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Shortening a kayak?
Dear All,
I have recently acquired 2 fibreglass kayaks. Given our lack of storage space, I am considering shortening them. Has anyone done this before? I have done some research into glass fibre moulding, and if I was to do it, was planning on making a male mould that I would leave wedged into the cut ends and lay the fibre over it. My brother has some experience of glass fibre moulding and is prepared to advise too. One is 3900 long, the other 4200 long. The width is around 600mm. I have calculated the volume of the shorter one as being around 360 litres. Surely I can afford to lose some volume given that some modern kayaks are as little as 180 litres and I'm not that heavy? I read a little somewhere about people shortening plastic kayaks, so I would have thought this would be more straightforward? I know it could be quite time consuming and messy but it seems a shame not to make use of kayaks that would otherwise have been destined for landfill! I have had some advice from another couple of forums advising that the paddling efficiency could be reduced, this is not too much of a problem as I will only be covering short distances on a placid local river. I understand that bouyancy and waterline depth will be affected too. Any thoughts/advice gratefully received! Regards, Nick |
Shortening a kayak?
How about posting pics of them, are they sea kayaks...or perhaps old slalom
racing boats? Either way, if they are being trashed anyway, why not experiment? From a face value POV, I would keep the ends intact as not to drastically change the handling characteristics (although any alteration will do this to some degree) and remove the volume from the middle say just in front of and just behind the cockpit? Keep it symetrical. wrote in message ups.com... Dear All, I have recently acquired 2 fibreglass kayaks. Given our lack of storage space, I am considering shortening them. Has anyone done this before? I have done some research into glass fibre moulding, and if I was to do it, was planning on making a male mould that I would leave wedged into the cut ends and lay the fibre over it. My brother has some experience of glass fibre moulding and is prepared to advise too. One is 3900 long, the other 4200 long. The width is around 600mm. I have calculated the volume of the shorter one as being around 360 litres. Surely I can afford to lose some volume given that some modern kayaks are as little as 180 litres and I'm not that heavy? I read a little somewhere about people shortening plastic kayaks, so I would have thought this would be more straightforward? I know it could be quite time consuming and messy but it seems a shame not to make use of kayaks that would otherwise have been destined for landfill! I have had some advice from another couple of forums advising that the paddling efficiency could be reduced, this is not too much of a problem as I will only be covering short distances on a placid local river. I understand that bouyancy and waterline depth will be affected too. Any thoughts/advice gratefully received! Regards, Nick |
Shortening a kayak?
Thanks for that, I hadn't thought of cutting them that way!
That might be an easier way of going about it. I'll have another look at them with that in mind! As for kayak type, one has Kiwi (Perception?) and Slalom on it so I'd guess it is an old slalom one as you suggested. The other one is unmarked. As you say, I've little to lose by experimenting! Cheers, Nick |
Shortening a kayak?
With the volume in mind, remember that the 180L modern playboats are
very different boats from what you are looking for. They have a flat bottom, they are very hard to paddle straight (without experience), and the ends can dive underwater. That being said, 360L would be fine (I think). An older whitewater kayak certainly had less volume and never had any buoyancy issues. I think I remember reading somewhere about someone doing what Grip has suggested. He cut a foot or two from the middle of his kayak (or canoe). I'll try and find it. |
Shortening a kayak?
Have a look at the pictures on these websites and see if your kayak has
a similar design: http://www.canoeslalom.co.uk/ http://www.jacksonkayak.com/kayaks06/ricochet.cfm wrote: Thanks for that, I hadn't thought of cutting them that way! That might be an easier way of going about it. I'll have another look at them with that in mind! As for kayak type, one has Kiwi (Perception?) and Slalom on it so I'd guess it is an old slalom one as you suggested. The other one is unmarked. As you say, I've little to lose by experimenting! Cheers, Nick |
Shortening a kayak?
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Shortening a kayak?
Thanks for the input!
The kayaks are not too different to the ones on the webpages. They are old though, perhaps 20 years? They came from a local army cadet unit, so have probably had a hard life! I'm not trying to create a playboat, just make something more manageable for our circumstances. Our local river is an old navigation and as such is not cleared and has many tight spots (fallen branches and overhanging trees) where a long kayak could get stuck. Plus I enjoy breathing new life into old things! Whatever I do with them, they'll need some TLC. I'll continue to think about it! If it's generally believed to be a complete waste of time, I'll fix them up and get rid. Any more information will be appreciated! Cheers, Nick |
Shortening a kayak?
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Shortening a kayak?
Michael Daly wrote:
wrote: Given our lack of storage space, I am considering shortening them. Sell them and buy the kayaks you want. I modify kayaks all the time, but shortening the hull is just a waste of time and money. Mike Agreed as well. Assuming you get the right materials to effect the repairs, there will still potentially be weaker spots and definitely make a heavier (and probably quite ugly) boat. Spiff them up, toss a coat of gelgloss on them, and sell them. Then buy boats you can store and are usable as they were built. Marsh |
Shortening a kayak?
Cutting a piece out of the middle of the hull should be no great
challenge. Just be careful to choose the locations of the joined halves that they match exaclty. Then sand off the inner surface around the cut and apply a couple of layers of fibreglass soaked in resin through the cockpit. Boat builders call it a "butt" join. I've used it in plywood boats. While the boat is in pieces it should be easy to prepare the inside, move the foot braces, etc. The challenge would come in enlarging the cockpit. I don't see how you can cut a piece out of the middle of a kayak without effecting the cockpit, and they tend to have moulded coamings to keep out the water and to allow a spray skirt to be tied on. Before cutting I'd want to figure out what to do about the cockpit. |
Shortening a kayak?
Wm Watt wrote:
Cutting a piece out of the middle of the hull should be no great challenge. Just be careful to choose the locations of the joined halves that they match exaclty. How many boats have you seen that have the exact same hull profile forward and aft of the centerline? Not many are designed that way. Then sand off the inner surface around the cut and apply a couple of layers of fibreglass soaked in resin through the cockpit. Boat builders call it a "butt" join. I've used it in plywood boats. While the boat is in pieces it should be easy to prepare the inside, move the foot braces, etc. That wouldn't be anywhere near strong enough. To do it right, you need the inner glass, but you also need to feather the joint back a couple of inches on the outside, lay in new glass to build the joint up to the original thickness, then apply new gelcoat. The challenge would come in enlarging the cockpit. I don't see how you can cut a piece out of the middle of a kayak without effecting the cockpit, and they tend to have moulded coamings to keep out the water and to allow a spray skirt to be tied on. Before cutting I'd want to figure out what to do about the cockpit. The only feasible thing to do would be to remove the coaming first, then enlarge the cockpit opening to the proper size after the boat is shortened. If the cockpit is recessed or the shape of the deck changes significantly, it will take a LOT of work to reinstall the coaming. The bottom line is that this project simply isn't practical. |
Shortening a kayak?
This idea of cutting a Kayak to size seems a bit dumb. Why don't you
just build a bigger storage space? Or if you want to work on a kayak buy a stitch and glue kit for a smaller Yak. But if you insist on cutting the kayak. Perhaps put in a 2 sturdy bulkheads about a 1 mm (or less) apart and cut between them creating two water tight sections that you can reconnect by butting the bulkheads together and bolting them firmly in place. You might even want to have 3 reattach-able sections stern cockpit and bow. |
Shortening a kayak?
Thanks everyone for your ideas!
I'll let you know what happens! Regards, Nick |
Shortening a kayak?
Brian Nystrom wrote: How many boats have you seen that have the exact same hull profile forward and aft of the centerline? Not many are designed that way. "Exact same profile" not required, just at a single point. How many do you want? These are 20 year old craft. The model names have been posted so you are welcome to look them up and let us know. Not many are designed symetrical fore-and-aft today but at one time all canoes and kayaks were symetrical. The many ways designers use to keep selling more boats is a topic for another discussion. Say they are not symetrical. Then the front section can be inserted into the rear section and locating the cutting lines is not as critical. Asymetrical would be easier. That wouldn't be anywhere near strong enough. To do it right, you need the inner glass, but you also need to feather the joint back a couple of inches on the outside, lay in new glass to build the joint up to the original thickness, then apply new gelcoat. It may or may not be strong enough in a patch or a scarphed panel but this is a tube. Any tension on one side is compensated by equal tension on the other. Just sand off the inside surface, position the two halves, cellotape around the outside to keep the resin from oozing out, and glasstape the inside. No need to do any fancy finish work to the outside. One does need, however to cut the hull carefully so the two pieces fit. People have reported using single sided taped butt joins on plywood boats to avoid the problem of finishing the outside surface. Apparently it does actually work there. The bottom line is that this project simply isn't practical. Where does practicallity enter into the hobby of paddling or boatbuilding? Giving up a day's pay to drive 200 miles to paddle down a river is practical? My own boatbulding is motivated as much by curiosity as practicality. Can it be done? Some don't like to spend money but time is no problem. |
Shortening a kayak?
Wm Watt wrote:
at one time all canoes and kayaks were symetrical. Care to back that up with something resembling a fact. It may or may not be strong enough in a patch or a scarphed panel but this is a tube. Any tension on one side is compensated by equal tension on the other. You really don't understand what a hull does in the real world. Tension has to be balanced by compression. Local loads have to be accommodated, not just overall bending moments. Mike |
Shortening a kayak?
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Shortening a kayak?
On 15 Aug 2006 02:50:18 -0700, in rec.boats.paddle
wrote: I am considering shortening them. Has anyone done this before? I had one on a trailer and backed it into a trellis, once. That probably doesn't count, though. Jones |
Shortening a kayak?
wrote:
This idea of cutting a Kayak to size seems a bit dumb. Why don't you just build a bigger storage space? Or if you want to work on a kayak buy a stitch and glue kit for a smaller Yak. But if you insist on cutting the kayak. Perhaps put in a 2 sturdy bulkheads about a 1 mm (or less) apart and cut between them creating two water tight sections that you can reconnect by butting the bulkheads together and bolting them firmly in place. You might even want to have 3 reattach-able sections stern cockpit and bow. Converting these to multi-piece kayaks is the only sensible solution other than getting rid of them and buying appropriate boats. |
Shortening a kayak?
Wm Watt wrote:
Brian Nystrom wrote: How many boats have you seen that have the exact same hull profile forward and aft of the centerline? Not many are designed that way. "Exact same profile" not required, just at a single point. How many do you want? These are 20 year old craft. The model names have been posted so you are welcome to look them up and let us know. Not many are designed symetrical fore-and-aft today but at one time all canoes and kayaks were symetrical. The many ways designers use to keep selling more boats is a topic for another discussion. What some people have done as far as design is irrelevent. More than likely, these boats are not symmetrical. Say they are not symetrical. Then the front section can be inserted into the rear section and locating the cutting lines is not as critical. Asymetrical would be easier. Are you kidding me? It's also quite likely that the ends are different enough that one will not fit into the other. For that to work, the fore and aft decks would have to be the same height, which is not common at all. That wouldn't be anywhere near strong enough. To do it right, you need the inner glass, but you also need to feather the joint back a couple of inches on the outside, lay in new glass to build the joint up to the original thickness, then apply new gelcoat. It may or may not be strong enough in a patch or a scarphed panel but this is a tube. Any tension on one side is compensated by equal tension on the other. Just sand off the inside surface, position the two halves, cellotape around the outside to keep the resin from oozing out, and glasstape the inside. No need to do any fancy finish work to the outside. One does need, however to cut the hull carefully so the two pieces fit. People have reported using single sided taped butt joins on plywood boats to avoid the problem of finishing the outside surface. Apparently it does actually work there. It only works because the boats are fully glassed inside and out after the panels are stitched. Perhaps some designs substitute fillets and tape on the seams for inside glass, but either way, the boat is substantially reinforced. I've never heard of a kayak kit or plan set that uses/recommends but joints without exterior glass and some interior reinforcement. The bottom line is that this project simply isn't practical. Where does practicallity enter into the hobby of paddling or boatbuilding? There's got to be a line somewhere. Perhaps others think this is a good idea, but I don't. Giving up a day's pay to drive 200 miles to paddle down a river is practical? I wouldn't do it. My own boatbulding is motivated as much by curiosity as practicality. Can it be done? Maybe you should offer to shorten these boats for the OP, just to see if it can be done. Some don't like to spend money but time is no problem. Knock yourself out, then! |
Shortening a kayak?
Michael Daly wrote: Wm Watt wrote: at one time all canoes and kayaks were symetrical. Care to back that up with something resembling a fact. Moreover, at one time all river kayaks were not only symetrical but were a standard 13 feet long. It wasn't until computer programs became available that all the different shapes appeared. It may or may not be strong enough in a patch or a scarphed panel but this is a tube. Any tension on one side is compensated by equal tension on the other. You really don't understand what a hull does in the real world. Tension has to be balanced by compression. Local loads have to be accommodated, not just overall bending moments. Any tension on one side is compensated by compression on the other. Mike |
Shortening a kayak?
Hanta-Yo-Yo wrote: You might just clip the ends back to the desired length, and then glass over the opening to be water proof. That way, the load handling central structure will not be compromised, as well as the rocker that is needed to turn easily. Also you will not have to mess with the combing if you plan to use a spray skirt. The sharp pointy ends are not needed really as demostrated in the newer generation of playboats and creekers. You are not looking to achive great speed characteristics, and depending on how good you are at the glass work, will tell how the finished product will be. You could always mount some sort of maiden form on the bow to scare off the swamp gods, or maybe attract a mermaid! HYY This is the best suggestion so far to take off a foot or so. I'd leave the bow alone unless more has to be taken off than can com eoff the stern. Cutting a foot off the back won't noticably effect bouyancy or stability. I'd put on a plywood transom. It would be easy enough to hold a piece of plywood against the cuttoff end and trace around with a pencil to get the shape. Then, if using an electric jig saw, set the base plate at an angle equal to the taper of the boat when cutting it out. A square cut transom won't fit the boat as well. The transom can be glued into the hull reinforced by bocks of wood glued in before or nails through the hull or both. The inside sruface of the plywood will have to be painted before it's put on the boat. My grandfather did this with a cedar strip canoe that had one end damaged. It worked well. |
Shortening a kayak?
Wm Watt wrote:
Michael Daly wrote: Wm Watt wrote: at one time all canoes and kayaks were symetrical. Care to back that up with something resembling a fact. Moreover, at one time all river kayaks were not only symetrical but were a standard 13 feet long. It wasn't until computer programs became available that all the different shapes appeared. A look at Charlie Walbridge's old book on whitewater kayak making proves this to be nothing but bull****. It also doesn't address sea kayaks and recreational kayaks. To this day, there are people designing kayaks without computer programs. It ain't rocket science. Any tension on one side is compensated by compression on the other. Glad you sorted that out. If you only reinforce on one side, as Brian pointed out, you'll get a weak joint. Hull-to-deck seams on some cheaper sea kayaks are only taped on the inside and are known to have split. No one I know would trust a one-sided seam for strength. Mike |
Shortening a kayak?
Michael Daly wrote: If you only reinforce on one side, as Brian pointed out, you'll get a weak joint. Hull-to-deck seams on some cheaper sea kayaks are only taped on the inside and are known to have split. No one I know would trust a one-sided seam for strength. Hull to deck seams are not only problems on fibreglass kayaks but also on fibregalss sailboats of all sizes, even very large, very costly ones. It's not because they are only taped on the inside. It's design and workmanship. I have a couple of open plywood sailboats which get quite a bit more stress than kayaks do. Sails can pull 75% dieways and only 25% forwards when going upwind. That putsa lot of twisting stress on the hull and pulls it over in the water, all too often to the point of capsize if you don't stay alert. The plywood panels on my boats are butt blocked with adhesives that are 1/20ht as strong as epoxy (urha formaldahyse and polyurethane). I've n to had any problems with teh butt joins even when the plywood has been delainating. Mike |
Shortening a kayak?
Wm Watt wrote: Michael Daly wrote: If you only reinforce on one side, as Brian pointed out, you'll get a weak joint. Hull-to-deck seams on some cheaper sea kayaks are only taped on the inside and are known to have split. No one I know would trust a one-sided seam for strength. Hull to deck seams are not only problems on fibreglass kayaks but also on fibregalss sailboats of all sizes, even very large, very costly ones. It's not because they are only taped on the inside. It's design and workmanship. I have a couple of open plywood sailboats which get quite a bit more stress than kayaks do. Sails can pull 75% dieways and only 25% forwards when going upwind. That putsa lot of twisting stress on the hull and pulls it over in the water, all too often to the point of capsize if you don't stay alert. The plywood panels on my boats are butt blocked with adhesives that are 1/20ht as strong as epoxy (urha formaldahyse and polyurethane). I've n to had any problems with teh butt joins even when the plywood has been delainating. I got kicked off the computer at the public library at the end of the time slot. So to continue ... The hulls on these two plywood boats are less rigid than the hulls on the kayaks I've paddled (about 20 models so far). I've done fibreglass repairs after reading one or two books on the subject. In spite of what you read from promoters of epoxy, polyester repairs can be made stonger than the origninal hull. The same repairs with epoxy are many times stronger than necessary. That's why I do not see any strength problem in cutting through a kayak hull and joining with interior taped butt joins. For the other reasons we have mentioned in this discussion (cockpit, reduced stability and bouyancy) it's not a good idea to take the extra lengthout of the centre of the hull so this part of the discussion is moot. |
Shortening a kayak?
Wm Watt wrote:
Wm Watt wrote: Hull to deck seams are not only problems on fibreglass kayaks but also on fibregalss sailboats of all sizes, even very large, very costly ones. It's not because they are only taped on the inside. It's design and workmanship. You don't get it, you never will. I'm a structural engineer and I know bad designs when I see them. Asymmetric joint construction is not good design. The hulls on these two plywood boats are less rigid than the hulls on [...] stronger than necessary. That's why I do not see any strength problem in cutting through a kayak hull and joining with interior taped butt joins. You do what you want. But don't advise others to do what is widely regarded as bad design and construction. Mike |
Shortening a kayak?
Michael Daly wrote: You don't get it, you never will. I'm a structural engineer and I know bad designs when I see them. Asymmetric joint construction is not good design. Gee, I got an "A" in engineering math at the UofT but note of that is relevant to the discussion. You've never tried splicing a kayak or any other boat, have you? What we see here is the triumph of theory over practice and knowledge over experience. You do what you want. But don't advise others to do what is widely regarded as bad design and construction. That's a piece of advice I'm not about to take. I've read over 50 boatbulding books, including books on scantlings and strengths of materials and on boat repair, done a lot of calculations, used and wrote boatbulidng computer programs, and tried a lot of different things, some of which did not work out. Butt joins are nowher condsidered bad desing or construction. Testing shows teh opposite. People can do their own test. Butt join two panels and then bend the result until it breaks (deforms in technical lingo). On plywood panels with epoxy adhesive the plywood breaks before the butt join. It's stronger than the rest of the hull. People can decide for themselves who they want to listen to. I've seen Michael's website which I like. (It's not about boat repair.) We've disagreed before, because he's been wrong before. Mike |
Shortening a kayak?
Wm Watt wrote:
Michael Daly wrote: You don't get it, you never will. I'm a structural engineer and I know bad designs when I see them. Asymmetric joint construction is not good design. Gee, I got an "A" in engineering math at the UofT but note of that is relevant to the discussion. There's a lot more to structural engineering than a bit of math. The essence of structural engineering is stress analysis and proper design within safety limits. On plywood panels with epoxy adhesive the plywood breaks before the butt join. It's stronger than the rest of the hull. Butt joins on fiberglass and butt joins on plywood are not the same thing. The difference in strength between the base material and the adhesive is significant. Plywood is thick and weak, fiberglass is thin and strong. Lapping a tape over one side of a plywood joint is not going to have the same effect as doing the same with fiberglass. As I've already pointed out - if single taped butt joints in kayak seams were sufficiently strong, we wouldn't see so many failures and so many paddlers condemn the manufacturing technique. If the joint was sufficiently strong, it wouldn't be so sensitive to labour and quality of construction as you have claimed. Mike |
Shortening a kayak?
Michael Daly wrote: Butt joins on fiberglass and butt joins on plywood are not the same thing. The difference in strength between the base material and the adhesive is significant. Plywood is thick and weak, fiberglass is thin and strong. Lapping a tape over one side of a plywood joint is not going to have the same effect as doing the same with fiberglass. Wood is as strong, pound for pound, as steel. Fibreglass versions of plywood boats weigh more. Plywood is as strong as fibreglass used on the same boat design. I don't get your point here. As I've already pointed out - if single taped butt joints in kayak seams were sufficiently strong, we wouldn't see so many failures and so many paddlers condemn the manufacturing technique. If the joint was sufficiently strong, it wouldn't be so sensitive to labour and quality of construction as you have claimed. I assume you mean single-sided taped butt joins. (I don't know if it's proper to call them "scarfs".) Single layer slingle-sided taped butt joins would problably be okay but if I were doing it I'd use single-sided double-layer joins, 4" glass over 2" glass. It adds so little in wieght, cost, and effort. A lot of experiments have been done in single- and double-sided taped butt joins in plywood with different adhesives and fibres. People have built with polyester, epoxy, and polyurethane resins, and glass and polyester fibre, to my knowledge, with satisfactory results. On the 19-year-old fibreglass kayak in question I'd stick with polyester (epoxy for those who want to spend more money) and glass fibre. Mike |
Shortening a kayak?
Wm Watt wrote:
A lot of experiments have been done in single- and double-sided taped butt joins in plywood with different adhesives and fibres. And other people have done the same with different results. However, we are talking about fiberglass boats here, not plywood. When you load a butt joint in tension, the asymmetric, single-sided joint will fail with a significant flexure in the joint. If it is symmetric, double sided, it will be in pure tension. The difference in strength is considerable. The difference in fatigue performance is considerable. Single-sided seams along a sheer line will _buckle_ if the hull is subjected to serious load - I've seen this happen. It buckles because the joint is not symmetric. Under those conditions, the single sided joint can split - I've seen this happen too. Why do you assume that _your_ experiments count for more than the experience that many others have had with single-taped joints? Good kayaks use a lapped and double-taped seam. That is much stronger than a butted joint and much, much stronger than a single sided seam. Mike |
Shortening a kayak?
Michael Daly wrote: And other people have done the same with different results. However, we are talking about fiberglass boats here, not plywood. When you load a butt joint in tension, the asymmetric, single-sided joint will fail with a significant flexure in the joint. If it is symmetric, double sided, it will be in pure tension. The difference in strength is considerable. The difference in fatigue performance is considerable. Single-sided seams along a sheer line will _buckle_ if the hull is subjected to serious load - I've seen this happen. It buckles because the joint is not symmetric. Under those conditions, the single sided joint can split - I've seen this happen too. Why do you assume that _your_ experiments count for more than the experience that many others have had with single-taped joints? Good kayaks use a lapped and double-taped seam. That is much stronger than a butted joint and much, much stronger than a single sided seam. A sheet of paper is also thin enough to fold. Once a tear is repaired with tape that part is stronger than the rest of the sheet. That's what you see in a butt join. It's thicker and more rigid than the rest of the hull. It won't flex. It won't fold. It can take more stress than the original hull before failing. If the hull's going to fold and fail it won't be at the butt join. Longitudinals and butts aren't comparable. Before there was firbreglass or plywood plank-on-frame hulls would work open along the seams but not at the butts where the planks were joined end-to-end. Longitudinals, being long and thin, are weaker. Butt joins are strong. The reason people scarf plywood and feather fibreglass is to get sufficient surface for adhesive strength. With butt joins the whole butt is the adhesive surface. A 2" butt is stronger than a 1/2" feather. As I wrote, I would probalyhy use a 4" over 2" butt. |
Shortening a kayak?
Wm Watt wrote:
A sheet of paper is also thin enough to fold. Once a tear is repaired with tape that part is stronger than the rest of the sheet. That's what you see in a butt join. It's thicker and more rigid than the rest of the hull. It won't flex. It won't fold. It can take more stress than the original hull before failing. If the hull's going to fold and fail it won't be at the butt join. Maybe you should spend a few years learning about stress analysis before making such ludicrous analogies. You haven't got a clue what's happening in a real structure. Mike |
Shortening a kayak?
Michael Daly wrote: Wm Watt wrote: A sheet of paper is also thin enough to fold. Once a tear is repaired with tape that part is stronger than the rest of the sheet. That's what you see in a butt join. It's thicker and more rigid than the rest of the hull. It won't flex. It won't fold. It can take more stress than the original hull before failing. If the hull's going to fold and fail it won't be at the butt join. Maybe you should spend a few years learning about stress analysis before making such ludicrous analogies. You haven't got a clue what's happening in a real structure. Mike Short of desinging, building, repairing paddling, and sailing in "real structure"s. You'd have to come up with something more subtantial than theory and hearsay to offer worthwhile advice. In a word, take your own advice above substituting "real structures" for "stress analysis". |
Shortening a kayak?
Wm Watt wrote:
You'd have to come up with something more subtantial than theory and hearsay to offer worthwhile advice. Theory is based on and validated by testing. In a word, take your own advice above substituting "real structures" for "stress analysis". In my case, real structures include ice breakers (finite element analysis of the USCG Polar Star when it was instrumented for ice forces on an arctic trip in 1981), offshore oil structures in the Beaufort Sea, aircraft (Canadair Challenger (now Bombardier)) some buildings and lots of other things. Your experience is playing in puddles with boats that never get tested. Since you don't even know that a structure without a straight load path _must_ bend, then you don't know anything that justifies your claims to expertise. Mike |
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