Reading an advice article about the writing of historical fiction, I came across what I assume is an eggcorn for the idiom “to shore up.”
eggcorn: the reshaping of a common word or expression in a way that makes sense to the speaker.
The person writing the article drew an analogy between the construction of Machu Picchu and the research that underpins an effective historical novel:
[The Incan builders] started at the base of the mountain, and built terraces all the way to the top to sure up the mountain.
The writing instructor then compares this physical foundation work to the writing of a novel:
Writing historical fiction is much like building Machu Picchu. You want your novel to stand the test of time and that means doing the historical research to “sure it up.”
Never until then had I come across the expression “to sure up” in the context of stabilizing, strengthening, or reinforcing something. The conventional idiom is “to shore up.”
As a verb, to shore or to shore up means to prop something up. For example, one might shore up a sagging gate to keep it from scraping the ground. A tunnel might be shored with concrete.
The verb shore derives from a noun that referred to a piece of timber or iron that was set against a building or a ship to prevent it from falling while it was being worked on. In modern usage, anything can be used to shore something up. One might shore up a wall by packing earth along the bottom.
The verb is used literally in the context of building, reinforcing, or repairing structures:
Anticipating a storm, the villagers shored up the sea-wall.
The first step is to remove the boards and inspect the post. If it’s also soft and rot-infested, you’ll have to shore up the roof temporarily and install a new post that’s treated to resist rot.
A Web search reveals a quantity of examples of “sure up” in contexts that call for “shore up”:
PANTHERS – Staying Hungry and Suring Up the Defense
The return of the big man sures up the middle of the offense.
Prosecutors could use the videotaped interrogations to sure up their argument that a confession was genuine.
One of the ways to sure up your home’s foundation is with Helical Piers installed.
The use of “sure up” for “shore up” is still relatively rare. It flat-lines on the Ngram Viewer, and a Web search for the terms in quotation marks yields 4,670,000 results for “shore up” compared to 365,000 for “sure up.”
Here are examples of the idiom “shore up” used correctly in a variety of contexts:
How Bobby Wagner’s speed shored up the Seahawks’ defense
Prosecutors had asked for the phone and bank records in a last ditch attempt to find evidence to shore up their case.
The bulk of the Snyder increase did not go directly to the schools; it went to shore up the underfunded teachers’ pension fund.
The Federal Reserve’s trillion-dollar effort to shore up the U.S. economy is likely to come to an end in October .
Use your analytic skills to understand [your critic’s] position and to shore up your confidence in your own approach.
At first, I thought that all the examples of “sure up” were incorrect versions of “shore up,” but I’ve decided that a few are being used with the meaning “to make sure.” Here is an instance of the latter:
Coal supply chain partners in the Hunter Valley have struck a long-awaited agreement to sure up coal producing contracts.
The headline above the sentence holds the clue that “shore up” is not intended:
“Historic” agreement reached in long-running Hunter Valley coal chain dispute, providing certainty on contracts
Bottom line: If what you mean is “to strengthen,” the idiom is “to shore up.”
If what you mean is “make sure,” the idiom is “to make sure” or “to make certain.”
Here are some other words that may be used to express the idea of “making sure” or “making certain” of something: