View Full Version : Cross-Planking On Flat-Bottom Boats
03-03-2004, 06:56 PM
I have been looking for information on cross-planking. In the study plan for Joel White's Egret, it appears that the outside bottom planking runs athwart the inside fore n' aft planks. I am wondering if there is a rabbet in the chine log for either bottom planks, and how does the topside planks fit near the chine. Would you plank the fore 'n aft inside bottom planks first, hang your topside planks, then your thwart planks on the bottom?
I haven't seen this plan but cross planking was typically fastened at the chine to the side planks or the chine logs fastened to the planks. I can understand placing fore and aft floorboards inside the cross planked bottom, but double planking is new to me. I'm sure the Munroe Egret was cross planked in typical sharpie fashion. Many sharpie/dory skiffs had fore and aft bottom planking, a typical dory setup.
03-03-2004, 09:19 PM
I am sure there is a small 'break-away' that shows double planks that are not in the usual configuration that one would expect in double-planking. The specifications read "single planked sides." This would lead one to believe that the bottom is double cross-planked. I should just buy the plans. I'd rather be building a Fredonia, but I'm dirt poor and short on time.
I just read John Gardeners book on classic small craft building and Building Heidi. They both show single cross planking. This would be good for me. I'd like to build the Egret as traditionally as possible. Of course this means that I would need to steam bend the house and coaming. I understand Joel White has written an articale that pretains to this for Wooden Boat. I have steam bent some things, and the Egret seems to be a good subjet for carvel planking. I have had some so-so results with spiling and fitting replacement planks. "Hmmm, that one will need a shim and a batten. Time for some new glasses Zeb."
03-03-2004, 10:15 PM
The Yankee Tender is double cross planked (and clench nailed). The inner planks are laid on the chine logs with no rabbet, and trimmed for the garboards. The outer bottom is then laid over the garboards, bedded in musslin. See WB 30. I guess you could say that the garboard creates a rabbet.
03-03-2004, 10:27 PM
The method mentioned for bottom planking the Yankee Tender created problems for me once when I needed to replace an 'inside plank' that warped, cracked and rotted. (The boat was actually an Asa Thompson Skiff, the precursor to the Yankee Tender). Hell to remove and replace.
If I were to build one of those from scratch I wouldn't use that method.
[ 03-03-2004, 11:29 PM: Message edited by: rbgarr ]
03-04-2004, 06:17 AM
As Thad said, the original Egret was likely simply cross planked like a flat bottomed skiff. Is it possible the fore and aft wood you are seeing in a detail is a keelson? That would make sense. After the cross planking was installed by running it past the planking and nailing to the chines, a fairly substantial keelson might be sprung; a fairly wide flat piece of stock running down the middle of the planking on the inside. This, along with a matching keel through fastened to the keelson, would serve to stiffen the bottom and provide stability for the center of the planking.
Looking at Chapelle's iteration in his boatbuilding book, he shows a more substantial keelson set on edge rather than the flat, with a single layer of cross planking.
Without seeing the plan I'm just guessing, but that's how I see it going together. I'd be wary of double planking this bottom because of the repair issues mentioned, not to mention the added complication in building. Simple cross planking is relatively easy to repair, is easy and fast to build, and it works well.
03-04-2004, 12:16 PM
Yes, there is a substantial keelson sprung on edge, or, most likely sawn, in Wooden Boat's study plan for White's version of the Egret. I should order the plan.
There is also Parker's Egret that presents a simple and strong construction method, pit, and modified accommodations below deck.. I would imagine that Parker has decreased the shear and the draft to facilitate the hanging of the one layer of 5/8" ply topside planks. It's a great design. I keep hoping he will draw-up a 28'MBLS with inside ballast and minimal deadwood for simple, uncovered, strip planking that lays over as few double sawn frames/ mold stations as possible. I know he can do it.
I still pine for my round-bow Friendship Sloop inspired, Malabar, Jr. influenced, double head-sail, gaff-rig sloop. But, that Egret has got me goin' again.
Frank E. Price
03-05-2004, 01:58 PM
I don't have it in front of me, but the Smithsonian Ship Plans, Maritime, catalog has Chapelle's drawings at $3.-$5.00 a sheet, and there are two or three of his Egret versions and a little bigger, say 28'-34'. The drawings include construction details sufficient to build the boats in the traditional way. I recommend them highly. There is no detailed instruction such as you'd find in more expensive plans drawn for amateur construction, but the boats are very doable if one has a modicum of understanding of his Boatbuilding book or similar work.
When I built my 18' sharpie skiff I set it up on four or five molds and a strongback. I notched out for the chine logs, got them faired up, planked the sides and faired them up (the bottom edges), then I let the keelson and sister keelsons into notches before planking the bottom and fastened the bottom planks to them as I went along. As per Chapelle, I nailed each plank to the chine log and side planks. My first plank boat, and it was a piece of cake.
03-05-2004, 04:38 PM
I looked closer at the plan in Wooden Boat Fifty Designs and discovered that it is the top of the house that is double planked at ninety-degrees. I really don't see that well. Thanks for the Chappelle information. I remember looking through his book on small fishing craft. Great stuff. I have solved some rigging problems with his books and some of John Leather's material. There is a great wealth of information availible here.
Funny, I was looking at William Garden's design for Boat and wondering where I'd put the cabin heater, in the event I couldn't get back down to Florida before the frost set in. I'm a little itchy to get back on the water.
I've found a yard to build but it's on the West Coast. I might want to put this together along the Missisippi or one of the other rivers that flow into the area that I intend to use the boat.
Hey, Larch! Maybe ya wouldn't be so itchy if ya got out of those bib overall and took a bath. Ya stink ...and get that red lead off yer face. That stuff 'l kill ya. A'ya, the ol' mans wearing on me, Zeb.
Thanks for the information. I'm still looking for a design that can be built as simply and affordably and provide the same personal satisfaction as the Egret, but Boat looks pretty good in the inexpensive department.
03-05-2004, 05:51 PM
Munroe's Egret featured in WB 56, in plywood looks like an economical approach.
03-06-2004, 01:41 PM
Thank you, I will have to order that back issue along with the plans. "Testing The Waters" is a web site that some one has set-up to document his building of the Egret. He is using plywood. I have been looking at his mold arrangement. It seems to be working.
03-06-2004, 07:24 PM
A note. Building a roughly twenty five foot sharpie upsided down, conventionally, I would let the keelson into the molds rather than, as I imagined, spring it in after planking.
As to cost, it depend on materials availability. I've got a couple white pines that, even though a bit knotty(open grown), would make the planking for a thirty foot sharpie, growing on my property. I've got a fellow with a bandsaw mill, next door. For very little cash I could have the materials to build say, Chapelle's thirty footer from Boatbuilding .
It depends on how you measure things. The ply for the same boat...I don't know, but I suspect even fir ply(ply has gone through the roof with the combined forces of housing markets and hooches in Iraq) would run upwards of three grand. Figure in the epoxy and aggravation of working with it.
I've got plans for what is essentially a Presto, multichine sharpie, thirty foot, and ten years ago the material cost was estimated at twelve grand. Triple that.
But it all depends. A complex equation only you can solve.
I will never build another boat out of ply and epoxy. I'd rather walk and bum a ride when I want to sail.
03-15-2004, 10:03 PM
Thanks, I have very similar feelings. I noticed that White's plans state "single planked topside, cross planked bottom." The single topside plank would measure about 4/4 x 52" x 34'. Jurassic Plank. I would compramise with some tradition single-plank 1/2" plywood; this seems to be the popular solution.
Pine is good. I priced some today. Doug fir is pretty inexpensive, here on the West Coast. As soon as May, I may be going to Seattle to build. My other option is out in the Anza Borrego desert -I'll need plenty of water for that.
Thanks. Epoxy is ugly stuff. I believe the word is "ick-a-putty."
Weekend before last I built a skiff with a Boy Scout troop from Andover. http://www.imagestation.com/album/pictures.html?is_owner=1&album_id=4287426785&hide=1&show_all=1&id=4287426785&upload_so urce=album_add&start=1
They wanted a boat they could build in two days. It took a few more of my days to get the parts out and ready, but we did it in two days and they really got into riveting and caulking -- as you can see if you can see the pictures.
03-16-2004, 06:57 AM
In many cross planked flat bottom boats of recent times, we are using solid plank with a sawn mortise on each side of the planking and it fills with caulking such as 5200. Yes I hear people screaming and beating the keyboard. But in rework we just run a knife down the joint and cut it. We do not use and tongue and groove method, and would not build the egret with double plank. Many of the deadrises were built cross planked and logged in the bow, and shaped to fit in vee design bottoms too. Saw your adjoining planks together to maximize the seam fits, too.
03-16-2004, 08:22 AM
how 'bout a rabbet with gorilla glue? or, for a more traditional product, roofing tar? that's what i'm considering when i get the chance to do my own.
03-16-2004, 11:52 AM
Thank you Thad!! Is the skiff your own design? How do you fit the chines? I see you left the side frames short, do they just butt up to the top of the chine timber sharpie fashion? Do you fit the chine to the stem and transom or do you leave it short at either end?
It's my own design, based on my understanding of how sharpie skiffs were traditionally built. I made a cardboard model (actually two of which I picked the slimmer) and scaled the shapes (for planks, middle thwart and transom) and took angles (stem, thwart, and transom). I got a couple of 14" pine boards and had a 10" cypress board that I ripped, these were the planks, with gain cuts for the lap ends. I cut 10 timbers with 5/8" relief to fasten to the lower planks before bending the top planks around, these were cut off short of the chine log which was short of the ends. For the bottom we fastened three pieces at random along the way, an oak bow plank grain fore and aft, and a plank under the transom, and then bent a keelson inside for additional bottom fastening and strength. Then we planked away until we had wedge shaped plank spaces left for which I cut matching wedges to drive home. The kids did lots of the marking, some planing of caulking bevels, and most of the fastening. The second day we caulked the bottom with the kids really getting into driving the cotton. Breasthook, rub, fore and aft thwarts, oarlocks and a couple of rub strips for the bottom completed the job.
03-17-2004, 03:38 PM
Thad- what did you plank the bottom with? From your description of driving the wedge planks it sounds like you have fitted the bottom pretty tightly. I've read of John Gardner using the wedges but my own experience has been that I have had to leave fairly large seams to keep the bottom from trying to push either the bottom of the transom or the stem out when it has swelled up completely. I've never had really green stock to plank with which surely make a difference. Has this boat been launched yet?
Excellent questions, but there is nothing I can do about it. Eastern White pine, air dry, about 4 inches wide. Wouldn't surprise me if swelling caused some problems, but it wouldn't surprise me if all worked out fine also, I hope for the latter. They will be laying on many coats of raw linseed oil (I know, Dave) and it is not so tight as you might imagine, so I'm expecting it to work. I will probably hear if there are problems. I expect we can deal with them should they occur. It was the last weekend of February and still needs finish, besides, the ice is barely out and today it's still Winter.
03-17-2004, 04:40 PM
Thad- Thanks. I imagine that the 4" planks not fitted too tightly would work out fine. I most often use 5 1/2" wide just because thats how it seems to work out best from the available stock. I've thought that about 4 1/2" stock with three fastenings at each end would be the ideal width for a bottom about 1" thick. I've also never had the chance to plank a bottom with white cedar, I wonder if that could be fitted tighter without any problems.
03-17-2004, 04:50 PM
What is the best way to get the chines out for the Egret. I've visited a page where the builder has laminated two or three pieces by bending the wood into his molds and clamping them. I've read other articles that take the chine off from the bottom of the first plank and and read the bevels at each station, cut the bevels into the chine and then bend it into a notch cut for the chine log.
Nice skiff from Andover. I lived on Main St. in 1976. Nice town, Thad.
Jack, those pine trees sound temping. Now if I could find a place to pitch a tent, run a twenty-amp power cable and ruin some good wood, we'd be in business.
03-17-2004, 06:59 PM
I just read Chapelle's chapter on flat bottom boat construction. This offers much information.
Larch, now that you have read Chapelle, how have we been doing?
I think it would have been nice to have green lumber, but then there is the other part of the story. After our agreement in the Fall the Boy Scouts arranged (paid) to stay at a Girl Scout camp in Beverly while we built the boat here in Marblehead. Friday before that weekend in early December we had serious snow, close to 30" in Andover and Beverly. The next date that the camp had open was the last of February. If I had had green lumber in November it would have been much drier the end of February. All Winter I had been thinking we would have to do the building upstairs in my shop, overcrowded with 10 people much less 20, but then the weather turned mild and we had two days in the 50s, beautiful weather for an outside project!
[ 03-17-2004, 08:16 PM: Message edited by: Thad ]
Frank E. Price
03-19-2004, 04:05 PM
I wouldn't recommend planking with green lumber. I built my 18' sharpie skiff with what was available, as my local sources didn't come through. The wood I used was not green, but was not dry either. I planked the bottom with caulking seams and a little wedging action. No leaks after a few days, but in the summer when the 'tween wind and water part of the stern dries out, it leaks. And when the boat is moving fast and the stern wave comes up, it leaks quite a bit. I keep a couple of bailers handy, on lanyards.
03-19-2004, 05:02 PM
Oyster, that planking makes sense. After reading Chapelle's material on flat-bottom building, I see the chine is spiled off the outside of the molds. Perhaps it is taken off the chine notches. With kiln dried fir, it seems tough to bend it onto the molds -maybe not. I see where other builders have divided the width into three pieces that are laminated in place.
I mention above that I'd like to pitch a tent somewhere and build this thing. I figure I'd leave the table saw, molds, and strong-back, jig tables, etc, behind when I launch. That is the sort of deal I have in the desert. In seattle I have to find a place to live, in addition to the yard fees. I'm going to look into Port San Luis yard, on the central coast of California. Last time I looked, they were still allowing people to live aboard as they worked on their boats, but it sure would be nice to build close to the area where I intend to use the boat.
Thanks for all the information and advise. Again, William Gardens 18' Boat (also known as June Bug) is looking really good. I came across his plans and article in an old Rudder. Thanks all. Hmmm, maybe Texas.
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