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At random: "I propose to you a new arm of war, as formidable as it is economical. Submarine navigation, which has been sometimes attempted, but as all know without results, owing to want of suitable opportunities, is now a problematical thing no more." - Brutus de Villeroi in a letter to President Lincoln, 1862
Draft Marks
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oldsubs
Posted 2018-04-16 8:47 AM (#88136)


Historian

Posts: 118

Subject: Draft Marks

I posted this on the other board and am reposting here for your enjoyment.

OK, You are just reporting aboard a USS Seawolf (SSN 21). You need to supervise the painting of draft marks. Lets say the draft marks on the bow run up to 30 feet. (I don't know whether they actually do.) You are smarter than the average rock and "I don't need to lookup no f'in plans, I'm qualified!!!"

How far it is between the top of the numeral "29" and the bottom of the numeral "30"?

For extra credit: How tall it the numeral 30 to be painted?
Sewer Pipe Snipe
Posted 2018-04-16 9:09 AM (#88137 - in reply to #88136)
Master and Commander

Posts: 1343

Location: Albany, GA.
Subject: RE: Draft Marks

My training in these aspects of submarine knowledge is definitely lacking. I will borrow Mike's answer of six from Ron's board, and if it is correct, that would make to 30 six inches high. Of course I spent the majority of my time inside the sub, not on deck. 
oldsubs
Posted 2018-04-16 9:24 AM (#88138 - in reply to #88136)


Historian

Posts: 118

Subject: RE: Draft Marks

Mike on the other board was wrong too. Not six inches for the question and y'all don't get any extra credit.

Be Well
oldsubs
Runner485
Posted 2018-04-16 9:36 AM (#88139 - in reply to #88136)


Master and Commander

Posts: 2161

Location: Lower, slower Delaware
Subject: RE: Draft Marks

Based on my not knowing anything about painted numbers on a boat I will guess the distance from 29 to 30 is 12 inches. The numeral 30 is 2 inches tall.

Enginemen are cool!
oldsubs
Posted 2018-04-16 9:44 AM (#88140 - in reply to #88136)


Historian

Posts: 118

Subject: RE: Draft Marks

No
No

Some might be.
GaryKC
Posted 2018-04-16 10:39 AM (#88141 - in reply to #88136)


COMSUBBBS

Posts: 2710

Location: Kansas City Missouri
Subject: RE: Draft Marks





(Draft Tower - Stainless Steel - 4 ...jpg)



Attachments
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Attachments Draft Tower - Stainless Steel - 4 ...jpg (48KB - 35 downloads)
Ric
Posted 2018-04-16 12:54 PM (#88143 - in reply to #88136)


Plankowner

Posts: 7592

Location: Upper lefthand corner of the map.
Subject: RE: Draft Marks

The distance depends on the curvature of the hull at that point. The higher you move up the hull the more the hull curves to "flatten the distance" vs the actual hight of the mark horizontal above the water. I could give a number but it would probably be wrong since I do not know the hull curve at that point.

oldsubs
Posted 2018-04-16 3:09 PM (#88144 - in reply to #88136)


Historian

Posts: 118

Subject: RE: Draft Marks

Your concept is right. The number for a 34' diameter hull would be just over 9" for the space between 29 and 30. 9.5 inches for the height of the 30.
Ric
Posted 2018-04-16 3:20 PM (#88145 - in reply to #88144)


Plankowner

Posts: 7592

Location: Upper lefthand corner of the map.
Subject: RE: Draft Marks

BUT...... the diameter of the hull is NOT 34' at the bow section. If I remember correctly the hull is already tapering at that point. Marks were taken from keel to water line and up from there. Hull could maybe be 30' or less at the point the marks were painted.
geno
Posted 2018-04-16 4:24 PM (#88146 - in reply to #88136)
Senior Crew

Posts: 119

Subject: RE: Draft Marks

I believe the marks are 1 (one) nautical foot from keel to waterline. This is measured in a plane regardless of the curve of the hull. The standard naval marking is 8.5 inches in height. I was a torpedoman so don't laugh, please.
Ric
Posted 2018-04-16 5:50 PM (#88148 - in reply to #88146)


Plankowner

Posts: 7592

Location: Upper lefthand corner of the map.
Subject: RE: Draft Marks

Are your knuckles raw?
Bob T
Posted 2018-04-16 6:17 PM (#88149 - in reply to #88136)


Senior Crew

Posts: 231

Subject: RE: Draft Marks

I last stood topside watch on Balao class Sea Devil about 1964. I remember 6 inch high numbers with 6 inch spaces, but others above have said this was wrong.

Taking on fuel oil in FBT tanks? Boat rises. Fuel oil is displacing water; fuel oil less dense.
oldsubs
Posted 2018-04-16 6:28 PM (#88150 - in reply to #88149)


Historian

Posts: 118

Subject: RE: Draft Marks

Bob

You are correct about the draft marks on Balao Class. They were on vertical surfaces so did not have to be distorted by the projection to the vertical. Yours (and mine) were 6" marks, 6" apart. Thus from the bottom one mark to the bottom of the next one would be one foot.

Nautical feet are the same as US feet and English feet. 12 inches in length. Now nautical miles are not the same as terrestrial miles. Its things like these that get landlubbers all knotted up. Try explaining why speed at sea is not in knots/per hour.

Ric. The projection difference due to the reduced diameter at the location of the marks is less than 0.25 inches.

Taking on fuel made the draft lessen. Let that be a lesson to y'all.

G'night
oldsubs
#crookedcaneart
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