Keel and Skeg Stringers

It most conventionally built wooden boats, the frames refer to what you might think of as the "ribs" of the boat running across ways (thats "athwartship," to you, matey!).  In the Glen-L Waterlodge, the framing members run longitudinally and are called stringers.

So building the boat frame means assembling the individual stringers and then tying them together with various cross beams. 

There were five stringers total.  Two side stringers, one keel stringer in the middle, and two "skeg stringers" between the keel and the side stringers. While the plans are relatively straightforward about building the stringers, there are lots of pesky details to consider, notches for cross beams, plywood reinforcement, butt blocks to make sure the plywood on the side stringers didnt leak, and a subtle curve to the deck that will sit on top of the stringers.

The keel stringer used big pieces of plywood to structurally reinforce the member and did not have overlapping two-by pieces.  The skeg stringers did have overlapping two-by pieces but no reinforcing plywood. The result will be two big storage bulkheads under the decks on either side of the boat.

The side stringers of course had plywood that covered the outside surface of the boat and no overlapping two-by pieces.  Well talk about these and their butt blocks in the next build day entry.

The notches for the cross beams were easy, though we still forgot a few and had to cut them out of the already assembled stringers.  The porch deck beam notches were not really dimensioned properly on the plans and so we had to do a little improvisation later. 

We built the stringers on the asphalt floor of the barn.  It was flatish and shaded, so we didnt bake as we fretted over the details of our new stringers.

One challenge we faced was making sure that each member we built matched all the others. The plans suggested literally building them one on top of another.  This didnt seem that practical, so we hit on a solution:  Using the plywood already cut to shape for the side stringers as a pattern for our other stringers.  That way wed know that all the angles would be correct and all the pieces of each member would be in the right place.

We used what we called temporary butt blocks just to hold the side plywood in place while we were using it as a pattern.

So in these photos, you can see the side plywood under our stringers as a pattern. 

From left to right: keel stringer, starboard skeg stringer, and port skeg stringer.

So for each stringer, the process was more or less:  Lay out the pieces for fit on our plywood pattern; put wax paper under anything we didnt want to be permanently adhered to anything below, temporarily screw down, as necessary; apply a thin coat of epoxy to both surfaces of every joint; apply a thickened coat of epoxy to one side of every joint; and finally fasten together all joints with stainless steel screws.

 

After the epoxy on the stringers sets, we could put the stringers on the building form. 

Exciting!  It is looking more boat-like every day. These incremental changes are probably pretty minor looking to other folks, and the progress may seem pretty slow.  But for us, it is crazy.  Look we had a pile of lumber!  Now we have this boat(ish) thing!  Amazing!

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Side Stringers

The side stringers are the sides of the boat.  So far everything weve been doing was stuff inside; here we finally tackle something that will ultimately keep water out.  Yikes!  And because of the complexity of the build and our boat-tardedness,  it took us about seven hours per side to assemble.

In our last build day, we finished assembling the keel stringer and the two skeg stringers.  We used the plywood  cut for the side stringers as a pattern to ensure that all of the stringers would be identical(ish). 

Ill spell a few things out here so you can appreciate the challenge of assembling the side stringers:

• The plywood for the sides was in 3 big pieces; 
• There were two long (and slightly warped) pieces for the top and bottom, and two end pieces cut at a slightly incorrect angle (remember that pesky 3 degrees?); 
• Once the pieces are coated in thickened epoxy, everything is slipperier than a greased pig; 
• And to top it all off, all screws holding it all together needed to go in from the outside (plywood side) with all the loosey goosey bits skittering around underneath as we try to put in screws from above.

Pretty much a recipe for disaster.

We hit on a helpful idea:  Temporary screws from the inside.  We could butter it up, put the pieces in place, and use temporary screws all the way through the two-by pieces and the plywood to hold everything together.  Then we can flip the whole thing over and put all the permanent screws in the plywood from the outside.  Later we remove the temporary screws.

Okay!  Sounds like a plan.  Or a sketch of a plan.  A lot of critical things needed to go right, so we made a step-by-step plan.  Later referred to in arguments during the day as "The Plan."  As in "Stick to The Plan!" or "Oh God, are we changing The Plan?"

The Plan was the thin dividing line between slightly stressful work and sheer madness.  The illustration on the corner of The Plan was what we didnt want to happen.

So we did the usual and put wax paper under everything, and coated everything with the first thin coat of epoxy.  This is more like painting, familiar, and not too hectic.

Then we tackled the butt blocks.  This is where the sheets of plywood that form the sides meet.  We put these in first, because we wanted to make sure that when we started attaching the two-by pieces the plywood wouldnt move or shift.  The butt blocks are six inches wide, buttered liberally with thickened epoxy (including between the two ends of the plywood) and secured with an assload of screws.

Then we got serious and epoxied all the two-by bit, including all of the ends where they would meet each other.  We secured them down temporarily with long deck screws to the plywood (and accidentally to the floor in a few places).

In a harrowing effort (would it stay together?!) we flipped the stringer over so the plywood side was facing up.  Now we could put in all of the stainless steel screws required by the plan.  A screw every two or three inches.  Thats a lot.

At this point, we are tired, probably dehydrated, covered in sticky epoxy, tangled in extension cords, our hair is falling in our eyes as we bend down, and little flies have decided that now would be a good time to investigate our nose and ears.  Our latex gloves are torn and getting tangled in the drill bit as it turns, the screws are not very sharp and so are not going in very readily, and there is still a lot of work to be done before the epoxy completely sets.  Just wanted to set the scene here.

But naturally, we handled it with superhuman grace, no one got frustrated whatsoever, and we maintained our amazing good humor throughout.  Any stories you hear to the contrary are lies made up by our enemies to slander us.

Kai hit on the brilliant idea to start the screws in the proper location with a few knocks of the hammer.  So she went around, ahead of the drill, putting in screws at the requisite distance, staggering them as necessary.  Again, wed discovered the razor edge of sanity and found the narrow path just this side of it.

So in the end, we had a side stringer.  And after another long day, we had two side stringers.  Woot. 

Here, all five stringers are in place.  The cross beams connecting them are a sneak preview of the next build day.  

Again, looking at our work at the end of the day, the boat is much more boaty.

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Didi 950 Build Stringers going on

Earlier this month I posted about the start of construction of the Didi 950 of Micheal Vermeersch in Ohio. Construction is progressing nicely.

The backbone components have all been fitted and glued. They have slotted connections, egg-crate fashion, with all of the bulkheads. Further into the project all of those junctions will be strengthened with structural epoxy fillets.

The sheer clamps have been scarphed into lengths sufficient to span the full length of the boat, from available shorter lengths. Before that they were also bevelled along both edges to remove excess material to save time later planing them to shape.  The sheer clamps are the major strength members along the deck edge. Normally they would sit flat against the inside of the hull skin but with these designs I turn them diagonally across the corner for a cleaner and lighter detail that also has a better balance of gluing area between the components that are being joined.

Now Michael is fitting the hull stringers. With this method of construction the stringers are arranged to suit the different regions of the hull skin. In the photo below you can see the sheer clamp, spanning the bottom corners of the bulkheads. Just above that is a topside stringer. There will be another similar stringer close to the chine that will accurately align the upper side panel.

The other full-length stringer that is in place is the tangent stringer that defines the edge of the curved portion of the hull that is laminated from thinner plywood. On top of the hull there is a stringer partially slotted in, defining the other edge of the curved panel.

Below the tangent stringer is a short stringer at the right in the photo. This is an additional stringer needed to fill in the space where the side panel increases in width due to the tightening of the radius toward the bow.

In the foreground are stringer lengths that will be scarphed together into the long lengths required. The angles have been planed and are ready for gluing.

 

 

 

 

 

Didi 950 with hull stringers being fitted.

To see more of this and our other designs, go to http://dixdesign.com/

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