Could you board a ship climbing a ladder?

Answer 1

Yes. If you mean "when normal stuff is going on," then today we prefer to use big ramps called gangways because it is safer. If it is a great distance, then today we use helicopters.

If you mean boarding in war, then in olden times when their were tall warship with sails, people would come up alongside the enemy ship and connect the ships together by throwing big chains with sharp hooks, to catch on the top deck edges of the enemy ship so that it couldn't escape. The top deck edges of a ship, which rise up to make a sort of railing, are called gunnels. The big chains with hooks were called grappling irons.

Once the ships are connected, then the attackers would lean out sideways with big wide ladders called scaling ladders, and these had hooks on the end pointed towards the enemy ship, to help make sure that they would not slip off.

Today, if you want to get on board a ship to take it over, you must use a small, fast motorboat with an engine designed to be quiet. You must then get onto the ship, and try to choose a time and a path so that people will not see you until you are ready. Often, the attackers do use ladders, or they throw ropes with climbing hooks, or fire the ropes and climbing hooks from special guns. Rich countries sometimes give naval commandos ship-climbing clamps with electromagnets, to strap to their arms and legs.

The very fastest way is to use a helicopter with ropes attached which hang down from the bottom. The helicopter hovers directly over the enemy ship, and then the soldiers grab the ropes and slide from the helicopter straight down the rope onto the enemy ship. For this, they just use gloves to grab the rope, with no extra ropes to protect them. This method is unbelievably fast, but it is noisy, dangerous, and takes lots of practice. You only use it if you have no choice, such as when their are terrorists who would kill hostages or use a bomb if you were too slow.