JIM, an 18 foot canoe yawl.

[Duncan Gibbs]

There's no doubt that regular spiling with a compass or tick stick is a great method. But, it seems to me, for those of us who aren't doing it all that often, it's a little prone to error. Those who do it a lot make almost unconscious allowances for their own particular ways of manipulating the various bits and pieces, and certainly get very good at it, but the rest of us need to make a few errors before we can adapt to our own patterns of behaviour. So, for me, it's worth the extra effort to form up a truss-pattern which can then be placed exactly where the plank is going, adjusted accordingly, and then copied with the plank. If I were to use the traditional method, I'd be making up a test piece anyway, and that would use more material. There's no need for me to save time with planking, and using a few extra sheets of plywood or mdf to get the planking just right is a reasonable price to pay, I think.

Rick

But where is the room for error in this?



I'm not sure I like the idea of splitting the stem and stern posts down the middle even with epoxy as the glue.

I'f'n you're going to all this trouble with these truss skivvy things, I'd look at today's experiences as a really good excuse to go out and build me steamin' box!

[PeterSibley]

Argue with St Iain of Oughtred.

[RFNK]

But where is the room for error in this?

All around. Trussed me.

Rick

[PeterSibley]

All around. Trussed me.

Rick

Pay the man !

[Duncan Gibbs]

Argue with St Iain of Oughtred.

It's all those black skivvies I wore as a youth: I'm a natural born iconoclast. In fact I'm wearing three of the things right now!

All around. Trussed me.

I was once presented with twice five number of puns in order to see which ones would make me laugh. No pun in ten did.

[m2c1Iw]

Trust you chose a suitable expletive from the boat builders dictionary after the lams broke actually that would have been from the list titled mild as it's only a minor set back.
Interesting the inner ones look like they took the bend OK from different stock I spose. I'd have another go perhaps use an outer form or more clamps wet the lams down first and select from straight grain flat sawn, should work.
Or make that steam box now as the skivied one suggests.

[RFNK]

I was once presented with twice five number of puns in order to see which ones would make me laugh. No pun in ten did.

That's not very punny at all

Rick

[TerryLL]

But where is the room for error in this?

The spiling batten used with either a compass or spiling block will allow you to transfer the exact shape of the plank onto the plank stock. But, it's not idiot proof. If the spiling batten is a lot more flexible than the plank stock it can sag inward between molds, throwing off all the points when laid out flat. It's also very important to avoid any edge set when tacking on the batten, as that edge set will disappear once the batten is laid out flat, throwing off all the points.

The possibility that little errors can creep into the process is the principal reason to cut the plank a bit oversize and do a trial fit. Geoff Kerr recommends cutting wide of the mark by a good 12mm in his WB articles on the Caledonia Yawl, and then testing the fit. When I planked up my CY, having that extra meat at the plank edges saved my grits more than once.

The trussed template method looks like it will produce a perfect pattern, but it's also susceptible to errors caused by edge set and flexibility. Cutting the plank a bit oversize and doing a trial fit is a lot easier than throwing away a plank and starting over.

[TerryLL]

.




I dug out Iain Oughtred's excellent book from under of layer of sawdust and discovered that he suggests a layered futtock method as his first choice ! Duh ! That's the way it will go now, 3 layers of 17mm.

Peter ,

Don't do it, don't do it. A glued-up plywood stem is just so amateurish. Yes it's easy, sufficiently strong and stiff, quick, and cheap. But this boat deserves better.

Just take those DF lams and lay them out flat on a towel. Put another towel on top and pour on the boiling water. In 15 minutes those lams will bend around that form with nary a complaint. Clamp them there overnight, unclamp in the morning. Truss up each one with some string so they hold their shape and let them dry for a day or two. Then back on the form with a decent layer of thickened epoxy. With that many lams you'll have a very stiff stem worthy of your effort.

[John How]

You also probably need to use more clamps applied as you round that corner with some cawls the width of the wood under them. They broke right there and they appear to be unsupported unless you removed the clamps from there.

[jim_cricket]

Peter ,

Don't do it, don't do it. A glued-up plywood stem is just so amateurish. Yes it's easy, sufficiently strong and stiff, quick, and cheap. But this boat deserves better.

Just take those DF lams and lay them out flat on a towel. Put another towel on top and pour on the boiling water. In 15 minutes those lams will bend around that form with nary a complaint. Clamp them there overnight, unclamp in the morning. Truss up each one with some string so they hold their shape and let them dry for a day or two. Then back on the form with a decent layer of thickened epoxy. With that many lams you'll have a very stiff stem worthy of your effort.

I don't know that he was talking about plywood for the futtock style layup. It works pretty well in solid wood, and is a little quicker and doesn't make as much sawdust as laminating. The downside is changing grain direction on either half of the stem (or frame). John Gardner was a proponent of this method of laminating. Its certainly a good way to do dory frames and stems.

[Vernon]

I don't see a problem at all with a stem glued up with solid wood. Iain shows a couple of methods in his book. Cut from solid wood in the traditional way - just epoxy glued at the joint that would otherwise be mechanically fastened, or glued up from staggered pieces like Crickets futtocks as discussed.

I chose to do the laminated way more for the best use of the material I had rather than the additional strength, it's not like them stems will be standing there all on their own. I would do them based on the best use of the material.

[jim_cricket]

[QUOTE=Vernon;3486498]...Cut from solid wood in the traditional way - just epoxy glued at the joint that would otherwise be mechanically fastened, or glued up from staggered pieces like Crickets futtocks as discussed.

A lot depends on the particular design of the stem. I'm not sure of the molded depth of Jim's stem, but it sometimes makes more sense to laminate. It does look like Jim has a very tight radius at the forefoot, though. Tighter by a lot than Oughtred's DE's, and similar to the Matinicus stem. In my case, I used the solid construction like Vernon mentions, but the molded depth is quite large, and the timbers are beefy. Any of these methods will produce a strong stem. On the Matinicus, the outer stem (apron) was laminated, but it doesn't wrap around the forefoot. This setup really consists of stem and knee.


This is the lofting of stem and sternpost.


and this how the parts were bolted together.

Cricket

[Terry Haines]

Since you've gone to so much trouble with the laminations & mold you might as well give it one more try. As has been noted before the inner (darker) lams bent fine and two of the lighter colored lams are OK too.

There are several possible causes. The broken lams may have separated from the others at the point of max bend so the bend in them became sharper. Or perhaps one broke at first and the force on it was transfered to the others which then followed suit. Also, it looks like the grain in the broken lams runs off the edge.

Try again but this time apply clamps or bindings as you bend the lams around the mold. Take care to cut with the grain, you can split a piece off the plank to establish the grain direction if it is hard to see, and arrange for the straightest grain to be at the sharpest bend.

Air-dried wood bends easiest but I find I can bend kiln-dried wood 1/8" thick around a 6" bend radius, with a little surface moisture applied a half-hour or so before, provided I take it slowly to allow the wood time to accommodate the bend. I use a water-based glue like Titebond III since it tolerates the moisture, and the glue edges get sealed by epoxy when the planks are attached. The moisture discourages splitting at the surface which leads to a full break. Heat is helpful for bending wood.

[gilberj]

You could pre-bend the thin laminations using dry heat. Instrument makers use dry heat with a bending iron. The bending iron could be something available for sale to luthiers or you can make one up with a short length of pipe and a torch. Pre-bend the laminations to as close to the final curve as you reasonably can and bend them the rest of the way as you lay up the lamination.

[TerryLL]

I don't know that he was talking about plywood for the futtock style layup. It works pretty well in solid wood, and is a little quicker and doesn't make as much sawdust as laminating. The downside is changing grain direction on either half of the stem (or frame). John Gardner was a proponent of this method of laminating. Its certainly a good way to do dory frames and stems.

I kinda flew off the handle there, thinking in terms of a plywood stem only. So let me offer a more balances opinion.

A stem made up of layered futtocks in solid wood is quite acceptable, and I did it that way myself on my first build. Dealing with the changing grain direction is a real nuisance when it comes time to bevel. Yes, Sir Iain offers that method using solid wood, so there'll be no objection from me. Be sure to remove any temporary fasteners as early as possible or you'll curse the heavens trying to get them out after the epoxy is fully set. Yup, made that mistake also.

[Terry Haines]

. . . Be sure to remove any temporary fasteners as early as possible or you'll curse the heavens trying to get them out after the epoxy is fully set. Yup, made that mistake also.

Sage advice indeed! I used thin nails to hold a laminated outer stem in place. Thinking the epoxy couldn't get much of a grip on the nails and would hardly be stronger than the steel I didn't bother to remove the nails for a couple of days. even though they were not in deep half the nails twisted off when I tried to remove them. Should have got them out at the epoxy's plastic stage. I have since been told heating them with a soldering iron would have released them . . .

[PeterSibley]

Peter ,

Don't do it, don't do it. A glued-up plywood stem is just so amateurish. Yes it's easy, sufficiently strong and stiff, quick, and cheap. But this boat deserves better.

Just take those DF lams and lay them out flat on a towel. Put another towel on top and pour on the boiling water. In 15 minutes those lams will bend around that form with nary a complaint. Clamp them there overnight, unclamp in the morning. Truss up each one with some string so they hold their shape and let them dry for a day or two. Then back on the form with a decent layer of thickened epoxy. With that many lams you'll have a very stiff stem worthy of your effort.

I'm not talking about using plywood Terry .... I'm sure I didn't say that . I have lots of good timber here, mountains actually . I was a bit disappointed that 1/8" laminates broke so looked up IO's plywood boat building book and there was his suggestion , a built up stem as his first option, laminations second .

I'll have another look tomorrow as today is all day driving. Thanks for the boiling water suggestion .We'll see how it goes but right now a multi layer lamination from flat timber meets standards.

[James McMullen]

Aren't you done yet? You've had a whole week to build this thing already.

[TerryLL]

I'm not talking about using plywood Terry .... I'm sure I didn't say that .

Peter ,

No you didn't mention plywood for the stem. It's not the first time I've shot off a reply before carefully reading the post, and probably not the last. My sincere apologies.

Terry

[Duncan Gibbs]

Am I understanding you correctly Peter?

Will you be making a stem a-la Mr Cricket's number above, or you'll be making a stem up in a fashion similar to a twin layered sawn frame?

[PeterSibley]

Am I understanding you correctly Peter?

Will you be making a stem a-la Mr Cricket's number above, or you'll be making a stem up in a fashion similar to a twin layered sawn frame?

Similar to a multi layered sawn frame Duncan, seems to be just as good as a lamination and with a huge saving in epoxy. At the moment I'm imagining something like a 1" core with 2 x 1/2" outside layers, all joints well offset .... but I'll have to have a good look at the timber sizes available in my racks.

[Duncan Gibbs]

A 'built up' stem like the one Jim posted would be even less epoxy. A couple of bolts wouldn't go astray. Much less end grain as well.

Once more I find myself agreeing with Terry:

Don't do it, don't do it. A glued-up [..]wood stem is just so amateurish. Yes it's easy, sufficiently strong and stiff, quick, and cheap. But this boat deserves better.

You prolly don't care though. It's all going to be painted. You'll even be a total epoxy convert by the time this is done. I know you Sibley!

[TerryLL]

A 'built up' stem like the one Jim posted would be even less epoxy. A couple of bolts wouldn't go astray. Much less end grain as well.

Once more I find myself agreeing with Terry:



You prolly don't care though. It's all going to be painted. You'll even be a total epoxy convert by the time this is done. I know you Sibley!

The biggest problem I faced using overlapping futtocks in solid wood for the stem was the weird changes in grain direction, which made cutting the stem bevels with a plane difficult. On my current build I went with Doug Fir lams, much like Peter's first attempt. Cutting the bevels on a laminated stem is much easier. Those lams will bend easily around that form after they've had a hot water treatment, so my advice is to give the laminated stem another go.

[P.L.Lenihan]

Very nice to see this thread underway.Congrats Mr.Sibley on a fine design choice. Canoe-yawls are such seductresses!!


And I do, must really say, like this bit from TerryLL;"Ain't nothin' more important to get excited about than how best to spile a plank." I'd buy the first series of rounds for him, just on those words alone!


Best of work on your boat Mr.Sibley. The pictures are always a treat!



Cheers!


Peter


P.S. another vote for giving the laminated stem another go but with hot water this time.

[John How]

I'm with the lam crowd as well, though what do I know. Some hot water on the bundle maybe and most important, lots of clamps and cawls to support the bend all the way around the corner. Also check your stock for runout. Then all the grain will be running in the right direction for an easy bevel. Then your back to arguing about spilling techniques!

[P.L.Lenihan]

Then your back to arguing about spilling techniques!

Yippee! I canna wait!

[RFNK]

Spilling is my speciality.

Rick

[P.L.Lenihan]

Keep your hand steady an' you'll do a lot less spilling and a whole lot more swallowing while the rest of us spile the nights away. I think that is what we do at night,isn't it?

[PeterSibley]

I know the trick to gently and lovingly shaping reversed grain ..... it's called a disc sander. I'm not a nice woodworker .

[Duncan Gibbs]

We know you're not nice, and that you're a woodworker: You are actually quite skilled at woodworking. But, you're right: Not nice!

[Terry Haines]

I know the trick to gently and lovingly shaping reversed grain ..... it's called a disc sander. I'm not a nice woodworker .

Sanding is being polite. I prefer a power plane . . .

[RFNK]

Keep your hand steady an' you'll do a lot less spilling and a whole lot more swallowing

And thus leaving moi completely unskiled ..... non!!

Rick

[andrewpatrol]

One wasted afternoon , well not totally wasted , I now have a great pile of sawdust and a lot of neat firewood starter and have learned how not to do something! I ripped out all the laminates for the stern post inner and the stem inner . All at around 1/8" x 2 1/4" but they really don't like the bend. Admittedly it's a hard one and my stack of oregon is dry 20 years .




I dug out Iain Oughtred's excellent book from under of layer of sawdust and discovered that he suggests a layered futtock method as his first choice ! Duh ! That's the way it will go now, 3 layers of 17mm.

Love this pic Pete ( with the big notation and arrows), If it makes you feel any better ( you're right probably doesnt) I glued up my stem and when I was patting myself on the back for very little springback and a job well done, and then I noticed that I'd put the clamp blocks on back to front so the stem was too small. AAAARRRRGGGGHHHH DDDDDDDOOOOHHHHH Had to make a new one. GGGGGGRRRRRRRRRRR

[PeterSibley]

Yep, I know that is there is a doppy way of doing something I'll find it so in the very rare moments of clarity I write myself notes !

[Sayla]

One wasted afternoon , well not totally wasted , I now have a great pile of sawdust and a lot of neat firewood starter and have learned how not to do something! I ripped out all the laminates for the stern post inner and the stem inner . All at around 1/8" x 2 1/4" but they really don't like the bend. Admittedly it's a hard one and my stack of oregon is dry 20 years .

That stem forefoot bend, although pretty tight, is generally quite short where the radius is tight - you can quickly use the standard 'big' pot on the kitchen stove with the bend section laid across and under the lid, and steam just the tight bend sections without much fuss - then let dry in the sun.

sayla

[PeterSibley]

I could laminate them but instead I've got out some 1" and 1/2" oregon and will layer them up, the 1" centrally and the 2 x1/2" layers on both outside faces, a nice balanced saw and glued construction .

BTW, that's the stern post .

[Terry Haines]

Love this pic Pete ( with the big notation and arrows), If it makes you feel any better ( you're right probably doesnt) I glued up my stem and when I was patting myself on the back for very little springback and a job well done, and then I noticed that I'd put the clamp blocks on back to front so the stem was too small. AAAARRRRGGGGHHHH DDDDDDDOOOOHHHHH Had to make a new one. GGGGGGRRRRRRRRRRR

Now there's a guy off the same mold as me!

I designed a canoe on mathematical principles - no, that wasn't the mistake - in which the stem profile was developed from the rib profile. Formed the curved ribs a dozen at a time on a jig and used one of them to create the stem profile. Built a pair of nice stems, carved the bevels etc. Then I took another look at the ribs and decided they weren’t quite right so I rebuild the jig and make a bunch more. They were perfect this time.

So I started to built the boat. It went together so easily, just as the mathematics had predicted. That is until the plank hoods started to work their way around the stem foot, when it started to get more difficult as the strips began to twist.They weren't supposed to twist; that was what the mathematics was all about. The danged stems were the wrong shape for the second batch of ribs.

I finished the build and it looks great but I’m not really happy with it: either mathematics or boat building is very unforgiving.

[TerryLL]

I finished the build and it looks great but I’m not really happy with it: either mathematics or boat building is very unforgiving.

Another fine example of how easy it is to design a boat that's difficult to build. The genius of Oughtred is that he designs very shapely and gorgeous hulls that are simple to build.

[JimD]

Might have bent better on the inside of the jig rather than around the outside. A length of metal strap around the outside might help, too, the way mast hoops are coaxed to take such tight bends. Also, that grain looks all wrong for bending. Sorry to sound nasty, Peter

[Terry Haines]

Another fine example of how easy it is to design a boat that's difficult to build. The genius of Oughtred is that he designs very shapely and gorgeous hulls that are simple to build.

Not really difficult. My designs aren't hard to build at all but I don't claim they can hold a candle to Iain's in the looks department! It was pretty straightforward to build, just not as easy as it was supposed to be. I was a bit cheesed off at myself for not realizing my mistake before it was embedded into the boat . . .

[skaraborgcraft]

Not really difficult. My designs aren't hard to build at all but I don't claim they can hold a candle to Iain's in the looks department! It was pretty straightforward to build, just not as easy as it was supposed to be. I was a bit cheesed off at myself for not realizing my mistake before it was embedded into the boat . . .

But think how well "the next one" will turn out!

[Sayla]

BTW, that's the stern post .

Doh! My assumption comes from remembering some of that photo with my stem.

[PeterSibley]

I had a bit of time today and ripped up a few length of recycled oregon, planed it flat and square then ripped it and planed it up, I'm really appreciating the machinery I have here .





I cut everything to shape, aligned it ready to glue but didn't glue it, it's going to be pretty cool here tonight and epoxy would just sit there , sticky until tomorrow. I'll do it on the weekend. I've set it up with 3 layers, the inner at 1" and the 2 outside layers at 1/2" . There is a lot of overlap and I think this will create a good balanced laminate. I've drilled the unglued assembly for 1/8" x 3"nails to hold everything in position and will replace them with 4" screws with cute little blocks on top to assist in removal should the epoxy harden before I unscrew them.



edited for spelling ....as usual !

[jim_cricket]

Looks great Peter, nice hunk of old iron for your planer.

[PeterSibley]

She's a good old thing Jim, about 50 years old, locally made with a cone clutch on the feed and a 2 1/4 hp 240v motor that never gets even warm.

[emma55]

Might have bent better on the inside of the jig rather than around the outside. A length of metal strap around the outside might help, too, the way mast hoops are coaxed to take such tight bends. Also, that grain looks all wrong for bending. Sorry to sound nasty, Peter

I would use blocks under the the clamp , Blocks with some concave surface . And on the next try ,clamp the lams on that apex of the bend first , I find that sometimes bending lams could take a few days a little at at time . And something that has all been stated thin spring steel or even some type of plastic can hold everything like a splint

[JimD]

I would use blocks under the the clamp , Blocks with some concave surface . And on the next try ,clamp the lams on that apex of the bend first , I find that sometimes bending lams could take a few days a little at at time . And something that has all been stated thin spring steel or even some type of plastic can hold everything like a splint

Blocks sounds like a good idea.

[TerryLL]

Alas, it seems Peter has moved on to a different stem construction.

[Terry Haines]

Alas, it seems Peter has moved on to a different stem construction.

- oh, futtocks!