im new to boats and am going to build my own from scratch and was wondering what props will give a giant roost i will be using a kv11,400 motor on 11.1 lipo

Firstly, A boat setup to have a giant roost will not be as quick as it could be if it were set up normally. What prop to use depends on a lot of different factors. What hull, how big, what motor etc etc.
From the looks of it you plan on using an 11400Kv motor. This Kv rating is waaaay to high (as in prop RPM over 100K per min). You will be better of with something around the 4000Kv mark.
People will need a lot more info on your plans to give the best advice.

The best hull for a rooster tail is a large mono hull with a large prop. I'd recommend a 32"+ hull running 4s+.

If you plan to use only 3s you will be looking at a hull around 28" or so. Take a look at the thread stickied at the top of the forum. A 3s motor should be around 2500-3500kv. To spin a large prop your kv should be in the mid to low range.

Look at the Feigao 540 XL or L size motors and ESC's rated for 120A or greater.

Ryan

Something to remember

BIG Roostertail = Slippage and slow boat
small Roostertail = Low slipage and FAST BOAT

Grim

thanks for the help i am going to be making a 20 inch long by 4inch wide main hull with sponsens just big enough to keep it prop down. with cf conecting rods and a propshaft that's ajustable up and down and. blades on the sponsens for steering i will be using an tekin r1 pro esc with lrp 3.0 turn bl motor i know they arnt ment to be in a boat but i have a speciale (spelling) water cooling kit from a pc. I am going to be building it out of cf i used to make custom cf rc car and truck bodies out of cf so if you guy's need more info then just let me know so. thanks agian for the help please keep it coming this will be my first custom boat so any tips or thoughts are welcome.

If this is the motor you are referring to, scrap the idea immediately.

http://www.rcmart.com/catalog/50721-...?cPath=293_946

We just told you a 11 000+ Kv motor will NOT work. Do things right and follow our advice.

Ryan

so would a 6xl motor work on 3s lipo

I thought that a surface drive setup with a large prop produced a pretty good roost. My SV with a 45-48mm 2 blade prop has a pretty good tail. Way more than the stock 3 blade prop. Sub surf drives won't put any water in the air.

Yes it would.

Make certain you use a surface driven setup as Scott mentioned.

Ryan

well i will be using a custom built prop mount that i will use a servo to adjuste the angle of the propup and down like this / \ just not that extreme only enough to get the prop in the water to go fast or surfase peircing to make a huge roost i know that i cant have both roost and speed at the same time hence the prop mount another thing i am wondering is will it damage the prop to sufase peirce and then go fully sumerged pending on what prop you guys recommend

i would be worried about the load on and of the prop in breaking the surface then submerging it
i will be corrected if this is wrong but i am only a adept boater

Submerged drive is for slow scale use. Fast boats use Surface Piercing Setups. If you have a large rooster tail it does not mean its slow.

These boats have a decent tail and go 60mph.

Ryan

im trying to get a roost about twice the size of the boat on the far side thanx for all the help too

That boat is throwing water 15-20 feet in to the air and you want double?

Let's be realistic here, you are talking about a boat that is exactly 1/2 the size of these at 20". The motor you wanted to use makes 1/4 of the power these do. The boats in the picture costs about $2000.

Ryan

o i cant really tell what size the boat or tail it im looking for about a 10 to 12 foot roost is that more relistic or am i still aming to hi

For what you want a 30" hull with the correct motor system would be pretty close to achieving that.

Ryan

I admire you for just saying I just want it to look good. . Should be pretty fast as well.