Engine Stringer Repairs

Well, it has been many months without an update!  Finally got Blogger working on the computer again, so its time to catch up.

Now that all of the intermediate frames have been removed and rough cut, there is room to remove the engine stringers for some additional cleaning and repairs.  The top edge of the 2”x6” Douglas Fir stringers have some splits, separating grain, and missing sections.  Here you can see where sections have been broken off and the grain is continuing to split beyond the damaged area.

So, the splitting and broken area is marked out, and the laminate trim router is used to remove the damaged area.  A small piece of wood is clamped on as a fence to control the depth along the vertical face of the stringer.

Using a small wood chisel, the ends of the routed area are squared off for the graving piece to be glued in place.

A piece of Douglas Fir with a similar grain pattern was used to make the graving pieces.  Trimmed for length and a tight fit in the routed area, the piece is glued with waterproof glue and clamped in place.

A couple of days later, after the glue has set, the graving piece is ready to be trimmed.  Using a small disc sander and then a hand plane, the excess material is removed and faired to the stringer.  A final light sanding and this area is complete.

A few other areas on the stringer edge were also repaired.  The steering box carriage bolts had been tightened a few times over the last 60 plus years and the head of two had crushed the stringer.  So this area was routed and graving pieces added.

Along the top of the stringer, the screw holes for the floorboards were filled with ¼” dowel and trimmed flush.

Finally, the stringers are thoroughly degreased, sanded to remove flaking bilge paint and then 2 coats of Clear Penetrating Epoxy Sealer is applied in preparation for painting.

Making Frames

Trying to find white oak at the local lumber supplier was a little disappointing.  Most of the flat sawn, 4/4 lumber, was either narrow or short, or both.  Finally, we were directed to a bulk lumber yard where we were able to pick thru large quantities of rough sawn, true 4/4 lumber, inspecting the boards for grain direction, knots, splits and checking.

First, the lumber is planed to the proper thickness, about 0.825”.  The planer snipes on the first and last few inches of the stock, but that is ok because 6” of each end is not used because of minor splitting occurring during the drying process.

No need to disassemble the frame pieces, we trace them directly onto the new frame stock.  One side is traced for each frame and the pieces are cut out on the bandsaw.  Then the new blank is traced to make the other half of the frame.

The center tie is traced as well, but the bottom of the tie is extended so it will align with the frame, eliminating the original gap from the bottom planking that allows dirt build up.  When cutting the pieces on the bandsaw, the keel and chine landings are left oversize leaving excess material so adjustments when fitting the frame.

With all of intermediate frame pieces rough-cut, the next step is fitting them to the boat and bringing them into alignment.

Full Steam Ahead

Construction of a Danenberg steam generator has been in the works.  We purchased Sandhog elements, iron fittings and pipe but decided on some minor modifications.  We built a frame using a small mover’s dolly and one, eight-foot long 2x6.

To support the 2” pipe, pipe hanger clamps were used.  Instead of using a calming chamber and glass sight tube, we are using a bucket with a toilet tank float, much cheaper than a sight glass and needle valve.  This will keep water at the proper level in the tube covering the heating element.

A gang box is used to keep pressure off the electrical connections of the heating element.  A 240-volt circuit was setup in the garage and a 12’ electrical cord connected to the box.  Filled with water and switched on for a test fire, we are making steam in about 2 minutes with lots of gurgling noises and occasional spits of water out the top tube.

The final piece will be a short piece of automotive heater hose.

Frame Inspection

We purchased an 8’-3”x3” aluminum I-beam and a 12’-3”x1/4” aluminum flat bar to use as a temporary keel.  The I-beam establishes the flat planing surface from the transom forward.  On the 16’ Resorter, the flat planning surface is about 5’ long measured from the transom.

The flat bar establishes the curve of the keel forward of the flat planing surface.  The bar is under the I-beam and attaches to the gripe forward.

With the aluminum pieces clamped in place, any gaps at the keel landings are noted on the frames.  When cutting the new frames, this additional distance will be added to the landings during the patterning process to bring the keel landings into alignment.

The even-numbered, intermediate frames are then removed for patterning.  Where the frame lands on the bilge stringer, the factory sometimes needed to adjust the frame alignment using shims.  The thickness of any shim is noted on the frame as well and this distance is added to the pattern.

There are 3 shims of varying thickness in the boat from the factory.

Straightening Up

Twisting of the hull from rough water torques the frame joints, leveraging the screws at the topside/bottom frame "knee" joint, causing them to loosen.  And as the bottom planks swell, they expand and push the chines outward from the frame landings, taking the topside frames with them.  Notice the 4 screws of this frame station are loose, the bottom one backing out quite a bit.

The seasonal swell/shrink cycles of the bottom planks works the frames and brass screws at the knee joint back and forth, elongating the screw hole in the frame or breaking the screw.   The chines are attached to the topside frames with a ¼”-20 carriage bolt and a screw at main frames.  The chines are attached only with a screw at the intermediate frames.  Bottom swelling, pushing on the chines, will pull the screw from the wood at the intermediate frames, or break the screw, creating a gap.

When the boat was built, these intermediate frame joints were tight against the chine.  The restoration process must bring the chine and frame back into alignment.  Over time, this spreading of the bottom planks causes leaking, structural weaknesses and failure of components.  After getting the boat leveled and blocked, it is time to pull the topside frames back into position for bracing.  Using pipe clamps at the topside frame, the clamp is hooked to the bilge stringer and tightened until the intermediate frame is tight against the chine.

With the joints tight, 1”x4” pine braces are screwed to the topside frames  below the knee to hold the frames in position.  With the all joints tight, we reconfirmed the chines were still level.  With everything set, the keel and chines were removed in preparation for frame inspection and replacement.

On The Level

With the bottom planks off, we are ready to get the boat setup and level.  Using 2 floor jacks, first the rear, then the front dollies were jacked up and the sawhorses assembled.

Crawling under the covering boards, it was tight quarters to assemble the sawhorses.

Setup on the adjustable sawhorses, we removed the bottom plank battens and the topside chine planks.  Then we began to level the chines port to starboard, first at the sawhorses and then each frame.  Using a 6’ level with equal length spacer blocks, the wedges under the support of the sawhorse where adjusted.

Next, we added supports about the perimeter to support and adjust the twist in the framework.  Cinder blocks, 2-2”x6” blocks, foam rubber and wedges are setup to lift frame stations into level.

Finally, the line projecting laser level was used to bring each frame station level port to starboard.   The wedges between the 2”x6” blocks were adjusted to raise the low side at the major frame stations until each was level.

A final check to confirm the sawhorses were still supporting the bilge stringers and all stations were level, the wedges were super glued to prevent them from moving.

Now we can begin pulling the framework back into shape.

Bottom Removal

With the boat on the dollies, we began removing the putty from the bottom for removal of the planks.

The putty was drilled out using a modified a 5/16” wood spade bit.  The bit removes the putty to the screw top and, most of the time, the small tip would find the slot of the slotted screws.

For the few screws forward, above the waterline, the factory installed wood bungs.  We used a scribe to split the bung and pop the bung free.  With all of the screws exposed it’s time for the screw gun.  Most of the screws came out easy, except for the few broken or striped ones.

At some point, a previous owner installed 5200 rubber in the gaps between planks in an attempt to slow leaking.  This is not a good idea on original planking because with each swelling cycle the plank no longer has room to move and pushes the chines out of the frame landings and can cause the planks to cup.  The planks came off easy after cutting the 5200 in the gaps and a little prying at the striped or broken screw locations.

Several hours later, we have a lot of brass screws to recycle.