88 SUNKLANDS OF PORT PHILLIP BAY AND BASS STRAIT 
It is high water, full and change at the undernaentioned places in Port 
Phillip as follows : 
h. m. 
ft. 
in. 
ft. 
in. 
Entrance to Port Phillip 
at 
XI 37 
approx, spring 
rise 
7 
0 
neap 
rise 
5 
6 
Queenscliff 
2 0 
fy 
yy 
yy 
3 
0 
yy 
yy 
2 
0 
Dromana Bay 
>> 
2 19 
yy 
yy 
yy 
3 
0 
yy 
yy 
2 
6 
Snapper Point 
>> 
2 14 
yy 
yy 
yy 
2 
8 
yy 
yy 
2 
0 
Point Henry, Geelong 
2 39 
yy 
yy 
yy 
3 
0 
yy 
yy 
2 
6 
Williamstown Hobson Bay 
>> 
2 53 
yy 
yy 
yy 
2 
3 
Queen’s Wharf, Melbourne 
>> 
2 48 
yy 
yy 
yy 
2 
8 
yy 
yy 
2 
2 
The tidal streams in the entrance depend on the relative levels inside and 
outside the port; the greatest difference in levels occurs at about the time of 
high and low water in the entrance, and the stream therefore runs at its 
strongest, 5 to 8 knots, at these times; slack water occurs at about 3 hours 
before and after high water in the entrance when there is no difference in levels, 
and the stream runs in from about 3 hours before till 3 hours after high water, 
out at all other times ; as the levels depend partly on winds, the times of slack 
water and the velocity of the stream are also affected by wind; the freshets 
may also affect the stream. 
On an average it is high water at Port Phillip heads about 3J hours before 
that at Williamstown, but owing to weather causes, this interval may vary 
from 3 to 4 hours. As the tidal streams in the fairway run for about 3 hours 
after the time of high and low water by the shore at Point Lonsdale, it will, 
therefore, be approximately slack water flood at the Heads when it is high water 
at Williamstown. 
The direction of the winds (Aust. Pilot, 1926) at the head of 
Port Phillip is as follows: 
No. of days a year 
N 59 
N.E 30 
E 48 
S.E 54 
S 64 
S.W 38 
W 17 
N.W 52 
Calm 3 
It is evident that the southerly wind is the prevalent wind but 
that northerlies are scarcely less prevalent. 
The velocity of the tidal streams is practically the same from 
top to bottom. The rate of the out-going stream through the 
West and South Channels is from 2 to 3 knots, and in the Inner 
Basin knots. A velocity of half a knot is sufficient to drive 
sand along the bottom, 1 knot fine gravel, and 3^ knots stones 
inches in diameter (Marmer, 1926). Nevertheless, although 
the scouring effect of the streams in the tideways is seemingly 
sufficient, it does not prevent the depositing of mud along them. 
Holes occur on the floor of the fairway at The Heads, and at 
