mjshp Posted February 20, 2012 Report Posted February 20, 2012 Went to check twist and square, there is shy 1/16th difference in the centerline to outer edge of the hull, and the similar shy 1/16th from transom corner to bow. Is this shy 1/16th small enough to call it good or should try to work it out? What other dimenions should i measure to check the squareness and for twist? Thanks, Michael Quote
John Burritt Posted February 20, 2012 Report Posted February 20, 2012 What you need to check is the straight distance from the stem to the corner on each side of the transom where it meets the shear. This will tell you if the hull is square. As you're working from a kit, measuring around the outside of the shear on each side won't work. You already know that the panels are the same length. You can check the symetry by pulling a line from the stem to the center of the transom at the top. Then measure how far the shear on each side is from the line you pulled into place. Measuring from the same point, these measurements should be the same. Quote
ecgossett Posted February 20, 2012 Report Posted February 20, 2012 My understanding from the boat school was things can be a little bit off on a stitch and glue and not be to horrible. Quote
mjshp Posted February 20, 2012 Author Report Posted February 20, 2012 Thanks for the clarification and help. The stem to sheer at the transom is less than 1/32 in difference port to starboard--this is measued with the boat level port-starboard. The centerline string to sheer at the nesting bulk heads is >1/32 but <1/16th, with the little extra on the starboard side. Thoughts? Quote
John Burritt Posted February 20, 2012 Report Posted February 20, 2012 Sounds disgustingly square. Also sounds like your variances are nothing more than variations in wood thickness. Good luck getting your gunwales glued on. Quote
mjshp Posted February 20, 2012 Author Report Posted February 20, 2012 John, Thanks again for all your help. First I have to make the gunwales. Quote
PAR Posted February 21, 2012 Report Posted February 21, 2012 A shy 1/16" is an exceptionally square boat. Be proud, decidedly not questioning of the result. Quote
hokeyhydro Posted February 21, 2012 Report Posted February 21, 2012 PAR is on target. 1/16" ??? I usually use metrics so we're talking about 1.5 mm. I'm not sure my semi-feeble eyes can read a scale that close. Well, I can and do it all the time when dealing with small measures like a 7mm x 14mm strip of wood, but for the entire boat? Hey, getting that sucker within 1/16" is cause for celebration. Well done! Quote
Tom Lathrop Posted February 21, 2012 Report Posted February 21, 2012 Went to check twist and square, there is shy 1/16th difference in the centerline to outer edge of the hull, and the similar shy 1/16th from transom corner to bow. Is this shy 1/16th small enough to call it good or should try to work it out? What other dimenions should i measure to check the squareness and for twist? Thanks, Michael You get the prize for the best alligned boat in the class. A gold star. Quote
Ray Frechette Jr Posted February 21, 2012 Report Posted February 21, 2012 I have got to say when I first saw the psot if there had been no responses I would have called for tolerance of 25 microns ... But that is just my lesser nature showing through wanting to egg people on.... Quote
mjshp Posted February 21, 2012 Author Report Posted February 21, 2012 The reality is all the credit goes to Graham. He designed the boat and cut out the kit. I just followed (mostly) the directions. The thing is I have ZERO experience with this, so I truly appreciate everyones help. Quote
JeffM Posted February 22, 2012 Report Posted February 22, 2012 Gosh, i wish I could measure my asymmetries in millimeters! Quote
Scott Dufour Posted February 24, 2012 Report Posted February 24, 2012 My boat was about off square about the same amount, and I have to say that I do notice a difference in performance. She pulls slightly to port when on a broad reach, and over a distance of 10 nautical miles, I find she's wandered a good ten feet off a straight line. It's not so bad in the northern hemisphere when the Coriolis Effect cancels it out, but it wreaks havoc when rounding the great capes. Quote
Charlie Jones Posted February 24, 2012 Report Posted February 24, 2012 I guess I should mention- when I was in Vandemere after Hurricane Irene "rearranged" things in Graham's shop, we releveled, and re squared that big power catamaran, to a tolerance of 1/16 inch. That's a 45 foot boat. Quote
PAR Posted February 24, 2012 Report Posted February 24, 2012 After the completion of a 36' powerboat hull shell (plywood lapstrake over frames) I won a bet she'd be under 1" in max beam difference. Measured from keel centerline, to underside of the sheer strake on each side, the hull was 7/8" wider on starboard then port. I won my 5 bucks and it was considered an exceptionally tight tolerance build. A short 1/16" oh pleeease, you're just showing off . . . Quote
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