Mike's journal

My Next Dinghy Project - Construction

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You can never have (or build) too many small boats :-). 
Here is the planning for this project, including a summary of various
nesting and folding dinghies that I found.
 
I decided on building the Spindrift Dinghy 10N.   
 

Start of construction

Spring Hill, 17 Jan 2012 So I guess this is the actual start of construction.  Woo-hoo!

I received 3' of ⅛" x 1½" T-316/316L stainless steel today and brought it over to the fabricator.  This is for the plate at the base of the mast and the connectors for joining the two halves.  Garry Prater's plan called for 2 connectors, but I think I'll add a 3rd in the middle as I've shown here.  For the two bolts on the left of this plate (that will overlap the trunk, shown in blue), I'll use the West System technique of drilling the holes oversize, filling them with epoxy, and embedding the bolt's threads into that epoxy plug.  I believe the West System guys have determined this produces a very strong connection*.

	Man-O-War, 16 Apr 2012
	Here is their figure from Chapter 14*:		The tests they show are mostly on fairly thick wood though and maybe not applicable to thin plywood like ¼".  I wonder if adding a bevel to the hole from the backside would compensate.  Like this --> I don't think I have an easy way to test the strength of this approach.  I'm guessing it's not quite as strong as using a nut and washer.  But I'd kind of like to use it for all the bolts - to reduce the number of toe-stubbers inside the dinghy.

Spring Hill, 26 Jan 2012 And the results back from the fabricator.  Hey, it's a start. Now I need to get back to Man-O-War to start on the hull.

Man-O-War, 24 Feb 2012 The plywood and resin arrive at Man-O-War.   Less than half of the shrink-wrap put on by Abaco Shipping (Heavy Lift Services) survived the passage :-(.  I should have done it myself.  Thankfully, everything in the shipment arrived.   The packaging and shrink-wrap of the plywood by World Panel Products was superb (really a 1st class outfit) and came through fine.
Man-O-War, 25 Feb 2012 I was fretting over having to construct a table for this.  But the skid that the plywood was shipped on ought to work.  Here it is laid on top of some cinder blocks.  Then the stack of plywood on top of it.   I'm in about the same spot I was before, next to the water.  Kewl.

Man-O-War, 26 Feb 2012 In researching this project, I came across a couple postings suggesting that a small increase to the freeboard might be a good idea*.  In particular, the post at the bottom of this thread seems both thoughtful and well written.  I quote from it: Note: I am adding 2 inches to the freeboard to the design. I did this on the fiberglass one I made, as did several others who built them in Panama. Most owners I know say they wish they had more freeboard...but the owners I know use them as dinghies for their larger boats, and often have to haul groceries and two adults around.... Might not be needed if you use it only for a fun boat, as getting splashed is part of the fun. If waters are choppy in your area, though, it is a modification worth considering. Be sure to think through how to do this! Simplest method to avoid mistakes is to draw the plans out full size, then continue the lines up: thus, extending the existing stem lines and the transom corners up along the existing lines. You will end up with a boat slightly longer and wider, but having the exact same shape as the original but just more freeboard. The author is somebody I'd like to buy a beer someday.  BTW, he has an interesting description of building a stitch & glue (Spindrift) dinghy using fiberglass only, when you don't have access to proper plywood.    Sidetrack asking in the B&B Forum ... There are no Spindrifts nearby that I know of, so I figured I'd ask in the B&B forum.  Except for Graham's reply (where I simply stopped monitoring the thread) I was really surprised by the level of vitriol, pomposity and rigidity in the response.  Maybe the election season is taking it's toll on reason?  Or I'm simply too sensitive. [28 Feb 2012] I wonder about the dynamics here.  Are there people on the forum with a different or more reasoned point of view but unwilling to express it, for fear of being ridiculed and ostracised?  I imagine it's the sort of social system that has been studied to death by psychologists, sociologists and industrial engineers.  Not the same as a Facebook or Twitter.  More like what happens in a company "too long in the tooth".  Where things get moldy, dogmatic, regimented, inbred, bureaucratic.  I certainly saw a bunch of it on the job.  There is a memorable scene from the movie, Brazil, where the protagonist needs to access a computer and the owner of the terminal does all he can to keep control.  It's 9:00 into this clip (just click on the Play button)---> Or on Youtube at higher resolution. The antithesis of course, is a vibrant, energetic, innovative community (in this case, I'm thinking the Panama cruisers).  Hmm. So, my desired use: Cruising, at times hauling lots of stuff/persons, potentially in sloppy conditions.  I think these are the tradeoffs in adding a bit to the freeboard: Pluses Minuses A slightly drier ride More carrying capacity Maybe a little better feeling of security The oarlock will be 2" higher over the water so less likely to catch on the backstroke More windage - roughly 15% more surface area Just slightly more weight More height stored on deck - say, 2 inches, but maybe less if the centerboard trunk rests on the hatch and that determines the height stored on deck - TBD The transom might have to be notched to lower the outboard - [7 Mar 2012] So, with the additional 2", the height of the transom becomes 17".  That looks like a good fit with my outboard which is 17" from the mounting bracket to the fin located above the prop. It looks like there is room to spare on the plywood.  I plan to add 2".  No progress today, as a front passes.

Man-O-War, 2 Mar 2012 The first step is to join 8' and 4' plywood panels to make two 4' x 12' panels to cut the 10'-long bottom and side sections.  The plans recommend either a butt or scarf joint.  A scarf joint just seems more proper.  I started out with an 8:1 ratio for the scarf (shown here) but switched to 12:1 for a 3" overlap.  12:1 seemed better on ¼" plywood.   Using the router worked pretty well - it just took a while.  I experienced some tear-out where the edge tapered down
to .. well, nothing, but found I could avoid that by leaving a slight (say ⅛" x ⅛" scrap) portion of the wood remaining, then removing that with a sanding block.  The edge then ended up paper thin, FWIW.   I used the other panels for my straight-edge guides.  This worked pretty well because I could line up the long edges of the panel I was cutting with the top and bottom guide panels.    I don't know that this is the best procedure, but here is what I did ... routed the edge down to the 12:1 ratio sanded it with 80-grit sandpaper on a sanding block to smooth down any rough spots and take off the ⅛" x ⅛" scrap from the edge wiped it down with a wet cloth to clean off the sawdust and open up the pores the next day brushed it off to remove any remaining sawdust exposed the wood to the sun for a couple hours to open the pores and try to get it as dry as possible - at the same time exposing the cans of resin and catalyst (West System 105 & 206) to the sun to warm them up a bit to make them a little less viscous pre-coated the wood of the joint with a generous amount of epoxy let that set for about an hour (unjoined) brushing it occassionally as the wood continued to (slightly) out-gas while it was still tacky, coated it with epoxy slightly thickened with colloidal silica to take up any voids and help the resin stay in place tacked the joined panels in place using finishing nails to keep them from sliding apart - using wax paper between the layups.  Then a nice flat 3x6 over the joints and a couple cinder blocks on top of that.  Ie. table top, wax paper, 1st layup, wax paper, 2nd layup, wax paper, 3x6, cinder blocks let it set for 24 hours drove the finishing nails through into the table this suggests "allow[ing it] to cure for 5 to 7 days before removing clamps".  I allowed a couple days before bending it, but mainly because the weather was bad and I couldn't work on it.  And this suggests "plac[ing] the leading exterior edge of the scarf toward the stern" which (if I'm reading that right) I did.

Man-O-War, 10 Mar 2012 I've cut out the bottom, side (wings), bulkhead, and transom pieces.  Then attached the wings to the bottom pieces and wired the bottom pieces together along the center line per the plans.  Now the thing sort of unfolds like an origami.   I think we tried to finesse it a bit (inserting the blocks, etc).  All that really needs to be done is support the ends of the wings to avoid stressing the fiberglass tape.  In hindsight, unfolding it is much easier that we made it look here.
Here is the initial result.  I need to go through and adjust the seams to get a better fit.
Man-O-War, 16 Mar 2012 Lots of wind and intermittent rain the last couple days so progress has been slow.  Anyway, I'd suggest when attaching the wings to the bottom and transom, first loosely wire them in a couple spots along the edge just to keep them from flopping around.  Early on, secure the transom and two or three wires on the aft ends of the wings because they determine where the bottom edge of the wings will rest on the surfaces of the bottom pieces at the aft end.  That overlap starts at 0 at the front end (where the butterfly glass tape is) to a fair amount at the transom.  And affects where you drill your holes as you go from the nesting bulkhead to the transom.   The fit of the forward bulkhead has been very difficult, with the chine not pulling in very easily.  I've checked and rechecked and don't see where I messed up on the measurement.  Hmm.  I ended up cutting a new forward bulkhead with the width across the spot where the chine is located ½" wider on each side.
The fiberglass tape where the wing attaches to the bottom has a lot of stress on it.  It started to break at the aft end where probably the most stress is located.  I simply added another wire tie there (using 12 ga. copper wire, where
the rest of my ties are 14 ga.) and that appears to have prevented further breakage.

Man-O-War, 24 Mar 2012 Here I'm attaching the gunwales, breast hook and knees.  A couple things to note:
	1.	I've run fishing line from the point above where the forward bulkhead is located (where the lines were drawn from the plans) back to the opposite corners of the transom to check for racking.  There was about ¼" gap between the two lines where they cross.  I pulled the two opposite corners of the hull down a little with light (⅛" nylon) line to
		take that out while the epoxy sets.  I also checked the distance between those points.  They differ by about 1/16" after pulling down the corners.
	2.	You can see in the photo a white line coming out just below the foremost clamp and running around the bow (where it then reenters the hull, forming a single tight loop and having the effect of pulling the sides together and reducing the angle at the bow).  I adjusted the line until I got the same angle produced when the gunwales are installed.  I installed the breast hook (using thickend epozy and 1" #6 screws) before installing the gunwales as the plans recommend.  This line holding the bow to the final angle then made that much easier.  The gunwales on the aft end didn't change the angle between the sides and transom much so fitting and installing the knees was pretty easy.  There, I installed the gunwales first, then the knees.
	3.	You definitely want to use some screws (I used 1" #6 bronze FH screws) to hold the gunwale strips in place as you work your way aft, gluing and clamping the strips in place.  The strips will be slipping around quite a bit otherwise.

Here are the clamps I made from some ½" plywood left over from the previous dinghy project.  The legs are 2" x 4" with two 1" x 1" spacers at the top.  I drove a small finishing nail through the legs and the spacers to keep everything together (important when in use, as the epoxy is on a countdown to setting).  The screw is a stainless steel deck screw with a square hole - handy for catching the screw driver in when you're juggling 3 or 4 things with just 2 hands.  I wrapped the legs in tape (I had some 2" clear packing tape) to keep the clamps from getting glued to the hull or gunwale.  These clamps worked out pretty well, I think.  They weren't *too* hard to make up - lay out all the pieces in a grid on the plywood.  Then it's easy to cut them out with a coarse blade and if using a jig saw, the option that tilts the blade to make it pull through the wood.  Ie. the plywood edges don't have to be pretty.  Make sure you have enough clamps.  I had 22 on each side and that was probably enough (though you can never have too many).

Man-O-War, 28 Mar 2012 There were a couple problems that showed up looking down the center line with the hull turned upside down.  First, there was about ¼" droop midway between the forward bulkhead and the nesting bulkheads - again, this is looking at it from the bottom.  This was easily removed by shaving a little of the gap in the seam forward of that.  I gradually tapered the amount removed up to where the fiberglass tape is located.  I first removed 4 or so of the ties in that area.  Then it was very easy to shave down the gap - effectively lowering the stem slightly (looking at the hull upside down) relative		Not a very good photo, but the idea is to stick the Japanese pull saw in the seam and carefully rasp it down a little at a time, checking the centerline for a nice smooth line as you go.
to the droop.  I used a small Japanese pull saw but any fine-tooth saw should do.  The pull saw is nice though because you can twist it a bit in the gap as you draw on it and in that way remove just the slightest amount of wood - in sort of a rasping motion.  I then reinstalled the ties.  The forward bulkhead had to be shortened slightly - the wood easily removed using sandpaper on a sanding block.  I'm using 40-grit sandpaper for these coarse modifications.  This Okoumé plywood is a joy to work with - uniform, easily shaped, takes epoxy resin like a bandit.  It sort of reminds me of Divinycell foam.   Second, there was a slight droop in the center line (again, looking at the hull upside down) a little before the transom.  It was maybe ⅛".  Same procedure - I removed 3 or 4 ties just before the transom and shaved down the gap until pulling it in caused the droop to go away.  Then I reinstalled the ties.  I suspect this sort of minor adjustments is standard procedure with stitch & glue construction.   I also rechecked for any racking.  To compensate for some I had initially found (see above where I used the fishing line to check), I had pulled down the corners while the epoxy was setting up upon attaching the gunwales.  There is absolutely none now.

Man-O-War, 2 Apr 2012 My back is killing me.  But I've managed to tape the inside seams.   Just one thing to note.. I had thought I would make the 1" fillet in the seams and tape them in one step.  I planned to let that set up and then remove the wires.  But my wire ties stood up too high for a 1" diameter fillet.  I suppose I could have flattened the wire loop inside the hull when I inserted them, but that could have made it a bear to pull them out after the epoxy had set.  It could also be because I used 14 ga. (12 ga. in difficult spots) copper wire.  16 ga. monel may have worked better.   Instead, I took the alternative path of making low "tack weld" fillets between the wire ties (the plastic West System mixing stick is ¾" diameter), letting that set, removing the wires, sanding the ¾" fillet to make sure there was a good bite, then going back and putting in the 1" dia. fillet and tape over it.    For the outside seams, I only taped over the centerline and around the transom.  Not the chine seams.  I figured they have good support in compression, with the sides resting on the bottom pieces.  And for tension, there will be two layers of 6 oz. cloth for support (ie. one layer inside and one outside), along with the inside tape.   Now I'm going to deviate from the plans a couple ways.  First, I'd like to shape the aft seats to form-fit the bow when nested.  Second, I'd like to sheath both the interior and exterior with a layer of fiberglass cloth.  That's because I'd like to not worry as much about breaking the hull's surface by pulling it up onto a knarly beach or dropping something into it from the dock.  I have some 6 oz. cloth for the floor and bottom, and 4 oz. cloth for the vertical surfaces.  So, my plan is to apply a layer of 6 oz. cloth inside and then -OMG- cut it in half.  Then I'll be able to measure for the aft seats.  An added benefit will be being able to fit the daggerboard trunk with the forward half hull in a more accessible position.  BTW, the plans stress waiting until the interior is installed *before* cutting it in half.  I'm thinking the layer of glass cloth will stablize any movement in the shape.  And I'll clamp the two halves together before gluing in those remaining pieces.  There may be a benefit over the original plans because the faces of the nesting bulkhead will be finished off and thus their angle meeting the daggerboard trunk will be in it's final form.  With regard to sheathing everything in fiberglass cloth, I figure that will add roughly 5 pounds to the overall weight.

Man-O-War, 11 Apr 2012 I measured the cloth for the inside and outside by draping it over the outside, twice.  The cloth is 60" wide which fits perfectly between the nesting bulkhead and transom.  So, I ran the length of the cloth from gunwale to gunwale - about a 6' length of the cloth.
Here are the results after glassing the inside.  Note the doublers for the connectors on the floor next to the nesting bulkhead.  I also rechecked for racking - still none.   The West System 6 oz. cloth is very nice to work with - it wets out easily and bends around odd angles pretty well.  It's expensive, but worth it IMO.  This is the first time I've used West System's cloth (as opposed to the cheapest I could find) and don't know why I was so stingy with the cost of cloth in the past - kind of
dumb.  It's like the plywood - if you're going to put a couple hundred hours into a project, you ought to go with the best materials.

Man-O-War, 12 Apr 2012 The cut ...		and the fit.
The fit is quite good now.  But this is before installing the keel which will push the bow half up a little - making the fit a little looser.  Still, it shouldn't be bad.  And as I said above, I plan to make the bow fit between the aft seats fairly snug. [26 Apr 2012] With the keel installed, there is a ¼" gap between the bow stem and the inside of the transom when nested.  Seems good to me.

Man-O-War, 2 Apr 2012 I am planing to use the connector design suggested by Garry Prater.   I sent Garry a note asking if, based on his experience, he would recommend any combination of A, B, or C bevels that I'm showing in this diagram from his plan.   He replied that he didn't recommend C.  He had tried it on his and it didn't really help but did make the "pointy" end of the bevel fragile.  Regarding B, he said, "The B bevel would work as long as it's a square cut (perpendicular to the plywood surface).  Making it parallel to the side works well.  It would serve to help guide		From: http://www.pbase.com/onceagain/connector_design
the bow section into the center although I never really had a problem with it."  He also suggested rounding the inside corner for B (to avoid stress there), which I've added to the diagram here.  Thanks Garry. [8 Apr 2012] Since then, I've modified the A Bevel a bit to make it clearer and added D.  I think A now appears to be more of a "guiding bevel" than a "locking bevel" when engaged, with less stress on the pointy edge.  And possibly viable.  D probably has the same weaknesses as C.

Man-O-War, 14 Apr 2012 Here are the two simple jigs I made for routing the connectors.
This is for the hooks. The horizontal stick, just above the clamps, is removed to make the long routes (on the aft half).		This is for the plates. The first route (for the hook) has been made.		And some of the results. I need to round over the edges yet.

I applied a layer of 6 oz cloth to the outside and both sides of the transom.  And then installed the keel and cut out the plywood for the seats.  I'm taking a short break now to go sailing.  I'll be joining Edmund on Panope from Barcelona to Corsica.  Here is my trip report.  Please check back here in July when I will continue this project.
 

Well, I'm back from the trip and slowly getting back to projects.  First up - the seats for the aft section.
I used a couple pieces of 1/16" (3mm) Okoumé plywood to make up each of the sides of the aft seats.  First, I figured out the shape of the top by cutting and fitting cardboard around the bow section as I lowered it into the stern half.  From the cardboard, I made a couple plywood forms for each side - the darker crescent-shaped plywood pieces in the photo above.  Then I laminated two pieces of the 1/16" plywood bent over the forms to make a ⅛" panel (shown here).  I also laminated three ¾" wide strips of ¼" plywood to make ¾" x ¾" rails where the side meets the top.  You can see the end of the rail sticking out in the bottom left corner.  I cut the ¾" strips "across the grain" to make them easier to bend.  They are temporarily screwed into the ends of the plywood form while the epoxy sets.		Here, the sides and top are fit together and we are looking down at one of the joints where the rails meet.  The blurry-looking spot is the top of the post which will be epoxied into the corner, upon which this joint then rests.  The rail on the left is the one that was glued to the laminate (see photo to the left).  I then notched that out to fit the three strips from the rail joining it here.  This is before gluing everything with epoxy.

I should have taken a photo of the glue-up.  But it wasn't anything special.. I found a nice, absolutely flat 2x10 plank.  I laid the seat's tops on that (upside down).  Then a couple cinder blocks to hold the plywood flat.  Then I put a liberal amount of epoxy on the pieces that would become the rails and posts, as well as pre-coating the plywood where the rails would lie.  I used thickened epoxy in the space where the posts meet the corners and a little where the curved rail meets the top (to take up any gap that might be there).  I put everything together, checking that the sides were square to the top and used a few small sticks, sheetrock screws and clamps as necessary to hold everything together until the epoxy set.  I then let it set up overnight.

After the epoxy set, I put fillets on all the inside joints.  I plan to cover the inside with a layer of 4oz. fiberglass cloth, so I beveled the edges of the rails and posts to make it easier for the cloth to bend around them.  I had done that before gluing everything together, BTW.  I need to sand everything smooth yet.    (Try clicking on the image for a better view)

Now roughly fit in place.  I've rounded over the corners with a ½" radius router bit - a milestone that I've been looking forward to a long, long time :-).   I'll leave those lower plywood form pieces in place (they're attached with sheetrock screws from the inside) until just before I epoxy the seats to the hull.

A small thing, but here are the seat supports (a.k.a. deadmen).

I laminated them from ¼" x ¾" Spanish Cedar strips I had left over from the strip plank dinghy.   I used thickened epoxy to take up any gap between the hull and the first strip next to it.   The clamps are simple but can apply as much pressure as you need.  For more pressure, use a stiffer stick or a wider piece where it presses against the laminates.  That little piece at the bottom should be placed on edge like this so the force isn't applied "cock-eyed".   I'll bevel that inner, exposed edge to a 45° angle.

I checked the hull for racking just before gluing in the seats.  Here, the fishing line was about ⅛" apart where it crossed in the middle.  If there had been a lot of racking, I planned to pull down the high corners of the aft hull before gluing in the seats.  I decided that ⅛" was not enough to worry about.   BTW, I noticed that the heat from the sun created quite a bit of stress in the plywood of the unglued seats - causing them to distort.  The proper fit was early in the day, which was when I glued them in.   Doing this project indoors would have been better.  Or at least, under a tarp.  The photos of the old MOW boatbuilders show them doing their small boats usually under a lean-to or the shade of a tree.  The big boats are usually out in the open.  I'm on the same spot shown about half way down on that page - where the captions say "William H. Albury Boat Yard, late 1940’s" and "A boat under construction at W.H.Albury Boat Yard, 1960’s".

For the thwart, I liked what Seaweed did and pretty much copied that.  Where I deviated: I opted for a narrow top over the daggerboard trunk.  I plan to mount the sail controls on a block glued onto the side of the daggerboard trunk and think that will work better with this arrangement.  And, I extended the ends of the seat to attach to the hull, making the support a little more straightforward IMO.

The seat is laminated from two layers of ¼" Okoumé plywood.  It is 9" wide.  The support rail under the front edge is laminated from three pieces of 1½" x ¼" Okoumé	This is still rough yet.  I'll trim the edge of the top over the dagger- board trunk so that it is flush with the support rails later.	I'll bond the seat top (both the top and bottom surfaces) and support rail to the hull with thickened epoxy fillets when I install it.
plywood.  This makes the seats appear to be 2" thick - a look that I liked in my previous dinghy.  The top and bottom edges are rounded with a ½" quarter round router bit so relatively painless when bumped.

Aft edge of the seat, looking at it from the bottom.   I'll add a little backing on what will be the top of the seat here as that sharp edge looks a little fragile.	And the forward edge of the seat looking at the support rail from the end, again from the bottom.   The little rolled edge, on what will be the bottom inside, is just an extra finger hold when lifting the bow section from here.
This is looking at the bottom of the seat where the support rails will butt up against the daggerboard trunk.   I covered the bottom of the seat with a layer of 4oz. fiberglass cloth before attaching the support rails.	Again looking at the bottom of the seat, now with the daggerboard trunk in place.
OK, I got a little carried away here.  This is the top of the daggerboard trunk where it butts up against the nesting bulkhead.   I was initially planning to use just one sheet of ¼" plywood for the seat top so I beefed up this area where it rests on the trunk.  Then I decided to use ½" for the top.  This extra support is now clearly unneccesary, but well.. there it is.  It weighs practically nothing so no harm IMO.	The aft end of the seat extends about 1⅜" from the end of the bow section, so about ⅝" space to hook over the ½"-thick top of the stern section's nesting bulkhead.
I'll screw this edge together as well.  Stainless steel screws on say, 6" centers.   This overhanging lip is the main reason I switched from ¼" to ½" for the seat.  ¼" didn't seem like enough to support this edge - especially with the weight of my rump resting on it.  ½" also seemed better for the narrow cover over the daggerboard trunk.   BTW, the background in this photo is the bottom of a Hinkley currently hauled out here at the boat yard.  Makes a nice backdrop :-).

Bow seat Man-O-War, 22 Aug 2012 Nothing much to report for the bow seat.  I used clamps and sticks to hold things in place until the epoxy sets (shown here).  Thickened epoxy to take up any gaps and for filets on all the edge joints.  I need to sand them, put a couple coats of epoxy resin on the new pieces, cut out the hole for the access plate and glue on the top.  I'm kind of obsessing over the oar storage and location of the access plate though.  Here I'm showing one (of many) cardboard models of the forward storage holder.   Kind of a cool squall move over us quickly yesterday a little before sunset.  There was some lightning flashes in it but I didn't manage to capture any :-(.  The new wide-angle lens is nice for this big sky stuff.   Tropical Storm Isaac is threatening to visit us early next week :-).

Canon T2i, Canon 10-22mm @10mm f/5.6, 1/80 sec, ISO 100

Oars Man-O-War, 25 Aug 2012 I like Seaweed's design for storing the oars.  Here is my mockup ----> In it, I'm showing the same blade pattern as my last set of oars (apparently a fairly old design).   But, the oar blade simply screams to be spoon shaped.  Here is a spoon oar design by John DeLapp that looks nice.  I have some ⅛" (3mm) Okoumé I could use to laminate the blade (and then maybe be able to refine that top spline a bit).   Builders (e.g. here, here, here) note that their blades have a true spoon shape (that is, concave in two dimensions).  These racing oars:

do appear to have a slight cup in them.  I wonder what it would take to create a true spoon shape if I laminated the blade.  Lots of pressure bearing down in the middle of the blade with an elongated ring-shaped form underneath, I guess.  My main concern would be not starving the lamination of epoxy.  Hmm.

Here is a mockup using the spoon blade from John DeLapp's article:
I've marked where the leather would be located on the upper shaft (click on image to enlarge).   To maximize the oar's length, I was thinking I could use a sliding piece of PVC or aluminum pipe, stored on the lower shaft.  It would be about 20" long.  The overall length of the oar would be 6'10".	Having the blade point aft and partially under the seat probably looks a little better (compared with the first pair of photos above).   I'll need to notch a little out of the seat support.  The wider blade doesn't quite fit otherwise.

 
There was a small bump in the road when I got to installing the connectors.  The good news is that the gap between the bulkheads when nested is small - about ¼".  The bad news is, well.. 

The gap between the nesting bulkheads is about ¼" on the sides

BTW, they are snug in the middle

The Perko clamp is a little less than an inch "thick"

So it doesn't fit in the available space :-(

BTW, the space between the stem and transom is about ¼".  The bow section's keel is resting on the floor of the stern section.

And the space between the hull and aft seats is pretty snug.  The hulls slide together very nicely now.

So, there isn't enough space between the bulkheads for the clamp when the hulls are nested.  I think some of the options are:

• Slide the bow section forward about ¾" to create the needed space.  That would push the bow up against the transom if the aft seats weren't already in place, and cause the bow's keel to no longer rest on the floor of the stern section (putting the weight on the aft seats and transom).  In my case, I already have the aft seats nicely fitting around the bow's hull.
• Flip-flop the cutout piece so that the clamp would be located on the inside of the bow section.  The cutout piece would then click into place as the two halves slid together.  The main problem, I think, is that the overhanging lip on the thwart would be a tight fit over the, now offset, stern bulkhead as they slid together.
  [todo: add a little diagram of that here]
• Use something thinner (or use bolts) to join the bulkheads together.  Garry's plans show a door hinge as an alternative to the Perko clamps.  This doesn't seem nearly as convenient for assembling the dinghy in the water.  As Garry describes it, to assemble in the water, you sit in the stern section.  The bow section is floating quite a bit higher than the stern section.  You go to one side, push down the bow secton, latch the clamp on that side, then do the same thing on the other side.  The door hinge wouldn't work here because it would need to be lined up to run the pin through it.  And trying to line up a bolt between the two bobbing halves seems challenging.

The solution I'm taking is to notch a small hole in the forward bulkhead that will "house" the clamp when nested.

The spot where the hole would be located is the small crescent-shaped piece of cardboard shown here.  The big chunk of cardboard above it is a mockup of the piece cut out of the stern section's bulkhead plus a protective housing over the top part of the clamp.	Here is a cardboard mockup of a protective housing for the lower clamp.  This was before I trimmed down the cardboard (to the lines).	Here the top and bottom clamps, with their protective covers, are shown clamped together.  The top one will be shaped down a bit in the final result.
I've also added a little ½" x ½" lip around the upper "protective cover".  The lip catches on the stern's bulkhead when the halves are joined.  You might need to click on the images to see what I'm talking about.  It should be easier to see in the finished results.   The cardboard is nice because it's ¼" thick so transfering the shape to the plywood should be straightforward - just trace out each layer of the cardboard onto plywood, cut, and finish.

Not much progress the past month or so.  The heat really slowed me down.  Then Sandy visited.  But I managed to glue the thwart in place, cover the fore and aft seats with 4 oz. cloth, and make up the protective housings for the clamps.  The housings are the light-colored plywood in these photos (click on image to enlarge):

Here the halves are joined and the clasp is closed.  We are looking at the bulkheads from inside the aft half of the dinghy.

Here the halves are nested.  We are looking at the outside of the bulkheads.

Here the halves are nested.  Now, we are looking at bulkheads from the inside.  Note the opening cut into the forward bulkhead to "house" the bottom clasp.

I've decided to implement the protective housings in aluminum, instead of plywood.  The main reason is to reduce the amount of wood that I have to cut out of the forward bulkhead (photo above on the right).  Hopefully that will make more sense when I have some photos.  I've ordered some 0.19" 6061-T6 aluminum from onlinemetals.com.

Oar Construction Man-O-War, 5 Jan 2013 I picked out a straight, plain-sawn 8' Fir 2x4 from the lumber yard's stack of #1/clear.  Then ripped it down the middle and marked where the oarlocks will be located.  Then turned each down to about 1⅝" diameter in my jig (right) using my trusty ¼" router with a ½" straight bit.  The first rounded oar handle (on the left) shows the 1½" PVC pipe about where it will be located to join the two halves.
To cut the taper where the blade attaches to the shaft, I made up this pattern and screwed it onto the shaft.  Then I cut along the line (well, about ⅛" above the line to allow me to clean up the cut). I used my jig saw so it was a pretty rough cut.
Smoothing it out was fairly easy using a sanding disk on the drill.  I used a template of the shape to make sure I had it right.	Click on image to enlarge to make sense of it

Here I'm gluing the blades onto the shafts.  I didn't have many clamps so screwed those sticks into the 2x12 plank underneath instead.
 
For the top splines, I'm using ¾" wide 6mm Okoumé.
 
The large round stick on the end (left over from cutting out the tapered pieces) is actually pulling up a stick from underneath.  Each of the ends of the shaft broke under pressure.  The 2x4 I used had the tightest grain I could find in the stack.  Spruce would have probably been a better choice but wasn't available.  Anyway, I was able to pull the shaft back fairly close to the blade before the resin set.  Later, I dribbled resin and finally worked thickened resin into the cracks.  After that set, I sanded down the bump.  The resin patch will probably be stronger than the original wood alone.
 

Finishing up Man-O-War, 31 Jan 2013 Just bits in finishing up..   Here is the holder (Click on image to enlarge to make more sense of this) for the oar handle.  I used 1" Divinicell, cutting the hole fairly crudely.  After the epoxy set from gluing it in place, I put a generous amount of thickened epoxy in the hole and inserted the end of the oar handle into it, with a piece of plastic grocery shopping bag over the end.  I removed the epoxy that squeezed out before it set.  After it had set and I removed the oar handle, I enlarged the opening a little with a Dremel tool to allow enough play to remove the oar easily.  After this photo was taken, I applied a layer of the 6 oz. cloth to protect and finish off the foam (although simply resin on the foam makes a plenty tough surface).

To finish the gunwales, I used a stick as shown and 38 grit sandpaper to fairly quickly even up the top surfaces and make them level.   For the hole for the mast, I initially drilled it using a 2¼" hole saw to exactly fit the mast.  Then I fit and glued in the mast step square to the mast.  Then I would like to have had a 2⅜" hole saw to enlargen the hole but didn't.  So, I wrapped some sandpaper around the 2¼" hole saw and slowly worked it into the hole.  Then I put 3 layers of the 6 oz. cloth inside the hole, fluting the ends to lay on the top and bottom surfaces [need a diagram here].

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Misc notes:
	-	Spindrift construction blogs:    All about Seaweed: Building a Spindrift 9ft Nesting Dinghy (w/ enlarged photos)  Expedition Dinghy  Building a Spindrift 11s  Notes and a photo  A 12'er shown stored aboard a (large) Crealock Building a Nesting Dinghy - a 9N.  Looks like he used Garry Prater's Perko Clamp trick for joining the halves.
	-	Other construction blogs:     Minipaw Dinghy "No Regrets" (nice writeup. I like his paint job)

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