Submarines.

[Des Taff Jenkins]

Hi Ivan.
The Dutch gave us Taffrail, perhaps they gave us sugar cubes from your cargo.
Des

[Colin Duncan]

Your question asks if submarines attacked on the surface. I am not an ex-submariner, rather ex-MN. However, I have recently been reading material on the battle of the Atlantic. I am particularly interested in what life was like for our Merchant Seafaring compatriots of those days. One of the things I discovered was that submarines often attacked on the surface. It became a favoured U-Boat ploy to creep into the middle of a convoy on the surface at night. The low profile of the sub, sometimes only with the conning tower above the water, made it a hard thing to spot. Once inside the convoy they could reek havoc.

We should not forget that there were about 30,000 Merchant seafarers of all nationalities who lost their lives in the Battle of the Atlantic. The prime target of Doenitz's U-Boots were merchant ships in what he called the 'tonnage war'. i.e. sink a larger tonnage of ships than could be built. He nearly succeeded!

[Keith at Tregenna]

While U-boats were faster on the surface than submerged, the opposite is generally true of modern submarines. The most common U-boat attack during the early years of the war was conducted on the surface and at night.

One U-boat would shadow a convoy and summon others by radio, and then the group would attack, generally on the surface at night. These tactics succeeded until radar came to the aid of the escorts and until convoys could be given continuous sea and air escort all the way across the Atlantic in both directions.

https://www.britannica.com/technology/U-boat