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Fishman38

fishman38 OK20

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For the record, the pictures below illustrate the method(s) I used to form the keel/stem bevel.  When I get to the planking I'll comment on how successful it was....

post-2179-0-50982900-1366581382_thumb.jpgpost-2179-0-24741500-1366581411_thumb.jpgpost-2179-0-83063800-1366581439_thumb.jpgpost-2179-0-19615000-1366581494_thumb.jpgpost-2179-0-13313500-1366581523_thumb.jpg

 

The saw blade is a metal cutter and the piece of angle iron clamped slightly below the bearding line provided an audible signal when the correct depth was reached.  That left only the center line along the bottom of the keel to keep an eye on.  Once I kind of got the feel of the process I no longer used the guide, just watched the two lines.  It only worked on the straightaways anyway.

 

One must really be careful when he gets into the curves and scarfs to be sure to work with the grain, not against it.  I'm quite sure the spokeshave would have worked better there.

 

I'm sure this all looks pretty crude to the pros out there but it seemed to work for me.  If it turns out ok I thought the pics might be helpful to some other novice builder down the road.  Later on I'll try to mention whether I recommend doing it this way depending on how it looks when I start planking.  Someone on here said something like "with enough glue and filler you can fix most anything".  I hope he's right!  I think it took me 7 or 8 hours (to finish the beveling).

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I've located a local source for clear douglas fir,  They stock only 16 ft lengths of 4/4 material but tell me they may be able to get some in 20 ft lengths thus eliminating the need for scarfing to make the stock for stringers, chine etc.. Making the scarf is no problem but how much of a problem for fairing the hull does such joints cause?  In other words should I wait for the longer stock if they can get it and maybe pay a little more or will it make that much difference?  Anyone?

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Scarfs cause no fairing problems, you must make them long enough so they don't cause a hard spot, causing them to bend unfair.   12 to 1 is good.  My Doug Fir is clear but has a lot of grain run out in a lot of pieces.  From the sheer clamps up I must steam every piece.  Even the good ones are cracking and splitting from the bend.  Always nice to have the longer stock, but it won't all be good.  Your boat may not have as much stress in your stringers.  My stringers and chine pieces are larger in dimension and the twist at is bow is difficult.  But doable.   One more stringer on each side and i'll be ready for fairing and planking.  

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No scarfs beats scarfs as long as its straight-grained wood. Scarfs work best if they're located where there's not a lot of twist in the wood. Also, I wouldn't put one scarf right next to another one. Stagger them.

Miyot got his post up ahead of mine. More specific. Hope it all helps.

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Miyot when you steam I assume you must fit and clamp it in place then give it time to dry before gluing?  Thanks for the tip to make the scarf 12:1.  Otherwise I'd probably have made them the normal 8:1.  I could hardly believe it but the grain on the stuff I looked at was very straight.  I couldn't see anything that looked like run-out.  Hopefully it's as good as it looks.  Of more concern to me is it seemed to be very dry and will pro'bly require steaming because of that.  That (steaming) will be another new experience for me.  I'll have to figure out a way to do that.

 

Once again thanks to you and to John for the input.  It is all very helpful.  This forum is amazing.  I'm just wishing there was a way to catalog all the info! 

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Fishman, I'm not steaming per-say.  I have been wrapping a couple bath towels around my stringers and a piece of 5 mil plastic.  I open the plastic and pour boiling water on the towels, then close the plastic.  I do this about every five min. for about 40 min.  I have had no problems bending them in with this procedure.  It would probably be easier to make a tube of 5 mil plastic several wraps thick and then staple it along its seam to keep it closed.  Slip it over the stringer, tie off the far end and run a steam hose into the other end.  I made a steamer out of a steel gas can and radiator hose for my last build and steamed a 16 ft white oak keel for  my Haven sail boat (16' X  8" X 1 3/8" keel).  This works excellent.  I can't get my steam setup close enough to the ground for it to work, and I'm to lazy to mess with it.  So I'm just doing the  boiling water thing.

 

I cover the frames with plastic, bend the stringer into position.  Put the twist in with some clamps, cut the miter at the stem and clamp it up.  I have broken or cracked every one that I tried dry, above  and including the intermediate sheer.  Ruining every stringer and sheer I had made up months ago.  Even with good wood and no grain run out, they would not go.  And being lazy, I continued to try.  I let them dry in position for several days, and then glue them up.  No problems.  I had chosen my best boards out of 400 board feet of Fir for the bend and twist at the bow.  I still have some good boards left, plenty to finish.

 

The Fir is good wood and holds fastenings well, but I don't like it.  Very splintery, planning is a chore. You have to be careful and go with the grain, like all woods, but Fir particularly so.  You can't take big shavings for fear of tear out.  Don't put any scarfs near the bow and don't steam any of them.  I don't know if the heat would ruin the joint, but I suspect it would.  You may not need to go to this trouble on your build.  I do.

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I found an Earlex Steam generator, which was reviewed by Wooden Boat mag a couple of issues ago (#229) for $56, free shipping.  Just ordered it today and I'm always leery of online buying until I actually get my hands on it but have been doing it for years with no problems.  We'll see.

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I intend to start laminating the transom tomorrow.  The West User Manual says to wet both surfaces with unthickened epoxy, then spread thickened epoxy on one of the surfaces.  The manual doesn't say so but my inclination is to spread it a little thicker (coarser notch) if applying to only one surface.  Would I be right?  Is the amount of epoxy per sq inch quantifiable, ie which notch should one use?

 

 

On the other hand, I just re-read the Gougeon book on the subject and it says to use a roller and coat both surfaces.  It also implies you can laminate several layers at once.  Since I plan to use plastic staples, it seems necessary to do one layer at a time and remove the horizontal part of the staple before applying the next layer.  What say ya'll?

 

One more thing, any thoughts on the number of staples per sq ft I should use?

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A couple of questions regarding scarfing:

 

Is it correct to say that, as a general rule the the plane of the scarf should cut across the wider dimension of the piece being joined.

 

But what if the piece, the chine for example, is to be bent in a direction parallel to that plane?

 

Does it matter long as one adheres to the 8:1 to 12:1 ratio?

 

Not sure if my description is correct.  If not I may be able to to post a sketch.

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On your side stringers and chines the scarf is a 90 degree  angle to its length, it will take the bend and twist.  If you were scarfing planks that were curved  or shaped like a crescent moon when layed flat out, those would have a dog leg scarf.

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If you are making 2 or more pieces of wood into 1 long piece of wood and want the joint(s) to be structural it should be 8:1 to 12:1 like you saidFishman38.  If the piece will be bent under tension I think it is slightly better to have the scarf faces near parallel to the bend, or, in other words vertical for a horizantel bend like a gunwale.  If it is not being bent, then which ever orientation yeilds the widest gluing surface.   I use 8:1 for almost all scarf joints.  I do use 12:1 for solid  masts or the 4 sides of a box mast.

 

A 90º scarf is a butt joint Myot.  Did you mean something else?  I don't think we are talking long scarfed planks here, but a dog leg scarf is a good way to save material in this application.

 

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If you are making 2 or more pieces of wood into 1 long piece of wood and want the joint(s) to be structural it should be 8:1 to 12:1 like you saidFishman38.  If the piece will be bent under tension I think it is slightly better to have the scarf faces near parallel to the bend, or, in other words vertical for a horizantel bend like a gunwale.  If it is not being bent, then which ever orientation yeilds the widest gluing surface.   I use 8:1 for almost all scarf joints.  I do use 12:1 for solid  masts or the 4 sides of a box mast.

 

A 90º scarf is a butt joint Myot.  Did you mean something else?  I don't think we are talking long scarfed planks here, but a dog leg scarf is a good way to save material in this application.

I used a 10 or 12 to one scarf on my side stringers and chines.  The scarfs are  on a 90 to the length of the stringer, across the fat side or widest part.  Fishman 38, I didn't spend a lot of time messing with the scarfs.  I cut them with a band saw, trued them a little with a plane and glued them up.  The stringers were cut out a little over sized.  Then planed to proper dimension after the epoxy cured.   Makes a good looking scarf.

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 The scarfs are  on a 90 to the length of the stringer.............

 

Miyot, I'm sorry but I guess I would have to have a picture to understand what this means....I just can't picture which angle is 90 deg.  I'm also trying to imagine what a dogleg scarf looks like, although as Hirilonde says I'm mostly concerned with the chines and stringers at the moment.  But out of curiosity I tried to find the term "dogleg scarf" in all the references I have to no avail. 

 

Incidentally, I'm finding that my radial arm saw does a pretty good job making the scarf cuts.  By turning the blade slightly off the horizontal it even works on up to 9mm ply.  About 7 deg off the horizontal plane (the table) yields the 8:1, about 5 deg for 12:1. Got the idea from the Gougeon book.

 

BTW, I'm still a long way from installing chines and stringers.  Took forever to get all the plywood and solid lumber rounded up.  Finally gave up on finding suitable fir locally and drove to Louisiana and hauled back a couple of 2x10x16' cypress planks from which I'm ripping material for chines and stringers.  More knots in it than I had hoped for so it's still going to require a deal of joining, most of which I hope to get done before cutting the legs off my work table to start assembling keel, frames, stringers and chines.

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This is a crude sketch of a dog leg scarf:

 

post-442-0-71943500-1367754622_thumb.jpg

 

It is a regular scarf where the piece are a little askew rather than continuous on the same line.

 

It is used when you want to cut the long piece on a very large radius curve and want to make the most of your material by not creating a cut off shape that may go to waste.  It is partuclarly useful for making planks which are inherintly curved.

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Thanks Hirilonde, the sketch helps. So to make one you just would make the two cuts on slightly different angles, depending on how big a dogleg you need.

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The bevel is still 8:1 but instead of being square to the piece it is just a little askew such that the 2 mating bevels yeild the angle you want for the dog leg. 

 

This gets me thinking about Myot's comment about the scarf being 90º  to the length of the board.  He is not saying the bevel is 90º, but that it is cut 90º across the board? aka square to the board?

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 it is cut 90º across the board? aka square to the board?  That is correct, that is what I was trying to say.

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Another, well maybe not dumb, I'll call it a "novice" question:

The inside corners CNC cut notches in the frames are rounded.  My inclination is to round over the inboard corners of stringers and chines end to end with a router. 

 

So should I round over end to end or just where the stringer contacts the frame. 

 

I think I prefer the latter.

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