Shouldn´t a seaplane tender be build with those CV rules in mind that define hangar space?
I agree.
And here they are:
"Design the ship as you normally would. Put in as much
'miscellaneous weight' as you can - that will usually
determine how big an airgroup your CV can carry. Now,
get out your pocket calculator. You'll make two pretty simple
calculations, each of which gives a possible airgroup limit.
1) Take the square root of miscellaneous weight; e.g., if
miscellaneous weight is 10,000 tons, the weight-based limit
for your carrier is 100 aircraft. (In addition, allow at
least 25 tons per aircraft, i.e., if miscellaneous weight
is just 100 tons, your ship can carry 4 planes, not 10.)
2) Multiply length x beam (both waterline) and divide by 750;
e.g., if your CV is 900 ft x 100 ft, the space limit is 120
aircraft.
For the metric gang, divide by 70 instead; if your CV is
280 metres x 30 metres, the size limit is also 120 aircraft.
Use waterline dimensions (if available), NOT flight deck
dimensions; they can vary a lot more, and we want a
consistant rule.
Your carrier's airgroup is whichever number is LOWER.
So in the example above, your CV has an airgroup of 100
aircraft. (That is for WW II or earlier planes. For postwar
CVs with jets, I'd estimate about 2/3 of the airgroup
calculated by this method.) Usually, the weight rule gives
a lower number of planes and thus sets the limit; the size
limit will usually apply to CVEs converted from merchant
ships with a great deal of miscellaneous weight."
So taking the 1924 Seaplane Carrier as an example, she reserves 250 tons displacement for aircraft and aviation facilities, allowing 10 aircraft by that measure.
Now for hangar space, multiply length and beam, and divide by 70. 120 x 15.6 = 1,872.
1,872 / 70 = 26.7.
So by both measures, she can handle 10 aircraft.