So You Want To Build a Cardboard Boat? Have You Gone Daft?

by Beth Young

The idea began like many of my other half-baked plans: with a supposedly useless bit of packaging.

You see, the truth is, I’ve been waiting for my water heater to go on the fritz for several years, because I knew when I ended up with a huge appliance box in my garage, I’d have no choice but to build a boat for Riverhead’s great Cardboard Boat Race.

I’m especially glad that my water heater started weeping out of all its seams this year and not last, when the Cardboard Boat Race was cancelled because Riverhead Town was afraid the river would be filled with dead rotting fish, as it had been in 2015.

So now, this year’s race is on for August 6, well outside the window of dead fish season in late spring. I’d had the water heater box for more than a month and I hadn’t done anything with it when I realized in mid-July I had just two weeks until the great race. I panicked. And then I sat in my backyard with a sheetrock knife, a tape measure and a pile of cardboard and tried to figure out how to build the boat.

I’ve always wanted to build boats, but I would begin work by trying to read about boatbuilding in books, most of which started with a whole bunch of engineering blather that just left me completely confused and not knowing where to start.

I had thought it would be the same way with cardboard boats, but, when I started reading on the internet, most of what I found was equally useless blather like “It’s Fun!” or “Be Creative!” I didn’t find any plans for cardboard boats, just Pinterest pins that claimed to be plans for boats but were really just pictures of boats already built.

There are some pretty strict rules in most cardboard boat races, but luckily, the rules for Riverhead’s boats are fairly typical: They can only be constructed of corrugated cardboard, duct tape, water-based glue and water-based paint. Within those bounds, well, Be Creative!

After hours of research, I came to a few conclusions:

First, and most important, I had to calculate how big a boat I needed to displace enough water to carry my 137-pound frame. This is the physics stuff that I feared, but it was really only one calculation. I had to divide my weight by 62.4, which is the weight in pounds of 1 cubic foot of water, to determine how many cubic feet the box within the boat that was carrying me should be. That figure worked out to 2.2 cubic feet, a number that shocked me because it was so damn small. Truth be told, I’d already started cutting up the water heater box and fashioning it into a paddler cubicle taylor-built to my exceedingly boring and normal proportions: 3 feet long, 2 feet wide and 1 foot deep. Essentially 6 cubic feet. Plenty of buoyancy.

But there is one problem I hadn’t noticed during the months the water heater carton languished in my garage: most cardboard boxes of this size have carrying handles punched in them that make them easier to move when they’re filled with heavy appliances. I began dutifully glueing and duct taping these handles shut. This box meant too much to me to abandon it at the 11th hour.

There are some other helpful rules I found deep within the internet — the first being that it’s much better to make seams on your boat by folding than by cutting, which sounds logical. After all, who would ever put a hole in a boat? The second is that the corrugations in cardboard wick water like a straw, so if you let any edge of corrugation remain exposed to the Peconic River, you’re asking for trouble.

A novice might think, ‘well, that’s what the duct tape is for,’ but the truth is that the best way to seal up those seams is with wood glue. The more wood glue you use, the better. And the best waterproofing for the boat isn’t duct tape either, but your latex paint, ideally applied in several layers, beginning with a primer like Kilz (the latex version! Don’t get disqualified for using the oil version!), which will soak into the cardboard.

And with using glue and paint comes patience, because you have to wait for these materials to dry. When gluing, make liberal use of your father or your boyfriend’s set of clamps they aren’t using out in the garage. If you don’t have a father or a boyfriend, get your own clamps. You might use them again. And also scavenge yourself some bricks and other heavy objects, to hold your glued seams in place.

But be careful not to crush the corrugation of your cardboard along the way. Yes, it’s a wick, but when sealed properly, it’s also your secret buoyancy ally.

After an evening of folding, cutting and gluing in my garage, I realized that I’m pretty lucky I still have two weeks left before the race. I have no idea what this boat will ultimately look like, but  I’ve got my work cut out for me. But I am finally living the crackpot dream I first had back when the Cardboard Boat Race started in 2010. I might not have the prettiest boat in the race, but I will at least be able to cross building a cardboard boat off my bucket list.

Oh yeah, and I’ll also have had fun being creative. If only there had been a Cardboard Boat Race down in Riverhead when my son was small. What a time we’d have had bonding in the garage with the clamps and the glue and the cardboard and the radio playing well into the night.

Registration for the Cardboard Boat Race begins at 9 a.m. on Aug. 6 at the Peconic Riverfront behind downtown’s Main Street. You still have time to build your own boat! I hope to see you there!