NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK. 83 
mum. In general, they are only permitted where a nonwater-tight member passes 
through water-tight or oil-tight members for the purpose of preventing leakage or where 
caulking is impossible, due to local conditions. However, oil stops are permitted where 
the material is 714 pounds nominal weight or less, in seams, laps, stapling, etc., where 
necessary to secure oil-tightness. 
Materials of stop waters used in United States naval construction are lamp wicking 
or canvas, saturated with a mixture of red and white lead, or the same material soaked in 
boiled linseed oil and then in red lead paint. Lamp wicking or canvas, saturated with a 
mixture of red lead and shellac, or soaked in a mixture of pine tar and shellac, is the 
standard oil stop for materials over 714 pounds; for materials 714 pounds and less the 
stop is made of ro-ounce canvas, soaked for half a day in clear shellac and then coated 
with a mixture of red lead and shellac, or 10-ounce canvas soaked in a mixture of pine 
tar and shellac. 
An oil-stop solution, manufactured by the Navy Yard, Mare Island, and used ex- 
tensively by that yard and other yards on the west coast, is made in accordance with the 
following formula :— 
Portland cement, pounds ................. I.455 
Lampblack, dry, pounds.................. - 2605 
Petroleunmspinit..callons sane seat eenel . 160 
Soyabeantoillicallonsweeesaaeee eerie .840 
itharger pounds yess eee ae eel kaa .00625 
Total volume, gallons..................... I 
Weight per gallon, pounds................ 9 
Approval has been given to use felt, dipped in a solution similar to the above, for 
stop waters and oil stops on scout cruisers Raleigh and Detroit. 
The CHAIRMAN -—Is there any further discussion? I will now call upon Mr. Frear, . 
the author of the paper, for any reply he may wish to make. 
Mr. Hueco P. Frear:—In submitting this paper the main object was to invite dis- 
cussion rather than to push innovations on the poor shipbuilder. The ground has been 
covered so thoroughly in the resulting discussion that I doubt if there is much to be 
called for in the nature of a reply beyond expressing my indebtedness to the gentlemen 
who have responded so generously with their valued contributions. 
Captain Robert Stocker’s contribution dealing exhaustively with the activities of 
the Bureau of Construction and Repair in connection with oil-tight work is of unusual 
interest and constitutes a most valuable supplement to the proceedings; the more so be- 
cause it is an authoritative statement of facts which could not be gathered as accurately 
and completely from any other source. In oil-tight work, butts fitted with single straps 
have rarely given continuous satisfaction and eventually reach a point where caulking 
becomes ineffective. These butts should preferably be lapped or, where greater strength 
is required, double strapped. 
The conclusion arrived at in regard to not painting faying surfaces of oil and water- 
tight work fully agree with the author’s views; indeed, it is believed that this practice is 
often carried too far in the specifications of some owners in the case of nonwater-tight 
work. Where seams are painted the material sometimes disintegrates and not only 
results in reduced friction of the joint but interferes with the natural rusting up process. 
