Lofting questions

[sea sprite]

Hi All,

I need some clarification on lofting for dories. I am looking at building a Beachcomber Alpha dory from John Gardner's Dory Book as my first boat but I am not sure I understand what all needs to be lofted. From what I gather I need to loft the frames/stations and the planking for length but not for finished shape. He also showed how to loft the stem but I became lost after step B. Is there anything else that I would need to loft or need to take into consideration? Thanks.

Chris

[Moose]

As another guy who's just starting, I just lofted the whole bag of chips. Everything. I used different color pencils for different types of line, and it started to look clear after about an hour. Good luck!

[Thorne]

There are some excellent books on this very issue / topic sold by our hosts. And I'm sure others will also be recommended.

http://www.woodenboatstore.com/images/325114.JPG
http://www.woodenboatstore.com/prodinfo.asp?number=325-114

[sea sprite]

Thanks for the recommendations. I guess its back to the books again.

[almeyer]

Also check out Greg Rossel's Small Boat Building (or similar title - CRS starting to take effect). It has a very good chapter on lofting.

[Clinton B Chase]

Hi All,

From what I gather I need to loft the frames/stations and the planking for length but not for finished shape. He also showed how to loft the stem but I became lost after step B.
Chris

You are right...you just need the frames and molds...you can loft those as accurately as possible (JG usually figures 1/8" inch error which is about as close as you can get in hand drawing!). Make 1/2 patterns of those stations and you are almost ready. For the stem, I am not sure how he does it...there should be a set of widths and heights from a reference point (perhaps a fwd perp or station 1). You'll lay out those widths and heights to get a set of points through which you'll spring a batten nice and fair and get the stem profile. Do the same for the transom. You'll get your plank lengths and shapes once you are set up and faired. I can help further on the lofting...feel free to contact me at Compass Project.org. We have built a couple Alpha-Beaches.

Cheers,
Clint

[almeyer]

I went back and reviewed the chapter on the Beachcomber-Alpha in John Gardner's Dory Book and also in Building Classic Small Craft. In either one I could not find offsets to lay out the profile of the stem. You've got the bottom and shear points identified, but not the profile itself. Barring any dimensions on the stem profile, use a flexible batten and your eye to draw a pleasing curve. As a check, lay out the lines for the knuckles on the profile view and pencil in these lines with a batten. The heights at the stem should be pretty close to the heights given in the Table of Offsets. If they're way off, you may want to consider redrawing the profile of the stem.
In addition to the frames, molds and stem, you'll also have to expand the transom. Rossel's Building Small Boats gives good instruction on how to do this.

[Bob Cleek]

There's a saying about boat builders: "A house carpenter works to the nearest eighth of an ince. A cabinet maker works to the nearest sixteenth of an inch. A boat builder works to the nearest boat!"

While you want to loft as accurately as possible, any boat will eventually move past engineering and into sculpture soon enough. This is why we say, "If if looks right, it is right."

I don't have Gardner's articles on this design right before me, but I do recall some of his stems were laid out with the intention that one would take up the shape "by squares" rather than by offsets. If you carefully enlarge the drawing until you have a pattern that is pleasing to your eye, and which fits the rest of your lofting, you'll have drawn your stem piece as it should be.

[sea sprite]

Thanks everyone for your advice and recommendations. They really helped clear a few things up. Clinton, I'll definitely take you up on your offer. Thanks again everyone.

Chris