Thanks again Brian…
… was thinking of a way to say just that. IMO, the hammer represents the hardest real world localized loading a hull would ever take short of getting shot. It comes on fast with alot of force and is very unforgiving. On the water if one were to run into something like this hopefully the boat would bounce or glance away on the first hit and not have to repeatedly endure the same force over and over. The closest I would think is running into submerged rebar at speed, or having paddler + loaded boat being picked up and dropped onto pointy rocks by some womping beachbreak… point loading the hull.
This tough layup would also help a boat endure a severe pounding on rocks. Survival of associated global hydraulic loading would also rely on how well the hull and deck are bonded together. The scariest thing I have seen on SOME of the mat / roving boats from overseas is how pityful the seam is done… ONE ply or even a couple plys of tape is going to open up like a worn out zipper.
Construction and repair.
"Your experience seems to indicate that "Brit" boat hulls may not take the punishment that we see in these movies."
While that's true, I'd say it's probably true for the vast majority of kayaks, regardless of their country of origin. It seems to me that Patrick's hulls are unusually durable, at least against hammer blows. Perhaps it's even a bit of overkill, though I'm not sure that's true if you use your boats hard.
"I've got one VCP boat and another on the way so I'm heavily invested. I do like their hull design shapes along with the myriad of other options and details."
Agreed. The designs are excellent. I'd love to see how a Pintail built with Patrick's layup would fare.
"Obviously, you don't want to go around bashing any boat into rocks"
Says who? How do you think I got the repair subjects for my photos? The people I paddle with tend to spend a fair amount of time in contact with rocks, intentionally or otherwise.
"but is there anything in terms of use of the boat and repair that I should be particularly aware of?"
Not really. The process is the same, regardless of the original construction. If you have a carbon fiber or Kevlar boat, you may want to use those materials for the repair, rather than fiberglass.
"What does diloene (albeit one layer) do for a Valley boat?"
That's a really good question. It may help prevent structural damage to the fiberglass from causing a hole, sort of like a "poor man's Kevlar". In the case of the most recent repair I made on a chine on my Anas Acuta, it did exactly that. I didn't realize I had damaged the boat badly until I put it up on the car and noticed it.
"Does anyone know if Valley is changing their layup materials/techniques under the new management?"
I asked that question - among many - of Peter at VSK (formerly VCP), but didn't get a direct answer. I suspect that it just got overlooked in the conversation. Based on how open they seem to customizing boats, I would imagine that it would be possible to order a boat with a custom layup. Since Peter spent much time at P&H, one would hope that Valley boats would be available with similar layups.
"I have seen your sequence of repair photos of an NDK Explorer on community webshots. Thank you--that is very helpful to be able to visualize the repair process that way. It sounds like that from the descriptions in this photo sequence that you find there to be considerably more damage done after impacts to "Brit" boats (specifically just NDK, or do you include Valley and P&H as well?) than would be the case from many North American manufacturers, right?"
Not necessarily, though chopped strand layups tend to be weaker than cloth layups. The type of hidden damage revealed in the photo sequence is typical of any composite layup. One of the things that makes composites strong is that they distribute localized stresses over a large area. That leads to the damaged area caused by a serious impact being larger than the impact zone. Some materials tend to spread the damage more than others. It has been brought up in other threads that chopped strand mat based layups tend not to spread damage as much, which is true (it's also why they're weaker). The question is whether you would rather have severe damage - such as a hole - in a smaller area or less severe damage (cracked, softened layup) over a larger area. From a safety standpoint, I like the latter option, though it does create more work when you have to repair the boat.
"PS: Might you have any photos of the procedure you used on the interior of the boat for the first layer of cloth?"
The interior layer is pretty easy, especially if the boat has a stiff layup and/or the surface to be repaired is gently curved, as in the Explorer photos. I make the inside patch at least an inch larger in all dimensions than the hole. Whenever possible, I like to put some kind of backing over the inside patch. Plastic cut from a polyethylene milk jug works well and is stiff enough that you can put a foam or inflatable backing behind it. Having the backing allows you to do all the fiberglass work in one shot, since it provides support for the layers you apply to the outside.
In working on the Anas Acuta, I learned one valuable lesson about repairing hard chine hulls. Once the chine is ground away, the side and top panels can move in relation to each other, so they need to be supported on the outside to keep them in the proper relationship and to prevent them from bulging outward. This is especially important if you're applying any pressure to the patch on the inside. The support can be as simple as a couple of yardsticks (or something similar), one on each panel, held in place by tape wrapped around the boat. Position them just outside the area where the fiberglass will be applied, or over top of the patched area once the layup is complete and is covered with plastic or packing tape. If the patched area is depressed slightly, it can be built up with extra fiberglass or gelcoat, but if it bulges outward, the only choices are to re-do the fiberglass work or live with a mishapen hull.
Thank you
the only innermost layer is Diolene
The innermost layer of my ProLite Valley boat is a blue and white weave. I’ve assumed this is the Diolene as the bulkheads are the telltale black and yellow of carbon/Kevlar.
Is this assumption likely correct?
Probably
I haven’t seen the blue/white weave you refer to, but the inner layer of all the valley boats I’ve owned or worked on has been Diolene. It’s a pretty coarse weave fabric that is generally not well saturated with resin in the boats I’ve seen. It will fuzz where it gets abraded, such as where your heels rest. That’s probably the best indicator that it’s Diolene.
Layup question
What do people consider to be the most ideal layup?
- Materials used (matt, glass, kevlar, graphite etc.)
- What combination of the above
- Total oz. materials used for hull and total oz. for deck
- Type of resin to use
- Materials and layup for seams
epoxy, s-glass, misc. core materials
I’ll leave it to the experts whether carbon or kevlar is best for long term bashability but my hunch is that the construction technique and details (weak spots) matters more than the materials.
another question, bnystrom…
This may be getting too academic, so please excuse me if it is.
You mentioned that the chopped strand mat won’t distrubute forces over as large an area as cloth and so the damage remains more localized but more severe at point impact–this being a disadvantage in the severity of the damage, but when it comes to a repair, it’s easier to repair because the damage is spread out over a smaller area than, say, a typcial North American standard layup, right?
Also, when you talked about diolene and the damage done to your Anas, you mentioned that you didn’t notice the damage done to the boat until you put it up on the car and could clearly see the outside of the hull. In other words, the boat didn’t have a hole punched through the hull because if this had been the case, you would’ve been taking on water and would’ve noticed that, although I guess this could happen in the fore or aft compartments of the boat and you may not realize the leakage for some time. Was there indeed a hull penetration in that incident with your Anas?
What I’m getting at is that, diolene, the poor man’s kevlar, may have kept the hull from being breached, if indeed it wasn’t breached in this incident, right? Well…if you have chopped strand mat that keeps the damage more localized so that repairs are easier because the affected area is smaller and diolene to help with through hull penetrations…maybe this is a reasonably good combination afterall? (I sure wish we could get those Brit boat manufacturers to weigh in on this discussion and justify their construction.) Other typical North American standard layups might not have hull penetrations either, but there may be more widespread damage that’s more difficult to repair, right? Is there really an advantage one way or the other here?
If I was on a remote multiday trip, I think I’d rather have a small repair than a large one, if the chance of hull penetration is similar overall. I’m sure there’s some information I’m missing here. Could you advise? Thank you.
British kayak construction
Generally I try and stay out of this debate because people tend to be fairly polarized in their views and no matter what anyone posts it will never be viewed as a definitive answer.
I can only offer my own experience of both British and North American kayak construction. My experience consists of 13 years at P&H, most of which as head of development with the latter part running the company until Pyranha (the British white water kayak manufacture) brought P&H and I decided this wasn’t for me and moved on Valley. Now I am one of the people running Valley and developing new stuff there. During this time I have also worked with and witnessed the construction techniques of several of the US manufactures.
First some of the facts regarding ourselves and P&H’s constructions:
There is no perceivable difference in the layups of either companies’ basic diolene constructions, both feature glass decks and a mix of glass weights and one layer of diolene in the hull. The only small difference being that whilst Valley uses a glass outside tape seem as standard this is a plus cost option with P&H.
Similarly with the standard Kevlar/carbon layups (Valley pro-lite) there is virtually no difference both having glass decks. The only real difference is that Valley also offers a full Kevlar/carbon option (ultra-lite), this features vinylester throughout, including gelcoat and is oven cured. P&H have experimented with constructions such as pre-preg but these are a very different beast with no gelcoat to protect the fibres of the laminate and built for weight rather than resilience (very trick non the less)
Regarding constructions generally: Yes glass cloth is stronger (weight for weight) than chopped glass but especially with polyester resins chopped strand glass adheres better to gel coats and cloths, than does cloth to gel or cloth to cloth also because of the way it drapes it is very good as a first layer especially on decks where it allow tighter contours for deck recess etc. This is very evident on many supposedly superior all cloth construction kayaks that then use non recessed deck-mounted hardware for ropes/elastics etc. These two reasons are why we deliberately chose to use glass mat next to the gel coat and on the decks.
Regarding vacuum bagging and other construction techniques: CD amongst others make great claim that they “bag” their composite kayaks. The Technique they use is not the aerospace vacuum bagging technique that results in a lower resin content and greater strength to weigh, it would better be described as a closed bag moulding technique where a pre measured amount of resin is literally poured into the mould and moved around under vacuum to consolidate the layers of material, the important thing is that no excess resin is removed in this process. Whilst I have to say I haven’t cut one up to measure the relative resin contents a visual inspection reveals a lot of excess resin in the V of the ends, my guess would be that kayaks made via this form of bagging offer no advantage over a well made hand laminated kayak.
Some final thoughts: many factors effect the durability of a kayak, for example the integrity of the seams are probably as important as the layup of the kayak, likewise bulkheads, as the saying goes a chain is only as strong as it weakest link.
I think on the whole the facts speak for themselves, whilst the constructions used on most British kayaks are not the lightest and sometimes don’t seem the most up to date, it does have to be remembered that these kayaks have a long and proven track record for reliable service both on expeditions and with many instructors where they see some of the hardest use any kayak will be asked to face. Whilst I’m sure this will not be the end of the debate I hope I have answered some questions.
Happy paddling
Peter Orton
Thank you.
This is the clearest and most complete explanation I’ve seen thusfar.
If I understand what Peter wrote and what else I’ve read of Valley layups, my ProLite Aquanaut’s decking is fiberglass matt covered with gel coat, and the hull (from the inside out) is Diolene, Carbon/Kevlar, gel coat. I also understand, and seem to see from the inside, an additional strip (Diolene?)along the keel line. Is this correct?
I greatly appreciate Peter Orton taking the time to read and post here. It is a new pleasure to have information, observations, and responses directly from Valley. Thank you.
Thanks for the insight, Peter
It’s great to hear the details directly from the source.
Your point about CD’s vacuum bagging is interesting and highlights the difference between merely vacuum bagging a hand layup and the superior “vacuum resin infusion” technique that some manufacturers use.
In my admittedly limited experience working with composites, one thing I’ve found is that putting a hand layup under some degree of pressure does help to ensure complete wet out of the reinforement materials, if not the optimum resin-reinforcement ratio. The biggest visible difference between a VCP layup and a CD layup is that the innermost layer is completely wet out and smooth on the CD, where the inner Diolene layer on many VCP boats seems rather dry and resin starved (at least on boats up through 2001). Would it not make sense to vacuum bag the hull to improve the wet out and bonding of the inner layer?
QCC
doesn't bag, but seems to be succesfull in how they wet theirs out. I no longer own one of theirs, but felt their attention to the building process was excellent. I noticed that they handled the issue of recessed deck fittings by useing some Swedish fittings that have a male / female parts with one part going on the under side of the deck and threaded into the other section which drops from the top partially through a hole drilled into the deck. A gasket is used where they thread together to seal it. This has allowed them to build their decks as strong as their hulls since a kayak is monocoque construction. They also lay up their boats so that the deck overlaps the hull in a form fitting way, then they glue them together rather then butt the hull to the deck and glass tape them together. Structually that should be an improvement, but don't know if it creates another set of problems.
What I find interesting is the two philosophies at work.
1. To build a boat so that if there is major impact the damage will most likely be local to the impact area.
2. To build a boat that may have greater structual integrity, but if it encounters an impact severe enough to damage the hull, the hull damage might be far more extensive.
Bnystrom
You might have missed my above post where I had another question for you. Would you advise on my questions to you above?
See: another question, bnystrom…
Thank you.
consequences more than philosophies
if you build for light weight then damage will be local and catastrophic depending upon the incident. If you build for durability without much concern for weight then local damages will show up before the catastrophic ones since what may be catastrophic on the lighter lay-up won’t manifest itself on the heavier lay-up.
Would be interesting to know
at a certain measured impact how extensive the damage will be and how extensive the repair job would be for some layups compared to others.
QCC calls its’ glass-kevlar layup it’s strongest, but does that mean if it is hit hard enough that the damage will be stretched and star fractured over greater surface area then lets say their all fiberglass layup. Without some data, one doesn’t know how much more impact if at all the kevlar layup will take over the glass layup to say that it justifies one over the other in all applications a boat might end up in.
Some materials such as kevlar (and I imagine this might be true for Diolene) don’t fracture or blow apart, but if deformed or stressed enough might carry the damage to the hull over a much greater area or delaminate from other layers making for a more difficult repair. Fiberglass typically just cracks and blows apart in the impact area alone. The question probably is how much harder of a hit can one take over the other and from that one could decide the merits for their own use.
Damage, repair and construction
The situation was that I was forcibly surfed into some rocks and hit the port chine pretty hard. It crushed/fractured the gelcoat and fiberglass, but it didn't penetrate, since it was not a pointed object. The Diolene held, but the fiberglass wasn't completely broken, so it's difficult to say whether it was critical to preventing a hole or not.
This points out the variable nature of composite failures. There's no practical way to simulate all the types of damage that can occur in the field. Every impact is different, as is the damage that results.
I see your point about having a penetration barrier on the inside of a hull and I agree that it's a good idea. However, I don't see it as a way of compensating for using weaker materials.
Peter pointed out that mat has advantages when it comes to conforming to tight curves and deck fittings (I'm not found of recessed deck fittings anyway, but that's another issue). Another advantage of mat is that it's relatively cheap. Peter also pointed out that it works best with the polyester resin that they use. These are all important advantages for hand layups.
On the other hand, cloth will conform just fine if it's used with proper layup techniques. I've owned hand laid up boats that were all cloth and very nicely made with no evidence of non-conformity in the layup. Cloth works just fine with polyester, vinylester and epoxy resins. While you can build a kayak any way you like, using cloth with vinylester resin or epoxy and vacuum bagging or resin infusion will result in a lighter, stronger and more resilient layup. It costs a bit more to do, but if you look at kayak prices, there's little or no difference between North American built boats that use better materials and methods and British boats built using mat and polyester resin. If anything, the latter are more expensive.
Another thing that needs clarification is the subject of "localized" damage and composites. While mat is often praised for keeping damage localized, it's a relative term and it's not always the case. The variable nature of the damage kayaks suffer makes predicting damage impossible. Sometimes, cloth layups will spread the damage over a slightly wider area, typically following the weave in the cloth. Sometimes the damage will be identical to a mat layup. There's also the possibility that the stronger, more resilient cloth layup will survive a impact that damages the weaker, stiffer mat layup. In severe accidents, the type of layup can be the difference between ending up with a "softened" hull with extensive resin failure, but that's still intact vs. a broken boat.
Given the choice, I'll choose stronger and more resilient every time. However, the handling characteristics of a boat are more often the primary reason to choose it and we live with whatever construction method the manufacturer uses. That doesn't mean we have to like it... ;-)
Thanks for the clarification!
at some point it’s counting angels
My Necky Chatham18 is supposedly made with a very efficient process but it’s not particularly light, it feels durable. I cut out the forward bulkhead (put a minicell one further back) and for the fun of it stabbed it a few times with an awl. It’s made out of that hexagonal core material with glass on either side. I’m assuming the bulkhead is alighter layup than the hull/deck. It looks like it has only a layer of high thread count glass on either side while the deck and hull have more layers.
Get this,with the curved bulkhead sitting on a 2" piece of minicell I stabbed it HARD with the awl. The awl is wood handled with a sharp tip widening to a 3/16"diameter shaft. The tip broke through but I couldn’t drive the hole thing through. I could see that the glass was finer than regular weave, damage was localized around the hole. Anyway I’m pretty sure I could have blasted through a piece of mat doing that. While bulkheads don’t need to be tough i figure it’s an indicator of how the rest of the hull will hold up. Fine weave glass tends to confine damage to a smaller area. I’m pretty sure that a mat glass deck of a given weight will blow holes through more easily than a glass deck of similar weight with finer weave.
Maybe a lighter weight cloth deck would show fractures over a larger area and the mat glass deck would allow little chunks to break through?
Either way at some point when the impact is big enough everything gets damaged and needs repairing.