xrayboat Posted July 9, 2015 Report Share Posted July 9, 2015 I have built a SOF and S&G single and would like to build a SOF tandem. I had an old russian one I wore out that was more comfortable than any plastic/fiberglass/wooden boat of various design that makes my sometimes seasick prone wife far happier in any kind of chop. While delighted w/ the performance of my old Ladoga 21' x ~30 " 62# boat (excellent design, inferior materials) and my used point65N doubleshot 20'1" x 26" 84#, I'm interested in building something ~18' x 25" day tripping low volume tandem SOF and hoping for <50#. Capefalcon mentions adding 6' to his 14 x 23" and happy w/ result. He does classes and customs, not plans. I was looking at various yost-style SOF singles in the 13-16' x 21-24" and considering scaling up myself (easier, I surmise in fuselage frame than in falcons more traditional build). I've seen only one set of plans for a MC baidarka in tandem (paddling light) and am personally disposed to 1-2 harder chines and something a little leaner. Q's: 1. has anyone got any advice/pointeres re: problems I should anticipate? 2. anyone else ever done something like this? 3. am I crazy? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Kudzu Posted July 9, 2015 Report Share Posted July 9, 2015 First, welcome to the forum. I have toyed with tandems off and on but the demand is very low and I don't really want one so it is hard for me to get serious about one. I have been thinking about them (again) lately though. I am not a fan of "scaling" boat designs because strange things can happen. There is a lot of subtle changes that would need to be made to produce a good design. That said, it is done fairly often and the people that post about it, seem happy with their boats. Of course we probably don't hear from those that have failures, no one like to admit they failed either. Those that do may not really have a good design but just don't have anything to compare it too? Not saying it can't be done but there are a lot of pitfalls. It all depends on your skills and experience. I seem to remember that Yost has at least one tandem on his site. I know his web site is down, but I am sure there are copies of his plans floating around. My biggest concern with a tandem is what size to make the stringers. When you add another person you have the potential to easily double the load on the boat and i am sure the stress is more than doubled. I don't know what size stringers he used but I would start there. Secondly, stability is so much more than just width but it is an important part, but hull shape has as much to do with stability too. But when you talk about a 24" wide tandem I suspect it would be rather tender with two people in it. Quote Link to comment Share on other sites More sharing options...
xrayboat Posted July 9, 2015 Author Report Share Posted July 9, 2015 Thanks. Maybe best I get familiar with software that lets me start w existing design and tweak to gauge impact of effects on perceived stability. I haven't used any of the hull modeling programs but think I probably should and put something less ambitious like a c15 or similar in the project q. I did expect to upsize stringers and probably let a symmetric middle swell a bit from the single design, perhaps scaling middle stations up to get a wider midsection advantage of a fuselage style is you could almost eyeball what looks to flow appropriately in curves, but would be elegant to do this fairing in software first. Thanks. Maybe best I get familiar with software that lets me start w existing design and tweak to gauge impact of effects on perceived stability. I haven't used any of the hull modeling programs but think I probably should and put something less ambitious like a c15 or similar in the project q. I did expect to upsize stringers and probably let a symmetric middle swell a bit from the single design, perhaps scaling middle stations up to get a wider midsection advantage of a fuselage style is you could almost eyeball what looks to flow appropriately in curves, but would be elegant to do this fairing in software first. Quote Link to comment Share on other sites More sharing options...
Action Tiger Posted July 9, 2015 Report Share Posted July 9, 2015 The easiest way would be to build a boat traditionally. Use anthropometric measurements for both paddlers. Start with beefy gunwales and deck beams, and determine volume and shape with the ribs you bend in place. People have been doing it for as long as we've had kayaks. I've done a dozen boats this way, but no tandems. Yet. Quote Link to comment Share on other sites More sharing options...
DURRETTD Posted July 9, 2015 Report Share Posted July 9, 2015 I've owned a tandem kayak (18' x 29", 85 pounds - I think) and it worked fairly well with two people. It was a pig when paddled solo: One person didn't sink the boat enough to get the intended stability, with so much boat above the waterline it got blown around badly, it was heavier than a single, tandems REQUIRE a rudder, and if I loaded it enough to compensate for the absence of a partner it was difficult to paddle due to the weight and the wide beam. If you want a tandem, you'll also need a single for the times you don't have a partner. I'd recommend having two singles instead of a tandem. It's easier (for me) to tow the other person's single than to paddle a tandem solo while the other person rests. On the other hand, Jeff's boats are so quick, inexpensive, and easy to build that if you build a tandem and it spends most of its time hanging in the carport it's not a tragedy - as it would be if you spent $4,000 on it. Dan Quote Link to comment Share on other sites More sharing options...
mfrankel Posted July 9, 2015 Report Share Posted July 9, 2015 I have been paddling a (slightly modified) C-15 with my wife for a few seasons. I am 5'9" and my wife is 5'1." Neither of us is heavy. If my wife was significantly taller, I would lose legroom and would probably feel a little cramped. For us, the C-15 is very stable, easy to paddle and surprisingly fast. My wife overcame her insecurity about kayaking in the C-15 and now prefers to paddle solo. But for orthopedic reasons, we need the tandem for longer and strenuous paddles. We took the C-15 on a 14 mile paddle on Long Island Sound last Sunday. It was delightful. Earlier this year, I did the same search you are doing because I like building kayaks, I would like to move on to a narrower, faster kayak with two cockpits, and at this point, I think it is safe to sacrifice some stability. There are double plans listed on the Clarkcraft website, but when I placed my order, they replied that they are sold out. I did not see the Falcon option. The only plans I found are the Yost plans Jeff mentioned. They are available on a weird website that archives old web pages. I think it is Internet archive wayback machine or something like that. I am shortening the plans a little so the double will fit in my garage better, lowering the gunwales an inch for ease of paddling, and for reducing the volume and modifying the deck slope so it looks less like a torpedo. A word on plan modifications. When I built Jeff's Ravenswood design, I changed nothing. Jeff says his plans are tried and tested and I believe him. Same with Dave Gentry. Before modifying his C-15 plans, I emailed Dave to get his blessing. Unlike Jeff's and Dave's plans, Yost never claimed his plans were tried and tested. He posted them for free. If builders told him the plans were no good, he took them down. I don't see internet pictures of completed Yost doubles. And now the Website is gone altogether. I doubt that you are messing with success modifying the plans. In any event, the Yost plans are multi-chined. I am planning to make the stringers 5/8 x 3/4, and the gunwales 5/8 x 1 3/8. Quote Link to comment Share on other sites More sharing options...
xrayboat Posted July 9, 2015 Author Report Share Posted July 9, 2015 Thanks for input to this point. I'm blessed/fortunate to have paddled many singles and own a number just want to add and refine the fleet. I far prefer the comfort/feel of sof to hardshell and while I love my fiberglass tandem performance but its weight and comfort pale to my own experience in sof tandem. The hard to find Ladoga sof Russian tandem I owned some years ago was fantastic-- I introduced scores of people to paddling in its front cockpit before its materials failed beyond my ability to repair (great design, inferior ingredients). It weighed 62# and performed well though I was expecting a nonfolding sof in lower volume design could go under 50#. I'm a fool for not recording offsets before that one was disassembled for last time. So... I've experienced great tandem performance in sof and want to build a replacement. While waiting for Kudzu to offer plans for a true performance tandem (no paddle clash), I may go w a rec boat either converting another old frame I have or mess-about or chuckanaut15 modification. I am interested in the anthropometric approach but have no experience w/ steam bending ribs. I did note that capefalcon uses same approach but would like someone to point me to a detailed instructional on that technique. Cheers. Quote Link to comment Share on other sites More sharing options...
Kudzu Posted July 10, 2015 Report Share Posted July 10, 2015 Under 50# should be easy. Long Shot is 18 feet and typically 35 lbs. If you kept a tandem to say 19 feet long, your only adding a pound maybe? Add some extra weight for larger stringers, an extra seat, coaming, foot rests. 40-45# is probably very realistic. I forgot to add a rudder, but still very doable I think. Quote Link to comment Share on other sites More sharing options...
mitchmellow Posted July 10, 2015 Report Share Posted July 10, 2015 Yostwerks had tandem plans: the Sea Tour EXP 20. You can still see the site on web.archive.org and should be able to find the offsets. If I remember correctly, it was 20 feet long with a beam of 26 inches, estimated weight was 55# and it was multi chine. Quote Link to comment Share on other sites More sharing options...
Action Tiger Posted July 10, 2015 Report Share Posted July 10, 2015 Steam bending is a whole world unto itself, but like most things, is very simple. There really are no hard and fast rules about steaming, except lots of hot, wet steam. And wear gloves. Probably an apron, too, if you plan to get your belly involved. With kayak ribs, you probably will. I think green wood works better than dry, but dry wood can soak up enough moisture to steam, if you keep it in water for a week or so first. I once used an old mantle to make ribs for a kayak. Straight, flat grain works best... usually. A couple of relevant books would be Morris and Cunningham. They both wrote books about building SOF kayaks. My research indicates these double boats were often used to transport "sports" in the front hole. Make a little bread by paddling southerners (everybody is a southerner if you live in the arctic circle, I guess) around and letting them play seal hunter. Brrr. Quote Link to comment Share on other sites More sharing options...
woodman Posted July 10, 2015 Report Share Posted July 10, 2015 The Night Heron looks like it could be turned into a hard chine SOF.....http://www.guillemot-kayaks.com/guillemot/catalog/boat_building_plans/tandem_kayak_plans_0 Quote Link to comment Share on other sites More sharing options...
CSayer Posted July 10, 2015 Report Share Posted July 10, 2015 Thanks for starting this thread! Great opportunity for another newbie to jump in for the first time! I'm just about to get started on a C15. Wanting a lightweight tandem, it seemed the best choice for a fairly new builder (one plywood pirogue) with a wife inclined toward stability. But I'm here on the board because I'm a fan of Jeff's book, and there seem to be a lot of good ideas that apply to either Dave or Jeff's designs. Will there be more builds in the future? Hope so...Jeff, if you ever do go with a tandem, I'd sure be interested. Quote Link to comment Share on other sites More sharing options...
Kudzu Posted July 11, 2015 Report Share Posted July 11, 2015 Wife and I were talking this morning over banana-pecan waffles and maybe it was all the sugar but we talked about the possibility of us paddling a tandem (divorce) boat. Really not sure this is a good idea and afraid it was just elevated sugar levels. But, I am going to dig around the folder and see if I can find any of my old tandem designs I played with and take a look at one. It's to hot and humid to enjoy paddling so what the heck.... Quote Link to comment Share on other sites More sharing options...
CSayer Posted July 11, 2015 Report Share Posted July 11, 2015 Nobody has ever made a bad decision over waffles. At a Waffle House, sure...but never over waffles. 1 Quote Link to comment Share on other sites More sharing options...
Kudzu Posted July 13, 2015 Report Share Posted July 13, 2015 Here is a concept I came up with over the weekend. Ignore the colors, they are just easiest to see on the screen. Reading about Baidarka tandems has me leaning toward a Baidarka style hull. Not so sure the styling is what I want to offer. To many people just don't like that. But it is starting point. 1 Quote Link to comment Share on other sites More sharing options...
Action Tiger Posted July 13, 2015 Report Share Posted July 13, 2015 I'm the type to be tempted to put the green on bottom, the red on top, strip of white between and black dots all over the top. Big old slice of watermelon boat. It looks cool. I'm with you about the baidarka, but then I like them. Mayhaps you can offer two stem options? Make an awesome snaggletooth boat, or a boring smooth tipped one... Quote Link to comment Share on other sites More sharing options...
mfrankel Posted July 13, 2015 Report Share Posted July 13, 2015 Jeff: Your design looks similar to the modifications I am making to the Yost plans, except for the baidarka stern. Trying to keep it simple. Mark Quote Link to comment Share on other sites More sharing options...
CSayer Posted July 14, 2015 Report Share Posted July 14, 2015 When you say you're not sure about the baidarka style, do you mean the bifurcated bow, or the fuller, higher volume hull form? Or perhaps both? It does seem that doubles run a bit chunkier... not surprising I guess, since "couple's rolling" is probably unpopular. I know it would be with my crew. Quote Link to comment Share on other sites More sharing options...
woodman Posted July 14, 2015 Report Share Posted July 14, 2015 http://cmamyc.com/yakayak/node/17 A free S&G plan..... Quote Link to comment Share on other sites More sharing options...
Kudzu Posted July 14, 2015 Report Share Posted July 14, 2015 When you say you're not sure about the baidarka style, do you mean ........ Styling mostly. Baidarka hull design is well proven but the styling is not everyone's cup of tea. Most people prefer the Greenland styling. I don't think I would offer a Baidarka as my first/only tandem. I would probably get the hull shape like I want and try to make it look more Greenland. Quote Link to comment Share on other sites More sharing options...
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