62 NOTES ON RIVETS AND SPACING OF RIVETS FOR OIL-TIGHT WORK. 
is essential. The same standard of workmanship does not exist throughout the 
yards of the world or in some cases even throughout the same vessel. It is obvious 
that there must be a common rule for all and, therefore, the required rivet spacing 
is designed to guarantee good results for average standards of workmanship. 
It was stated above that the rules for rivets and spacing of rivets for oil-tight 
work had been arrived at by a process of evolution, and it may not be out of place 
to refer briefly and in a very general way to some of the early bulk oil carriers and 
to some precedents in connection with conversion jobs on account of the large 
number of vessels which have been and will be converted to carry fuel oil. 
While there were probably some barges in existence prior to 1872, it was in 
that year that the first bulk oil-carrying steamer was built at Palmer’s, Newcastle 
on Tyne, England. Although this vessel was built especially for carrying oil in 
bulk, she had a double bottom, and the indications are that the rivet spacing was 
the same as in vogue at that time for water-tight work. Following this date, new 
bulk oil carriers were built from time to time, but perhaps for about three decades 
converted vessels contributed more or less to increasing the fleet. 
During this period the spacing of rivets, even for water-tight work, was in 
some respects greater than at present and vessels frequently leaked a little when 
new, but they were built of iron and the joints soon rusted up tight, thereby in- 
creasing the friction of the riveted joints and resulting in stronger and more 
durable vessels under existing conditions. This rusting-up process, however, 
would not take place in the case of new vessels built to carry crude or lubricating 
oils in bulk, and on that account some of the converted vessels were tighter than 
new tankers. It was during this period that the importance of the friction of the 
joint referred to above became more generally appreciated. 
Oxidation, however, takes place in tanks carrying gasoline, and this rusting-up 
process, undoubtedly, penetrates into the seams. On this account it might be 
beneficial to carry a cargo of this character on the first voyage or two as is some- 
times done. Tests have demonstrated that, while the friction of the joint has no 
effect on the ultimate strength, it has a safe factor above working stresses where 
workmanship is good. If there is the slightest slip, defective rivets will come to 
light; therefore, in oil-tight work intimate metal-to-metal contact is of the 
greatest importance for permanent oil tightness, especially where subject to alter- 
nating stresses set up by the working of the ship. 
Serious recurring damage, constant necessary repairs and resulting cost to 
underwriters during much of this part of the history of oil carrying in bulk were 
attributed to inadequate scantlings, improper distribution of material, insuffi- 
cient riveting, poor workmanship, long tanks, overloading and limited knowledge 
of manipulating large quantities of water ballast, especially in the case of excep- 
tionally long tanks. Investigation by Dr. James Montgomerie over a period of 
thirteen years prior to 1909 conclusively showed that recurring damage was more 
frequent where the tanks were over 30 feet long. 
The early tankers, both new and converted, had relatively less beam and 
were consequently easier in a seaway, yet the penetrating character of the oil 
