CoopOnDaCooper Posted October 6, 2013 Posted October 6, 2013 Building my first SOF kayak..... I'm sure to make some mistakes, leading me to constructing another boat...and another, quite likely. I am constructing my strongback at present. I bought 3 2X4X12 and 1 5/4X6X12, all Pressure-Treated. I had to do this because it's quite likely my strongback will have to live in the weather. I don't have a garage or storage shed long enough to take it. This will likely be the same fate of the 'yak, as well. All of which leads me to two possible ways to address this. Knowing that cedar is rot resistant, not rot-proof, and no natural wood is rot proof- encapsulate with epoxy, or start with a material that can take exposure to the elements for a good long time in the first place.. pressure-treated wood. Yes, I am aware that SOF construction doesn't need epoxy, is beautiful on it's own merits, etc... and I agree. But if I can use modern materials to supplement this (with the obvious caveat of let's not make it into a moonshot) and increase the durability of the project- why wouldn't I? Obviously the boat will be heavier. A quick google search shows us SYP 2X4X8 is about 1.28lbs/linear foot... so 10-1/4 pounds (10 pounds, 4 ounces) Treated is about 15% heavier. Of course this all depends on species of lumber, etc... Yes, the weight difference will be substantial- about 3 pounds, maybe more. I'm still going to have a darn light boat- and to be blunt, the first thing I need to work on lightening is my arse- and I'm doing that... I won't be able to store the boat indoors ( I live in Charleston, SC, so frost really shouldn't be a concern). I realize that there will be a UV concern with the coating. I'm ok with having to redo the finish now and again (although, I may have a solution to avoid that, too). The point of this is to find out if a SOF is worth doing to a high-end level (all cedar, etc) when it won't be able to be "babied". It'll be strapped to my fence in the back yard (basically, a kayak rack) year round. Quote
PAR Posted October 6, 2013 Posted October 6, 2013 Epoxy doesn't stick well to the latest chemicals (CA) used in PT lumber. Even if not using epoxy, the usual selection of PT stock is farm raised and pretty lousy stuff. Very wide growth rings, lots of defects, pith and pitch pockets everywhere and generally not what a typical wood worker or boat builder would desire in small dimension, dynamically loaded stock. This stuff works fine in a static load situation, if sized sufficiently for the inherent weaknesses (2x4's, 2x6's etc.). Used as framing in your aunt Millie's back porch, it'll be fine, but ask it to be long, thin and constantly twisted, flexed and load tested in a boat, well, it'll rear up and show you pretty quickly what it's able to tolerate, usually with a resounding crack. Quote
CoopOnDaCooper Posted October 6, 2013 Author Posted October 6, 2013 That's EXACTLY the sort of info I was looking for.Thanks. Sounds like PT is fine for the strongback, but I will make this boat out of non-PT, and epoxy-encapsulate. Thank you sir! Quote
Hirilonde Posted October 6, 2013 Posted October 6, 2013 I store my Curlew outside for 5 months each year upside down. None of wood gets wet. I see no reason to use epoxy. 1 Quote
GaryMinor Posted October 7, 2013 Posted October 7, 2013 I'm also building my first SOF kayak (Mess About). I am building my strongback out of one piece of 4'x8' 1/2" birch ply. Not Baltic Birch. It is a box beam. The bottom is 6", The sides are 4" , and the top is whatever is left (approx 10") after saw kerfs. The top and bottom have shallow groves to help with alignment.The completed beam will be 16' long. The whole assembly is held together with screws. The reason that I'm mentioning this is that I plan to disassemble it when not in use. It will stack on end, using less than 1/2 sq ft of floor space, and each piece is no more than 8' long. If you are intrested in more details, let me know. Gary Minor Quote
labrat Posted October 7, 2013 Posted October 7, 2013 A lot of people store trailer boats outside under tarps. In addition to putting it upside down as already suggested for the water issue you could also use a tarp to keep the sun off the hull. I am guessing you would get a reasonable amount of UV in your location so a cover of some sort would be worthwhile. Don't use nylon as UV kills it very quickly. A cheap replaceable poly tarp would do for a while. Or if you wanted something to last a bit longer maybe a polyester canvas. That could be painted as well to make it last longer. Quote
CoopOnDaCooper Posted October 7, 2013 Author Posted October 7, 2013 Mr. Minor: I am quite interested in info on your strongback, but it sounds like advanced woodworking skills are required. Got pics? Sent from my MB886 using Xparent Green Tapatalk 2 Quote
Kudzu Posted October 7, 2013 Posted October 7, 2013 Here is about the simplest and most effective strong back you will find Quote
CoopOnDaCooper Posted October 8, 2013 Author Posted October 8, 2013 So sad it's funny: I was offloading the lumber off my truck's rack when I got home. Granted, I wasn't gentle- un-strapped the safety lines and chuck each piece over my head... The 5/4 board fell on the ground and freaking shattered into two pieces. Seriously, there's a cleavage plane as if it was made of rock! Now normally, I am a big fan of cleavage... But in my lumber, notsomuch.... Definitely a good demonstration of the false economy of trying to save a few bucks on materials. Lesson learned! Quote
CoopOnDaCooper Posted October 8, 2013 Author Posted October 8, 2013 Mr. Kudzu (don't feel comfortable calling you Jeff as if I know you, yet... I'm Southern, you understand I'm sure.....) That is one gorgeous boat. I'd love to do a strip-built boat in the future, but think I will have to let that wait for a while, yet... Quote
GaryMinor Posted October 8, 2013 Posted October 8, 2013 Here are some pictures of my strong back in process. I haven't assembled it yet, so I can't say for sure that it is going to work like I expect. I am building my strongback out of one piece of 4'x8' 1/2" birch ply. Not Baltic Birch. It is a box beam. The bottom is 6", The sides are 4" , and the top is whatever is left (approx 10") after saw kerfs. The top and bottom have shallow groves to help with alignment.The completed beam will be 16' long. The whole assembly is held together with screws. This shows the pieces of a 4x8 sheet of 1/2" ply, arranged in the original order. The shortest pieces are 2' long. http:controlware.netMessaboutone.jpg This is the pieces rearranged to show how they are assembled to build the left end of the box beam. http:controlware.netMessaboutleft.jpg This is the pieces rearranged to show how they are assembled to build the right end of the box beam. http:controlware.netMessaboutright.jpg Note that the topmost pieces are 8' each, and that there is only one joint between them. That joint is shown in both the left and right pictures. I am fortunate that I have a tablesaw that can handle a full 4x8 sheer of plywood, and keep the edges straight. Straight edges for the side pieces are important. The other pieces... not so much. The groves for the sides to fit into the top and bottom are not necessary, but they help with the assembly process. I cut them with a router and a guide fence. A dado blade on a table saw should work. Other designs will work, and may be better in some ways. I wanted something that I was sure was straight. I wasn't comfortable with lumber yard boards. Also, I wanted something that could be taken apart and stored easily. Quote
GPStick Posted October 8, 2013 Posted October 8, 2013 I made a plywood strong back. Hung it from garage ceiling with the boats. Like your plan. JoeSent from my iPhone using Tapatalk - now Free Quote
CoopOnDaCooper Posted October 8, 2013 Author Posted October 8, 2013 Which plan are you referring to, gps? Quote
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