How do you build a good boat?

[scsr]

I have been trying to do this for a while, but I haven't yet figured out how to do this. I can make an okay boat, but that's probably not going to be enough. The game doesn't exactly teach you how to make a good boat. It just gives you a blueprint that is basically a slab with a motor and hopes you figure out the rest...

[Bwixie]

for optimal speed you want anything in or below the water surface to have a wedge shape front and back, unlike land or air vehicles which only need a front wedge.

[scsr]

Yeah, the current boat has that, but I think the speed increase was about 4-7 km/h, so not much

[Gammaboy45]

A good keel or weight on the bottom can help stabilize it and prevent it from spinning over if you put too much power into it. If you don't have fins or mass below, making the boat wider can also help with tipping. Place your bouyant blocks as far out from each other as plausible: your boat is only ever really as wide as its supporting base. Your center of mass must be between your buoys or below them at all times.

Make sure you put all your engines far enough down so that at full speed they don't leave the water. You can do steering any number of ways, the expected way is usually to put a paddle on the back with a steering hinge-- however, I prefer to use the 1 PC motor on the front facing sideways. It's faster and lets you turn at a standstill.

Bear in mind that boats are affected by their fluid dynamics. You can effectively build an aquatic submarine plane with motors for propulsion, and similar logic would apply. Parts like fins will resist motion and help stabilize, and a pointed bow and keel will cut through water a bit more efficiently.

[Paulie]

I just made an RHIB for pioneers and did the whole water section with just that.

[blackphoenixx]

Spread out your buyoancy blocks and keep center of mass below center of buyoancy. The wider and/or deeper you are the more stable your boat is.

Make sure your center of thrust is level with center of mass or slightly below it (being too far below will make your nose lift out of the water or even backflip you, being above it will push your nose into the water, slowing you down or making you sink in the worst case).

Don't be afraid to add some weight blocks to fine tune your balance. You'll want a little weight for stability anyway, especially if you're dealing with wind & waves.

That should cover the basics to build something workable.

For steering you can just put your engines on either side of the ship and use OR gates to trigger one side to go backward and the other forward when you press A & D.
You'll still want some kind of underwater tailfin or paddle/rudder for directional stability though.