Sailing the Windmill: Flotation and Air Tanks

Skip Kendrick, #1985, Tank Girl

April, 1997

We bought this old boat, hull number 1985, last year primarily to rescue it from the years of obvious neglect. We stripped and sanded till our hands took on the appearance of gnarled root knobs and gained a grip that frightens even the most dedicated hand-shakers. We is my wife, Trish, and her husband, me, Skip. As the boat began to look like wood again, and the possibility of actually sailing her seemed greater than chance, the problem of flotation came up. This old boat was built without air tanks. At some point in her previous history, someone added chunks of Styrofoam cut to fit the hull and deck shapes, but only between the amidship thwarts . The Styrofoam was pretty filthy and moldy and we removed it and used most of it as shock absorbers when helping friends move furniture. I kept just enough to replace it in the event we actually might someday use it (some of us have a little problem throwing out useless trash).

Indeed, the Mid-Winters were upon us and the boat was unfinished so with only one coat of epoxy, no paint, no varnish, and old moldy Styrofoam for flotation, we raced. Well, we flipped and flopped around the course having a great time getting no where fast. But we were pleased and now have bragged to all about how we did not capsize and did not come in last! We beat two boats, so were third from last. We "beat" the guy who couldn't sail because of surgery (and so his boat stayed on the trailer) and we "beat" the guy who volunteered for race committee duty. So we beat the boat that stayed on its trailer and the boat that was anchored at the start line (committee boat)! No where but up to go....

The Styrofoam flotation was never put to the test, thank goodness. I checked on air bags. I read in the Windmill Annual about air bags as a possibility and saw a message on the Windmill Forum about them too. Don Malpas suggested that we forego air bags and put in wooden tanks. He sent us a two-page diagram/instruction pamphlet. Air bags, he said would keep the boat from sinking too far under, but would still allow it to fill with way too much water for fun or comfort (I don't think he actually said "comfort," this is a Windmill after all).

But you know, with an old wooden boat, and thoughts of restoration, not improvements, something removable seemed better. It was a hard time deciding what to do. More thoughts and more suggestions all kept bringing me back to plywood air tanks. Fine; I knew when I was licked. Plywood it would be. But what kind? Here in Tennessee, it's pretty hard to find okoume or any marine plywood. WoodenBoat and Boatbuilder magazines have run articles debating the use of luan, and other non-marine plywood. After looking at all that, it seemed that West System epoxy would pretty much seal any kind of wood, so it was really a matter of appearance and price (there must be some kind of metaphor on life here).

Luan or Birch? I sought more advice. Don Malpas voted for birch, if those were the only two choices, but really pushed for okoume. Others put in their two-cents worth and even the Windmill Forum brought a reply that birch is really nice...for kitchen cabinets! No one voted for luan except penny-pinching me. So I bought a sheet of birch and a sheet of luan and sanded and coated them both with epoxy. Actually, I cut out test panels from the cardboard templates of the air tank panels - partly this allowed me to see what each would look like in the boat, but mostly it gave me the chance to work with both and test both by submerging them overnight in a bucket of cold water. They both survived the submergence; boy that West System Epoxy is amazing stuff. But you know, luan is full of holes. Those must be the voids the magazines talk about. One hole in the middle of the plys showed up while sawing and caused some nasty splintering. I could easily see that the initial cheap price of luan could double as new panels would need to be cut to keep things looking good and working properly. Those voids ruin everything. And then the luan looked like crap. It would have to be faired and painted, which means more epoxy and fairing filler and paint and thus even more money. The price advantage was slipping away. Besides, I was after a boat with nice wood, not paint.

Birch was better. But every time I looked at it, and worked with it, I kept hearing that guy who wrote about kitchen cabinets. With the test panel in place, birch looked pretty yellow and not A pretty yellow either. It too had voids, but not as many as luan. But it had knotholes on one side. It was full of them and you really have to pay attention to laying out the templates when cutting the birch so you don't get knotholes in the wrong places. So the birch seemed better, but only a little. And it too would require double the purchase of panels to replace the pieces ruined by the knotholes. Both Luan and Birch looked pretty bad, bad enough to be covered by paint, and they both would required buying at least four sheets, not the two sheets actually needed. Shoot. What to do?

Without telling Trish, I ordered Okoume from Edensaw Woods in Port Townsend Washington. I did tell her eventually; over a nice dinner the day before it arrived at the house! Trish was not much on buying this old wood boat in the first place. When we brought it home and had spent several rather trying days of stripping yellow painted delaminated fiberglass from the wood hull (why do people cover wood with fiberglass anyway?), she suggested we name the boat The Last Straw! After seeing the price-tag on the okoume, she was certain that's what it's name was. I eventually convinced her otherwise, but Tank Girl has retained her alias.

The Okoume was three ply, 4mm, Dutch mahogany from Israel. Marine Plywood. The plywood itself was not too pricey; only $38.00 for a 4x8 sheet. But the shipping was over a hundred dollars! All told it came to $196.00 for two sheets on my front lawn securely wrapped in 3/4" particle board, cardboard, and metal straps.

The okoume went in the living room against the wall behind the piano where it stayed waiting for me to cut it up. I just couldn't. We lived with it against the wall for about a month, while I continued to sand and measure. Just to make really sure I knew what I was doing, I cut a full set of panels and end pieces and braces out of luan! Only when the luan panels could be fitted neatly did I feel ready to try cutting a piece of that expensive okoume. I guess most people can go from cardboard templates to expensive wood, but not me. I am not a woodworker; I do not have the tools (well, now I do!), and have never attempted to build anything out of wood except a small child's rowboat from an article in an old copy of Cruising World. The rowboat worked pretty well and is such a cute little boat. But we know of no six-year-olds to row it! In Tennessee, people look askance when we ask to borrow their child for a test row. With my 145 lbs, the child's rowboat sinks to its gunwales and is readily swamped by the wake of a passing sailboat! But that's another story....

The first panel cut from okoume went well. So I cut the remaining panels. They got their coat of epoxy and another too. They went in smoothly and were easily filleted, again with West System Epoxy and the fillet blend filler. They look great! Even with the okoume behind the piano one could see that it was far better than the luan or birch. No Voids. Smooth cuts all around and it took epoxy like it was meant to. Once in the boat, it looked even better. If you are like I was - thinking of Okoume substitutes - don't. Just go ahead and spend the money and get the okoume. It was the best decision of all just based on the appearance. The boat looks better than ever. By the way, I cut round access ports with laminated backings in each of the six tanks. The plans said to make them rectangles, or was it squares? Anyway, round is just as easy and I like the look better. The access ports are indispensable. They are held in place by six brass screws and have gaskets cut from an inner-tube. The plans are not real clear about whether continuous tanks should be separated by bulkheads, but mine are! We now have six separate areas (and six access ports). The plans say the ports are needed to get to hardware under the deck and to sponge out any water that may get in the tanks. True. Condensation is a problem too, so opening the ports ventilates the tanks.

This past Sunday, Trish and I took Tank Girl out to the lake for a flotation test. Without the mast, boom, etc., we put the boat in the water and tipped it over. It easily went over on its side, but stopped just as the gunwale hit the water. The air tank actually made it hard to push underwater. Here I was, in four feet of water, trying with all my might to push the boat under water while it floated on its side. It did not want to float on its side! It insisted on righting itself despite my best efforts to hold it down. Now don't get me wrong - it does still turn turtle! With it on its side I was just able to stand on the air tank trying to use my weight to push the side straight down under the water (I was really trying to get the whole tank submerged and look for any leak-indicating air bubbles) and all it wanted to do was pop up and right itself. With a little effort and a "run" at it, I could flip it completely over. I then was tired so sat on the turtled hull and just floated along with the breeze. Then I flipped it over and pushed the other side under the water for the air bubble test. This was all done in four feet of water, protected cove area, and no mast, no sails, no daggerboard, no rudder, just bare hull. I stood beside Tank Girl to flip it; I did not go into deep water and try to use a daggerboard to right it. That's for next Sunday! Naturally, with wind and sails turning turtle will be much easier.

Well, after about 20 minutes trying to sink the boat I gave up and flipped it rightside up. There was a bit more than 2-3 inches of water in her. The 2-3 inches is stated in the instructions or the annual or somewhere I can't remember now. We actually got more like four inches maybe five inches of water in the righted hull. But this small amount of water is nothing and our old transom flaps had most of it bailed out in no time. No bailing! A little sponging would have helped to remove the last inch or so. I should also mention that our air tanks do not cover the area between the forward thwarts where the mast goes. The beam tanks also do not cover the tangs for the side stays. I decided to leave the old tangs as they were and stop the tanks about 3 inches short of the thwart the tangs are attached to. This meant I did not have to shorten the side stays or alter the tang-attachment hardware. This also meant that two rather large areas allow water to flow into the boat when it's on its side and probably accounts for the 4-5 inches we got instead of the 2-3 indicated by others' experiences.

To wind up this bit on air tanks, don't even bother with air bags, Styrofoam, or cheap plywood. Our tanks work like I could not even have imagined. Trish's confidence in Tank Girl is now completely secured. There is nothing like knowing you can't sink, that you can flip it back upright and just keep on sailing! And that okoume is light, strong, and so good looking. As Trish says, "You are too proud of yourself to leave any room for others to be proud of you too!" I guess I have been strutting the past few days, but then a winter of sanding, tortuous decision making, and a dwindling checking account resulted in a beautiful boat that is 100% self-rescuing. Put in those air tanks; use okoume. You too will be extremely proud of the result and your wife just might keep sailing with you!

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What to install tanks in your old woodie. The WCA has an article that suggests how to do it. Order Information Sorry, no templates.