ACDC
design by Skip Johnson

It is all Shorty’s fault. I had been cogitating, ruminating and generally wasting time thinking about Proas for a while, thinking that a Pacific style Proa would be an ideal trailer sailor type craft for the shallow waters I’m most familiar with. Problem is, there are way too many unknowns and a serious shortage of rules of thumb for such an unconventional craft. To whittle down on the unknowns, you’ve got to build something and try it out. But what to build? Sure don’t want to spend too much time and effort on a purely experimental boat, but there aren’t many guidelines for purely experimental boats either. I had been considering building a boat to the old 3 meter multihull rules, but a 10’ boat is pretty darn short for a boat that is trying to find the path to easy speed.

Then along comes Shorty’s $50 sailboat race with just the right combination of restraints plus the additional challenge of doing it for less than $50.00. A couple of quick iterations of materials/cost settled down that the boat had to use no more than 2 sheets of plywood (5.2mm luan underlayment). Fifty bucks vanish pretty quickly in all the little odds and ends. Fortunately, there were two semi loopholes in the rules. First I already had a mast (12’ piece of 2” aluminum tubing from a previous sailing canoe) and a $2.00 finish allowance was pretty generous for a boat that’s going to have a lot of surface area.

Fourteen feet long overall and an eight-foot long float, two sheets of plywood disappear pretty quickly. Instead of the precise mathematical dance (with plenty of guesswork) involved in designing a stripper canoe, It was time to use scissors and cardboard.

The first attempt in the background had a pretty clunky looking hull but the float looked pretty good. So lets try a vee shaped main hull so no plywood needs to be ‘wasted’ in bulkheads. The result in the foreground looked good and appeared would have enough floatation, barely. The architect’s scale holding the hull and float up was the serendipitous hint to use a single crossbeam that you could ride like a broomstick and use less material. Another iteration of material pricing and things are looking good, but there’s not enough plywood for the shear webs in the crossbeam, but I’ve got some heavy duty cardboard boxes I’d snatched from the trash that should work fine as long as it doesn’t get wet. The design is done and under budget (click here for spreadsheet) time to build.


(click image to enlarge)

Being one of those projects that might should be lost in the mist of time, I didn’t take any pictures during construction except for the one time there was a snail on the crossbeam, which might have been a sign from somewhere.

Building actually went pretty quickly, there’s not a lot of material in a $50 boat. Stick a few pieces together, then scratch head awhile then eyeball the next pieces together. All the while coasting on the edge of DT’s building a boat without a single drop of epoxy! A couple of weekends and its done, rigged in the backyard to get the right lengths on the trucker knot turnbuckles in the yellow poly rigging (proper yachtsmen are probably turning over in their graves). What to call a very unserious boat that goes either way? ACDC naturally, with a backup name of cardboard broomstick

The first outing and race are covered elsewhere, suffice to say Ken Abrahams beat me and everyone else soundly in a very small kayak (little material) with an umbrella (the Mary Poppins gambit) showing one more time the absolute superiority of the simple solution.

ACDC floated, leaked a little and would have been a disaster in any kind of wind. Steering oar / broomstick was wayyy tooo small. Had the oar been larger it would have destroyed the oarlocks. The sail shunting scheme was an open invitation for Murphy to make his season at least, if not the year (but it was simple). Anyway for less than fifty dollars I’ve got the framework to do some semiserious experimenting.

May 22-23, I took ACDC, the previously $50 proa and a new almost finished stripper canoe to the Duckworks Messabout on Magnolia Beach, near Port Lavaca, TX. Turnout and weather were good, though the 15 gusting to 20 felt like 20 gusting to 30. Whatever the windspeed, it was blowing offshore so the water was smooth for at least 100-200 yards offshore.

ACDC now has a slider assembly like a drafters parallel bar (remember those?) to change the tack from one side of the biaxial (also known as Bolger, Xmas tree, AYRS…..) sail to the other. The cardboard shearwebs in the crossbeam have been replaced with plywood. There is a stronger oar and oar sockets. A padded seat has been added. A 6” strip of 12 oz biaxial glass has been added down the keel line. There is a certain perverse pleasure in the knowledge that any finishing done to date has been done with a belt sander.

ACDC waits patiently for me to screw up enough courage to hop on a boat held together with bailing twine after reading Wade Tarzia’s report in the proa_file group written from the hospital emergency room.

After paddling and sailing on everything in sight I finally ran out of excuses and slid ACDC into the water.

Damn that boat is fast, accelerates quickly and tracks like its on rails. Tracking straight is a very good thing. My carefully thought out oar ball socket isn’t working at all and I’m flailing the steering oar around every which way trying to steer the boat and finally gain some control jamming the oar into the face (wrong) side of the socket and keeping it in place by brute force. Running parallel to shore, I pinch into the wind a bit to slow down and try to shunt.

Shunting works, sort of. The shunting line slides the tack to the other side of the sail quickly and easily, but somehow I am backwinded and moving at a fair clip with the float completely under water. Grab the oar in both hands and paddle like mad to drag the boat around 180 degrees and sail back to shore.


This picture shows ACDC in a resting position, which allows water to drain out of the float.

Safely on shore, it's time to think just a bit about what happened. Everything happened fast. I haven’t done much sailing for many years, just paddling and water skiing, so I don’t have any automatic reactions to unlearn. The problem is my reactions are just slow. In any event I’m grateful, and surprised, the boat got back to shore all in one piece. Don’t think I want to know how slack the (nominal) windward stay was while we were running backwards, or more importantly, how close the mast was to going over center so I could try to top Wades tale. The fundamental principle of spreading the loads out wherever possible, to keep stresses low, seems to work.

After resting a bit, I decide to take ACDC out again and try to learn more. The wind still seems strong to me, but ACDC hadn’t really been in any trouble until backwinded. Plus, I couldn’t see any easy way to reef a Tyvek sail without shutting the window in the sail, which would be courting disaster even with the roll of duct tape strapped to the mast to appease Murphy.

Second time out with just a little bit less adrenaline and everything starts out fine not fighting the oar quite as much and we are still fast and shunt a couple of times without incidence. Then the shunt line jams at one of the turning blocks and we are backwinded again. Rather than fight it again, I drop the sail and skull, and skull, and skull to shore. Walking up the shore with ACDC following on a short leash might seem disheartening or even disappointing to some, but in this case, its not bad duty for a dirty old man.
Two times out and backwinded both times, Pacific Proas aren’t supposed to do this. May be the very deep vee of the main hull is over powering the float and spinning the boat around as it drifts downwind, or it may just be operator error. Time will tell, but the day is over.

Early next morning. A little less wind and variable, time to try again before packing up and heading home. Much better, the boat glides away from shore like it is on wings and most importantly, I find that the boat responds quickly to just a little twist of the oar, no more pushing and pulling trying to horse the boat around, it only needs to be nudged a bit. This is fun. I run along the beach pinching up at times to see how the boat goes to windward (slowly) but it will stay in control far further that I would have expected. Then fall off and accelerate again. Shunt and head back to campsite, a little closer to a run but everything still under control, along with a feeling my sail trimming skills need a lot of work.

Back at camp, a cup of coffee and strut a bit, then take ACDC out one last time. Once again, we are gliding and it is great, all I have to do is learn the finer points handling the boat. We, as in boat and I, run along the beach again and get up to where the beach turns more Westerly and we aren’t ready to venture farther afield yet so its time to shunt again. Jammed shunt line again. I pinch in again and get up to shore before the point and unjamb the line. Maybe I should have called ACDC “Goes where pointed”. The wind has shifted a little and its difficult to get backed off the beach far enough to turn a bit before the boat runs back up on shore, but we make it. Back along the beach to camp, reflecting on how the second time out each day seems to always have more problems than the first.

What to do next? Don’t know for sure. I think there’s a way to rig the oar so I can let go for a minute with out disaster happening. The shunt line needs to be larger diameter and it’s time to clean up some of the connections so the boat can be rigged a little quicker, although the boat assembles and disassembles pretty quickly now. The oarblade is still a little too flexible even with a layer of 5oz glass both sides. I will trim the size down just a bit and cut a scallop out of the end before adding another layer of glass. Slather some latex on the bare wood pieces and oil finish the closet rod sliders. Better hold down or permanently fasten seat. Rig a little sheave on halyard or double up to get a 2/1 purchase for raising sail. Big thing is to get some stick time on the boat, learn to sail it and see what works well and what doesn’t. I think the main hull wants to be shallower with less wetted surface with a float that provides most of the leeway resistance, but am afraid yet to mess with something that appears to be working. ACDC is about as big as I would ever want to go for a cartop (uh, truckrack) boat. For an easy to use boat, a 20 something pound solo canoe (picture below) has no peer and is what I’ll carry to the water most often, which cuts down on stick time, but hey it’s a hobby.


EasyB

Skip Johnson