Can't think of good title, need your help though!

[dmede]

Sorry, I didn't know how to summerize this issue into a subject line you would notice. :D

I am getting ready to transfer measurments from my plans to my planking stock to get out the plank shape for my garboards (measurements supplied in plans).

This requires measuring across the plank width at each station from a single straight basline along one edge of the plank. The problem with the garboards is the plank is scarphed together in a dogleg so it's shaped like a very shallow V with no long straight edge and my bench ins't long enough to use as a straight edge (I need 12').

The only idea I have come up with is to tack down a line from one corner of the plank to the other and measure off this line.

Got any better ideas?

dave

[ 03-04-2005, 02:37 PM: Message edited by: dmede ]

[John of Phoenix]

... transfer measurments from my plans to my planking ...is known as "lofting"

Your solution is fine, "If you don't have a straight line, make one up." Sure. Another would be to strike a centerline and measure from there, not much different than yours.

What are you building?

[Ian McColgin]

Actually sounds like he has plans not yet lofted.

Lofting is making full size plans, in a nutshell. But there's more.

Go to our WoodenBoat store, buy Viatse's little book "Lofting." It's a few pages in under boatbuilding.

[dmede]

I know what lofting is :rolleyes:

This boat only requires fullsize lofting of the bulkheads, mid frame and stems. The plank dimensions are given in the plans and, in a sense, lofted directly onto the planking stock. No spiling.

My issue is how to get a good straight base line for those measurments. Idealy I would have a very long straight work bench to lay the stock on and I could measure across the stock from the bench edge. I dont have that. So I need to create a straght edge for the planks somehow (since they are not straight themselves).

Make any sense yet? For each station I have two sets of measurments away from the base line, taken together they describe the width of the final plank at that station, I then connect those spots with a batten to get my fair planking stock - lofting on the stock itself. But my stock is doglegged so I can't use its own edge for measurments. I need advice on how to create a temporary straight edge:

Solutions include:
Line tacked to each end of plank stock to measure off of. But may be too flexible or might pull board into a funny shape if held too tight.

Or tack down a 12' length of wood, but will probably not be perfectly straight unless its a good size peice and jointed.

This doesn't even make sense to me anymore. You'll all just have to come over to my house and take a look. I got cigars and scotch
;)

[dmede]

Sorry John, I didn't answer your question. It's Harry Bryans 12' Fiddle head canoe.

http://www.harrybryan.com/harrybryan/fiddle12.html

Harry has been kind enough to spile the planks and give the measurements in his plans.

I think my main concern with the line is that it will need to be tight to be good and straight and might pull the thin stock out of shape. No way to knwo until I try I guess. Thanks.

[ 03-04-2005, 04:23 PM: Message edited by: dmede ]

[htom]

I'd make a temporary workbench out of some sawhorses, three 14' 2x6 on edge, and two 2'x8' sheets of 3/4" MDF.

[John of Phoenix]

Nice looking boat. A dogleg garboard…

I think I may have had a similar problem with an oddly shaped 20' curved keel. No place to draw a line from one end to the other to measure from.

Ok, get a piece of paper somewhat larger than your garboard and tape it to the garage floor. I like that heavy gauge red paper used in the remodeling industry to protect floors and carpets. Use the edge of the paper as the reference line and draw the garboard onto the paper. The full size drawing can now be taped to the lumber then transfer enough points to duplicate the drawing onto the piece for cutting.

Does that help?

[dmede]

Bingo! I knew there was an easy answer I was missing.

Yeah that might just work.

[Gary E]

Your taut string will work fine. Quite often when a straight referance line is needed we would anchor a piano wire at one end then let the wire fall over a V'd roller bearing with a 10 lb weight hanging on it. This will provide a straight line. For your work, I would use a length of mono from a fishing rod and anything heavy that's handy.

[dmede]

After remembering that the base line intersects the board at the ends of the cut plank and not at the ends of the plank stock, I went ahead and tacked down a line of mono to use as my base line. Worked great, thanks all.

[Ken Hutchins]

IMO I would rather spile the planks, it is not difficult and I'm sure would produce better results. There is bound to be some differences between the plans and your actual boat.

[dmede]

Well there are of course some differences, but you can easily adjust the measurements in the plans to match the actual widths at the frames and bulkheads you've already built.

I didn't even do that and I ended up with a very close fitting garboard just from the provided garboard lofting measurments. Any differences were similar to those I experinced in my last boat where I spiled the planks. IMO, for a boat like this with only three wide planks per side and knuckled frames, having the measurments in advance so you can loft right to the planking stock is a great help.

dave

edited to add: if you take your time and get the original lofting and construction of the bulkheads and mid frame right, and set it up corectly on the building base there is no reason the premeasured planks can't be a very nice close fit, needing only minor refineing once offered up to the boat (as would be the case with a spiled plank).

[ 03-07-2005, 01:57 PM: Message edited by: dmede ]