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bartenderdave | profile | all galleries >> Miscellany >> Nesting Pram: Little Blue Duck tree view | thumbnails | slideshow

Nesting Pram: Little Blue Duck

Construction photos for a 7-foot 6-inch nesting pram tender for the Bartender. Based on Steve Lewis's DinkyDink.
Cardstock model from scale versions of stitch and glue panels.
Cardstock model from scale versions of stitch and glue panels.		 Stem oblique; design based on DinkyDink, Lewis Boat Works.
Stem oblique; design based on DinkyDink, Lewis Boat Works.		 Stern oblique view.
Stern oblique view.		 Model glued to reference-lined vellum.
Model glued to reference-lined vellum.
Stations every inch at 1:8 scale makes for 10 slices.
Stations every inch at 1:8 scale makes for 10 slices.		 Extracting height and offset measurements.
Extracting height and offset measurements.		 Homemade tool articulates for horizontal and vertical measurements. Ugly. It works.
Homemade tool articulates for horizontal and vertical measurements. Ugly. It works.		 Scale plan view of Bartender cockpit; coaming line dictates tender cross section.
Scale plan view of Bartender cockpit; coaming line dictates tender cross section.
Lofting: Offset and height data at each station are transferred to a grid on plywood.
Lofting: Offset and height data at each station are transferred to a grid on plywood.		 A line is drawn following the batten, visible at ends of props. Batten establishes best fit, a fair line.
A line is drawn following the batten, visible at ends of props. Batten establishes best fit, a "fair line."		 Previous line was chine height. This is sheer half breadth.
Previous line was chine height. This is sheer half breadth.		 Close view.
Close view.
Completed lines at stern; plywood is 30 inches across. Rear transom line will define intersections.
Completed lines at stern; plywood is 30 inches across. Rear transom line will define intersections.		 Height reference line connects sheer ends. Keel line references half breadths.
Height reference line connects sheer ends. Keel line references half breadths.		 At the bow, the lines cross, making measurement extraction tricky.
At the bow, the lines cross, making measurement extraction tricky.		 Original station lines erased, to bring out frame locations. Third one from stern defines the nesting bow.
Original station lines erased, to bring out frame locations. Third one from stern defines the nesting bow.
Building surface. Cross bars at frame locations, square and true. Transom supports TBA.
Building surface. Cross bars at frame locations, square and true. Transom supports TBA.		 Ends of cross bars level all ways, sized for individual frame widths.
Ends of cross bars level all ways, sized for individual frame widths.		 Leg anchor -- blue screws fix each leg to the concrete. Really solid.
Leg anchor -- blue screws fix each leg to the concrete. Really solid.		 On to frames. Pretty skimpy -- hoping these will be herky enough to survive paneling.
On to frames. Pretty skimpy -- hoping these will be herky enough to survive paneling.
Corners are gusseted with quarter inch plywood, here a chine.
Corners are gusseted with quarter inch plywood, here a chine.		 Frames are glued up on the body plan; each the right bit long to establish the sheer, later.
Frames are glued up on the body plan; each the right bit long to establish the sheer, later.		 Forward transom in position, during clampup of backing for attaching plywood.
Forward transom in position, during clampup of backing for attaching plywood.		 Rear transom, same stage.
Rear transom, same stage.
Frame C is a double, to separate the halves, here receiving backing for attachment bolts.
Frame C is a double, to separate the halves, here receiving backing for attachment bolts.		 Backing is some thin hardwood, glued on -- eight bolts, all told.
Backing is some thin hardwood, glued on -- eight bolts, all told.		 Detail of carriage bolt attachment; collars are stainless from McMaster-Carr.
Detail of carriage bolt attachment; collars are stainless from McMaster-Carr.		 Both transoms and two frames were pre-beveled using info from the lofting surface.
Both transoms and two frames were pre-beveled using info from the lofting surface.
This series shows the forward transom, with some added wood in the first photo, here beveled on each end.
This series shows the forward transom, with some added wood in the first photo, here beveled on each end.		 Down a little further.
Down a little further.		 Top view. Next shot shows the completed bevel in profile.
Top view. Next shot shows the completed bevel in profile.		 This is a rolling bevel, with a greater angle at the keel than the chine. Most bevels were simpler.
This is a rolling bevel, with a greater angle at the keel than the chine. Most bevels were simpler.
All the frames up except the double, C.
All the frames up except the double, C.		 Frame C gets some backing for screws, in glue-up phase.
Frame C gets some backing for screws, in glue-up phase.		 Rear half of C gets some added wood to accomodate the bevel.
Rear half of C gets some added wood to accomodate the bevel.		 Extra wood is now glued on.
Extra wood is now glued on.
And here, beveled close to fair, on the bottom. Sides also required some added wood.
And here, beveled close to fair, on the bottom. Sides also required some added wood.		 Starboard frames faired on their flanks, looking aft.
Starboard frames faired on their flanks, looking aft.		 Looking forward; very gratifying to see all those bevels come in.
Looking forward; very gratifying to see all those bevels come in.		 Frames can be detached and reattached reproducibly to building surface, facilitating notching.
Frames can be detached and reattached reproducibly to building surface, facilitating notching.
Screws are #10 self-piercing sheeters, with rubber-backed washers. Very handy.
Screws are #10 self-piercing sheeters, with rubber-backed washers. Very handy.		 Time to cut notches for chine logs and keelson, here the starboard chine area, double frame in the center.
Time to cut notches for chine logs and keelson, here the starboard chine area, double frame in the center.		 Aft end, fully notched.
Aft end, fully notched.		 Keelson glue-up, in two layers. Full thickness too stiff to bend on without depressing frames.
Keelson glue-up, in two layers. Full thickness too stiff to bend on without depressing frames.
Added support between frames B and C, to keep keelson fair.
Added support between frames B and C, to keep keelson fair.		 Couple of failed efforts to bend on the chines lead to wetting the wood and gradually developing the bend.
Couple of failed efforts to bend on the chines lead to wetting the wood and gradually developing the bend.		 Easing the wood in over half an hour gave no failures; mega clamps the key, some weighted to rotate the piece into place.
Easing the wood in over half an hour gave no failures; mega clamps the key, some weighted to rotate the piece into place.		 Chine logs and keelson completed, aft portion. An airy framework.
Chine logs and keelson completed, aft portion. An airy framework.
Forward starboad chine log, first lamination: lots of twist and a captured notch in the transom.
Forward starboad chine log, first lamination: lots of twist and a captured notch in the transom.		 Fairing: excess wood over a frame is filed away to establish the correct bevel. The logs and the keelson are planed fair.
Fairing: excess wood over a frame is filed away to establish the correct bevel. The logs and the keelson are planed fair.		 Looks good, except to either side of the double frame; not enough curvature there.
Looks good, except to either side of the double frame; not enough curvature there.		 Reason: should have sprung the stringers through the double frame; wood being added.
Reason: should have sprung the stringers through the double frame; wood being added.
Now the chines are fair on either side of the double frame. Ditto keelson.
Now the chines are fair on either side of the double frame. Ditto keelson.		 Note almost a quarter inch of wood was needed between frames C and D in the center to correct the line.
Note almost a quarter inch of wood was needed between frames C and D in the center to correct the line.		 Starboard panel in place, held in position with plastic washers while the epoxy cures.
Starboard panel in place, held in position with plastic washers while the epoxy cures.		 Bronze screws through plastic medallions. Four mm okume too thin for proper screw installation.
Bronze screws through plastic medallions. Four mm okume too thin for proper screw installation.
Most are 3/4 inch number 8's, and demand careful tightening; these are guide screws, a bit longer.
Most are 3/4 inch number 8's, and demand careful tightening; these are guide screws, a bit longer.		 Rapid Dave sets screws on a bottom panel.
Rapid Dave sets screws on a bottom panel.		 Clamp fiend at work.
Clamp fiend at work.		 Bow portion of the starboard bottom.
Bow portion of the starboard bottom.
Stern, also in glue up.
Stern, also in glue up.		 Mega clamps, for buddy Ralph, who really likes clamps.
Mega clamps, for buddy Ralph, who really likes clamps.		 Last panel, in dry fit.
Last panel, in dry fit.		 Edges masked, to reduce remnant squeezeout. When cured, it is a bear to remove.
Edges masked, to reduce remnant squeezeout. When cured, it is a bear to remove.
Filled, faired, and ready to glass.
Filled, faired, and ready to glass.		 Oblique view; masking identifies sheer line, eases removing excess glass at green stage of curing.
Oblique view; masking identifies sheer line, eases removing excess glass at green stage of curing.		 Bottom glassed; port side glass taped in place, ready for layup.
Bottom glassed; port side glass taped in place, ready for layup.		 After layup and spreading resin but before removal of masking ... to be done mid-cure.
After layup and spreading resin but before removal of masking ... to be done mid-cure.
Starboard sheer in clampup. Hull glass has been filled with 2 coats of resin.
Starboard sheer in clampup. Hull glass has been filled with 2 coats of resin.		 Bungie assist on the forward end of the star sheer. Eases the clamp up.
Bungie assist on the forward end of the star sheer. Eases the clamp up.		 Port sheer, installed. A deliberate, careful task.
Port sheer, installed. A deliberate, careful task.		 Bungies help pull in the sheer ends, for good control in glue-up.
Bungies help pull in the sheer ends, for good control in glue-up.
80-grit sanded overall
80-grit sanded overall		 Off the jig. Tabs at ends will come off and then it goes back on the jig.
Off the jig. Tabs at ends will come off and then it goes back on the jig.		 Sheer guard sections on transoms needed, yet. 65 pounds, as is.
Sheer guard sections on transoms needed, yet. 65 pounds, as is.		 Time to slice the hull, here using the saw to pre-clean the kerf slot of shim material.
Time to slice the hull, here using the saw to pre-clean the kerf slot of shim material.
Cutting from the outside, halfway across the sheer a loud pop gave this.
Cutting from the outside, halfway across the sheer a loud pop gave this.		 The port sheer also cracked when hit with the saw, even though clamped tightly. Time to regroup.
The port sheer also cracked when hit with the saw, even though clamped tightly. Time to regroup.		 Glue up of the split section; white plastic covers the cut area.
Glue up of the split section; white plastic covers the cut area.		 Second attempt, after glassing the sheer to the hull ply. Saw cut from the inside this time.
Second attempt, after glassing the sheer to the hull ply. Saw cut from the inside this time.
Pulling across the center of the hull.
Pulling across the center of the hull.		 And down the opposite chine; seam wedged to maintain an open kerf.
And down the opposite chine; seam wedged to maintain an open kerf.		 End of the line; note glass reinforcement and clamped plastic keeper. No splits this time!
End of the line; note glass reinforcement and clamped plastic keeper. No splits this time!		 Separated halves.
Separated halves.
Mating half-frames.
Mating half-frames.		 Overall view; yes, they do re-mate when the bolts are installed!
Overall view; yes, they do re-mate when the bolts are installed!		 First nesting; frame stubs will go away soon.
First nesting; frame stubs will go away soon.		 Frame stubs removed; profile view. Can you spot the seam?
Frame stubs removed; profile view. Can you spot the seam?
Overhead view. Sheer rail needs glass.
Overhead view. Sheer rail needs glass.		 Separated and upright for fiberglassing the sheer rails. A fun job.
Separated and upright for fiberglassing the sheer rails. A fun job.		 Saturation coat of resin on the eight Meranti plywood corner braces.
Saturation coat of resin on the eight Meranti plywood corner braces.		 Corner braces installed; last set in glueup.
Corner braces installed; last set in glueup.
Springback of hull mandated serious clamping pressure to fully mate the halves.
Springback of hull mandated serious clamping pressure to fully mate the halves.		 Oblique view.
Oblique view.		 Port side profile view.
Port side profile view.		 Starboard side clamps. Springback made for a quarter inch gap at the rails before clamps applied.
Starboard side clamps. Springback made for a quarter inch gap at the rails before clamps applied.
Fillet detail.
Fillet detail.		 Two coats of resin, aft section.
Two coats of resin, aft section.		 Perspective view; lotta sanding coming up.
Perspective view; lotta sanding coming up.		 Mockup of skeg, in slot, to fine tune the mating to hull.
Mockup of skeg, in slot, to fine tune the mating to hull.
Mahogany skeg, held in alignment for dry fit. Screwed in place from the keelson.
Mahogany skeg, held in alignment for dry fit. Screwed in place from the keelson.		 Combined glue job to the hull with glass over the fillet and up the sides.
Combined glue job to the hull with glass over the fillet and up the sides.		 Same stage; alternate view. Glass gets cut off at the green stage of the resin ...
Same stage; alternate view. Glass gets cut off at the green stage of the resin ...		 As here, and the fillet area is cleaned up, in preparation for ...
As here, and the fillet area is cleaned up, in preparation for ...
Application of biaxial tape along the edge.
Application of biaxial tape along the edge.		 After wet out with resin, and again trimmed at the green stage.
After wet out with resin, and again trimmed at the green stage.		 One fill coat of resin, after cleanup and fairing of tape edges.
One fill coat of resin, after cleanup and fairing of tape edges.		 Thwart mockup in the aft position, for solo rowing. Shorter legs take over for tandem rowing ...
Thwart mockup in the aft position, for solo rowing. Shorter legs take over for tandem rowing ...
Shown here, in an end-on view. Oarlocks here are about right for two passengers.
Shown here, in an end-on view. Oarlocks here are about right for two passengers.		 Solo position
Solo position		 Tandem position; couple bags of sand simulate aft loading for the second passenger -- a bit light, though,
Tandem position; couple bags of sand simulate aft loading for the second passenger -- a bit light, though,		 Sand bags, alone. Getting out of this thing will be tricky!
Sand bags, alone. Getting out of this thing will be tricky!
Forward seat/thwart completed,
Forward seat/thwart completed,		 Close-up; separates for ease in painting. In use, forward part could extend farther when two are aboard.
Close-up; separates for ease in painting. In use, forward part could extend farther when two are aboard.		 Mockup of rear seat/thwart; testing on the lake showed the lowest height is best (this is highest).
Mockup of rear seat/thwart; testing on the lake showed the lowest height is best (this is highest).		 Halves nested; view from the center frames. Black material is gasket to cushion halves.
Halves nested; view from the center frames. Black material is gasket to cushion halves.
Halves nested; view from the transoms. Note spacer separating halves.
Halves nested; view from the transoms. Note spacer separating halves.		 Side view of transoms. Spacer will be replaced with ply glued to inner half, and some chafe protection.
Side view of transoms. Spacer will be replaced with ply glued to inner half, and some chafe protection.		 Side view of inner half butting against seat/thwart of outer; bolts under seat will hold halves in place.
Side view of inner half butting against seat/thwart of outer; bolts under seat will hold halves in place.		 Other contact is at sheer and will require some more quarter inch neoprne.
Other contact is at sheer and will require some more quarter inch neoprne.
Roughed in the rear thwart. This is the seating surface -- glueup of edge reinforcement.
Roughed in the rear thwart. This is the seating surface -- glueup of edge reinforcement.		 Cleats in place, fresh glueup.
Cleats in place, fresh glueup.		 Drywall screw/plastic washer combos hold cleats in place while resin cures.
Drywall screw/plastic washer combos hold cleats in place while resin cures.		 In place; ring bolts secure forward edge; top cleat will secure it aft.
In place; ring bolts secure forward edge; top cleat will secure it aft.
Painted and outfitted in nesting mode: blue hull; light gray interior with bright rowing stations and rear thwart.
Painted and outfitted in nesting mode: blue hull; light gray interior with bright rowing stations and rear thwart.		 Nesting achieved by bolting the center frame of one half to the rowing station support of the other.
Nesting achieved by bolting the center frame of one half to the rowing station support of the other.		 Bungie to ring bolts (see next photo) across bow rails. Neoprene chafe/padding at contact areas.
Bungie to ring bolts (see next photo) across bow rails. Neoprene chafe/padding at contact areas.		 And now eight bolts join halves to make a dinghy; oars in position for tandem use.
And now eight bolts join halves to make a dinghy; oars in position for tandem use.
View from the bow.
View from the bow.		 Oar leather made from neoprene gasket material, stitched on; my first!
Oar leather made from neoprene gasket material, stitched on; my first!		 The Duck nesting over the engine box, aboard Surf Scoter.
The Duck nesting over the engine box, aboard Surf Scoter.		 Looking aft; needs tie-down points each side. Ideas?
Looking aft; needs tie-down points each side. Ideas?
Tilted back to allow the engine box to open.
Tilted back to allow the engine box to open.		 Stepping over to the dinghy; not bad at all.
Stepping over to the dinghy; not bad at all.		 At the catch -- good trim.
At the catch -- good trim.		 End of the power phase of a stroke -- note the bow digging in.
End of the power phase of a stroke -- note the bow digging in.
Boy, this thing is light on the water, no?
Boy, this thing is light on the water, no?		 Becky says: Little Blue Duck, and so it is henceforth
Becky says: "Little Blue Duck," and so it is henceforth		 Second mate, exploring the MARAD Basin, off a bit towards Tongue Point.
Second mate, exploring the MARAD Basin, off a bit towards Tongue Point.		 Second mate enjoys the view from the engine box. First time I've seen the big boat from the water, with the boot stripe on.
Second mate enjoys the view from the engine box. First time I've seen the big boat from the water, with the boot stripe on.
A little stern bling, to identify the duck. From Action Signs, easy and quick.
A little stern bling, to identify the duck. From Action Signs, easy and quick.		 Hung the dinghy against the shed wall, off the bow eye.
Hung the dinghy against the shed wall, off the bow eye.		 Bungie on cross-line is insurance.
Bungie on cross-line is insurance.		 Pulleys and cleat a simple system for haulage and tieing it off.
Pulleys and cleat a simple system for haulage and tieing it off.

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bartenderdave17-Jun-2010 02:47
No washers. Does not leak so far. Only the bottom two bolts are below the water line.
George 13-Jun-2010 12:19
Did you use any rubber washers or anything to seal the bolt joints?

Thank you
bartenderdave04-Mar-2009 01:44
Brian, I suspect you will fare well if you adopt the technique I did. Once you have the modeland pull offsets from it, lofting will allow you to bring it all in to fair lines. I would not have accepted that until I did this project. Lofting really is the heart of fine tuning a design.

A 1/8th model of the Kingfisher will come in about 2 feet 8 inches LOA, and will be a lot easier to turn into offsets. Probably best to use foam core board or similar. Maybe posterboard.
Brian Steeves 27-Feb-2009 23:17
Does anyone have any ideas on how to convert a stitch & glue plan to frames for applying srtips for construction like a cedar strip canoe. I have the plans for "Kingfisher" rowing shell, but do not want to use the stitch & glue construction of the plans. I'd really like to have a table of offsets for the plans, but have been able to find any to date. If I have to make a model the way mentioned in this article, is this going to provide me with enough measurements to end up with a 22'6" boat that is fair? I believe that my problem is going be finding enough measurement points for a boat this long and narrow. A table of offsets would certainly help, I believe.
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