Hi everyone ive started a new hull it measures at 27" x 16" approx , not to sure what size engine to use ? and once we have sorted that out , is there any specific measurements for where it should be positioned

thanks johnny

The engine placement depends on alot of things. As far as I understand, you want it near the blance point, But your overall COG should be about 25%-40% from the transom.
Another thing I learned, is that there is alot of trial and error, so if you can make your engine mount adjustable, thats would be ideal.

Post some pics with progress!!

What hull style is it? Flat? Slight V? Hydro?
Can we see a pic of the hull?

A boat with that width will be very stable. My boats are 26-28" x 12-13", and I run ball bearing .46's with no problems.

Without seeing what you have, I'm gonna say that your looking at using a .46 or .61.

Keep us updated. [8D]

just tryed to upload some pics , there was something wrong will try again

[img][/img][img][/img][img][/img]

I agree with Chris about the 46 , but think that a 61 might be too much engine ( this of course depends on WHAT you made the hull out of and how much it weighs ) ....

And since everyone else asked .... what the heck ... I will too ...

Got any pics ?????

[img][/img][img][/img][img][/img]




Ok this is how far i have got , it is plastic and each compartment will be air and water tight , a bit more work to do before i put the top on

Nice work! [8D]

It looks like its gonna turn out to be pretty light. I'm gonna suggest using a .46 on your boat. If you use a 3 1/2 to 5 lbs per 1 hp ratio, you'll get good performance and response from your machine.

Keep up the good work and keep us posted on your progress~ [8D][8D][8D]

I was thinking of making an engine mount like this , so that it would be easy to adjust and set to the perfect angle

Thats a good idea!

Keep us posted. [8D]

I like your adjustable stand idea. You might want to add an adjustable brace to the back of the mount to keep it from flopping forward or back if those pivot points get loose.

100% with you on that jasperrc, I will not for one second trust just the 2 pivit screws to hold the engine in place. It is very important that your engine mount can be lock down tight. I will say that you are on to something with the adjustable engine stand, throw in a 1/4 scale servo, a couple of cams, and a 3rd channel radio, then you would have a boat that would have a good take off, top end and one that would be hard to get stuck.
I'm not sure on your plans of connecting the stand to the hull, I recommend haveing as much as possible of the engine stand legs tied into the hull. On all of my boats the engine stand is connected from the transom all of the way to the grass rake. Just keep in mind that the engines may be small, but once they are loose, they are some mean sons a guns.

I am 100% with you guys aswell , the plan was just to show the type of thing im thinking about it needs to be made safe

i was thinking of a motor like this , what do you think ?

Engine would work ... but by all means ... do NOT count on the manufacturer specs for deciding a prop ... I currently have TWO airboats with buggy engines ... ( one TORQ and one M-16 ) and BOTH run different props , and BOTH do NOT come close to what you would think they SHOULD run for props . ( FTR - the M-16 was brand new and the TORQ was also LIKE new .. didn't even get it broken in , when I pulled it out to put in a big bore in one of my buggies )
I also used the original motor mounts ( buggy mount ) since it made it a LOT easier with the pull starter shrouding in the way if you tried mounting the conventional way )
And glad someone else piped in about the pivot thingy ...
The idea is good , but , I would try more with TWO points .... one being a stationary pivot and the other being an adjustable pivot , which , would also give a fellow ( or gal ) the same advantage . Look at the next symbols and then think


. )



Got it ?

Ok i think i wont get the buggy engine [] i will stick with an aero engine 46 / 48 size , ive looked and looked plenty to choose from but what make should i go for ????? HELP!!!!!!!!!!!!!! [:@]

Most all of the aero engines work well on the airboats, the main thing is to get the engine needles set. The aero engines are designed to be reliable, where the buggy and other engines are designed for high rpm's and higher horse power. If your planning to set it up as a pusher, look for the engines with the larger cooling fins and the BB engines have a better life span, with running under harder loads.
[link=http://cajungatorairboats.com/v-web/bulletin/bb/viewforum.php?f=9&sid=b64cef672fb7c53814c77fd9d679 3689]R/C Tips[/link] check out the carb 101, it is a very good way to set your needles.

I'm a big OS fan myself. [8D][8D] I would go with a ball bearring motor no matter if I was going to use a pusher or puller. The only down side to OS is the price, but to me and my experience....the extra money is WELL worth the reliability and dependability.

If your looking for a economically priced motor...go with the Super Tigre.

Although the OS46AX puts out 1.65 hp compared to the Super Tigre 61 that puts out 1.75 hp.

Don't let the price of the super tiger engines fool you. Their engines are rated by BHP which is the power that it takes to stop the engine. I have ran a number of different engines, and so for IMO the EVO's and the ST have been the most reliable.
Ex: the ST G45 Power Output: 1.45 BHP at 16,000 RPM, this engine is super reliable, and will push the boat your showing like a bat out of hell.
The Evolution .46NT is guaranteed to start quickly and easily, this is another good engine and will hang in there with the best of them.
As I said before most all of the aero engines work well on airboats, the key things are have the correct prop for the boat, and have the carb set.
A good tip for any engine is take it down and clean up any casting marks, and check to make sure the the top of the cylinder is smooth and flat.

Oh , what the hell ... want a REALLY REALLY ( did I say REALLY yet ? LOL )good engine , get a JETT .. ( thats the name of the company - not style )

Being out of work for the last month means i dont have much to spend im looking for something around £40 / £45 []

was thinking of an AP 15 , CC2.26 R.P.M. 3000 / 17000 what would that be like ?

[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXFV69&P=0]Same Price Bigger engine[/link]. This engine will work well on your boat.

THANKS MAN , that is a real nice engine

After taking a good look at loads of engines i found this Thunder Tiger 42GP 6.90 cc and its in my budget do you think it will be ok ?