cracker39

I have two airboats that use the same .46 nitro engine and fuel tank which are both mounted on a piece of 1/4” ply for a quick swap from one boat to the other (4-5 minutes to change boats). I’m thinking of building a 3rd hull to use the same engine. This will be a hydro hull. I’ve noticed on another link that several different hydro hull airboats all have a water rudder rather than an air rudder. Is there a good reason for this? I know that my electric tri-hull performs better with a water rudder.

I'd like to invert the engine for better balance as I've seen in these hydros, but not sure how to reach the glow plug for starting. How do you do it? With a remote switch?

Are there any photos showing a bottom view of home-built hydros showing the hull shapes?

This is my basic design and a 1/3 scale model that I made from Dow blue foam just to see what it will look like.

ISIRC10

I think the reason most hydro hulls have water rudders is that the hull shape is most suited for carving through the water, not sliding on it. With air rudders, an airboat tends to slide in the turns (which is beneficial in some cases) and they are mostly found on flatbottom airboats which are not suited to carve throught the water, so they slide through the turns. Also, I find that water rudders give a sharper response, but that just might be a flaw in the construction of my air rudders [sm=red_smile.gif]

just my 2c

bayward

Borrow an idea from the heli guys.

[link=http://www.amainhobbies.com/product_info.php/products_id/14364/n/Revolution-Remote-Glow-Plug-Adapter]Remote Glow Adapter[/link]

Bob

cracker39

Thnx for the responses. I considered that sliding might be difficult with the inside of each sponson hull being straight up and down. I like the way my little electric tri-hull makes sharp turns with the water rudder.

That remote glow adapter is cheaper than I thought they'd be. I think for now, I may just keep the engine upright like it is. I'd have to modify the mounting platforms on my boats to put the throttle cable on the other side and that might make them too short. If it ain't broke, don't fix it.

stackeddeck

Talk to Selph Inflicted

he makes hydro airboats

http://www.rcairboats.net/page3.html

you could ask him and I'm sure he'd happily answer any questions.

you can send him a pm here.

( he's a great guy I'm about to buy the SI3 60 serious nitro airboat from him )

good luck

DJLaPalme

The above answers are correct. For precise control a water rudder is used. For scale airboats(sliding turns and running the hill) air rudders are used. For the type of use you want from your boat go with water rudders. All of the high speed hydro type boats(Selph-Inflicteds) that I have seen use the water rudder. Turning your engine upside down will cause you to have to be very carefull when starting so you don't flood the engine. Dennis

donahue_85

I have an Aquacraft Alligator Airboat, it has air rudders on it as it is a scale airboat. I have not owned this machine very long, but I have found that air rudders are by far harder to use. As I said, my boat is a scale model, so of course everything is just like an actual airboat. I am going to agree with everyone else on the water rudder, as your boat is a puller type hydroplane. I really don't think air rudders would do you much good on a puller, just my 2 cents.

BlackwaterPirate

Awesome! Thanks Bob! What a super idea...! xD

Brian