Hydrofoils, Or: WTH Am I Doing Wrong??

[ThomJ]

Hi all, I'm having a little trouble getting a hydrofoil design of mine working. I've attached screenshots of the vessel in question. A little background on this boat: I never intended it have hydrofoils when I first started building it which is why it looks like some weird hydrofoil fishing boat. I'm having MANY problems getting this thing to work, I've spent probably about 8 hours just messing around with wing placement, wing angle, swapping out wings for control surfaces, changing propulsion methods, basically everything I can think of. At one point I did have a setup that kind of worked but it was so unstable it was a 50/50 chance that the boat just took off while trying to get it onto the hydrofoils. The biggest problem I was having was that once I was up on the forward foil (which is relatively easy) it...just keeps going up! The foil comes out of the water and the whole thing does a very graceful back-flip. Cool, but not really what I want. The rear of the ship however is almost impossible to get out of the water. So a question for the experts out there, is it possible for a ship of this design to even be converted to a hydrofoil or is there just too much surface area at the front of the ship for the wind to catch and flip it? I know the props are mounted below the CoM but they are on a pivot so I can trim them upwards to prevent the torque moment one would normally get from having them in that position.

https://steamcommunity.com/sharedfiles/filedetails/?id=2095497335
https://steamcommunity.com/sharedfiles/filedetails/?id=2095497365
https://steamcommunity.com/sharedfiles/filedetails/?id=2095497382
https://steamcommunity.com/sharedfiles/filedetails/?id=2095497415
https://steamcommunity.com/sharedfiles/filedetails/?id=2095497441
https://steamcommunity.com/sharedfiles/filedetails/?id=2095497468
https://steamcommunity.com/sharedfiles/filedetails/?id=2095497488

[Ra-Ra-Rasputin]

I believe the best method for this is uploading the boat. It's very hard if not impossible to determine how it behaves from images, or even video alone.

Hydrofoils are more complex than people give them credit for. Unlike in real life we don't have certain forces (such as ground effect, certain leverage physics) helping us, and basically the foil must take care of multiple issues, including roll balance, pitch balance, altitude adjustment and thrust (unless you're using airplane props or something).

[ThomJ]

Here it is! https://steamcommunity.com/sharedfiles/filedetails/?id=2095593551 It has an auto-clutch so you should be able to just start the engine and go.

[Goobs]

My first thought is that wings may not be the best choice, generally control surfaces and fins have quite a bit more more physics effect - Wings can't tell in stormworks if you're in water or not, so you're not going to get any effect from them until some rather extreme speeds for a boat. Plus, stormworks wings resist motion against the flat surface, they don't deflect or actually create lift.

[ThomJ]

Interesting, I haven't really seen other hydrofoils with wings so I was kind of wondering if there was a reason, I guess that's it. I just kind of figured "oh I need more lift and wings create lift" haha. I just replaced the wings with fin rudders and it does perform slightly better, the main problem now is the hull can get out of the water but as soon as it does the bow just dives right back in. That and there is pretty much zero roll stability, it's very hard to keep upright.

[Ra-Ra-Rasputin]

Here you go, your hydrofoils work now.

https://steamcommunity.com/sharedfiles/filedetails/?id=2095647473

You might need to tweak those engines a little, not only are they chewing through fuel, but they get just a little bit warm. I've also added some roll balance in there, but to make it good you need to make it compensate for turns too.

Anyway, it hits 85 knots now, which is pretty fun. I'd have fixed the roll issue and the engine overheating issue and tweaked the engines, but it's getting close to 4 am again, and i know if i do that, by the time i stop it's 6 am the next morning and you have an airplane that looks exactly like your boat, can transform into a mecha, and has a button that uppercuts the megalodon.

It's not like some of those haven't happened before when i've gotten a little bit too much into it.

[ThomJ]

Wow, and just like that it works like a dream! Thanks! Haha yeah I just kinda left the engines as they were so I could get as much power for testing as possible. On one iteration I was actually able to get them down to 11 RPS while doing 100 knots. Again, horribly unstable though.

[Shillelagh]

My hydrofoils work better as planes then as boats.