S/V NIGHTCAP

Monday, January 5, 2015

Marine Log Book Pen

The Zebra F-701 can be refilled with a Fisher cartridge to create the perfect all weather log book pen for on the water use. Completing the cartridge swap requires removing the plastic tip insert with a paper clip which allows the Fisher cartridge to drop in without any further modifications. The barrel knurling can be coated or taped to prevent pocket chafe.

https://www.youtube.com/watch?v=zlgbRxZaAqY

Saturday, December 20, 2014

Square Pocket Protractor

A grid map tool that is modified with 1/16" drilled holes makes for the perfect pocket chart plotting protractor. Drill the holes by hand using a 1/16" bit spun with the index finger and thumb. Make a pilot hole at the spot to be drilled using the point of a divider leg.

Monday, June 16, 2014

Longhand Sight Reduction

An obscure sight reduction formula derived by a Frenchman named Doniol is the only reduction method that can be quickly done longhand without logarithms. Needed are four place cosine, sine, and haversine tables which can be found in the 1958, 1962, 1966, 1975 vol 2, and 1981 vol 2 Bowditch editions.

http://fer3.com/arc/m2.aspx/Haversine-how-derive-it-Bernecky-jun-2015-g31663

Doniol Formula

Sin h = n - ( n+m )a

Same name:
n = Cos ( Lat-Dec )
m = Cos ( Lat+Dec )
a = Haversine LHA

Contrary name:
n = Cos ( Lat+Dec )
m = Cos ( Lat-Dec )
a = Haversine LHA

rule:
Lat + Dec > 90 use (-)Cos of Complement

When haversine tables are not available then substitute
a = ( 1-Cos LHA )/2

Tuesday, May 20, 2014

Ditty Box

Every boat should have a go to ditty box for storing miscellaneous extra items collected over the years. Rubbermaid tubs work well and are in various sizes to fit available onboard space.

Wednesday, December 25, 2013

Paracord Dispenser

A paracord dispenser can be made from a plastic jar by drilling a small hole in the center of the jar lid to then feed the paracord through and finished with a figure eight knot. The full length of the paracord is stuffed foot by foot into the jar which results in tangle free dispensing.

Friday, November 15, 2013

Improvised Artificial Horizon

A salsa container and a black plastic coffee can lid pair up well to form an improvised artificial horizon suitable for sextant celestial navigation practice when a sea horizon isn't available. Punch quarter inch holes around the perimeter of the coffee can lid to create a baffling effect that smooths and settles disturbances at the surface. Fill the salsa container to the rim with water then float in the plastic coffee can lid. Tap and spin the lid to remove any bubbles trapped under the lid.