At the Bloomington Historical Society Museum in Bloomington, MN we have a diary written by John Pilgrim who was with Co. A, 117th Infantry, 30th Div. and was aboard the Northumberland from May 11 to 23, 1918. I recently had the opportunity to attempt to transcribe it. His brief diary entries which mention a collision are:

Monday May 20
Sub chasers come to meet us. Glad bunch of boys to get there all OK. Funny whistle the Chasers have. There was 17 of them. Some mine sweepers. We sure feel safe now. Nothing but goat to eat though. No good.

Tues May 21
Foggy as hell yet. Rough weather. Don’t like it worth a dog on. Went over 12 mines. Missed one 12 feet I saw this. Looked fearful. Saw some subs, but they did not shoot at us. The Chasers got him. Good old boat, but she is kinda rocky.

Wed May 22
Saw the Coast of Ireland. Nice sight. Looked all over the old coast. Was a welcome sight. One boat sunk by a tin fish. We was going to land at London but changed to Liverpool. At 12 o’clock we hit a sub Chaser and it sunk. We saved the crew, all but 8 men, but it surely was bad. But had we not hit that we would have hit one of the troop ships. Worse yulkey (likely?)

May 23
At 12:30 am moon we hit a small boat which goes between Ireland and England. Sunk it in 5 minutes. All the crew lost and some awful sight. The front of our boat knocked all to hell. May 23 Landed in Liverpool at 1:00 PM. Fine city. Looked around some. Loaded on train. Key wind at 3:00 o’clock PM for Dover. Road (rode) through England in the Coaches 8 men to a dooo. Fine Country.

This does not answer your question directly, but as a primary source it may be of interest.