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DoryJoe21
08-19-2015, 11:29 AM
Hi everyone,

I am a little confused as to the proper (or perhaps more common) method of lapstraking.

The majority of dory boats I see make use of frames which are notched in step with the planking, so as to provide the most bearing surface for the skin of the boat. This it seems would necessitate using frame guides first, then adding the actual frames, scribed to fit, afterward.

However, in Gardener's plans, he shows simply a straight frame, and a double bevel on each plank, not just the top beveled for the next overlapping plank, but a bevel on the bottom of that overlapping plank as well.

I understand that a double bevel is used at the stem and stern for flushing purposes regardless of frame style.

Does Gardener's plan require this double beveling because the frames are straight, not stepped? Or is most lapstraking double-beveled, regardless of stepping or not?

It seems, I have also seen examples of a single bevel on the top of the preceding plank, with a straight frame.

Is this a matter of simply style/preference, or is there a generally accepted method?

Thanks in advance.

Joe

Eric Hvalsoe
08-19-2015, 01:01 PM
I've always called that a dory lap, on both planks full length. I've only seen that, or something like that, on some dorys and guideboats. I can guess why on guideboats. A dory expert will come along and explain why it was done on dorys. Other lapstrake forms, the length of only one plank lap is beveled. By the way, a dory lap is not the only way to bring the plank ends in flush, also known as the gain. Quite a few people take all the meat off only one plank. But that is getting away from dory construction.

nedL
08-19-2015, 01:24 PM
The nuances of lapstrake construction are quite regional and are typically also associated with the hull design. What boats are you looking at and what boat are you considering for building?

Edit:..
Ok, I see you are considering a Banks dory. Even those are (were) construction specific (in the nuances) by region. Traditional American dories were built using 'dory clamps' (the metal brackets you talk about in your other thread), while dories built in the Canadian Maritimes were typically built with grown crook frames.
Dories would have typically been built with no caulking needed.

While growing up I had an ancient old Banks dory (built probably sometime in the 30's -50's maybe), 16 ft overall, so I guess about 12ft on the bottom. She was built with grown crook frames, a splined bottom, steel (or iron?) clench nails, and oddly enough a original centerboard. I kept her in the water and she did not leak a drop. I rowed & sailed her for lots of miles, and quite frankly I quite enjoyed rowing her.

https://im1.shutterfly.com/media/47b8df10b3127ccec36a6a34600400000010O02Bbs3DVuzZA9 vPhI/cC/f%3D0/ls%3D00200375837020080201030327945.JPG/ps%3D50/r%3D0/rx%3D550/ry%3D400/

ahh, .. Found a picture.

debenriver
08-19-2015, 01:40 PM
Depends a lot on the shape of the boat and the number of planks. On all my round bilge designs the frames are not flattened at all for the lapstrake planking. That is because, like traditional clinker there are a lot of planks (typically 9 to 13). Plank width will typically be 100mm to 170mm. With this number of planks and the shape and twist that there is, the planks lay nicely fair on the frames. The only bevel is the top edge of each plank to receive the bottom edge of the next. At the stem and the stern there is a shallow rebate cut out of the bottom edge of the "next" plank so as not to leave a little "tunnel" for water to leak through.

All the planks will be developable by their nature – though it is not true that you can't induce double curvature in ply because to a certain extent you can, especially in a long, narrow item like a plank, that is twisted as well as curved.

On all my newer designs, I provide all the shape data to set each plank out, so there is no need to take patterns etc. They can also be cnc router or laser cut if wished.

If you have fewer, wider planks, then the frames need to be flattened to receive them.

DoryJoe21
08-19-2015, 02:03 PM
Hi guys,

Thanks for the responses.

Yes, I am looking to make the Banks Dory right now, and I am trying to work out a few design points in my head first of course.

I am not quite sure what I will be doing frame-wise. I'd love to find good crooked pieces. I might be able to get black cherry or perhaps even apple. There would be the seasoning factor, that I have to take into account. But If I start working on the build, I could employ dummy frames, and then add the real frames at the end.

I'm just not sure if this dory lap is necessary because of straight framing, and if I stepped the frames, I'd be avoiding the double beveling. To me it seems that the less beveling the better in a lapstrake, to leave less room for error. But, maybe I'm wrong. Maybe it's more work to build without permanent frames and step them afterward.

Joe

Gib Etheridge
08-19-2015, 02:22 PM
Or....

If you're building straight framed, as in the banks dory, you can apply the garboard (and I'll repeat that it can easily be strip built in place and that that produces a better product do to the lack of severe cross grain at the ends) then bevel the upper edge (if you're building upside down on a ladder frame, which I find much easier) then apply a wedge to the frame, making it stepped without all of the scribing and fitting.

If you use narrower planks you lessen the need for stepped frames but I don't like the way crap gets into the gap and stays there.

As for natural knees I have found that with all of the work and time entailed in finding, milling and drying them that it's much easier to just laminate. I do see natural knees as the prettiest and saltiest of all, but it takes too long to build a boat as it is.

willin woodworks
08-19-2015, 02:42 PM
The 16' Banks Dory in The Dory Book is a cinch to build. Build it upside down on a ladder frame or a strongback and use the actual frames as your moulds. Use white Oak for the frames with a glued and screwed half lap. White Oak for the stem and transom.
I planked one with 3/8 ply and epoxied the laps. I scarphed and epoxied the ply to make continuous planks. I screwed the ply to the frames as is at the laps and cut gains in the ends for a flush lay at the stem and transom. I used TBIII to glue the Oak. You don't need stepped frames. The garboards are screwed and glued to the frames, transom, stem and chine logs as is the bottom.
I used ply for the bottom as well. The boat is stiff and solid like a dory should be but lighter than a solid planked dory. I added chine logs to give the garboard/ bottom joint some more meat.
Its a little more tender than it should be but it rows well with two adults and it can carry a Sh*t load of stuff....

DoryJoe21
08-19-2015, 02:53 PM
Gib, I was thinking that one could just epoxy wedges onto the straight-frame, but I didn't know if that was common place.

Laminating is also an option. I'm not crazy about the idea, and I don't have much experience doing it. But, I suppose it's simply a matter of a form and plenty of clamps.

As for the garboard strip planking. So you would just butt and glue the strips together until reaching the straight run? Or would the strip planking require a certain joint?

Also, Gib, am I right to assume with a stepped frame the "dory lap" or double bevel is not necessary? Or is it not necessary regardless of frame, and more dependent on plank width? Let's assume a typical dory, four planks or so.

Joe

Gib Etheridge
08-19-2015, 03:29 PM
[QUOTE=DoryJoe21;4627751]Gib, I was thinking that one could just epoxy wedges onto the straight-frame, but I didn't know if that was common place. I don't know that it's commonplace, but I've done it and it works.

Laminating is also an option. I'm not crazy about the idea, and I don't have much experience doing it. But, I suppose it's simply a matter of a form and plenty of clamps. Affirmative.

As for the garboard strip planking. So you would just butt and glue the strips together until reaching the straight run? Or would the strip planking require a certain joint? I would do all full length strips square edged and glued and nailed with hot dipped galvy box nails to clamp while the glue cures. I did that on a couple of dories long ago and they're still just fine. If I ever do it again I'll predrill before nailing because the odd nail will deflect and come out the surface or end just below it only to be discovered while sanding. Prerilled nice and square through the strip being applied and with a length of 1 3/4 time the width of the strips that won't happen. Glue is enough, TIII if your joinery is good, and there's no reason it shouldn't be, or epoxy if there are gaps, but the nails are out of the way so you can apply one strip right after the other without waiting for the glue to cure.

Also, Gib, am I right to assume with a stepped frame the "dory lap" or double bevel is not necessary? Or is it not necessary regardless of frame, and more dependent on plank width? Let's assume a typical dory, four planks or so.

I don't quite know what to advise, there are so many variables. With straight frames the dory lap bevel can be uniform from stem to stern. I once cut all of my dory lap bevels on the table saw. They were New Hampshire eastern white pine (which I'll never use again) and 3/4 inch thick. I could have just cut them to a knife edge but thought that would not look quite right so I left about a light 1/8 inch still square on each edge then used the block plane to bevel that to the same bevel as the big bevel, which produced a VEE groove reveal at each seam inside and out. Looked pretty neat and since it was the same bevel (same angle) from end to end on every plank it was probably the easiest thing of all to do. It sure was quick.

Of course this left a little VEE grooved leak at every lap at the stem and transom, but a little pine triangular filler glued into each one took care of that in a few minutes. The outer stem covered those little gaps but I did the wooden fillers anyway to exclude water.

I've never seen anyone else do that. I like to do things my own way which is often a bit unorthodox, but it worked perfectly and looked good.

That was the easiest lapstrake construction I ever did, I'm surprised it's not the standard with straight frames.

Gib Etheridge
08-19-2015, 03:32 PM
Also, if I were going to strip build the garboard on a Banks dory I would add a chine then start at the sheer and strip the whole thing, with a meranti ply bottom. Should take about a week, minus the finish.

TerryLL
08-19-2015, 06:22 PM
The larger question is why in the world would you plank a flat sided dory in anything but plywood?

DoryJoe21
08-19-2015, 06:42 PM
Thanks for the information, Gib.

That does sound like a very quick method. I do like a good amount of lap showing, though, so more traditional will probably win here.

Joe