Can anyone identify this instrument?

[GBTrust2021]

I found this item in a case at my father's house and would like to know what it is.

He was a long time sailor and one of his uncles was in the fishing supply business in San Francisco in the '40s and 50's.

Searching for PBI and some of the terms on it have not gotten me anything similar.

Thank you in advance.

Clint

[Yellowtulip]

It looks like a kind of Pelorus.

https://en.wikipedia.org/wiki/Pelorus_(instrument)

[Jim Cate]

Looks like it simply does the magnetic to true heading (and vice versa) calculation.

Jim

Edit: Yep, there are sighting tabs on the arm, so Pelorus it is, although it would need a dedicated spot on the boat to accurately align it with the centerline of the hull.

[Polar Opposite]

Originally Posted by Yellowtulip

It looks like a kind of Pelorus.

https://en.wikipedia.org/wiki/Pelorus_(instrument)

I agree. You can see the notches cut into the plastic as a sighting aid. It also has a correction for compass error (magnetic to true bearing).

[Alan Mighty]

Originally Posted by GBTrust2021

He was a long time sailor and one of his uncles was in the fishing supply business in San Francisco in the '40s and 50's.

Searching for PBI and some of the terms on it have not gotten me anything similar.

For sure that is a "Morris Pelorus" manufactured by the Pilot Bearing Instrument Company, run by Frank Morris, in 1948.

A handy device on the chart table.

[Alan Mighty]

Originally Posted by Alan Mighty

For sure that is a "Morris Pelorus" manufactured by the Pilot Bearing Instrument Company, run by Frank Morris, in 1948.

More importantly, Clint, welcome aboard Cruisers Forum!

[GordMay]

Greetings and welcome aboard the CF, Clint.


What Alan M said.

[Yellowtulip]

Originally Posted by Jim Cate

Looks like it simply does the magnetic to true heading (and vice versa) calculation.

Jim

Edit: Yep, there are sighting tabs on the arm, so Pelorus it is, although it would need a dedicated spot on the boat to accurately align it with the centerline of the hull.

It could be used to judge “risk of collision” by aligning one bit with a shroud or stanchion and the other bit on the other vessel, couldn’t it? And relative angles between landmarks for a position line?

[Paul Howard]

A pelorus was often used when correcting a compass for deviation and creating a deviation card for the differences in deviation on various headings.

[ussvdharma]

Looks like a plastic excuse for a Pelorus used on the bridge of boats to confirm azimuth to sighted objects or boats. de Susan W7KFI ussvdharma

[Alan Mighty]

Originally Posted by GBTrust2021

I found this item in a case at my father's house and would like to know what it is.

He was a long time sailor and one of his uncles was in the fishing supply business in San Francisco in the '40s and 50's.

I'd allow that Clint has a right good chance of finding, in among his father's books, a first edition (1949 if my recollection be aright) of "Marine Atlas", the two volume chart-based guide to the Pacific Northwest.

Frank Morris, 1907-74 peace be upon him, put together "Marine Atlas" quite likely with the help of his aforesaid Morris Pelorus. At least the first few editions of "Marine Atlas" were published by Pilot Bearing Instrument Co itself.

By my ciphering and if my supposition that the first edition were 1949 was correct, "Marine Atlas" has been in print for just over 70 years now. A tribute to Frank Morris.