| My Next Dinghy Project - Construction |
Last updated: Man-O-War, 28 Apr 2012
You can never have (or build) too many small boats :-). Here is the planning for this project.
Spring Hill, 7 Jan 2012
I decided on building the Spindrift 10N.
Here are the costs (so far) ...
| Item | Cost | Ship- ping | Source | Notes | ||||||||
| Plans | $65 | $5 | B&B Yacht Designs | The plans consisted of 13 A3 (11½" x 16½") sheets of drawings and instructions, and 25 8½" x 11" pages of material list, sources, their prices for materials and hardware, etc. The plans include pretty good detail on the sail rig. The materials list includes a couple alternative manufacturers (Ronstan, Racelite and Harken) with model numbers for all the sailing hardware. There is a helpful list of recommended sources for the plywood, aluminum tubing for the mast and other materials. There is a CD included with about 250 photos of Spindrifts under construction and finished. All in all, it looks like a pretty good set of plans. | ||||||||
| Plywood | 4 sheets @ $68.80 = $275 | $10 | World Panel Products |
 BTW, B&B is offering 6mm Joubert "Okume marine plywood BS1088" at a simiar price ($75 as I write this) but the price sheet says they "do not ship plywood - pickup only". |
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| Fiberglass & resin | $479 | $50 | boatstore .com | I chose to use West System epoxy and cloth. boatstore.com had the best prices I could find. Note that this line item includes 3 yds of 6 oz. cloth that I plan to use on the bottom. That added $45 to the cost not in the original plans from B&B. | ||||||||
| Hardware for the sailing rig | $133 | $16 | B&B Yacht Designs | Except for one or two items, B&B had the best prices (and generally much lower than I could find elsewhere) for the hardware for the sail rig. Curiously, the 2 Harken micro blocks were of an old design (and didn't match), but at $6.50 each I guess I can't complain.. well, too much. I'll pick up a couple new ones at West Marine next week. | ||||||||
| Misc hardware | $21 | $6 | Duckworks | Auto-release Clamcleat CL257. B&B had been out of these. |
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| $xx | $x | Sheeve for the top of the mast. | ||||||||||
| Line | $69 | $10 | P2 Marine | The line for the sail rig. 40' x 5/16" and 100' x 3/16" of NER Sta-Set in various colors. This order also included a Harken 4mm bow shackle. | ||||||||
| Sail | $340 | $22 | B&B Yacht Designs | I got the sail with a zippered luff and 1 reef point. Included were the insignia and sail #, and a sailbag. It looks to be well made. BTW, the sail from Sailrite with a sailbag was $234 for the kit + $275 labor. |
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| Clamps for joining the halves | 2 @ $48 = $96 | $4 | discount marine supplies .com | These were expensive, but I expect they will be very convenient. Garry Prater, who came up with this idea, described to me how he was able to join the two halves in the water and how he did that once in gale-force winds in an emergency - when he had to launch his dinghy to carry out an anchor in the Intracoastal Waterway during a sudden storm. (Times like that make for *very* vivid memories :-) | ||||||||
| 5" dia. watertight deck plates | 3 @ $13 = $39 | $3 (tax) | BOW | These will be for access to the floatation compartments. | ||||||||
| Stainless steel | $15(mat) $75(fab) |
$13 |
Online Metals | I ordered 3' of ⅛" x 1½" Stainless Steel Flat Bar T-316/316L for the mast plate and the brackets to join the two halves. I'll have a local fabricator drill and countersink the holes and make the bends. | ||||||||
| Oarlocks & sockets | 2 sets @ $20 + $30 = $70 | $5 (tax) |
West Marine | I like these sockets because they have replaceable nylon sleeves and are nice and quiet. I'll probably install 2 sets of sockets to have a 2nd rowing position - where I can sit at the bow to balance the boat when need-be or for occasions when I want to row for a while facing forward. | ||||||||
| Mast | $154 | $19 | Online Metals | I went with the 6061-T6 from Online Metals. Spindrift's large plan sheet calls for 2" aluminum at the base while the materials list calls for 2¼". I called the designer, Graham Byrnes, and told him that I liked to go out in "fresh" conditions and asked whether the larger diameter mast would be better. He said the mast size has evolved a bit and that yes, I should not have any problems (like permanently bending the mast in strong wind) with the larger diameter. They had found the larger diameter mast bent less in normal conditions, maintaining better sail shape and sailing faster. That was the reason for the change from the original plans. He said he has sailed the Spindrift in over 500 races. | ||||||||
| Shipping & customs | - | about $770 | Abaco Shipping, Arawak Agency (Customs Brokers) |
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| Base boat Sail rig Total |
$ 985 $ 886 $1871+ |
$xxx | ||||||||||
| Start of construction | ||
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Spring Hill, 17 Jan 2012
So I guess this is the actual start of construction. Woo-hoo!
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Connectors
| 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 |  |
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| that epoxy plug. I believe the West System guys have determined this produces a very strong connection1. | ||
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Man-O-War, 16 Apr 2012
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Here is their figure from Chapter 14:
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The tests they show there are mostly on fairly thick wood though and maybe not applicable to thin plywood
like this. I wonder if adding a bevel to the hole
 compensate. Like this --> I don't think I have an easy way to test that, but I'd kind of like to use it for all the bolts (rather than a nut and washer on the inside) - to reduce the number of toe-stubbers inside the dinghy. |
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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. |
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Materials arrive
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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 and came through fine. |
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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. |
Freeboard
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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.[29 Feb 2012] I just came across another post suggesting the ride could be drier. 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. 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):
It looks like there is room to spare on the plywood. I plan to add 2". No progress today, as a front passes. |
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Scarf joints
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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 on the skinny edge, but found |
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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 ...
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The "Butterfly Step"
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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. |
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Here is the initial result.
I need to go through and adjust the seams to get a better fit. |
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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. |
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| 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 |  |
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| the rest of my ties are 14 ga.) and that appears to have prevented further breakage. | ||
Gunwales, breast hook and knees
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Man-O-War, 24 Mar 2012
Here I'm attaching the gunwales, breast hook and knees.
A couple things to note:
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| 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 of the bow). The angle is that 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 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. |
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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).
I then 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 worked out pretty well, I think.
Make sure you have enough. I had 22 on each side and that was probably enough (though
you can never have too many). |
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Shaping up
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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 bow slightly (looking at the hull upside down) relative
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 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. |
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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. |
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Seams
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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 and then remove the wires. But my wire ties stood up too high for a 1" diameter fillet. It could be because I used 14 ga. (12 ga. in difficult spots) copper wire. 16 ga. monel may have worked better. |
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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 2 layers of 6 oz. cloth for support, along with the inside tape. Now I'm going deviate from the plans. 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 weight. |
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Fiberglass Cloth
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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.
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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 it 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 |
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| hundred hours into a project, you ought to go with the best materials. | ||
Snip
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Man-O-War, 12 Apr 2012
The cut ...
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and the fit. | |
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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. |
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Connectors
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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 |
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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. |
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Routing out for the connectors
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Man-O-War, 14 Apr 2012
Here are the two simple jigs I made for routing the connectors.
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 The horizontal stick, just above the clamps, is removed to make the long routes (on the aft half). |
 The first route (for the hook) has been made. |
 I need to round over the edges yet. |
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Short break
Man-O-War, 28 Apr 2012
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.| Misc notes: | ||||
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Spindrift construction blogs: All about Seaweed: Building a Spindrift 9ft Nesting Dinghy Expedition Dinghy Building a Spindrift 11s Notes and a photo A 12'er shown stored aboard a (large) Crealock
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Notes about adding a bit to the freeboard: A note about adding 2" (the last post in that thread) A note that suggests adding 3-4" to the freeboard
[IMO, that would be too much] "VERY wet" ride "Kind of wet when motoring in a chop" (Reply #284)
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| - | Woodfinder | |||
| 1 | Chapter 14: Hardware Bonding of The Gougeon Brothers on Boat Construction describes the technique for embedding bolts in epoxy. | |||