BottOm Pannel

So for my Rouge River Dory I need at least 15'2" bottem pannel (maybe longer since there is rocker to the bottem, but thats what the plans in Fletchers book say). So my problem is that if I use 1/2" ply for the bottem then using the suggested 12:1 ratio for scarfing together ply wood I will have a 15' pannel, just bairly to short. Is it ok to change the 12:1 ratio and just do like 3" in on the ply so I will have enough length with just 2 boards (dont really want to buy another pannel cause thats the only place im using 1/2"). Or what are my other options?

 

Also what type of faseners do you use to attach bottem and side pannels to frame?

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Permalink Reply by Jordan Davis on February 8, 2011 at 12:11pm
You really need to use proper technique when scarfing. There are unbelievable amounts of pressure on those scarf joints and if you do not allow for enough surface area where you join the panels they will "POP" and you will end up having to do it all over again anyways.  Stick with the 10 to 12:1 ratios here.  There really are no shortcuts.  Also, you will most likely want to have some 1/2" around for decking/storage/fly decks on the boat so having an extra piece won't be so bad.  Also,  you won't want to scarf in just a 6" to 12" piece.  There will be too much pressure on a 6 to 12" bend in the rocker.  You most likely would want 3' worth of ply to evenly distribute pressure over the bend in the bottom ply.  I am no expert, but I have snapped scarfs, so I guess I have learned from my mistakes.  Hopefully this helps.
Permalink Reply by Rick Finnell on February 8, 2011 at 12:39pm
When you say snapped do you mean glue failure or did the plywood break ?
Permalink Reply by Jeff Peak on February 8, 2011 at 1:10pm
your math is wrong (and spelling, but who's counting..."bottOm")...If you're using .5" ply, a scarf joint at a 12:1 ratio will be 6"...leaving your bottom pannel 15'6".
Permalink Reply by Ben Kittell on February 8, 2011 at 2:13pm

Sorry for the spelling error, not my best subject. You are right, I guess math is not my best subject. Maybe thats why im not in school right now...

 

Thank you for pointing that out jeff, so hopefully 15'6" will get me there. Cutting it kinda close though.

 

Jordan, I am planning on using 1/2-3/8 fir ply (not the same really expensive stuff used on bottOm and side) for decking.

Permalink Reply by Jeff Peak on February 8, 2011 at 4:21pm
Ben, I too have spent too much time on MtnBuzz, guess thats where I learned my poor internet manners.  I sometimes forget that the woodenboat crowd is far more civilized than that...my apologies, kind sir...
Permalink Reply by John Greenleaf on February 8, 2011 at 4:31pm
Ben, One other possibility, assuming you have not already bought the wood - many places do sell 4'x10' sheets in addition to the standard 4'x8' sheets. You can then scarf a 10' er to an 8'er and that would get you out to 17'6". J.G.
Permalink Reply by Eric Loudenslager on February 8, 2011 at 6:15pm
From the plans in Roger's book it is not easy to determine the actual bottom panel length because of the rocker. You may want to contact Roger to see if he can tell how long the panel needs to be. According to the plans the straight-line distance is 14' 10-1/4" (15"-2" - 3-3/4"), but that is not the panel dimension. You could also "loft" the shape of the bottom. Take a batten (1/8" or so by about 8' x 1") mark the positions of the frames on the batten (use 0.5" for each 1" on the plans). Then measure the distance of the widest frame from the edge of a piece of plywood (about in the middle of the plywood sheet's length); anchor the batten at that location using a couple finish nails. Then move to the forward frame locations, one at a time, and anchor the batten the distance each frame is from the edge of the plywood sheet. Do this moving to the stem and transom ends and you will have the outline of the bottom panel. Then you can measure the length, minus the overhang on the transom itself. To mark the location of the frames on your batten use the side panel measurements on page 271, not the table of offsets on 267.
Permalink Reply by lhedrick on February 8, 2011 at 7:21pm

Because of the shape of the bottom you are going to have some large pieces which will be cut off.  Just scarf the 2 sheets together and if needed use part of the cut off and scarf on more if needed.  The scarf joints will be very strong so it doesn't matter how many us use.

 

This is an issue which isn't really worth spending any time on.  It will work out fine.

Permalink Reply by lhedrick on February 9, 2011 at 2:50pm

Ben,

 

I had a conversation with my friend Ryan who built a Rogue from the plans in Rogers book.  He said he had an issue with the numbers on the stem.   The stem image and dimensions are on page 268.  From what he described when the sides were bent to the stem the didn't come in at the correct angle.  He made adjustments to get things to fit.  When I hook up the stem after milling it I attach 1 side with epoxy then pull in the other side.  I would recommend making a short stem section from scrap before doing the milling of the actual stem so you can be sure it's correct.  Done glue it all up until you are sure.  If for what ever reason you find the same issue, post your findings as I am sure Roger would like to know about it if something needs to be adjusted.

 

L

Permalink Reply by Ben Kittell on February 9, 2011 at 3:09pm

Thanks for the heads up. I was already planning on waiting to glue the stem, but now i will use a scrap piece for pulling it together. Hopefully I will get access to a camera soon and will start a blog of the build.

 

Also, emailed Roger and he said the bottom pannel comes out to be right about 15' so two sheets should be perfect.

Permalink Reply by Roger Fletcher on February 14, 2011 at 7:17am
Ben, I think you asked me directly about bottom panel length. It's right at 15'. Also, I notice that Larry commented on someone having a challenge with the stem. Larry, can you clarify? Someone tried to build the Rogue dory with 3/8-inch side panels and he/she had a nightmare of a time. The bends on that boat, given the flare, are tortuous. Quarter-inch side panel is best to get both bend and wrap, and is more than adequate strength for the boat.  Also, the fit will be off if there is a modest error in the side panel cutout. She's a lovely boat that has stood the test of time on the Rogue, but also the most challenging to build among the free form built boats in the book. Whatever you do, take time, think it through, and have great fun with the project.
Permalink Reply by lhedrick on February 14, 2011 at 2:11pm

Roger,

 

My friends name is Ryan and his boat was built about 3 years ago.  I had a short discussion with him a week ago and asked about what he ran into.  He told me it was related to the stem dimension.  Possible the linear dimension of the back cut which has a half length of 3 inches.  That would make the full width 6 inches with 45 degree sides.  The stem cap shows 1 5/8 with space for 1/4 sides.  I will try to sketch one out and see if the numbers match 45 degree angles.  He said he would check his notes.  I will be on the river with him this summer and will check it out.

He also mentioned something about and bad number on the half length on one of the frame dimensions.  He said it was something obvious like feet in stead of inches.  I checked the book but I didn't spot anything and he couldn't remember what it was.  When he was building the boat he mentioned something which was not working out.  I told him to email you with the information but, I guess he just didn't get around to it.  Minor stuff as it didn't hold him up.  When I nail it down I will send it to you if there is something there.

 

 

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