JEM Watercraft
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Tolerances
http://www.jemwatercraft.com/forum/viewtopic.php?f=7&t=71
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Author:  jem [ Mon Dec 20, 2004 1:03 pm ]
Post subject:  Tolerances

In all our drawing packages, we shown measurements down to 1/16" increment for U.S. Standard and 1 mm in metric.

The reason we put these small increments into our plans is for the builders who feel more comfortable with exact, precision measurements.

Truth be told, you could be off as much 1/4" (6mm) on a boat with only a few panels and up to 1/8" (3mm) on the most complex plans we have and still have an exact fit. Those tolerance can get even looser when measuring total lengths of butt-blocked panels.

With wooden boat building, the tolerences do not matter as much because you can fix just about any "oops" you make.

So the "official" recommendation it to do the best you can to be precise but don't concern yourself if you're off a little bit. If you're not sure, just post or e-mail and we'll get you through it.

Author:  toolman [ Mon Nov 21, 2011 1:44 pm ]
Post subject:  Re: Tolerances

how much gap would be allowed between the fore and aft floor panels of the freedom 13.If more than 1/4 would you use blocks the fiber glass? big ooops

Author:  jem [ Mon Nov 21, 2011 6:01 pm ]
Post subject:  Re: Tolerances

Not 100% sure what you mean by gap. You mean when panel splicing to make the full length panel?

Author:  toolman [ Mon Nov 21, 2011 8:11 pm ]
Post subject:  Re: Tolerances

Yes it's the gap at the seam between the front and rear floor panels to make the full length panel .Hopefully I can save them by using a block and fiber glass

Author:  jem [ Mon Nov 21, 2011 8:57 pm ]
Post subject:  Re: Tolerances

IF you use a wooden butt block, it should be ok.

You could always cut the panels so you have about a 1" wide gap and fill that with a 1" strip of wood. Easier to fill in than trying to make a 1/4" shim.

Author:  toolman [ Tue Nov 22, 2011 12:06 am ]
Post subject:  Re: Tolerances

Thanks for the help I'll try the block I'm sure that will work(heres hoping)

Author:  toolman [ Wed Nov 23, 2011 10:35 am ]
Post subject:  Re: Tolerances

here is how my block turned out .Thanks again for your help http://s1130.photobucket.com/albums/m534/toolman519/

Author:  john the pom [ Thu Nov 24, 2011 7:36 am ]
Post subject:  Re: Tolerances

The hard bit about a first build, or a first anything for that matter is "what can I get away with, if I make a mistake"? The answer is probably a lot more than you think.
Say your bottom panels ended up an inch short. Could be side panels or deck panels for this exercise. You're gonna have a gap to deal with. Two ways of dealing with a gap. Fill it in with epoxy and woodflour. Cut the other bits down to match the "new" length. You might end up with a boat that is either an inch shorter, big deal, or a wedge of filler instead of a straight fill in. As its on the bottom it would NEVER be seen 'cos you'll probably either paint, or graphite over that wedge.
That's for the longitudinals. Even across the panels gaps can be overcome/disguised. Worst case your boat ends up an inch wider or thinner. You have to get your head around that if you do make a mistake, then the fix is not gonna be too difficult. The boat might end up with slightly different characteristics than any other boat. It won't be insurmountable, it probably won't even be noticeable. My last build I deliberately used a common fix to a frequent problem that I didn't have! This was because I had learned by making that mistake on a previous build that the adjustment to fix it enabled me to put a lot more Vee in the boat which was what I wanted. It's only a bit of plywood. Our mistakes are "character traits" in OUR boats

"yeah I did that deliberately"
:mrgreen:

Author:  jem [ Thu Nov 24, 2011 9:01 am ]
Post subject:  Re: Tolerances

Amen brother Jon!! :D

Author:  toolman [ Thu Nov 24, 2011 5:40 pm ]
Post subject:  Re: Tolerances

Thanks for the insight John ,I did have another problem with the deck panels not coming together right but with a little tought I worked it out. I guess I'm a little nervous cause it my first build but it's also my wifes Christmas gift. Thanks to you and Matt for the input.

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