74 NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK. 
that perhaps the real way to make double-riveted laps is to close space the rivets on 
the caulking edge and wide space those on the rough edge. That would give the advan- 
tage of a double-riveted lap in bolting up and at the same time save a large number of 
rivets. 
Mr. Rospert W. Morre tu, Member:—I have not had a chance to study Mr. Frear’s 
paper, so I cannot discuss it fully, but two or three things occurred to me as I read it over. 
With respect to the double bars against the T bars, we are inclined to favor the 
double angles, for the reason that Mr. Norton mentioned, but we do think there is some 
advantage in the T bar, due to the fact that there is somewhat of a vacant space between 
the heels of the double bars in which the oil or water or rust will collect, and we have 
known cases of contamination of cargo due to dirty oil which lodged in those spaces, 
entering the tanks after they were loaded. It is true that there is a certain amount of 
oil which collects in those spaces. That is one reason why we favor the use of counter- 
sunk heads in the bounding bars on the rough side of the bulkhead. 
With reference to the caulking of the rivets, we are strongly in favor of driving 
rivets that do not need to be caulked, and we believe that if it is known by the workmen 
that the rivets are going to be caulked, that they will not be so careful about them as 
they would if made to understand that the rivet is to be a good, solid job without caulking. 
We favor, however, the caulking of the rivets in both flanges of the bounding angles 
and both sides of the bulkheads, because it is difficult to get at these places after the 
bulkheads are in the ship and the brackets are in place, and therefore it has seemed 
preferable to caulk them while we have an opportunity to get at them. 
But in these matters it is very difficult to make any rules, because conditions vary 
with the different yards, with the class of workmen available therein, and we must be 
governed by the conditions which exist on the spot. In the same way it is rather difficult 
to make any rules applying to common, straight-away work, as opposed to places where 
it is difficult to get at them, such as corner staples, and a general rule which might apply 
to conditions in one place would not apply in another place. 
In regard to the center-line bulkheads, it is true in a general way that we can carry 
the same cargo on both sides of the center line, so it is not usually necessary to have 
the absolute tightness there that we have in the transverse bulkheads. That is the 
general condition, but it frequently occurs that we carry fuel oil in half a tank on one 
side of the center line and cargo on the other side, in cases where we have to take a large 
quantity of fuel to provide for the return voyage. It has become necessary to do that 
in several cases, and under such circumstances it is essential that the center-line bulkhead 
be absolutely oil-tight. For that reason we would hesitate considerably in making a 
single-riveted seam in the center-line bulkhead. 
I am inclined to believe that a revision of the rules might be towards a diminution 
of the number of rivets required, but that, again, is a matter which requires very careful 
thought, and we may not apply it to all situations occurring in the ship. It might 
apply to certain straight-away conditions, but might have to be modified to meet the 
particular conditions that would be met in the various members. 
Mr. J. W. Stewart, Member:—I have read with interest the paper written by 
Mr. Hugo P. Frear, which opens up an important subject to shipbuilders today, and I 
compliment him on his methods of treating a peculiarly difficult subject. 
