If a sailboat lies unattended even for a short time, decks and canvas can quickly become grubby from bird droppings and windblown dust. I have frequently counted fifty of the little darlings perched along the triatic stay on my schooner Britannia, all having a merry chirp while doing other things…
I spent a lot of time looking at intricate and expensive products that are supposed to frighten birds off boats, including acoustic devices, but it's practically impossible to keep birds off every part of a sailboat's rigging when they can even hang on vertical stays. After testing these products thoroughly, (see bird deterants), I came to the conclusion that the most effective and the cheapest method for keeping bird droppings off a sailboat is an awning.
I especially wanted to protect the center cockpit canvas Bimini on Britannia to shield it from the fierce Florida sun as much as rain and bird droppings. There is also a secondary benefit from a good awning; it keeps the temperature down inside the boat, in Britannia’s case by some 10 degrees Fahrenheit when it's 90 outside.
I shopped around all the local canvas and sail-makers and received lots of advice about what material was best for an awning, along with prices. These varied from, “We'll beat any price,” to “I'm going to need a second mortgage for this job!” The average of all these was about $1500 that was way above my budget, so I started to consider how I might make one myself.
The simplest and cheapest way to make an awning is to buy a "tarp" and drape it over a boom, then attach it to lifelines with bungee cord to form a simple tent. The main boom on Britannia passes directly over the cockpit, so making a tent seemed like the easiest way. Most tarps also have eyelets every 18” inches or so all around, so threading bungee cord through the eyelets and hooking the other end to the rails was simplicity itself. However, after I installed my tent I discovered it had a few shortfalls. Firstly, by tethering the tarp to the rails it became quite a scramble to edge along the side decks to get into the cockpit, especially with an arm full of groceries. Secondly, the tarp rested on the boom and the top of the Bimini, causing chafe to both materials in strong winds. A third problem was that my awning looked, well really cheap, mainly because it was really cheap! What can you expect for under fifty bucks?
Awnings can also be stretched between horizontal poles attached to masts or rigging, that generally overcomes the access problem. But they flap about alarmingly in even a slight breeze and rainwater also collects in a flat awning to the point where they can capsize. They don't shield the early morning and evening sun very well either. I wondered how to overcome these shortcomings and make an awning that was both effective and looked a bit more professional.
An idea came to mind from seeing the covered wagons in an old Wild West movie, and I wondered how to make a curved cover like those wagons. Such an arrangement might also hold the tarp clear of the boom and Bimini, reducing chafe and allowing wind to pass between them. The height should also give more headroom along the side decks.
The supports on covered wagons were called "bows," made of Hickory wood. The question was, how to make them and be able to stow them on the boat when not in use?
I found the answer with modern tent poles that use flexible aluminum rods to support a curved roof. These are demountable rods that slot into each other to form a very strong yet flexible continuous rod “bow” held together with bungee cord through their whole length. When not in use they fold into a bundle only 28” inches long for easy stowage. Britannia’s main boom is 16’ feet long, so I guessed I would need three bows to support the tarp over the boom and another for an overhang in front of the mast. I measured the approximate lengths I would need by curving a metal tape and measuring from the toerail to just above the boom, then doubling it. I ordered four rods from https://tentpoletechnologies.com, who made all the lengths to my exact size. If a rod happens to be too long it's easy to remove one section and re-knot the bungee.
I anchored my bows to either side of the boat using 3/4” inch plastic PVC tubing strapped to the stanchions with hose clamps. The bows then just dropped into the tubing and rested on the toerail, forming four perfect arches. Britannia's beam at the mast is 13’ feet, tapering to 10' feet at the stern. A tarp would need to be much wider than this to curve over the bows, so I measured the length of the front and rear bows, down to a point where it offered maximum coverage against rain and bird droppings, yet with enough clearance to walk through. From these measurements I drew a sketch of the shape.
The nearest tarp size I could find was a 19’6” x 17’6” heavy duty in 12mil weight. Tarps are available in many different sizes and colors, so it should not be difficult to find one to fit almost any boat. I choose one that is silver on the outside to give maximum heat reflection. Do not make the same mistake I made by buying the cheapest lightweight 5mil tarp for my simple tent. These are too thin and flimsy for a boat awning and it soon wore through at the chafe points. The 12mil thickness is much stronger and has survived some strong winds, and the bows will easily support the extra weight of a heavier tarp.
I first laid the material out on my garage floor and it can be seen to be a trapezoid shape. Rather than just cutting the tarp down the middle and gluing it, I decided to taper it by overlapping the center folds and gluing the overlap joints. This strengthened the center section and ensured the joint remained waterproof. The front only needed a little tapering from 17’6” down to 16’ feet, but the back was only 12’ feet wide that required quite a large overlap
This was when the messy part started, because I used sticky contact glue and a 4” inch roller.
I first folded the center overlap and rolled a liberal amount of glue to both sides, all the way along the fold. After the normal drying time of about ten minutes I carefully pressed the fold together from the center to the back and front of the joint. Working from the center ensured that there was no creases in the fold. I then placed some strips of timber over the joint and pressed it firmly together by walking on it. I left the joint overnight to set, then turned the tarp over and glued the other side of the fold the same way. The finished taper is a neat, very strong double glued waterproof overlap joint down the center of the awning.
I installed the bows and draped the tarp over them, but since the awning extended forward of the mast by some 2’ feet I had to cut a hole to fit around the mast. I did this with the awning in place, then reinforced it back in my garage, where I also installed a row of eyelets into the front joint and threaded them together with bungee cord. The awning also overhangs the aft hatch.
For hold-down tethers I bought 5/16" inch bungee cord with hooks on both ends. I cut one of the hooks off to be able to thread the cord through every second eyelet along the length of the tarp on both sides and a simple overhand knot stopped the bungee coming out of the eyelets. I fastened the front and rear of the tarp to the bows with cable ties, through the eyelets and round the bows.
Positioning this large awning is quite easy for two people when there is little wind. We just pulled it over the bows then hooked the tethers to the lifelines on each side. I attached the front hoop to the running backstays and the rear hoop to the mainmast backstays with bungee. Even in a moderate wind the awning hardly moves because the wind passes through and over the structure.
Suddenly I had my own covered wagon.
This inexpensive awning protects Britannia's Bimini from weather as effectively as any expensive custom-made canvas cover, and due to the increased height of the bows we can comfortably move along the side decks. Temperatures in the cockpit are also significantly lower than without the awning and rain just runs off, washing bird droppings with it.
Awnings on boats, even those made of expensive UV-resistant material don't tend to last more than a few seasons when exposed to the elements day in and day out. Replacing a cheap tarp is therefore a lot less expensive than a custom canvas. My project cost $300, including tarp, bows, tethers, rollers and a pot of glue.
I now think my awning qualifies as quite professional looking, even if I do have to ignore the occasional snide remark, "It looks like a replica of a wild west wagon," because envy is just another form of flattery. Anyway, the covered wagons were called “Prairie Schooners,” so my awning is spot on.