# Thread: Lofting question - offset from outside of plank

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## Lofting question - offset from outside of plank

I've lofted the lines for a boat that were drawn to the outside of the plank. How do I measure in the accurate distance from the lofted body section lines to get the correct offset for the line to the inside of the frame so that I can now loft those lines?

I'm using this technique but I'm not positive that it works, and this boat has 22 stations and six waterlines through the hull (another through the keel). What I'm doing so far is, using the plan view, if I'm working on Station 12 at the LWL, is to draw a line from where the LWL intersects Station 11 and 13. Then, I'm measuring over the thickness of the planking and frame to get the angled dimension. Then, going to the body plan section for Station 12, I am measuring over, using the angled dimension, perpendicular from the face-of-planking line I have drawn, and where that new line intersects the LWL is where I am assuming the correct offset for planking and frame is at for that specific location (where Station 12 crosses LWL inside of the frame).

This is my first lofting project so if my reasoning so far is "unique", just blame it on me being a greenhorn at this. But I am a very picky person when it comes to being accurate and if I do all this work to create the "new" inside of frame lines, in addition to having already lofted the outside lines, I want it to be accurate. Close won't cut it. If I set up some molds and drop a keel plank on them with a rabbet cut into it, and it doesn't match up with the frames when I bend them over the mold, after having went through all this, I might just get a little ornery with myself.

The other thing, is the way this section detail shows the garboard basically butting into what is just one side of the rabbet. This actually works out like this too once the lines are lofted. It's because the keel plank is only 1-1/8" thick and also specifies the distance that the bottom of keel plank is below the rabbet line. Is this adequate? It's basically like a seam between planks and that's all. There's actually 3/16" to 1/4" of wood on the inside edge of the plank.

Capture.jpg

3. ## Re: Lofting question - offset from outside of plank

You normally loft the sections and then loft the waterlines and buttocks from them and check that all three are fair (and part of the same boat!). 11 stations are usually enough for basic lofting and fairing, splitting the DWL into 10. But maybe you have 22 frames??

Then for the inside of planking, work on the sections (so you can make the temporary moulds – or laminated frames – or whatever). Simply measure the planking thickness perpendicularly from the lofted line of the station – do it about every 100mm or so and fair in with a batten. Or make a short length of timber (say 50mm long) the thickness of the planking and sit this on the lofted station line about every 100mm and tick off the inside of planking – fair in with a batten as usual.

If you need the inside of planking on a waterline or a buttock, draw the waterline on the body plan grid (the sections) and measure the horizontal distance the inside of planking is from the outside. With a buttock, measure the vertical distance. You don't normally need to draw whole new inside of planking waterlines or buttocks – unless you want to derive the shape of a component – like a bunk front or bunk top – or want to find the bevels of sawn or laminated frames.

1⅛" does seem a little thin for a wood keel - how big is the boat??

Cheers -- George
Last edited by debenriver; 07-03-2018 at 07:07 PM.

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## Re: Lofting question - offset from outside of plank

I'm pretty sure it's a 12 1/2, he has another recent thread about it

one hell of a first boat to loft. your drawings might not be accurate. have any others that show the rabbet line at that sta. ? or maybe you could find photos of a 12 1/2 under construction to give a clue

i just started lofting a round-bilge boat and ran into similar issues. I ended taking a spiling block or small dividers to mark the plank thickness from outside to inside, then sprung a batten and faired it. totally a pain in the butt compared to the hard chined, straight sectioned boats I've lofted before (at scale and full size) I'm sure the ol' timers had a better way about it but ill be damned if I can figure it out

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## Re: Lofting question - offset from outside of plank

The diagonals and some other lines, like the sheer, are approximately square to their center in at least one direction, leaving one bevel to measure. Amidship, the sheer and diagonal deductions will be plank thickness. As you move to the ends bevel will increase and adjustment over plank thickness increases.

6. ## Re: Lofting question - offset from outside of plank

Originally Posted by George Ferguson
snip
I want it to be accurate. Close won't cut it.
Building wood boats is about getting it close, but you're still working with wood and no two boats will ever come out exactly the same. You might need to adjust your tolerance scale.

Just about every book I've read on small boat building says just subtract the nominal finished thickness of your planking stock, it'll be close enough. They also say to leave a bit of meat in the rabbet for a final fitting when you get the garboard ready to hang.

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## Re: Lofting question - offset from outside of plank

Wow! I posted this today and looked back online and have some quick responses..........but none providing an explanation. Or, maybe I wasn't able to phrase the question accurately. Anyhow, I do appreciate the answers. And there just might be an answer there if I read the responses enough times. I've been known to come to a conclusion too early.

Telenorth, you are correct. The boat I am lofting is Nettle, a Herreshoff 12 1/2, and using their record set drawings that they sell at Mystic Seaport. I love the little boat design and have had a lot of fun lofting it. But, the thing about boat plans, I've discovered, is a lot of information is provided in very subtle ways and those subtle ways of relaying the info are expected to be utilized as required by the person using the plans. I want to have the lines drawn and faired, outside of plank, inside of frames, detailed sections in the body plan, profile view, and plan view, along with everything else I can figure out to draw, including little things like the floors with bevels, and layout of deck material, etcetera. But, I want it all to be accurate within a 1/16" of an inch. I actually do this on my "breaks" and spare time when I'm not working my "real" job. If I were building the boat right now, I'd probably just make the molds to the lines drawn to the outside-of-plank lines, set them up with battens included, and use a piece of wood to scribe the thickness of the plank and frames, and then re-cut the molds to the new lines. I know there is a way to do this accurately in the lofting process though, and I think I am correct but if I am wrong then 176 little points I'd have to come up with, just might be wrong. I won't know I have them right.

Debenriver, I've "lofted" the boat with a confidence that I now feel very good about being accurate to the drawings of Nettle. It took several times, with some completely new starts, to get it right but now I've got the lines to the point where I can start detailing them. I did not start with the body sections though. The books I've been using by Howard Chapelle and Allan Vaitses say to loft the profile view, plan view, and diagonals, and then, reconcile them in the body plan. It took me a while to get it through my thick skull but I figured out they really meant it when they said to, FIRST, loft out what I call ALL the edges and make sure they are fair, BEFORE lofting the curved waterlines, buttocks, diagonals, and stations. If that is done, in all three views, profile, plan, and body, then it saves a lot of wasted time when drawing in the rest of the lines. The drawings I've been using do not have a set of offsets either, and they are somewhat distorted, so fairing those "edges" first really pays off. I also figured out, after I created the first set of stations in the body plan, that the profile view and plan view can be used to check each other against each other to make sure the lines are fair BEFORE creating the station lines in the body plan. I've lofted the lines with the thought process of the hull being separate from everything below the keel plank. That's helped me to define the "edges" so that it simplifies the process in my mind. I also did that because the more I looked at photos of original H12s the more I realized it appeared to be that way and not like the curved transitions shown in the plans. It makes sense too because as long as the top of the lead keel and deadwood have the same defining edge as the bottom of the keel plan, they'll match up perfectly. And when lofting a boat where you have to scale the lines, and you don't have a table of offsets, fairing up the edges, including where the bottom keel plank meets the keel, pays off. And, I did this, probably on the third go around, in the body plan too, including the fairing of the keel plank to lead keel connection, the sheer, face of stem, and transom (up to the sheer). A lot of the dimensions for doing this are actually defined in the construction plan sheet and the lines plan. You don't even have to scale very many of them if you look for the tidbits of info in the plans. I think that's because those lines are so critical to defining the boat. That's why I am hesitant to change a detail like I posted above or make the frames 7/8" instead of 13/16" like the plans specify (although I don't believe they used dimensions specified to the 16th originally).

Thad, your comment states exactly why I am looking for help from someone who knows how to find those accurate measurements from face of planking to backside of frames. I thought about just using the diagonals, which are a big help in these drawings, but then I remembered that by themselves they don't provide the extra little degree of accuracy you can get by using all the points where the stations cross the waterlines and buttocks. You are correct that amidship the measurements at the stations are basically very close to the actual thickness of the planks (1/2") and the frames (13/16"). And near the bow and stern the angles get up to around 33 degrees where using just the actual thickness of the combined plan and frame measurement would not be accurate at all, and I'd end up with a mold that, when used, would not allow the planking to end up matching the lines plan. In fact, the planks would pass beyond the face of the stem and not even come close to hitting the rabbet line.

Oh well, I'll probably work on this tomorrow using the technique I think will work. Hopefully someone can verify that it's accurate or at least tell me a technique that is accurate.

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## Re: Lofting question - offset from outside of plank

Originally Posted by Peerie Maa
Peerie, I should have went to this link before I wrote the book, I mean last comment. But could you clarify that what they are saying by bevel, that they are talking about the angle where the curved waterline in the plan view intersects with the station line? I think my assumption on that is correct. At one point, Ross says you can take the average of the two angles on either side of a station. That sounds a lot like what I am doing in my technique. Anyhow, I feel better about the way I am doing it and will proceed more confidently.

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## Re: Lofting question - offset from outside of plank

George I recommend you get your hands on the Gougeon Brothers boatbuilding manual and look at the lofting chapter. The most flexible, accurate and efficient way to determine station bevels and deductions is with a master bevel board. The Gougeon manual illustrates the master bevel board. Very few books do, offhand I can't think of another one. Then ask more questions.

Waterline and butts in half breadth are generally of no use in determining accurate bevels and deductions. As Thad mentioned, sheer and diagonals can be more in the ball park. Or you can learn the master bevel board and get an accurate bevel and deduction anywhere you wish - it all happens in the body plan. Accurate station bevels lead to accurate deductions.

I agree if you are merely talking about the planking thickness of a small dinghy then this kind of accuracy is not critical. If you are talking about something more, than accuracy begins to matter.
Eric

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## Re: Lofting question - offset from outside of plank

Originally Posted by Eric Hvalsoe
George I recommend you get your hands on the Gougeon Brothers boatbuilding manual and look at the lofting chapter. The most flexible, accurate and efficient way to determine station bevels and deductions is with a master bevel board. The Gougeon manual illustrates the master bevel board. Very few books do, offhand I can't think of another one. Then ask more questions.

Waterline and butts in half breadth are generally of no use in determining accurate bevels and deductions. As Thad mentioned, sheer and diagonals can be more in the ball park. Or you can learn the master bevel board and get an accurate bevel and deduction anywhere you wish - it all happens in the body plan. Accurate station bevels lead to accurate deductions.

I agree if you are merely talking about the planking thickness of a small dinghy then this kind of accuracy is not critical. If you are talking about something more, than accuracy begins to matter.
Eric

Yes, this. Specifically, page 182 will begin the section on how to deduct planking thickness. I recently built Eric's Hv13 design and with 1/4" planking I could have cheated with a simple deduction. But, the internal connections within my brain won't let me do things like that without knowing the ramifications. So nothing for it except to dive in. I lofted as if I had thick planking that needed my full attention. Yes, it was an intellectual exercise but one that I wanted to pursue.

In the end, one realizes that there are so many tiny variables in a boat that slavish adherence to formulae and calculations becomes ludicrous. Accuracy is a floating definition. (I've allowed the pun.... sorry.)

Jeff

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## Re: Lofting question - offset from outside of plank

You are on the right track in principle to allow for the varying thickness in the frame plus planking dimension. I think you will be happy to learn that there is a tool just for this purpose and even better - you get to make it yourself. It's called a bevel lifter and appears in S.S. Rabl's book: SHIP AND AIRCRAFT FAIRING AND DEVELOPMENT which I was introduced to by Greg Rossel..
I will describe it and try to post a picture as well. Actually this is right from the book:
"This tool is constructed similar to an overgrown carpenter's bevel gauge, with the exception that it is set vertically and has feet that keep it perpendicular to the floor. A sliding arm allows the base of the triangle, one side of which represents a frame space, to be increased or decreased. A lock nut at the upper end is fixed in the stationary part, and the arm can be fixed to prevent its moving it desired. A mark lining up with the pivot point on the top is placed on one frame line and the pointer placed on another. Due to the fact that the pivot point is exactly one frame space above the floor, the arm takes the angle that would exist between the particular frames on the actual ship."
All this happens on the body plan so you can stop going back and forth and back and forth. You pick up as many bevels along a given frame as you think is necessary, Mark them on a bevel board to show how much the angle increased your plank plus frame dimension ,then go back to the body plan to plot where the line of the mold should be. I simply use these points to set my nails to pick up the shape of the mold,but you could draw the mold of you are so inclined.
I'm not going get into whether all this is necessary - that is another discussion entirely. What I do know that if you do it, that will make two of us... I did it when I lofted my Flatfish which is Joel White's centerboard version of the Fish class which of course is a scaled up 12-1/2.
IMG_20180704_111955.jpg
Sorry about the picture quality. I'll dig out the one I made and take a picture of it.
Cheers,
Bob

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## Re: Lofting question - offset from outside of plank

George,
Here's a picture of my bevel lifter. I found having a weighted base helps.IMG_20180704_125541.jpg

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## Re: Lofting question - offset from outside of plank

[QUOTE=113bob;5612596]George,
Here's a picture of my bevel lifter. I found having a weighted base helps.IMG_20180704_125541.jpg[/QUOTE

113bob, thanks for posting both of these photos. This is very, very helpful. The tool and the photo of the drawing both allow me to visualize why this makes complete sense. The line drawn between the two stations is like a diagonal plane and the tilting straight edge of the tool gives it a 3D effect to show the "angle" of the planking as it passes over that station. If the width of the tilting angle piece were the thickness you were trying to offset, you could literally use that to scribe onto a board and then transfer the marks to the body plan without even having to do any measuring or math, or anything.

I wonder if this is like the master bevel board that jpatrick and Eric Hvalsoe were talking about in the Gougeon book. And I see why others kept mentioning diagonals.

I'd already started drawing sections of the boat at each station using a line starting at the rabbet and running out mostly perpendicular to the waterlines in that area. I've finished one and offset the thickness of the planking and frames. Once I get a few others done so that when I draw in the new waterlines, I'm going going to compare them to the results of using a tool like this.

Thanks a bunch! I'd already given up and figured I'd just make molds (whenever I do build this boat, if I do) to the face of the planking, set everything up with battens running over them, and then scribe back using a block of wood the thickness I want to offset. Then, re-cut the molds. That was the only way in my head I knew I could for sure get it exactly right.
Last edited by George Ferguson; 07-04-2018 at 01:33 PM.

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## Re: Lofting question - offset from outside of plank

Works for me. Will work for you too.

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## Re: Lofting question - offset from outside of plank

George,
A couple more things:
I've assumed that since you are concerned about deducting frame and plank thickness to derive the shapes of your molds that you have lofted the boat, full size and reconciled all the dimensional info you have and are now looking at a finished body plan, half-breadth and profile and diagonals that are all faired to your satisfaction and all agree with one another. Is that where you are now?
If so great, let's continue.
If not, you should really get to that point - where you have accurately depicted the shape of the boat before you get involved in all the bits and pieces.
That being said, back to your suggestion to use a 1-5/16" arm on the bevel lifter. Again, in principle, a good idea, but in practice a little cumbersome, trying to line up the outer edge with a station line and Mark the mold line from the inner edge when the angle of the arm to the floor is different each time you use it.
Below is a picture of the kind of bevel board you create from the bevel you pick up using the bevel lifter and what I was referring to earlier. You draw a line parallel to one edge offset by the combined thickness of your planking and frame. In your case, 1-5/16" , in my case it was 1-1/2" . You record the bevels as you lift them - I lettered them, on the board and on the body plan. Then, using dividers you pick up the distance along each bevel line from your combined thickness reference line to the edge of the board and transfer that distance to the body plan where you picked up the bevel. Repeat that for each bevel along that station, and those points represent your mold line (or inner frame, if you prefer). You can fair those new points of you want to draw that line, or do what I did and just use those points to set my nails to pick up the shape directly onto my mold stock, and do the fairing step there.
IMG_20180705_093520.jpg
That's it for now.

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## Re: Lofting question - offset from outside of plank

The bevel lifter, and a master bevel board, and some other tricks are all operating on the same principal. With a known station spacing, it is simple trigonometry.
The bevel should be read fore and aft then averaged, for an accurate station bevel at any particular point. That usually means adding another station at each end of the boat.
A master bevel board (and maybe the bevel lifter) allows you to use whatever station spacing is handy. You can quickly mark a corresponding measuring stick off the master bevel board. Bevels are read square to the tangent of any particular point on the station line - rather like a diagonal passing through - but I mean really square as best you can judge.

Still worth a look at Gougeon.

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## Re: Lofting question - offset from outside of plank

Originally Posted by Eric Hvalsoe
The bevel lifter, and a master bevel board, and some other tricks are all operating on the same principal. With a known station spacing, it is simple trigonometry.
The bevel should be read fore and aft then averaged, for an accurate station bevel at any particular point. That usually means adding another station at each end of the boat.
A master bevel board (and maybe the bevel lifter) allows you to use whatever station spacing is handy. You can quickly mark a corresponding measuring stick off the master bevel board. Bevels are read square to the tangent of any particular point on the station line - rather like a diagonal passing through - but I mean really square as best you can judge.

Still worth a look at Gougeon.
Eric, thanks for the info. I've taken a break from the lofting for a few days but I may visit it again this weekend. After seeing the photo of the bevel lifter above, I realized it was simple math, like you are saying. And I agree about taking the average. I do plan on purchasing the Gougeon book you'd recommended. I've been using a book called Lofting, by Vaitses, and Howard Chapelle's book called Boatbuilding. I also have a book by Larry Pardey where he builds the hull of Serrafyn that is interesting. All of these guys take a pretty much general approach to measuring planking/frame offsets.

After drawing a few sections at right angles to the sheer, I realized that's something that also can be done fairly quickly so that the lines can then be redrawn to the inside of the planking. For deducting at the transom, I actually think that is the probably the easiest way to get very accurate results.

Having said all that, I've happened upon a new little beauty, William Garden's Eel canoe yawl design, and have ordered the plans. After having been learning to loft with the H12 drawings where there are 22 stations, the plans for Eel only have eight body stations. That's going to feel weird with so few stations. I'd even added a few extra stations at the stern of the H12 where the lines change so much, and a couple of more buttocks to get a better feel for how the midship was fairing out. The H12 also has sloped waterlines which can fool a person setting up the grid to create the body stations. That was interesting as well. But, I read in one of my books that sloped waterlines were not uncommon because of how some of the larger boats would be set up for construction. It does create an issue with being able to keep the lines drawings condensed to a smaller area. And it gave my mind some pain until I studied it for a while and realized how to "look" along the plane of the waterlines while "looking" at the stations in the body plan. Even with the slight distortion in the lines plan for Nettle, I would recommend someone wanting to practice their lofting, to use those drawings. Having to create your own table of offsets to get started with, the closely spaced stations, the simplicity of the boat, all make it a good drawing to use for learning. And, I may even build a boat based on those lines one day.

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## Re: Lofting question - offset from outside of plank

The Gougeon book describing the Master Bevel board is excellent, and this is one of those things that once you see it you go, ‘Oh, so simple, duh, what took me so long to understand it?”
One of the mental blocks here is that you are focusing on understanding how waterlines, station lines, butt lines all interact with each other, you forget that while you have defined the shape of your dream boat, now you have to go and cut the pieces.
The phrase to remember is the saw cuts a bevel normal to the curve, in other words the true bevel is alway the one that is perpendicular to the curve at that point. The bevel you pick up on the loft floor may be quite far from being perpendicular to the piece you want to cut out.
For example, if you look at a Plan view intersection of a Station and a Waterline at the Sheer, the bevel you measure might be pretty close if the Station is close to perpendicular at that Waterline when you view it in the Body Plan. But if you did the same thing at a Station and Waterline crossing in the Plan view but when you look at that crossing in the Body Plan it is a nowhere near perpendicular to the curve.
If you follow the steps in Gougeon, it will make sense, but the first time bending your mind around the concept will give you a headache...just get on your knees and follow the steps.

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## Re: Lofting question - offset from outside of plank

Originally Posted by Paul Schweiss
The Gougeon book describing the Master Bevel board is excellent, and this is one of those things that once you see it you go, ‘Oh, so simple, duh, what took me so long to understand it?”
One of the mental blocks here is that you are focusing on understanding how waterlines, station lines, butt lines all interact with each other, you forget that while you have defined the shape of your dream boat, now you have to go and cut the pieces.
The phrase to remember is the saw cuts a bevel normal to the curve, in other words the true bevel is alway the one that is perpendicular to the curve at that point. The bevel you pick up on the loft floor may be quite far from being perpendicular to the piece you want to cut out.
For example, if you look at a Plan view intersection of a Station and a Waterline at the Sheer, the bevel you measure might be pretty close if the Station is close to perpendicular at that Waterline when you view it in the Body Plan. But if you did the same thing at a Station and Waterline crossing in the Plan view but when you look at that crossing in the Body Plan it is a nowhere near perpendicular to the curve.
If you follow the steps in Gougeon, it will make sense, but the first time bending your mind around the concept will give you a headache...just get on your knees and follow the steps.
Paul, I plan to put in a supplemental station for each station that would be offset the same thickness of the mold "stations". Then I was going to flip over the molds and press them back onto the lofting floor nails at those stations. Then I was going to finish the molds to both lines. Wouldn't that work?

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## Re: Lofting question - offset from outside of plank

I think what you are saying George, is that you plan to strike another Station line by deducting a consistent 5/8” or whatever the plank thickness is, and use that for your mold? And if you are building upside down you will have to deduct for ribbands as well...?!?
You have not made a ‘real’ deduction though. Get yourself a 2 x 4 and your tri-square and strike a 90 degree line across the 1-1/2” face, and then strike a 45 degree line. Now measure the length of those two line...the 90 degree line will be 1-1/2” long, the other quite a bit longer. Now look at your Body Plan and visualize the planks ( not the Waterlines) crossing the Station curve. The Eel does not have 45 degree bevel, shapely though she is, but you can see the error that creeps in.
When we built a 65’ Garden Motoryacht, the station molds were deducted from outside of plank. From Chine to Keel rabbet the deduction was Plank Thickness(1-1/2”) plus frame thickness (1-3/4”), for a total deduction of 3-1/4”. From the chine to the Sheer we deducted that amount PLUS another 1-3/8” for the ribband thickness.
It was common to slide the hot steam bent frames inside the Ribbands from kell to chine, and then bend them outside the ribbands from Chine to sheer. This made for substantially quicker framing manhours.
Do the Master Bevel Board, and follow the steps to make your deduction finds. PM me if you get stuck.
Do it...it is good for your brain! And good for the boat.

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## Re: Lofting question - offset from outside of plank

Originally Posted by Paul Schweiss
I think what you are saying George, is that you plan to strike another Station line by deducting a consistent 5/8” or whatever the plank thickness is, and use that for your mold? And if you are building upside down you will have to deduct for ribbands as well...?!?
You have not made a ‘real’ deduction though. Get yourself a 2 x 4 and your tri-square and strike a 90 degree line across the 1-1/2” face, and then strike a 45 degree line. Now measure the length of those two line...the 90 degree line will be 1-1/2” long, the other quite a bit longer. Now look at your Body Plan and visualize the planks ( not the Waterlines) crossing the Station curve. The Eel does not have 45 degree bevel, shapely though she is, but you can see the error that creeps in.
When we built a 65’ Garden Motoryacht, the station molds were deducted from outside of plank. From Chine to Keel rabbet the deduction was Plank Thickness(1-1/2”) plus frame thickness (1-3/4”), for a total deduction of 3-1/4”. From the chine to the Sheer we deducted that amount PLUS another 1-3/8” for the ribband thickness.
It was common to slide the hot steam bent frames inside the Ribbands from kell to chine, and then bend them outside the ribbands from Chine to sheer. This made for substantially quicker framing manhours.
Do the Master Bevel Board, and follow the steps to make your deduction finds. PM me if you get stuck.
Do it...it is good for your brain! And good for the boat.
I just ordered the Gougeon brothers book.

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## Re: Lofting question - offset from outside of plank

Bravo! If we were in the same room, well, in my shop, the process could be fairly easily gone over. Having the printed procedure in front of you will no doubt answer the bulk of your questions.

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## Re: Lofting question - offset from outside of plank

Originally Posted by George Ferguson
Paul, I plan to put in a supplemental station for each station that would be offset the same thickness of the mold "stations". Then I was going to flip over the molds and press them back onto the lofting floor nails at those stations. Then I was going to finish the molds to both lines. Wouldn't that work?
Yes - After determining accurate station bevels, and after determining accurate deductions based on those bevels, for which Paul and I recommend the master bevel board as illustrated in Gougeon, you will draw a deducted body plan inboard of the original body plan. You can choose to draw the full deducted body plan or draw half stations. That gets into how you choose to make the molds and there are different ways to skin that cat. You can make the molds directly off the body or make half patterns off the body. One of the benefits of actually understanding this bevel business can be to roll the bevels on the band saw when you cut the molds. That will determine in part how you assemble the molds off the body plan.

The way I illustrate the difference between a true and apparent bevel to my students is to take them over to the bandsaw. A bandsaw blade cuts square or 'normal' to the line.
The degree scale is based on that fact. Set a bevel rule and the table to 30 degrees. There is only one way for that rule to sit on the bandsaw table and align with the blade. If the rule sits off kilter on the table it no longer aligns with the blade as you eyeball it. That is the difference between a true and apparent bevel. This is the view you achieve in the body plan with accurate bevels and deductions. This is the way you can communicate with a bandsaw or do any numeric transfer of bevels, or in fact ever consistently pick or or read a bevel. 'Square to the cut line' as we said at Bates.

FYI - The story I heard was that a former instructor at Bates demonstrated the master bevel board to the Gougeon Brothers. But I can't verify that.
Last edited by Eric Hvalsoe; 07-07-2018 at 01:12 PM.

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## Re: Lofting question - offset from outside of plank

Eric, JPatrick, and Paul, and all others who kept at me about the Master Bevel Board from the Gougeon brothers book, I want to really, really say thanks! I came back from lunch today and the book was delivered and waiting on me. I went right to the section in the Lofting chapter about the Master Bevel Board and read it. You can now call me a convert! That is by far the simplest way to get the planking offsets! Everyone should have that book and here's why. The \$43 I spent on that book, if that technique was the only think I learned, and I only used it to build one boat, it would pay itself back to me several times over. I have to say I finally ordered the book because of Paul's comments just prior to my last one on here. I honestly didn't think I would benefit that much more from having it. But I will. A lot!

As others, I'm not going to specifically explain how the technique works. If you read this and you are curious, you need to just buy the book. I think the book is that valuable. I bought the hardback copy for \$43 and you can spend less if you want to on a used copy, or go with a soft cover for slightly less. I'll say this though. You basically create a Master Bevel Board, and it has to be like they say, not just any bevel board. That bevel board will then be part of your forever tool kit which you will use to create what is basically like a short ruler tailored to the specifics of the boat you are lofting, and that has angles and provides dimensions, that will take just a few seconds to measure/mark offsets every six inches along a station drawn in the body plan where you need to take offsets. If you can add two numbers in your head and divide them, the only thing you'll need is your pencil and the little stick I described earlier that is like using a ruler. No tape measures, protractors, or any getting up and going back and forth to the profile or plans views. You just focus on the stations you've already drawn and use the "ruler" and mark with your pencil.

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## Re: Lofting question - offset from outside of plank

To save others \$43,the book is now available online as a free download.It is worth reading the relevant section thoroughly.

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## Re: Lofting question - offset from outside of plank

Originally Posted by John Meachen
To save others \$43,the book is now available online as a free download.It is worth reading the relevant section thoroughly.

https://www.westsystem.com/wp-conten...k-061205-1.pdf

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## Re: Lofting question - offset from outside of plank

nice to hear . . .
My master bevel board has been with me nearly 40 years, since trade school.
Eric

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## Re: Lofting question - offset from outside of plank

I have mine, and also all my deduction finds for various Station spacing and Total deduction widths. Never know when another chance to use one will come along...hope springs eternal for another building contract!

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## Re: Lofting question - offset from outside of plank

Indeed

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