Servos

[steve palgreene]

What are the main servos they use in the gas sport hydro boats I was told they have to be over 200 oz .

 

[Scott Tonak]

I like to be at least 200 oz. on the rudder and use a trusty old Hitec 645 mg on the throttle which is overkill but for the price why not.

Check out the Hitec 7954 for an awesome rudder servo!

 

[Dennis Somers]

Something you may want to look at for future hydro builds ( or any hull ) is setting up a "right turn pull" for linkage on your rudder. There are some very good digital waterproof servos these days that can be mounted right at ( or very close to ) the transom to keep your link as short as possible. When it's not having to push against a long deflecting rod, PLUS the water resistance on the rudder blade, you don't need huge servo torque for great control. You can use similar for throttle, and that leaves a very small radio box that can be mounted wherever it will serve the hull the best ( balance/access/ect. ). Speedmaster offers left and right pivots for their rudders.

The Hitec waterproof servos are actually certified. Others are "labeled" waterproof.

 

[Jim Allen]

The rudder linkage shown in the photos allows a pulling action for right rudder. Therefore servos used can be placed anywhere in the hull. It can be used on any type hull & all of the moving parts are fully hardened. It also can mount either 1/8" & 1/4' thick rudder blades.

Jim Allen

 

[Grimracer]

Something to ponder.. it takes more power to make the boat go straight again then get it into the corner...

Grim

 

[Hydro Junkie]

Good point Grim. When turning right, as when we are racing, the boat is already trying to turn right due to the prop-walk effect that is pushing the rear of the boat to the left already. Therefore, bringing the rudder back to center would take more power than turning it to the right. At the same time, you could expect turning to the left would take even more grunt since you're fighting the prop that much more. The little things we never think about when setting up a boat

 

[Dennis Somers]

Theories are fun to bench-race over, or speculate on from several hundred feet away on a driver's stand. But for any of us that have actually steered a full size race boat down straights and in and out of corners ( left and right ), I can tell you that it takes a very strong upper body to wrestle a boat through extremely rough water in the turns, than it does to let go of the wheel and have the boat straighten out immediately from water pressure. That's not theory, it's in-boat racing experience.

Slowly, more heavy gas model racers are winning with right pull, less heavy duty servos. I'm not saying everyone should do it. We at SRI Motorsports have set all our hulls up this way for many years, and our gas boats will corner in rough water at mid 70s with no bad manners. Just something to think about ...

 

[Hydro Junkie]

No arguments on any of that since I had a friend that raced outboard hydros. He often talked about how hard it was to get his boat to turn and what he did to fix the problem. In the end, he had to quit due to age and, unfortunately, injuries.

As far as the R/C boats go, you said the two magic words:

SET UP

Every type of boat has it's own quirks and learning what those are and how to deal with them can make the difference between a good boat and a problem boat. It sounds like, Dennis, you and your group have yours figured out.