Bivalve: Building a Strip Planked Cruising Yawl


    One of the fondest memories from my youth is the trip I took with my Uncle Henry on Long Island Sound. He had built  a plywood outboard runabout in his backyard, and used the craft to access his half of a small sandy islet, far out in the Sound. I was in my early teens, and it amazed me that the man had made the boat himself, with his own hands.
    For years after that, I wanted to build a boat for myself. I started looking for a suitable sailboat design in the mid to late 1980's. I didn't want to make the mistake of taking on a project which might be too difficult, time consuming or expensive to finish.  I needed a boat which would be cheap and easy to build, but still be enough of a boat for my wife and I to do some coastal, lake and river cruising. I was given a box full of old Woodenboat magazines, and like a thousand others before me, was drawn to Steve Redmond's canoe yawl, Elver. I sent for plans in the late 1980's, and built the boat in 1991/92.
    The boat promised to be a simple one... all the materials used were available at the local lumberyard. The design does not rely on any premium hardware, like expensive winches, blocks, turnbuckles or stays. The boat is a super lightweight design, with a cruising displacement of only 1,400 pounds... with crew and provisions! The actual trailering weight of the boat is only 900 pounds, and can be trailered by the smallest of cars.

    The boat's actual method of construction is very simple, too. Redmond used what he calls a "master curve", which is an enlarged version of a ship's curve. Every curve on the Elver's hull matches a portion of this full sized curve, and only needs to be traced from it. This eliminates the need for lofting the design. I traced the curve on a piece of masonite, and marked off the beginnings and ends of each bulkhead's section. Plywood bulkheads are then cut out, using this as a guide.
The bulkheads are reinforced with spruce framing, and these are set up on the flat, 3/4" plywood bottom. In this picture they are just stood up on the grass, before framing was added, to get an idea of the boat's ultimate layout.
 
Here is the Elver's bottom, with the centerboard trunk attached. The trunk will eventually support one side of the bunk. 

 

After the bulkheads are set up on the bottom, and the inner stem, inner stern and shear planks are added, the boat is strip planked. The strips are ripped from common 1x12 cedar house siding, to the actual dimension of 3/4" x 3/4". These strips are then glued to each other with epoxy, mixed with fine sawdust, and nailed with galvanized brads. The brads are only to hold the planks while the epoxy sets... they are not a factor in it's ultimate strength. After curing, the hull is faired smooth, then coated overall with unthickened epoxy. In one test piece I noted that the epoxy would soak in a full 1/8", leaving only a small portion of each strip "untreated". This process makes for a very strong and watertight hull.
After strip planking, the deck and cabin are sheathed with 3/8" marine plywood. I used phillipine rotary cut ply, which was only $36 a sheet back in 1992. But I also scrounged suitable materials wherever I could. A couple of bulkheads are made with a fine, 5 ply plywood from Asia, which were used in some particularly high quality packing crates.
The "cozy" cabin of the Bivalve. This is an extremely small cabin for a 20' boat. The double bunk is just that, and no more. The person to port (me!) must sleep under the deck, and this gives no room to turn over. An average sized person cannot sit on the edge of the bunk, as there is insufficient headroom... to prepare food on the galley shelf across from the bunk, the chef must sit on the floor! We tried a couple of overnight trips after we had our daughter, but the three of us just could not fit on the bunk... and it was time for a larger boat.

 
Here is the Bivalve at it's permanent mooring on Lake Mahopac, NY, in the mid to late nineties. It was a simple matter to retrieve the boat and trailer it to other destinations, but the convienience of having a mooring was a luxury I miss today. 
In addition to our frequent sails on the lake, we sailed the Bivalve on several trips on the Hudson River, and took a five day cruise on the Chesapeake Bay. We took the boat across the bay from Elk Neck to the Sassafras, and then cruised 12 miles up that creek. The picture to the right shows the us moored to Daffodil Island, in Worton's Creek off the Sassafras. The Elver's extreme shoal draft allows nosing into the shallowest of waters, and stepping off the bow and walking to shore.
    Our cruise on the Chesapeake was quite an experience in extremes,  from pure joy to pure terror. The joy was in light wind cruising down these paradisical waterways, over shallows sandbars, into pristine coves. As we entered the Sassafras, we were quickly overtaken by a graceful ketch. It passed us, then bore off to port to avoid one expansive shoal area. We were able to continue across the shoal, and overtook the ketch! Of course they quickly caught up to us, and passed us, further on.
    The terror was found out in the Bay itself, beating and motoring against 2 and 3 foot chop with a 900 pound boat for four hours at a time, as we dodged Navy Frigates in the middle of the bay, while crossing the intracoastal waterway. The boat would rise as quickly as a floating leaf would on the wicked chop, but would then drop it's nose as the waves passed, and slam so hard the fillings in my teeth would rattle. This part of the cruise, taken with the blood drained from our fingers as they clamped on anything non-moving, was a lesson in the advantages of any sort of keel whatsoever, and the dangers of using a flat-bottomed boat to do a roundy boat's job.
    The Elver itself is a controversial design. As originally designed, the boat had only four inches draft, with board and rudder raised. As such, the boat would sail, but not very well. Bob Hicks, the editor of Messing About in Boats, got a ride in a very early Elver, "Ammophilia", somewhere in Massachusetts. His resulting observations, as published in an editorial in his magazine, were less than flattering to the design. He claimed the boat pointed very badly, and was very difficult to tack.
    This editorial elicited a very strong response from the designer himself. Soon afterward several "optional" modifications were added to the design by Redmond, mods which he later denied were added in response to the published editorial, or really even needed at all. The sheet, which was included with later plans, states, "The boat sails fine as built", meaning, "those early boats as originally designed". The modifications include a full length skeg, which is really a 2'x8" bolted on end down the center of the boat, or really just off center. It has a depth of about 1 1/2" at the bow, and is it's full 7 1/2" at the stern. In addition, Redmond suggested a rudder with more "bite", and specifies that the centerboard be more "carefully" shaped than originally implied.
    As an aside, I was privy to a very historic meeting between Gordon Talley, the owner of Bufflehead, which was the original Ammophilia, and Bob Hicks. I was speaking with HIcks in Mystic Seaport years ago, when Gordon walked up to us. Bob had no idea who it was yet, nor of course that he was the owner of the boat he had reviewed years before. So Bob went on about the poor performance of the boat, and said "I only reported what I observed, that is all"... while Gordon listened, bemused. I then introduced the two of them... "Bob, this is Gordon Talley, owner of Bufflehead, nee Ammophilia". There was a bit of awkwardness of course, but Gordon explained that he had put the mods into the old Ammophilia, and it worked just fine.
    I built our Elver with these options from the start. The irony to this is that I ended up with a full 11 1/2" draft at the stern of the boat! But although you have this draft, it does not reflect itself in additional interior room, nor demand any additional ballast... which would still be small, but desireable, considering the extreme lightweight of the boat to begin with.
    The pros of the boat I outlined at the beginning of this article... the shoal draft, ease of construction, light trailering weight, and low cost to build. Our Bivalve cost us only $2,500, a majority of which was the 11 gallons of West System and System Three epoxy it ate up. The sails cost only $188, as I sewed them myself.
 
The Bivalve soon after launch still had "some wrinkles in it's sails". The pinch in the mainsail is caused by the "brail line", which is a traditional way of quickly dousing a sprit rig. The brail runs to the mast head, and down to where you can reach it. 
 

Here is a video I made while building the boat, and converted and uploaded to Youtube a few years ago. it surprises me just how popular home building still is... as of April of 2011, I have almost 85,000 hits! I really only expected a few hundred hits on this.


    The cons of the Elver are certainly numerous. But whether they are understandable, and therefore acceptable, given the self-imposed constraints the designer was attempting to meet, would be up to others to decide. The cabin is very small, and I feel it could use space better. If I were to build the boat again, I would build a "V" berth up front, instead of the offset berth specified. The cockpit is really too small to stretch out in. If one were to cut out the rear cockpit bulkhead for your legs and feet, it would become a sleeping cockpit. And there is a huge amount of unused space under the cockpit decks, space you would be advised not to fill too readily, given the limited ability of the design to handle additional weight. So I found that while the space in the Elver is tight, there was unused space all around me I really could not access.
    Another aspect which only occured to me after using the boat for a couple of years was the fact that I was really sailing a 26 foot boat. The bowsprit and boomkin extended out to this size, in other words. This was the maneuvering size of the boat when in close quarters, anchoring in a cove with other boats, pulling into a slip, etc. We always needed to unslip the bowsprit to avoid skewering anyone walking on the docks, when pulling up into a marina. And many marinas stipulate that the size of the boat you pay for be the actual size of the boat when rigged. But even if you could talk the marina into ignoring the length of the removable spars, you would have to measure the rudder... which extends a couple of feet behind the boat, and pay the additional slip fee for that. So if you are keeping the Elver in a marina, check first... and if you are willing to pay for 22 to 26 feet at the marina, perhaps it would make sense to build a boat which uses all of that length instead.
    And as I mentioned, you are also sailing a boat with almost one foot of draft. One has to count the skeg, the lowest point of the bottom. So again, if you have to live with the (admittedly small) draft of one foot, perhaps it would make sense to build and sail a boat which makes use of that amount of draft. For instance, many small Bolger cruisers... up to the AS-29, in fact... have and use thier small draft to the fullest... you live in that extra foot below you.
    Another consideration... and anyone is welcome to disagree, but only after living through it... is the lack of a self-draining cockpit. If you keep this boat at a mooring, you will be pumping hundreds of gallons of water out each summer, after every time it rains. And if it is a big rain, it will make it over the sill of the companionway, or if you put in limber holes, before then, and into the cabin. Buy a good pump. If your Elver is covered in the yard, water will still get in. You will be replacing tarps as the UV rays kill the last one, pumping the boat out anyway, and fighting mosquitos and rot... as a major portion of your upkeep of a wooden boat with a non-draining cockpit, you will be doing all this. It's a big deal. Don't shoot the messenger.
    As for performance, I never found it as bad as some have. One thing to consider in evaluating an Elver performance report is whether it has the later mods, including the skeg, or not. Most really bad feedback I've come across has been for boats without the modifications. Our boat would point to within 55 degrees off the wind... not sterling, but acceptable. But in light winds, leeway would cancel too much of our upwind gains. I've had people counter with, "Well ours pointed better... to XX degrees", many times. Well ours would point it's nose to higher figures, too... but the boat is sliding sideways to it's limited lateral resistance, and much of the gains to pointing higher would be lost by slipping. This is called "pinching", and in our experience, the Bivalve would usually be pinching at higher than about 55 degrees.
    Tacking an Elver is an art more than a science... you must release the jib when the mere thought of tacking occurs to you, and then "power" the boat through the tack by pulling in the main as turn the rudder. This must be done gradually... and at the proper moment, backwind the main, and pray like hell.

    As for heavier wind, the boat sails better, points better, and tacking is easier. But always conscious of the fact that this is a capsizable design, I never wanted to test it's limits. It would heel to a maximum of about 12 degrees, and then stick there. When I say "heavier wind", I'm only talking about conditions to about 20 mph... for when you approach these wind speeds, things begin to quickly get exciting. You can reef the main, or take it in entirely and sail under main and jib alone. Or you can take in the mizzen and jig, and sail under reefed main alone. So as Redmond's original Small Boat journal tells you, you have "many reefing options". What it does not say is just how effective those options are. And therin lies the real story... for I experimented at length, under many different conditions, with every concievable sail combination possible... and short of all full sails, it was nearly impossible to get the boat to point at all.
    If one were to consider building a small cruising boat, I would recommend other designs. As an example, Ian Oughtred's Grey Seal, which can be built in full keel and shoal versions, will appeal to many of the same crowd who are drawn to the Elver. The Grey Seal will have more room, sail better, and look better (in my opinion). It would be just a bit harder and more expensive to build. The plans are available from Woodenboat Magazine, which also ran a two part article on building the boat. I almost built a Grey Seal, and still wish I had.
    I recently came across the wonderful pocket cruiser design for "Penguin", by John Welsford. It just seems a really practical small boat, which uses it's limited space to the maximum. But I don't know much more about it than the article linked above.



Penguin, by John Welsford. A fat little boat with sitting headroom, which seems to use it's volume well.


Or buy an O'Day 22 for under $1,000, and sail it on the way home. Our boat pictured above. Weighs 2100 lbs., draft 1'
 11", 700 pound keel, sitting headroom, sleeps four. Sink, stove and head. Self-righting, unsinkable, self draining, fast... and it points.







To the left is a few minutes from a nice sailing day on the Hudson River, in September 2008.
        Another possibility would be any of the wonderful designs by Philip C. Bolger. In his Micro or Long Micro you will also have an easy to build boat... but one with much more room in it, is self-righting, and which will perform far better than the Elver.       
        The Elver offers features not available in any other designs. It is a very unique boat, which may fit, and has fit, the requirements and desires of many builders. To be sure you are one of those builders it is important to know this boat throughly, but also the myriad of other designs out there, so you can make the best choice of how to spend thousands of dollars, and many months or years of your life.