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Historian
Posts: 190
| 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?
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Master and Commander
Posts: 1796
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. |
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Historian
Posts: 190
| 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 |
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COMSUBBBS
Posts: 2672
Location: New Jersey | 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!
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Historian
Posts: 190
| Subject: RE: Draft Marks
No
No
Some might be. |
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COMSUBBBS
Posts: 3667
Location: Kansas City Missouri | Subject: RE: Draft Marks
 (Draft Tower - Stainless Steel - 4 ...jpg)
Attachments
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 Draft Tower - Stainless Steel - 4 ...jpg (48KB - 626 downloads)
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Plankowner
Posts: 9164
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.
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Historian
Posts: 190
| 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. |
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Plankowner
Posts: 9164
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. |
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Old Salt
Posts: 272
Location: Vista, Ca. | 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. |
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Plankowner
Posts: 9164
Location: Upper lefthand corner of the map. | Subject: RE: Draft Marks
Are your knuckles raw? |
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Senior Crew
Posts: 233
| 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. |
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Historian
Posts: 190
| 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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Draft Marks
