use some pre-pregged material and autoclave it. And besides cost, there could be a trade off. This boat would be very light. For me, hunting inland lakes and streams being lightweight is an advantage and not a disadvantage. Hunting large bodies of water or the ocean, maybe having more weight associated with the boat is a good thing.


Different needs, different costs and so on determine how one would build the 19' boat you ask about.


And don't believe everything you read in that article coming from experts. I can point to more than one example of what the experts say based upon old science, old theories, and old world ways of building watercraft that have been scientifically proven wrong. If these folks aren't current on the absolute latest technology, they can't speak to what they don't know about.


Mark W
 
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Mark W. I'm surprised you were able to easily punch a hole in a Kevlar canoe. My son and I have been to the BWCA twice in the past three years and used Kevlar canoes both times and being an aluminum canoe user for the past 50+ years with a 10 day BWCA trip in 1969 I was very impressed with the Kevlar canoes. We went over at least eight beaver dams getting stuck half way through. I don't think we abused the canoe as I didn't want to be without a way to get out. At 17ft. and I believe 45LBS it preformed nicely. I have a 15ft. Raddison aluminum at 43 LBS which is much more stable then the 17 Kevlar was but it doesn't travel through the water nearly as good. So if I'm wanting to cover some distance and 8 or so portages per day I'm going Kevlar. Now as far as a duck boat I would most likely pass on the Kevlar. If I'm looking for abrasion resistence I would install a urethane keel protector. I would want to protect the outer finish as much as the glass underneath.
 
Many moons ago I was duck hunting with George Soule. He took me into his barn to show me the little all-Kevlar canoe he had just finished. He remarked that he didn't think too many people were working with Kevlar for, specifically, canoes yet. He then proceeded to take a 2-pound ballpeen hammer and take a mighty (well, as mighty as a small, 80-something man could take) swing at the hull. Hammer bounced out of his hand, and other than a little mar where the hammer hit, no damage done. I thought that was pretty cool. I had worked with fiberglass and polyester resins a lot, making reproductions of 1935 Auburn Speedsters. To say the least, as swing on one of those with said hammer would have some pretty serious effect.
That was a fun story to remember.
Gary
 
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Derek, I suspect that the site of failure you reference in that CF boat is largely a consequence of poor compaction of the laminate, allowing air to remain in that rail/coaming area. Take a look at Trek Bicycle's optimum compaction low void (OCLV) production technique for GF lay-up in multi-directional;variation of vacuum bagging. Kestrel was the principal CF frame builder for the mountain and road biking community for some time, Trek, Giant, Specialized,etc. all build one or more CF frame bikes. They used to be the common at triathlons but a rare sight at The Tour de France, as well as the road and mountain bike race circuit. Now the TDF peleton is composed nearly entirely of CF framed bikes, which have survived mass pile-ups and car crashes, far better than their riders.

There are a number of CAD programs, some proprietary, that enable ready hull stress point calculation and determination in boat building without the need for multiple hull production. Boston Whaler has one that they have used in hull production since 2005. As quick examples of its use/benefits: They actually changed the location and base configuration in their Conquest series hard top frames produced by Taco because they were so rigid they would result in delamination of the cuddy cabin exterior as originally designed. This software was also used to determine gel coat stress crack formation sites on the exterior hull. After ten years, I have four gel coat stress cracks on this boat-one of which is a consequence of railing stanchion screw hole. The largest is a whopping inch long.

Mark, I agree, there is no end-all/be-all material for a duck boat hull. I think Rich Sheffer's approach to go with several biaxial cloth layers in the hull would be the route I would go, WITH a CSM backing between the biaxial cloth laminates, along with the use of a slow setting Epoxy resin- a little heavier than his lay-up, but with a nearer zero delamination risk and slightly greater strength and stiffness. I would opt to cover my fiberglass stringers,however, with Kevlar cloth "caps" over an laminate layer of E-glass cloth. I would follow Mark's lead with the use of a synthetic panel (undecided on which material to apply here) as the underlayment on the deck, and a COOSA material transom.

I also own a Poke boat. My advice on them would be to always buy one used;walk away fro any boat with the interior painted; and always carefully inspect the hull for any sign(s) of delamination, particularly around the cockpit and coaming area. I am eventually going to have to strip the paint off the bottom of mine and apply a Dynel layer on it. I am going to be repairing my partner's Hoefgen's bow, initially with Marine-tex with a Dynel scrap overlay.

Tom, I used a urethane keel protector applied over my Marine-tex epoxy repaired(some gel coat chips and wear spots, but no deep gashes) TDB-17' classic's bow/keel area for a combination application in abrasion protection during groundings, as well as protection when breaking through skim ice. In a sea ice formation environment, that would likely be adequate. For dual freshwater, salt or brackish water, I would opt for something more substantial. I opted to back-up the full bow area, during my boat's refurbish, with two layers of 45 degree opposing strand oriented sheets of Kevlar 7 ounce cloth, as well as three layers down the first six feet of the keel line for crush protection. On a broader surface area bow, or in an exterior application for abrasion protection, I would consider use of Dynel rather than Kevlar, however. If I had multiple pairs of hands, a nice Dynel wet-out and lay-up sequence involves "impregnating" the Dynel sheet with resin on a work table; rolling it around a dowel to squeeze-out the excess resin; then applying it to the work surface section of the exterior hull, prior working the air out of it. I got caught in a wind shift near the end of last season, down on Lake Michigan, that resulted in roughly a half-foot of stacked-up skim ice built up on the last twenty feet of water at the ramp I put in at. I shifted some weight astern prior running the bow up onto it; walking forward with the motor in neutral; breaking it up under the hull. Luckily the wind wasn't strong enough to pile it up on the ramp.
 
Mark W. I'm surprised you were able to easily punch a hole in a Kevlar canoe. My son and I have been to the BWCA twice in the past three years and used Kevlar canoes both times and being an aluminum canoe user for the past 50+ years with a 10 day BWCA trip in 1969 I was very impressed with the Kevlar canoes. We went over at least eight beaver dams getting stuck half way through. I don't think we abused the canoe as I didn't want to be without a way to get out. At 17ft. and I believe 45LBS it preformed nicely. I have a 15ft. Raddison aluminum at 43 LBS which is much more stable then the 17 Kevlar was but it doesn't travel through the water nearly as good. So if I'm wanting to cover some distance and 8 or so portages per day I'm going Kevlar. Now as far as a duck boat I would most likely pass on the Kevlar. If I'm looking for abrasion resistence I would install a urethane keel protector. I would want to protect the outer finish as much as the glass underneath.
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We punched a hole through while portaging. I was in front carrying the canoe and he was in back not paying attention. Somehow we banged into a tree that had a stub branch at just the right height. Poked a hole right through it. Hard to believe I agree.

Mark W
 
Back in the late 90's hockey sticks started to become one-piece composite VS. wood/aluminum. These sticks flex very well allowing guys to shoot the puck over 100mph, but you can see em snap like a twig too. Sticks are made in state of the art facilities and quality control is serious, yet forces come against them in games to break them easily. I wonder if the forces are that great or if there's minor defects in the laminate/material???

I realize its not duck boat hulls, but I consider the materials to be expensive and problematic to work with even for companies with budgets and engineers to develop their products.

Considering the market for duck boats VS. high end canoes or bicycles, its quite different. Renting a canoe in the BWCA usually means somebody is more careful than than a duck hunter and their boat. Not too many duck hunters wearing Teva sandals and cargo shorts portaging around that I'm aware. I'm thinking, how can I repair damage when it happens regarding duck boats. From that perspective traditional materials are good since repairs are easy and boatyard resins will bond well and save some costs.

If you're trying to achieve stiffness or impact resistance and save weight maybe kevlar or another reinforcement will benefit you? I think the debate is when guys say it's unnecessary or the differences are negligible between weight or utility of specially reinforced areas on boats.

I would agree a flats fishing boat built light and strong enough to draft shallower without sacrificing anything could be worth the extra cost to customers. Its sort of splitting hairs though because guys argue you wouldn't notice the differences or that the additional cost doesn't justify minor improvements while also creating possible headaches.

Personally I think those types of materials are best in specific applications, duck boats not being at the top of the list. I would never criticize panels, or stems/stringers with special reinforcement. I use core material and composite board along with blended poly and VE resins. I've used epoxy and my .02cents is the cost is too high for what people will normally buy. If I added more expensive reinforcements and vacuum bagging a tiny marsh boat could cost over $3K when guys could find a variety of utility boats to accomplish their goal on craisglist for $300 or less.

Most boat builders are using the best materials they can to make the best product they can sell and profit from. If a single customer wants a more expensive boat that is made differently I could not justify the costs in my small shop because the setup and time required would add cost on top of materials. I would need to have multiple orders for boats of that type at the higher price to start vacuum bagging parts with epoxy/kevlar. It wouldn't be simple quick switches for me to go between different setups and lamination schedules. Having considered all the materials and methods I think small utility duck boats are ideally constructed from E-Glass. I've worked with some really junky resins and some very good. I don't study all the technical data on each but once I dialed in my materials and schedules I go with what works best for me.

I tend to agree with those from the hulltruth.com thread that believe certain fabrics have their place rather than they can be good anywhere you use them. A final example is a kevlar canoe which is one part made in a mold and finished with hardware attached VS. a duck boat type canoe with one hull mold and one deck mold. The canoe can be bagged in one try to finish a part VS. the duck boat which would be bagged once to finish the hull but what do you do to seam the boats together??? Bag it again to get an immaculate bond inside the boat or just goob it together with 5200??? Either way the build is more tricky to complete and be confident in than a canoe which pulls out of the mold 95% done with only seats and rub-rails to be added.

I'm no expert or engineer just trying to contribute to the discussion so I don't get singled out for ridicule by all the jerks on this site. Haha.
 
Mark W. I'm surprised you were able to easily punch a hole in a Kevlar canoe. My son and I have been to the BWCA twice in the past three years and used Kevlar canoes both times and being an aluminum canoe user for the past 50+ years with a 10 day BWCA trip in 1969 I was very impressed with the Kevlar canoes. We went over at least eight beaver dams getting stuck half way through. I don't think we abused the canoe as I didn't want to be without a way to get out. At 17ft. and I believe 45LBS it preformed nicely. I have a 15ft. Raddison aluminum at 43 LBS which is much more stable then the 17 Kevlar was but it doesn't travel through the water nearly as good. So if I'm wanting to cover some distance and 8 or so portages per day I'm going Kevlar. Now as far as a duck boat I would most likely pass on the Kevlar. If I'm looking for abrasion resistence I would install a urethane keel protector. I would want to protect the outer finish as much as the glass underneath.
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We punched a hole through while portaging. I was in front carrying the canoe and he was in back not paying attention. Somehow we banged into a tree that had a stub branch at just the right height. Poked a hole right through it. Hard to believe I agree.

Mark W
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I had to laugh, yea that wasn't too bright. Not to be a smart ass but your supposed to carry those canoes in the center with one person. We tried the two person but decided my son did a much better job on his own. One real short portage we unloaded and carried over up right
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I sold a Boston Whaler to a guy out in Washington. The hull was still under factory warranty. He decided to remove the existing GPS and fishfinder units, Garmin and NorthStar, repsectively to put in two "CHIRP" technology Garmin units in the existing cut-outs. Apparently, a BW technician got a little carried away with the epoxy mastic that the used to "weld" their two-part hulls together, gooping it all along the outside edge of the North Star unit. I called BW to turn it in under the hull warranty. The initially denied the claim. He sent them a registered letter with photos and "explained" that he thought sharing the information with the broader boating community would be a good offset to the money he would lose via having to cut-up the exterior of the electronics unit in order to remove it. He received a check from BW sent registered mail. I had to grind away some excess by using ,my Foredom tool, it is less viscous than two-part epoxy, but once set it holds: light grey like PC-7.

Actually, I should have qualified my comments on use of epoxy resin in terms of building a personal use boat, not a production boat-very good point.

I don't know whether i would broadly agree that renters of boats are more careful with the hulls than Duck hunters. Where I shake my head is how often I see duck hunting boats stored or left idle for long periods with water standing inside them, enduring repeated freeze/thaw cycles, etc. Water does move through polyester resin fiberglass laminate as vapor and via capillary action. Unsaturated core can waterlog as well as encapsulated wood, the only difference is the rot sequence's duration. I have seen literally boatloads of "non water absorbing" flotation foam encapsulated in water, as well as nearly full of water due to its slow breakdown over time. I used to dive out of a BW 17' Sokkonet to service current meters that were moored on fixed tether clamps on cable buoy arrays off the Ludington Pumped Storage Plant in Lake Michigan. There was one section of deck that was sponge soggy in a two by two foot area. We finally pulled it inside the "Carp Rigger" (pole barn we used to repair and fabricate trapnets and gillnets) and cut it out in the fall- a big time mess.
 
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Mark W. I'm surprised you were able to easily punch a hole in a Kevlar canoe. My son and I have been to the BWCA twice in the past three years and used Kevlar canoes both times and being an aluminum canoe user for the past 50+ years with a 10 day BWCA trip in 1969 I was very impressed with the Kevlar canoes. We went over at least eight beaver dams getting stuck half way through. I don't think we abused the canoe as I didn't want to be without a way to get out. At 17ft. and I believe 45LBS it preformed nicely. I have a 15ft. Raddison aluminum at 43 LBS which is much more stable then the 17 Kevlar was but it doesn't travel through the water nearly as good. So if I'm wanting to cover some distance and 8 or so portages per day I'm going Kevlar. Now as far as a duck boat I would most likely pass on the Kevlar. If I'm looking for abrasion resistence I would install a urethane keel protector. I would want to protect the outer finish as much as the glass underneath.
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We punched a hole through while portaging. I was in front carrying the canoe and he was in back not paying attention. Somehow we banged into a tree that had a stub branch at just the right height. Poked a hole right through it. Hard to believe I agree.

Mark W
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I had to laugh, yea that wasn't too bright. Not to be a smart ass but your supposed to carry those canoes in the center with one person. We tried the two person but decided my son did a much better job on his own. One real short portage we unloaded and carried over up right
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Being a smart ass is perfectly allowable for the situation. Earlier in the trip, same buddy wasn't paying attention and was pointing out various birds flying overhead. A little too excitedly. We tipped and the water was freezing and the ind howling. Luckily we had others with us who turned around wondering where we were. They came a rescued us as I don't think we could have gotten to shore with the wind and by the time they got us to shore I could barley hold on it was that cold.

Buddy is still one of my best buds but I will not get in a canoe with him ever again.

Mark W
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Mark, I have to say that that is the only negative I saw with the canoe we had. Other then the canoeing which I really like we go to fish for bass. I was a bit out of practice casting and put the lure in a tree. While getting it out my son said not to stand up. I told him that was a good idea after I dumped over the canoe. It was the last week of June so the water wasn't too bad. In fact that was the best of the five days. It rained the other four days. Two years before we went the first week of August which should have been in the 80s but never got out of the 60s Though we haven't had much luck weather wise before we got back to Ely I was ready to go back out. We're hoping to go again in summer of 2017. My oldest daughter wants to go this next time. The first time I was in the BWCA was in 1969 for ten days. We had three to a canoe which enabled us to do postages in one trip. At 17 years old the 78LB canoes were easy to portage. Now I have my son handle that. My daughter can also handle the canoe on portages. She is big into cross fit. I'm not real comfortable with three in the Kevlar canoes as there a bit tipper then I'm used to and adding another person can further complicate that. I'm thinking of going with a canoe and kayak. I guess I got a little off the thread subject.
 
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