Qfyilyi

What could be meant by "best centre" in the following:

I swallowed down my heart in me as I touched the spar-deck, for a single instant balanced myself on my best centre, and then, wholly ignorant of what was going to be alleged against me, advanced to the dread tribunal of the frigate?

I cannot be sure since it is here used within a literary context where the author wanted to refer to the subject (about to be accused) regaining his pivotal centre of physical (if not emotional) balance.

A vessel has numerous functional centres, here are just a few as given by
Splash Maritime :

Centre of buoyancy (B):
The centre of area of the underwater transverse or longitudinal section of a hull at a particular trim, hence the point at which the force of buoyancy is regarded to be acting vertically upwards

Centre of effort (CE):
The centre of areas of all sails or areas of a waterline.

Centre of flotation (F).
This is the centre of gravity of the area, or centroid, of the water-plane of a ship and is equivalent to a pivot point of the vessel on any change of trim.

Centre of gravity (G):
The centre of weight of a vessel, hence the point at which the force of weight is regarded to be acting vertically downwards.

Centre of lateral resistance (CLR):
The centre of area of the designed underwater longitudinal profile of a hull around which a vessel will pivot from wind on the beam.

and a shifting corresponding displaced prime pivotal centre "metacentre"(https://en.wiktionary.org/wiki/metacentre)

I have to surmise the author was referring to this pivotal centre in human terms as the best centre about which to steady oneself.

On cruise ship forums the advice for "best" cabin with the smoothest ride will be in the area around the point that the ship moves around i.e. metacentre Note that the fore / aft metacentre may be further back than midship but varies from vessel to vessel.

There is a very very slight possibility that that it meant "right centre" since starboard was "best" side (however in context that seems to make no sense) see "Best Bower" here https://www.caribbean-pirates.com/nautical_glossary.php as to why starboard was the best side I have only the note that it was the "captains side" however modern convention is that for passengers "best" changes from Port Out to Starboard Home (POSH) see best bower link.

In the expression

[1] for a single instant (I) balanced myself on my best centre,

the phrase my best centre refers to the essence of what one is, to his or her moral, psychological, emptional, or spiritual core. It is this core that is the basis of one's fortitude ('the strength of mind that enables a person to encounter danger or bear pain or adversity with courage'). In trying times, such as those in which the protagonost finds himself, one needs to hold on to this center in order to find psychological, emptional, moral, and spiritual balance; in other words, to remain in good condition in those four respects.

Here are some other examples of usage of the phrase one's best center.

First example

“Ye see." He touched my chest. "Ye can always come back. No matter how seasick ye get when yer boundaries shift, no matter how strange yer mind is actin', ye can find a home in this empty space, this silence behind yer thoughts. It's always there. It's who ye are. Waitin' to be rediscovered. The truest center o' gravity is not the center of the Earth. It's at the center of the soul. And because it's everywhere, Michael, it gives us our deepest stability.”

From his suggestive power perhaps, or the cumulative effects of our all-night vigil, my light-headedness gave way to the liberating emptiness l'd experienced at the end of our golf round. There was surprising stabilty in this vanishing state, a sense that nothing could limit, disturb, or attach itself to me.

“There's nothin' to knock off balance," he'd said. “This is our best center because it's everywhere—and because it's no single thing at all." (source)

Second example

This example is from a letter written by Rev. Oliver Heywood to his son in 1701, on the occasion of hearing that the son's son had died shortly after birth.

It is a mercy you have a centre after your various circumferences; but your best centre is above, you must pitch your anchor within the vail, Heb. vi. 19.

We need to explain at least three things here: (1) the use of after, (2) the use of circumferences, (3) the Biblical reference (Heb. vi. 19).

Let's start with the word circumferences. It is here used figuratively. The OED explains that, in this sense, it is used roughly as a contrast to center when the latter means 'fig., esp. with reference to an immaterial or abstract thing; the most essential part; the heart, the core'. Some examples of usage: in the context of talking about the second coming of Christ, The hour is at hand, and the hour brings forth the central man of the universe. Gather together his circumferences. (source) Another example: Jonson's impresa¹ appropriates also the hermetic image of the God who is both center and circumference. (source). Some other examples of similar usage are here, here, here, and here.

^{1impresa: (heraldry) an emblem or device,2 usually accompanied by an appropriate motto; a device with a motto used in the 16th and 17th centuries.
2device: (heraldry) an emblematic design used especially as a heraldic bearing.3
3bearing: (heraldry) a figure borne on a heraldic field.4
4field: (heraldry) the whole surface of an escutcheon.5
5escutcheon: (heraldry) a defined area on which armorial bearings are displayed and which usually consists of a shield.}

The word after is used in its meaning of 'in accordance with, according to'. Some other examples of similar usage: Managing the campaign after his own ideas, he speedily involved himself in quarrels. To build after one particular pattern. Woven moccasins called opanci, which had a curled toe after the Turkish custom.

So when Rev. Heywood talks about a center after [his son's] various circumferences, he means something like the following: his son has various areas of activities, obligations, interests, etc. These are his 'circumferences': things that he ahs to deal with, within which he lives and functions. We may think of his son's existence being 'circumcribed' by these, by everything he is and does; this is the Rev. Heywood's son 'circumscribed', i.e. at his broadest. In contrast to this, the son also has at least one center, which is his core or essence. The reverend implies that the son perhaps has several centers, or perhaps several possible centers, corresponding to ('after') these varied ways the son may be circumscribed. Not surprisingly for a reverend, Rev. Heywood then suggests that one's best center is to be found in God.

The Biblical reference (Heb. vi. 19) is to this sentence from the King James Version (the word vail is an archaic spelling of veil; indeed, in the OED's entry for veil, many older examples of attested usage use the spelling vail): Which hope we have as an anchor of the soul, both sure and stedfast, and which entereth into that within the veil. The Contemporary English Version renders that as This hope is like a firm and steady anchor for our souls. In fact, hope reaches behind the curtain and into the most holy place. Here curtain refers to the following: in the tent that was used for worship, a curtain separated the “holy place” from the “most holy place,” which only the high priest could enter.