The quotes below tell us something about not only the characteristics of IPA, but how it was perceived by drinkers of the day.
We''ll start with part of a letter to the journal "The Chemist":
"Of all the fermented liquors as drinks, and I have paid some attention to the subject, I give the decided preference to the bitter pale ale, manufactured by Messrs. Hodgson and Abbott; and the reason why I give such decided preference to this is, because, from the many examinations that I have made of it, we are convinced of its purity; 2ndly, because it contains comparatively a small quantity of alcohol; and, 3rdly, because it contains a large quantity of hops. This ale has a peculiar bitter and agreeable taste; and I call the attention of medical men and physicians to it, considering that it would be found of much advantage to patients recovering from low febrile states, and during convalescence after various complaints, as it strengthens the body and gives vigor to the system without exciting the brain: for this purpose I prefer it to wines of any description, from observation of its effects. I am, Gentlemen,
"The Chemist, Volume 4", 1843, pages 77 - 78.
I draw your attention to this phrase: "it contains comparatively a small quantity of alcohol". It's clear that the author, a medical man, did not consider IPA particularly alcoholic. I repeat yet again: IPA was not a strong beer by the standards of the day. Just in case you'd already forgotten.
"Ale is prepared with pale malt, and on this account is much lighter colored than Porter and Stout. The strongest kinds of ale are richer in alcohol, sugar, and gum, than any other kind of malt liquor : but though they thus contain a larger amount of nutritive matter, they are not fitted for ordinary use, on account of their intoxicating and stupefying qualities, and are especially to be avoided in diabetic and dyspeptic cases. On some persons they act as purgatives. The Pale Ale prepared for the India market, and, therefore, commonly known as the Indian Pale Ale, is free from these objections. It is carefully fermented, so as to be devoid of all sweetness, or, in other words, to be dry; and it contains double the usual quantity of hops : it forms, therefore, a most valuable restorative beverage for invalids and convalescents. It is taken with benefit by many persons on whom other kinds of ale act injuriously. For ordinary use at table, the weaker kinds of ale, popularly known as Table Ale, are to be preferred."
"A Treatise on Food and Diet" by Jonathan Pereira, 1843, page 200.
He mentions two types of Ale: Strong Ale and Indian Pale Ale. The former, because of its high alcohol content, the author (a doctor) considers "not fitted for ordinary use". IPA, on the other hand, "is free from these objections", i.e. is not high in alcohol. So yet another contemporary source saying IPA was not a strong beer. Eventually this fact is bound to get through even the thickest of skulls. The evidence is overwhelming.
Dr. Pereira makes some another significant observation about the nature of IPA: the high degree of attenuation. It was vital that pretty much all fermentable material had been fermented out before putting a beer on the ship to India. No-one wanted the beer to start fermenting or, worse still, pick up an infection in transit. Removing all the food for either yeast or bacteria was the best method of avoiding such a catastrophe.
IPA was not a strong beer. Just repeating that for luck.