Melissa appeared at the birthday party already flustered from a fruitless search for a five-point-harnessed car seat for her very tall three-and-a-half-year-old. He’s plenty big enough for a mere booster seat, but he’s not mature enough — he keeps wriggling free from his seatbelt, frighteningly fast, while Melissa’s on the highway. "What am I going to do?" she asked. "There are only four carseats in the world that are big enough for him, and they’re all hundreds of dollars, and they’re only just big enough. He’ll outgrow them."
We, three of us engineers and one a capable seamstress, and all of us parents, sipped our tea and tossed out suggestions. Intensive seatbelt training? No, not secure enough, and she needs a solution now — it might take weeks before she felt he could be trusted. Special, large carseats made for developmentally disabled older children? Just as expensive. Restrain him more securely in his booster seat somehow? Hmm.
"He doesn’t have to be really restrained," she said, "he just has to think he is. He won’t even try to open a doorknob if he feels the slightest bit of resistance. I think it just has to be different from the seatbelt. He already knows he can get out of that," she sighed, "even if I pull it all the way out so it ratchets back in and locks against his chest."
T. O. M. joked, "You need some kind of straitjacket."
Hannah ran with it and suggested, "Suppose we make a canvas panel that the seatbelt goes through, something that ties behind him?" She looked around for a pencil to draw what she was thinking of, then prodded by T.O.M., went to the dry erase board — we were in their schoolroom — picked up a green marker and sketched a little boy sitting in his booster seat, wearing a cloth panel with a channel through it for the chest strap and another channel across his lap, a smile on his face.
"No, you have to draw him screaming bloody murder." She changed the smile to a wide open O. "Does the seatbelt come out of it?"
"No, I would sew the seatbelt into it. It would become a part of the seatbelt. And it would have a tie that went back between his legs and tied to the one that went over both shoulders."
"So it would be a seatbelt suit." "A suitbelt!"
This seemed like a good idea at first and we were satisfied, especially as Hannah said she already had the necessary canvas, thread, and needles; but we kept thinking, because it seemed unnecessarily complicated to get him in and out of it.
"What if we use nylon webbing?" We all own the same type of booster seat, so it was easy to collaborate. "Suppose we run a loop through here — and here — and then another one up from here –" "It’ll be easy — but we’ll need to use one of those chest clips they have on car seats. Does anybody have an old car seat? " It seemed that we had all just thrown one out and failed to cannibalize the hardware first.
Then Mark remembered the simple harness in the kids’ bike trailer, how the strap runs from above the left shoulder, down through a ring on the end of a second strap that comes up from between the child’s legs, and then back up above the right shoulder. "Oh, let’s do it like that! You only need two pieces." The sketch on the whiteboard acquired a second layer of scribbles, then a third.
Hannah disappeared into her basement sewing room and came up with a fistful of nylon webbing, cut in pieces three feet long, purple and blue and brown. "Why do you have that?" we asked delightedly. "I was going to make backpacks for the children — a few years ago," she answered sheepishly.
"Show me what you mean," said Melissa, and I took a couple of pieces of webbing, got out of my chair and turned around — I draped one length around the back, then looped the second in my hand and put my knee on it to hold it to the chair seat. "We drill a hole down through the seat here — and this loop comes up from the seat. We put a ring on the loop. The ring is about at the middle of his chest. This other piece comes down over his shoulder through the place where the seatbelt goes, passes through the ring, then goes up through the other side and around the back of the seat and connects with the other side. You’ll put a click-buckle, or whatever you call those things –"
"The kind of plastic buckle that’s on a fanny pack," Hannah interjected.
"–Yes, that thing, you’ll put it on the shoulder strap to close it. So all we need are two pieces of webbing, one ring, one buckle, a little buckle to hold the strap underneath the seat, to keep it from coming back up the drill hole."
"I’ll use my quarter-inch router bit," volunteered Mark.
"I’ll go to Midwest Mountaineering tomorrow on my way to the grocery store and buy the buckle," I volunteered. "We’ll have it for you tomorrow afternoon!"
"But will it still work okay in a crash?" Mark went to the board and showed how the seatbelt itself would still provide all the crash restraint, the webbing’s only meant to restrain him in his position — just like the booster seat it would be attached to. "But will his throat go against it if he leans forward?" "Not if we have it tightened correctly — the ring will pull the shoulder straps down to the middle of his chest."
We were satisfied, and Melissa was delighted — she’d save three hundred dollars! We poured another round of tea while she told us how glad she was to have engineers for friends. I picked up my diaper bag and examined it. I’d added a sternum strap to it a couple of years ago so it wouldn’t slip off Milo’s shoulders when he carried it for me. I picked up a long piece of nylon webbing tangled on the floor and examined it too.
"What are you doing?"
"This buckle’s the right size." I had the sternum strap off in a minute and showed the click-buckle to Hannah, along with the two small friction buckles for tightening. "Here, take this — cut it here — sew it there –" She disappeared downstairs again, and I ran out to our van to fetch a booster seat, the kind with the back and headrest. Hannah returned with the female half of the buckle secured to the end of the strap. I ran the other hand through the male buckle, passed the strap through both shoulder-strap channels on the back, and clicked the buckle closed; the strap now hung loosely like a necklace.
"That looks like a choking hazard," said someone. But Mark had already picked it up. "Take off the seat cover," I said; maybe the seat already had a hole in it for some reason, one that we could use to pass the bottom strap through. But Mark had already detached the back from the seat — and there was a place to attach the strap! He looped it through; I handed him one of the little friction buckles, and he ran both ends through the friction buckle to close the loop and put the back back together. "There."
"How does that work?"
I unclicked the click buckle on the "necklace," ran one end through the loop of webbing that came up from the bottom of the back — "this part will run under his bottom and up between his legs" — and clicked it closed again. "There — a perfect Y-harness."
Someone went and fetched her little boy and told him, "Look, we have a new seat for you!"
"A new seat for me?"
"Yes, um, the kind that race car drivers have."
"A race car driver seat for me?!?"
We opened the buckle, sat him in the seat, pulled the loop strap up between his legs, ran the shoulder strap down over his left shoulder, through the loop strap, and back up over his right shoulder. Click. He was in, and grinning happily. (I guess Hannah’s sketch had been correct the first time.) It didn’t quite fit, so we fiddled with the buckles a bit, and eventually sent Hannah down to the sewing room to splice two straps together, and then went out to retrieve a seat that actually belonged to Melissa and not to me, but finally — after a little more than an hour — we had engineered a supplemental restraint system that (a) didn’t interfere with the seatbelt, (b) hadn’t required any tools except Hannah’s sewing machine, (c) was quick and easy to fasten and unfasten, (d) made the boy happy, (e) used common household materials, at least if nylon webbing and sternum strap bits can be denoted "common," and (f) did not cost 300 dollars.
I haven’t heard yet if the boy has managed to escape from it, but I’ll report back soon.
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