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Beowolf
10-17-2000, 07:42 AM
Hey everyone: Another rookie question.

I've begun to strip plank the hull on my 16 foot daysailor. Right now, my procedure has been to "dry fit" the strips on. That is to say that I've been doing my best to get the correct bends and twists into each plank, predrill the holes and screw them into place. Now that I have several of them attached in this fashion, I am going to mark them, dismantle them, and reapply them with epoxy. Although I rather enjoy the job, as it is really exciting to watch the hull take form, is their a way to expedite the process? It seems to me that if I try to fit the planks on with the epoxy in place that most of the epoxy will get scattered all over the hull before the plank is secured properly.

Thanks in advance

Jeff.

Art Read
10-17-2000, 12:40 PM
Hi, Beowolf... Never having attempted strip planking, take this for what it's worth... Sounds like you're doing it just right. I know that it's hard to dismantle the work you've already done, but it really is the only way to ensure you're getting it right, lacking a lifetime of "experience"... I'm carvel planking my project, and have had to "dry" fit, fine tune and final finish the interior of EVERY plank before fastening it down for good. This was AFTER making doorskin patterns for each strake... The temptation to get things done to see how it'll look is hard to resist, but the final results, (that you'll have to live with long after she's launched) will reward your patience and self-denial many times over. (Or so I keep telling SWMBO when she sighs over the ever-retreating launch date...)

christevens
10-17-2000, 04:45 PM
Apologies in advance: I am really Ross Faneuf (rfaneuf@tidewater.net) but the WB remember your password thingie says I'm someone else, and I used Chris Stevens' name in order not to lose all the typing below. Sorry.

I built a 36' strip-planked cutter single-handed. You are on exactly the right track. My strip planks are mahogany, 3/4" x 1 1/8". They are nailed to frames with #12 bronze boat nails, and edge nailed to each other with #10 bronze boat nails. Each plank joint and each frame joint is fully epoxied with System 3 epoxy thickened to about the consistency of mayonnaize with silica. I would fit each plank in place, clamp it up to the frames, then predrill all nail holes, using a jig for the edge nail holes (not only does this make it possible to drive all these fastenings with wet epoxy in place, but it mostly makes sure you won't blow any of the edge nails through one surface of the hull or the other).

I would do one plank at a time, not several, as you are setting out to do. To glue up, I would turn the plank over and clamp it to existing part of the hull - that is, as if you just rolled the plank 180 degrees like opening a book. Then clam so the two plank surfaces which you're going to glue are side-by-side (that is, the new plank and the previous plank). I would use spring clamps suspended from cords at each end to help support the plank while maneuvering and rotating it- my longest ones were 38' long. A plank more than 10-12' long is really hard to manage without something like that, especially when slathered with epoxy.

I would then generously slather the two mating surfaces of the planks, and the joint surfaces of the frames. You want to make sure you completely the gap in the joint (yes, there will be a gap) I'm never happy with a joint unless there's noticeable excess squeezed out (I call that excess squeezle). Now you have to rotate that messy plank, position it, and fasten it. I would (1) remove a couple of clamps from one end, leaving 6-8 dangling; (2) attach a spring clamp to that end to support it - invert the clamp so that when the plank rolls over, the clamp is on top; (3) unclamp to the other end - the messy plank is swinging around, but you have located that other spring clamp so that it's mostly not getting epoxy all over everything; (4) roll the plank into position when you unclamp at the end; line up an edge nail hole using a piece of wire; clamp lightly to a frame; drive the first edge nail and the first frame nail; (5) proceed down the plank, clamping two frames ahead, and driving edge and frame nails in the order they occur on the plank; you've previously made sure, by marking, that the edge nail locations are staggered; (6) when you're close enough to the far end so that spring clamp is making it hard to lay the plank in, unclamp it, lightly clamp to the last frame/stem/whatever, and finish nailing; (7) quick like a bunny scrape all the epoxy squeezle off (best tool is a stir stick sanded to an angle); scrub last bits off with paper towels; the more epoxy droozles you get off wet, the better; (8) catch your breath, take off those gloves full of sweat, and do a plank on the other side.

My boat took 88 planks on each side, and a total of 84 on the deck. The whole process I've described above took maybe an hour once I was used to it, maybe a little more. I built upside-down, working up from the sheer, which I recommend in the strongest possible terms. You will find you need occasional 'stealer' planks - planks which taper at the ends - when the amount of curve in the plank is getting a little too strong. You can make these by either bandsawing and planing a taper onto a plank, or making a long wedge and feeding a plank married up to the wedge through your table saw. I used the latter method with a wedge 1/2" by 7'.

You will often see books recommending coving the edges of strip planks, but I think it's a waste of time with epoxy. I tried it, and you should also be aware that the geometry of those joints is imperfect, and does not produce the effect shown in the books, except in a few places on the hull where the curvature is just right. Otherwise, the coving actually creates misalignment. And it make creating stealer planks a nightmare. You're much better off with plain square edges, with the epoxy filling the gap.

My hull is finished with 3 layers of meranti veneer and 2 layers of polypropylene cloth; I got an AA rating on a recent survey.

I'd be happy to respond to further questions.

Eric Krueger
10-17-2000, 07:20 PM
This is Ross Faneuf again; boy, something is amiss in the WB user/password system. I'm not sure about this image link, but here goes. This are two pictures off Rockland Maine in late August; I launched the boat (name - Ceol Mor) about 10 days before, and this is our first sail.
http://albums.photopoint.com/j/View?u=1273842&a=9431891&p=30924325

and this one
http://albums.photopoint.com/j/View?u=1273842&a=9431891&p=30924326


[This message has been edited by Eric Krueger (edited 10-17-2000).]

[This message has been edited by Eric Krueger (edited 10-17-2000).]

[This message has been edited by Eric Krueger (edited 10-17-2000).]

[This message has been edited by Eric Krueger (edited 10-17-2000).]

Don Z.
10-18-2000, 01:19 AM
OK, this falls under the "I haven't tried this, but I read about it in a book once..."

In _Boatbuilding with Baltek Duracore_ a similar problem is mentioned... I don't know how effective it is, but the book mentioned that because epoxy is gap filling, the strips can be laid, and then the epoxy applied in the same manner that a bricklayer repoints mortar. I'm just a simple minded cavalry officer, not a brick layer, but I like the idea... any one out there with any experience?

Beowolf
10-18-2000, 08:01 AM
Ross...
1st: Your boat looks great!
2nd: Thanks for the tips! I've been mentally applying your procedure for about a day now. (Hopefully I'll gather up the courage to actualy glue one down this week!)

Tony...
Ross is right on the mark in terms of bead and coving. I looked into it on my boat and the best arrangement that I could think of was to use a bead and cove whose diameter was considerably larger than the thickness of the strip. Even then, this would only be most effective in areas where there is little edgewise bend. Otherwise the inner edge of the cove is going to be pushed against the adjacent strip below the bead and cause a splitting stress on the cove. With speed strip, I believe that there is enough "play" in the tongue and groove joint to allow 7 degrees of edgewise bend. In essence, this still allows you to allign the strips with the tongue and groove joint, yet you will still have a gap to fill on the outside of the bend.

Don...
I gave some real serious thought to just trowelling on some thickened epoxy to the pieces that are fastened to the hull. However, this will not allow any epoxy to set in between the strips and the bulkheads. This , in my humble opinion, seems to be an area of great importance, especially after you drill some holes through the sealed edges for the screws to go in. Heck, I'll probably fillet and tape that whole area anyway...just paranoid like that...but it seems like that's a real important area to have a bit of epoxy.

John R Smith
10-18-2000, 09:35 AM
Gosh - and I thought strip planking was suposed to be quick and easy. Look, I don't mean to be a wet blanket or anything, but wouldn't it be better just to build the thing in good old-fashioned carvel?

John

KurtFrazell
10-18-2000, 10:42 AM
This is Ross Faneuf, once again under someone else's false colors. Weird.

What is easy about strip planking is that you don't have to spile and shape each plank. The 'old-time' version also avoided calking, and allowed a boat with fewer frames.

All I said about carefully filled joints and all the rest is because I'm something of a fanatic. My boat is essentially a huge piece of plywood; at a guess from cutouts etc. the void rate is about 2-3%. It's also heavily encapsulated. I personally would not be comfortable with troweling on epoxy; my attempts to fill cracks or voids after the fact indicate that troweling achieves very little penetration - maybe 20-25% of the joint. More if there is a large gap. This is probably enough for a lot of purposes, but I wouldn't be happy.

I don't know if it's mentioned elsewhere, but boat building is a real test of one's tolerance for boredom, with the boredom factor going up rapidly as the size and complexity of the boat increase. By the time I'd done about 6 planks, I had the technique down and it was just work from then on; and I had 170 planks to go. So it's not exactly exciting. On the other hand, you might as well do the best job you can, because no matter how tedious or complex the procedure you use is, you will get used to it and good at it. I bet that making, scarfing, drilling, and fastening planks takes maybe 65-75% of all the time involved; the gluing part doesn't add so much that I would feel that saving time by troweling on epoxy was worth it.

Take what I say with a grain of salt; this boat has taken 21 years so far, and obviously I have a real high capacity for deferring enjoyment.

About scarfing: I made a sliding table jig for my table saw to cut the scarfs, so that was quick (I assume the various books, or other postings here, will tell you how to do that). I would scarf up 2-4 planks at a time, with 2-3 joints per plank. I would: (1) line up a joint by hand; then drill a 1/8 hole through the middle of the joint for a peg (1/8" dowel); this makes sure the joint doesn't slip & slide when wet with epoxy - you won't believe how a joint which stays in beautiful alignment when dry whill slither about when lubricated by epoxy; (2) make up a medium thick epoxy mix and brush onto all joint surfaces; (3) insert peg in each joint and assemble; (4) clamp up with 3 spring clamps and small cauls with plastic taped surfaces (to release from the epoxy; make sure alignment is good as you do so (make sure joint doesn't 'scissor' into misalignment the long way); (5) wipe as clean as possible.

This requires very little cleanup. I would typically end a day by making up enough planks for the next day. On a Saturday I might succeed in getting on 8 planks; on a weekday morning before going to work 1-2.

As an aside, I planed the entire inside and outside of the hull with a compass plane going about 45 degrees to line of the planking, resulting in a very fair hull. One of the reasons for drilling for all edge fastening is so there won't be nail popouts to make this impossible. I think this was probably the most fun part of building the hull, and I had arms like Popeye for about a week or two afterwards.

Beowolf
10-18-2000, 07:05 PM
Hey folks: A couple of quick thoughts.

JohnR, (Didn't you once start a thread titled "Epoxy is Crap"?) http://media4.hypernet.com/~dick/ubb/smile.gif Since one of my main prerequisites was that the boat must be trailerable, I elected against carvel planking. And since I have a near endless supply of rippings for strip material, it seemed the route to take. As for quick and easy, those are simply empty promises that boat builders clutter their own books with.

As for the bead and cove arrangement. I'm not entirely ready to throw the baby out with the bathwater on this one. If you simply konck down the inside edge of the cove, either with a handplane afterwards, or by running your tablesaw blade at a slight angle before, you should be able to do away with the splitting stress. In this case, you have a strip which should require less edge nailing in order to keep it in alignment.

Speaking of edge nailing. In accordance with the "Book of Meade", I'm using dowels instead of nails in order to eliminate the fear of punching through the hull anywhere. The local Lowes carries 1/8 dowels in poplar or red oak. If they will also be more or less sealed with epoxy, is the poplar the better choice?

And lastly...Scarf joints. I built a simple fence that sits perpendicular to my mitersaw fence. Turning the saw 7 degrees produces a 8:1 scarf. 4.5 degree produces a 12:1 scarf. The only thing is that the pieces need to be clamped securely to the fence in order to keep them from being pulled into the saw.

Thanks again everyone

Jeff.

Chuck Gullage
10-18-2000, 07:53 PM
Ross Faneuf again.

Actually, the issue with coved joints is alignment, not strength or splitting. They just don't do what is claimed.

A drawing of coved strip planks in a book always shows the planking nice and fair with a bunch of cove joints drawn as circular segments. Hard to imagine a draftsman doing it any other way. But real-life geometry doesn't work that way.

I found this out the hard way; my entire hull has coved planks, because I got out all the planking stock before I did any planking. I quickly discovered I had alignment troubles, particularly near the transom where the curvature of the frames is strong. So I cut a couple of little bits of planking stock (about 2" long) and saw how they really behaved in use.

I'm not going to try to draw this here, so bear with me while I try to explain things. As you lay on planks (any planks, obviously), each lies at an angle to its predecessor which depends on the curvature of the frame/mold. This is a slight angle with strip planks, but still noticeable where curvature is strong. Think how that coved joint behaves when the plank edges are at an angle, if you keep the cove tight (and if you don't, what good is it?). the male side of the joint rotates about the center of the cove radius; as it does, a gap appears on the inside of the frame between the two edges (formed by the edge of the preceding plank) and the edge of the new plank sticks out beyond the edge of the predecessor on the outside, making a bump.

It's remarkable how noticeable this is; on my boat, the gap/bump was more than 1/8" at the transom; that bump has to be planed off on the outside, and filled or planed on the inside. If planed, my 3/4" planking is suddenly less than 1/2" thick.

What's really wanted is to keep the inside edges of the planking exactly lined up (that's boatbuilding exactly - within say 1/32" or less). You can do that with coved planking (I did) by making sure the edges are aligned when you drill for the edge fastenings, which they line up the planks when they are driven. And when you do, the cove joint opens up just the way a plain square-edge joint does. So all that coving turns out to be for naught.

By the way, I'm sure dowels work just fine to align the edges. But I'm a belt + suspenders type, so I nailed. I would do so again, for two reasons: (1) they pull the joint down as tight as possible; this tends to even out the wiggles you get in all planks; (2) it's easy to drive nails when you're in a hurry; dowels have to be driven quite carefully or they'll break. Anyway, I'd rather reach into a box full of nails than cut all those thousands of dowels and give each edge a little chamfer (trust me, you'll need a chamfer). If you go with dowels anyway, I'm sure ordinary hardware store birch will work fine.

[This message has been edited by seagull (edited 10-18-2000).]

Don Z.
10-19-2000, 01:23 AM
I'm ignorant... as I said, I only read about it. But if you are screwing the strips to the bulkheads, why not epoxy them too? Then when you pull the screws, you can fill with a syringe... or, epoxy the strips to the bulkheads, and if the "gap" is the same as the screw diameter, you can screw them with a washer, and use that to hold them in place until cured.

I can't comment on the "gap penetration"... I still don't understand pointing well enough... but I'm a cavalry officer, not a bricklayer... I don't get that part either... which is why I haven't done it yet...

George Roberts
10-19-2000, 07:27 PM
There appears to be some misunderstanding (perhaps on my part) on how to lay bead and cove strips.

On a convex surface only the center of the strip touches the forms. The current cove fits into the previous bead and the current bead sits off of the surface. It takes a bit of forthought to position the strip properly. If you try to lay the edges of the stripn on the form, you will fail.

On highly curved areas part of the cove needs to be planed away.

A concave surface is similar except that the edges touch the forms.

On square edged strips the same holds but you can slide the strips across the grain to adjust for errors.

Chris B
09-04-2001, 12:42 AM
For filling voids or gaps, rather than trowel on or inject-put a Shop-vac on one side and suck it through-saw this one in Fine Woodworking and it does work, have sacrificial hose and crevice tool for the sucking, as they get pretty cruddy

Syd MacDonald
09-04-2001, 11:13 PM
when using thickened epoxy, I always prime the surfaces with unthickened epoxy first. Is this done when using the troweling method?
Glad to see this thread again. Lots of useful info.