Boat Thread

[AustralianFries]

Yeah yeah, I know. Inb4 Kerbal Space Program. But still, I've seen some pretty cool boats out there. After watching a few boat videos of crafts that can go 200m/s+, I though "Hey, this will be easy. I can beat 200m/s in no time!" (By the way, in the year or so I've been playing, I've never even attempted to create a boat.) Well, easier said than done. I managed to get a wopping 5m/s out of my boat. I don't know how some of you guys do it.

Post pictures of boats you built! What's the highest speed you've achieved? Any tips for the rookies out there? I've seen some amazing interplanetary boats fly to Eve and back. I've also seen some Spaceplanes that can land in water without spontaneously disappearing into the nothingness. Any of those out there?

Here's my awesome boat. Since spoilers are disabled and I love you all, I've taken the time to resize/crop my pictures.

[Dweeb of Kerbin]

This is my first boat which I landed on another planet (Laythe)

In transit:

It's hard to say whats it ultimate top speed is, but the safest it can do safely is mid ~20m/s.

[nerdboy64]

Funny you should post this, as I've actually been working on boats quite a lot recently. This is my best design so far. With a top speed of about 30 m/s, it's about as fast as a real-life speedboat. It's pretty maneuverable as well, but if you turn too sharply you'll spin out. Those rockets and plane wheels on the sides are just to get it off the runway and into the water.

EDIT: Here's a video!

Edited May 22, 2013 by nerdboy64

[AustralianFries]

-snip-

Oh wow that's a cool looking one. I like it. And yeah, the most tedious part of boats seems to be getting it into the water without damaging it before getting there in a hurry.

[Darren9]

I've had some fun with boats. My favourites are the personal hydrofoil and amphibious rover. Try and keep it so no parts break the surface when you move to go fast, they're either in the water or above it - then they don't break up.

[erGo]

Here's hydrofoil I made from stock parts to rescue kerbals from a pod that landed on water near KSC. I can't remember the top velocity, but I think it was around 50m/s. It has 2 jet engines for acceleration and 1 jet engine for deacceleration since the slope to water near KSC is so steep that if you let this craft to roll freely to water it'll gain too much speed and crash when hitting the water.

[Piloter]

I came to boats without reading any of the threads or looking at any videos so I could do it with a clean mental slate. After a few false starts I wound up with an all-terrain Kerbal rescue craft, the inventively-named KATV-One. It looks pretty stupid.

With landing gear up and engines off it'll wheel-cruise at ~15.5 m/sec. Having wheel reverse makes it a LOT easier to go into the water...I didn't realize HyperEdit could do that so my entire design has been built to roll off the runway and down the terrain to get launched.

No matter if it's self-powered or jet-powered, the foils have to rise up. The long nose will scrape the ground if it bounces off the runway at any less than ~40 m/sec. Going faster, the suspension rebound tends to dig the nose in. So with foils at maximum trim, the KATV swans down the runway and approaches the water no faster than 7-8 m/sec. I try to keep it to five.

Once in the water the KATV fires up the jet engines again and leisurely cruises away from shore far enough to get into deep water for the foils, then slows to a crawl to avoid embarrassing accidents. 25% throttle yields an alarmingly slow ~8m/sec until the foils come down. All at once, thanks to clever hotkeys for the servos. Binding both hinges to the same group preserves their relative orientation, meaning that the hinges move equal amounts in opposite directions.

With the foils fully deployed, the extensions come into play. Because I haven't yet added an angle-of-attack rotational adjustment (ugh!), the center of lift goes below the center of mass and acts to pull the craft downward. By giving more up, it can handle more speed. The nose also extends separately...this is one of those things that used to help in high-speed flight and speedboating, then became somewhat useless but it looks cool as heck so I kept it in. LARGE control surfaces help here, as does SAS, but the speed limiting factor is when the leading edge touches the surface. The rover wheels really slow the boat down with mass and drag and shifting the CoM around, a prior version (Failboat Five) would reliably cruise at 150+ m/sec but this only manages ~110.

Same 25% throttle and now it'll do ~50m/sec. Hydrofoils....they really, really work. As long as the subsurface bits don't MOVE, because then SAS will just explode your boat the first time it wiggles them. The rescue system extends....stacked ladders. Unfortunately the pWing plugin is really a pain in the ass here, the trailing edge is not 'solid' to the point where you can attach things to it, and ladders just vanish if you try.

Fun fact...between Kerbal collision issues and pWing solidity issues the rescue system doesn't actually work in the water. They can climb the ladders but never sit in the seats...the boat can never remain completely still, so when the Kerbals hit a moving surface (like the pWing) they just go catatonic, little arms wide, and can't move until they roll off from acceleration. On LAND it works great! I'm going to see if I can't improvise something with the boat parts walk-through struts and maybe put the seats on the actual winglets instead. Anyway, it'll do ~110 m/sec under jet power before the front wheels dig in and destroy the boat. I lock the gimbals and enable SAS because otherwise there's a nasty steering wobble issue that I can't track down. At certain speeds I start getting a pitch-bob issue which the nose extension seems to help with.

It's easy to get out of the water, too. Bring it near shore and down to ~5-10 m/sec, pull the foils all the way up, and apply careful power. As long as the slope is shallow enough for the front overhang, it'll climb right out.

Did I mention it flies? Raise the foils and hit full power. The end of the runway (~150m/sec) will bounce the nose up and it'll start climbing. The foil angle IS the nose trim, bringing them down again mostly level will lower the CoL until the pitch is neutral. You can also dial in some negative trim this way. Extending the nose and winglets will result in a little more roll stability although it doesn't need much attention as-is...once airborne there's a LOT of lift. It'll fly stable or unstable as you want, with or without thrust vectoring. (The original engines were the stock basic jet engines and they worked fine too.)

100% throttle, cruise speed in level flight is ~180m/sec. It's not the world's fastest, best-looking, most efficient, technically impressive, or best-manuevering plane but there's good control authority (especially yaw) and it still flies fine without the could-loop-a-brick vectoring from the B9 F119s. It also has an absolutely beautiful landing approach...you can chop the engines and it's still got lift at around 40 m/sec. There may be enough lift to slow it down enough to land it at ~10m/sec on the water which I think is about the threshold for things ripping off, but so far I don't have the deft touch to make that happen. (Maybe if Squad adds joystick support.) So for now it has to land on kerra firma before transitioning to a boat again, but....it flies, it drives, and it floats, and it'll do 100m/sec+ in all these things.* I call that pretty good for a clean-slate challenge.

*if you call high-speed taxiing 'driving', although you won't take off for another 50+ m/sec.

Parts used:

B9 Pack

Aviation Lights (not really essential)

Procedural Wings

D@mned Robotics for .20

Mechjeb 2

Some semi-cheaty SAS unit (1 ton, 370 torque) I can't remember where it came from.

Boat parts pack (for the rudders only, they're never in the water anyway but they provide good torque.)

[SourBacon]

Here's a boat, er, ship rather, that I just finished. It's approximately 910 parts, and needless to say, I put it in the water with hyperedit and then I can't physically do anything else. It has a working turret and missiles that would function properly (they did in tests) if not for the incredible lag. Enjoy, the KSS Douglas Mk2:

[Bishop149]

I recently made a boat, it does a mighty 25 m/s!!

Having had a look here it seems the key is to minimise the amount of stuff in the water, just a few wing parts poking in it seems. I might have another go and see if I can break 50 m/s

Sorry for dark image!

[Kerbonautical]

I made some boats a while back. The trick to getting high speeds is using the big silver air intakes on the underside as you can see in my shot here

I was towing another Kerbal along for the ride on a little platform using KAS like a Kerbal Wakeboarder and still managed to get well over 100m/s as you can probably see by the water effects but unfortunately I disabled the interface to get better shots, you can always copy the design and see for yourself though!. I doubt it's wise to turn at those speeds though.

PS. The air intakes AND girders are important to getting the high speeds. The air intakes are very buoyant so they push the vessel well clear of the water, then the girders have incredibly high crash tolerance (as do the intakes)

so you can essentially crash your way across the surface at ludicrous speeds while never having to worry about tearing your boat apart. And yes, you can get high enough speed to make a working seaplane this way too. It was Danny2462 who originally found the exploit.

Edited May 13, 2014 by Kerbonautical

[Kasuha]

Crash tolerance of girders and intakes is only used when landing/falling into the water. When you're just going through it horizontally and no part is gaining contact with water, you can go way over parts' crash tolerance. But pull it a bit out of the water and put it back at that speed and it explodes.

Here's my amphibian seaplane:

Javascript is disabled. View full album

[troyn123]

I've tried a couple times... Using the rotating parts in the Infernal Robotics package, I tried making a paddle-wheel... It topped out at around 2 m/s. :-|

http://i.imgur.com/PY6a4xL.png

My catamaran worked pretty well, once I added a tiltable hinge to change the pitch of the engine (to keep it from nose-diving). Still only tops out around 23 m/s, on land or in the water though:

http://i.imgur.com/ztA8L5Y.png

http://i.imgur.com/YqX2SF5.png

My first attempt at a kethane mining submarine was a huge failure, it sank like a rock:

http://i.imgur.com/5gYMEDh.png

But the second attempt actually works!

http://i.imgur.com/eUNhQrr.png

I've seen a handful of designs that use backwards facing air intakes on the bottom, they have a high crash tolerance (80 m/s I think) and seem to be buoyant. That keeps it from blowing up as it slightly bounces in and out of the water...

[gchristopher]

This hydrofoil topped out at 145 m/s while carrying a rover as cargo. It was dropped off by a VTOL for an amphibious challenge.

Here's all I know, stolen from other, better, boats:

- only have low drag aerodynamic parts underwater, the bounding boxes determine buoyancy.

- don't have any part come into new contact with the water while running (I use physics-ignoring small hardpoints for the risers)

I had to fiddle with thrust, CoM, and angle of small control surfaces under the water before it'd stay level at speed. It doesn't corner well. It flies very poorly. Nosing up even slightly will launch 2000m in the air to its death.

200 m/s should be very doable with a little more thrust/drag.

Javascript is disabled. View full album

[sal_vager]

Good thread, very "exchangy" though, so I'll float this one over to the Exchange

[Mareczex333]

An old carrier. I was using welding part mod (for cpu performance reason)

Javascript is disabled. View full album

[Bishop149]

Inspired by and gaining tips from this thread I had a go at making some hydrofoils last night, with some success.

Pics below but first some things I learned:

- It is very important that the crafts CoM remain stable as fuel tanks empty, at high speeds even a small shift in inclination due to CoM changes can become catastrophic. To do this, pick a fuel tank as the core, then add additional fuel tanks / engines / cockpits etc in such a way that the CoM does not really move from the position it was in when your craft was the just the core tank alone. Set up your fuel lines so that tanks drain towards the middle with the core tank draining last. Once you have a stable core add length and the hydrofoils 100% symmetrically at either end.

- With any lifting surfaces you use make sure they are symmetric but inverted at either end. . . if they all point the same way you'll start generating a decent amount of lift which can mess up stability. Basically you want the have the lift /downforce from wings at either end cancelling each other out

- Following the above principle its then not a bad idea to put a few canards at the extremes of either end to help keep the craft stable. . . I dunno if its strictly needed but I disabled the yaw and roll controls for the canards to be safe. . . having them only control pitch.

-Large wings with just a couple of radial intakes (like those in designs below) make the best hydrofoils. . . over do the intakes and it might be a bit too buoyant, the craft will bounce around like a mad thing when it hits the water from chutes and at speed might lift up enough that you have things breaking the surface repeatedly and snapping off

- If your dropping the craft by parachute (as I was) then the flatter it hits the water the better.

- If you're going for speed use turbo jets, if you don't mind sacrificing about 20-50 m/s for a vastly longer range / higher fuel efficiency use standard jet engines. I personally began to favor the latter.

Ok some pics of ships that worked (or not), mostly designed to be Kethane tankers for shipping around Laythe.

This was about my first attempt, it was small worked very well top speed of about 145 m/s which it could maintain until the tanks ran dry with no dramas. . . . the tanks ran dry pretty quick however.

I then tried to make a much larger, longer range craft and this one was a failure, it was over-complicated and as a result unbalanced. . . also had WAY too many intakes on the hydrofoils and was over buoyant.

This was a back to basics approach going for pure speed. . . no Kethane transport, just Jeb! Topped out at 167 m/s

Following the high speed success of the above, this one is basically a larger version modified for Kethane transport, and despite it's much larger size it actually beat Jeb's speed record pretty quickly getting to 176 m/s . . . decided to cruise at 130 m/s however for safety. The map below shows how far it got after burning 1/3 of its fuel. I'm gonna continue going tonight and see how far it will get. I'm confident it will cross the ummm Kerbindian Ocean to the sub-continent on the other side and maybe get a fair way of the way back to KSP as well. Very successful test all in all!

[gchristopher]

Sped Boat Mark I. All stock.

Tops out around 320 m/s. Not useful for actually going anywhere. All the relevant design features are in the screenshot.

Edited May 15, 2014 by gchristopher

[kola2DONO]

One of my favorite crafts i've ever made :

Lands, takesoff, crashlands and drives on water perfectly, it also flies!

[Megalodon 720]

Ekranoplan here! That actually works! Reaching a whopping 157.5m/s.