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Cedar Strip Kayak
Fergus OMore:
At the risk of being 'up the creek without a paddle' might I ask why a sea kayak design be reduced in length?
Somewhat quizzically
Norman
sparky961:
I already have a very nice 17' boat. I was going for something very light and nimble to be used primarily on small lakes. Good question though.
Fergus OMore:
OK but surely reducing the length also increases the depth? Not necessarily the manoeuvrability because this requires rocker as I have no doubt that you are aware.
I'm one of the old brigade who used 'folders' like my old Klepper T65 and Slalom 55. One of my old mateys( well in his 90's) used a Prout- or so he said. Found Blondie Hasler's mob just a bit too - well- dangerous.
I trained with the British 1948 Olympic coach and we had a rather long K4- in case you don't have such things now- that seats 4. It came from Royal Canoe Club on the River Thames on the deck of an empty collier returning from the London fired power stations back to the Tyne.
your post is consequently very interesting.
vtsteam:
Looks good Soarky. :thumbup:
Tables of offsets were originally developed from solid carved hull models constructed in lifts. The lifts were traced around on paper to produce waterlines, and stations erected at convenient mould spacings. Not necessarily frame locations. So they could be at irregular spacings, as indeed the lift spacings were often as well. All of these measurements (offsets) were relatively inaccurate because of the degree of scaling up needed to produce a ship. So the table of offsets for the model was used only as a starting point to loft out the lines full scale on the floor of a mould loft and faired there with battens.
In later times, fairing and development happened not through carving a solid model, but by drafting. Additional lines were needed for that in the form of buttock lines and diagonals. Nevertheless the very small scale of most drawings still needed to be corrected by lofting full scale to avoid unfairness on a finished vessel. Tables of offsets which were proven out full scale this way are called "corrected offsets."
Because traditional tables of offsets are developed to aid construction spacing, and for fairing and development, they aren't necessarily spaced or described ideally for quick entry in computer programs. Rather they were done that way for conventional lofting purposes. Just a situation now where old meets new. I worked on computer programs to do naval architecture design work in the late seventies and early eighties, and it was definitely a pain doing the conversions -- the usual traditional small craft NA practice up to that time was in giving offsets as three numbers -- feet inches and eighths, and even using a plus for indicating a sixteenth occasionally in the table. All that is pretty irrelevant now unless you just eliminate the computer altogether and do it the old way, start to finish.
sparky961:
--- Quote from: Fergus OMore on January 08, 2016, 08:06:47 AM ---OK but surely reducing the length also increases the depth? Not necessarily the manoeuvrability because this requires rocker as I have no doubt that you are aware.
I'm one of the old brigade who used 'folders' like my old Klepper T65 and Slalom 55. One of my old mateys( well in his 90's) used a Prout- or so he said. Found Blondie Hasler's mob just a bit too - well- dangerous.
I trained with the British 1948 Olympic coach and we had a rather long K4- in case you don't have such things now- that seats 4. It came from Royal Canoe Club on the River Thames on the deck of an empty collier returning from the London fired power stations back to the Tyne.
your post is consequently very interesting.
--- End quote ---
Both the length and rocker, amongst other things, affect the maneuverability. Anyone who's paddled a 10' Big Box Store Plastic Special kayak will be keen to tell you that they don't track worth a damn. They have, however, very little rocker to speak of. Incidentally, nor do they have many other redeeming qualities.
In modifying the length, I did not do so linearly. The process is described well in the book but essentially you leave the cockpit mostly the same, while taking most of the length from the narrow bow and stern. This preserves a lot of the volume but does sacrifice efficiency a bit. Considering this is already a very narrow boat, I'm not worried about it. I don't expect given my own weight and the boat size that I'll be able to load it down with gear like my other expedition boat. But that wasn't the intention in the first place.
Looking at the big picture, I was trying for a balance. It is intended to sacrifice tracking and speed while gaining (in this case by losing) in the weight department. My estimates and comments in the book put this somewhere around 30 lbs. My current boat is almost double that. Hard to say how things will turn out... likely more like 40-45 lbs but we'll see. I have no experience laying fibreglass so that might be where it gains a few lbs extra.
Interesting to note that you were kayaking long before I was even born. It might have even been before my parents were conceived. ;) Were they still making them from animal skin in those days? ;) Perhaps more ecologically sound when you think about it. I'm privileged to have the opportunity to partake in the stories of your wisdom, experience, and undoubtedly some mistakes over those years.
I had never heard of a K4 but I'm somewhat familiar with the current K1's. I always have a good laugh watching the clips of the Olympics. If you haven't seen them, picture taking the narrowest kayak you can fit an adult male's hips into. Now get out the shoe horn and stuff a guy with the upper body of Arnold Schwarzenegger (thank you spell check) into said boat. Fire off a starter's pistol and it looks like the Road Runner on a Jet Ski. Not quite the kind of paddling I'm into but I like watching the slo-mo to improve my own technique.
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