Plan Study: Sponge Docks Skiff

Easy to build, inexpensive to run, fast, and fun...

Article by J.F. Bedard

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The West Coast of Florida is dotted with Barrier Islands and a time-honored father-son activity is to explore their every nook and cranny. The excuse might one day be fishing and the other beach-combing, but with adventure just a stone’s throw away, one only needs an easy way to get there.

In that spirit I acquired an old 12-foot tinny early last year. It was a bit smaller than what I thought I needed but I had little spare time to design my own, let alone build it before summer.

We used that boat a lot and in the process I learned a few valuable lessons. First, the same applies for powerboats as for sailboats: Small is beautiful. A tiny outboard will get you in the 15-20-knot range, and burning 4 gallons of fuel in the same day will require a special effort. You’ll get the best spot by the beach while the big guys are anchored 100-feet off. You’ll go out more often, because launching and retrieving is effortless, so even after a big work week you’ll be game. You don’t even need a ramp, you can just “swamp-launch.” Of course, this is Small Craft Advisor magazine so I’m preaching to the choir!

My point is that as the season advanced my “ideal” boat grew smaller and smaller, pretty much to the size of the boat I was actually using. Parallel to that, I was toying with the idea of designing the absolute simplest boat to build, something to help people get over the hump and try their hand at boat building. I also had up my sleeve a nice 16-foot Garvey hull that could be scaled down. Garveys are small scow-type work boats from the New Jersey coast with flat and wide bottoms making them especially good at carrying cargo. Their shallow draft also makes them natural clamming and fishing boats. Maybe I could melt these in the same pot…

That’s how the Sponge Docks Skiff came about. She grew to 13 feet LOA and gained over a foot of beam. I gave her a gentle traditional sheer and a tiny foredeck, but otherwise kept to the mantra of uber-simplicity. In that regard, there are many details worth mentioning:

• The hull is all 9mm plywood (3/8") and the seats 12mm (1/2"). The bulkheads and stringers are 6mm (1/4"). The panels are thicker than necessary to reduce tedious internal framing and speed up construction. The weight penalty is marginal as the completed hull weighs in at 250 pounds.

• 10 cubic feet of foam-filled compartments mean more than 800 pounds of flotation in conjunction with the hull, easily surpassing ABYC requirement. All the compartments have limber holes for air circulation and water evacuation.

• The boat is tiller steered. More confident and experienced builders might want to install a side console, which the boat would love, but that adds a little complexity and cost.

• By Coast Guard sticker she could accommodate 29 horsepower, and with that much she’d be wicked fast, but she’ll be happy with 10 horsepower.

• The hull panels are marked for bulkheads, stringers and seat placement so can literally be built without a tape measure.

• The kit hull panels are scarfed asymmetrically port and starboard so as to avoid assembly mistakes. Stitch holes are pre-drilled and transom panels have lamination lineup-pegs (Three pieces make the transom a massively strong 13/8")

• She’s built on a simple cradle, right-side up, using a plastic-ties stitch-and-glue technique, and comes with a simple set of plans and a clear instruction manual geared towards beginners.

• She’s got a large aft steering bench, under which lays the fuel tank, a middle bench with storage, and a forward seating/lounging/casting platform with dedicated anchor well.

• She has two skid rails underneath for tracking that also double as longitudinal stiffeners.

Numbers

She is designed to float on her lines at 840 pounds. After accounting for outboard and fuel tank, that means about 500 pounds of payload. She’ll accommodate almost twice that for the occasional in-laws visit. She’s got 7° deadrise at the transom and draws 4" light, 6" loaded.

Sea trials

She was to be tested with three different bottoms: No chine flats, external chine rails, and integral chine flats. The soft launch took place at this November’s Cedar Key get-together, where Hugh Horton, Simon Lewandowski and I were to have a “Clam-Girl retreat”; I dragged them both for the ride.

I was pleased by how effortlessly she climbed on plane. We were surprised by how dry she was despite the wide foredeck, especially since she had neither chine rails nor flats. The old Evinrude15-horsepower took us to 17 knots. The extra beam made her feel very spacious and gave her impressive stability. I could actually stand on the gunnel midships without risk of capsize.

A few weeks later, we installed traditional chine rails on her to see if there was going to be a difference in performance, and then took her out for a spin. What originally started out as sea trials quickly turned into a sea-doughnut-derby. In addition to demonstrating excellent tracking, the boat proved to be lots of fun.

Variation

I can already see this design will spawn a few variations. Being dry, easily driven and spacious, this hull can be adapted to many different forms and functions. There is already the 16-foot traditional, co-designed with Michael W. Jones, a 16-foot camp-cruiser, a 24-foot center console, and Hugh Horton is “curiouser and curiouser” about an 11.5-foot cartopable Torqueedo’d one. (This design is now available in 13, 16 and 19-foot versions—Eds)

All in all, this little Sponge Docks Skiff 13 fulfilled her requirements and more, being easy to build, inexpensive to run, fast, and fun. •SCA•

First appeared in issue #110