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http://www.marinemodelmagazine.com APRIL 201525

of screws/washers will be more difficult to deal with a close-by

exhaust unit. Vibration of the body of the exhaust unit will also play

into your servo-holder’s height within the hull; so giving the pipe/

cover gap a bit of extra space will prevent everything from the

undoing of the sealing tape to the meltdown of the lid, box and even

the components mounted inside the radio box.

Servo-Mounting optionS

Along with the placement of your hull’s radio box, you’ll also have

a few different ways and techniques to affix your two servos in the

container’s interior.

Although the majority of I/C boat servos are positioned in an

upright position there are times when laying them on their side or

even at an angle may be in your boat’s best interest. A really low-

profile hull/box combination will demand a lay down servo layout

while a very small/tub-style box on an outrigger or an outboard

tunnel design can mean angling one servo to clear the other

components inside the hull/box spaces. Supporting this style of

servo attachment can add a lot of vibration stress to the servos;

but you can decrease this stress when installing either the throttle

or rudder servos. Adding a section of either double-sided tape or an

equally thin piece of foam padding between the servo case and the

bottom of the radio box will help dampen-out the shakes generated

by a running I/C boat.

tack the servo-holder together after which you can further lock/seal

the wood box using a wide series of adhesives and/or sealants.

Depending on the unit’s actual servo requirements the wooden

radio box might require the addition of a layer of light fibreglass

cloth and resin to its exterior which will both make it waterproof and

stronger once it’s mounted inside your hull.

As a side note, before you add any cloth/resin to the outside of

the ply radio box structure make sure that on those areas where

it contacts and slots-into the boat’s engine stringers have enough

space so the fibreglassed box will still fit between the rails.

Box Mounting

Now let’s say you’ve purchased your radio box and can move on

to its placement in your hull. If possible, you can mount the engine,

tuned pipe and transom hardware before adding the box, however

it may be necessary to loosen/remove these pieces while you’re

installing both the container and its servos, linkages and battery

pack. The chore will also demand creating your home made/

custom throttle/rudder control rods; plus they will in turn require

sealing grommets where they must pass through the walls of the

box. Regular hobby shop piano wire is commonly used for I/C

boat linkages and you can solder any number of different threaded

couplers to the solid metal rod once you’ve determined their length

requirements inside the box/hull. For most nitro/petrol marine craft,

I’d recommend using the largest stoutest/largest-diameter piano

wire possible to ensure there’s no flex in your finished linkages.

Your wire limits will revolve around the soldered-on couplers you

have chosen which in turn will need to closely match up to the

clevis/ball-ends that will connect the servo/rods to one another.

Again, as your power craft grows in size, power and on water

speeds, all of these parts will have to be tough enough to avoid

problems at the lake; so when in doubt, use the biggest control

hardware pieces you can!

As for the actual fixing of the radio box you’ll have several

options that can include regular fasteners, adhesives and even a

metal hook/rubber band arrangement found on some R/C aircraft.

Fasteners that are easily accessible once the box is in place are

useful if you’re racing your boat, as shunts that put any amount of

water inside the hull/box could mean having to detach the radio

container to clear the problem. The rubber band/hook set up makes

the box removal go even easier especially if you use quick-release

clevises on your boat’s carburettor/rudder arm connections. On

those boats that position the engine’s tuned exhaust directly over

the radio box lid area you’ll need to space the aluminium, carbon

fibre or steel pipe high enough to both clear the top cover and allow

you to mount/remove the lid as needed. Tape-down box covers

won’t demand a lot of pipe clearance while those using a series

Choosing a radio box, its attachment system, its linkages and

sealing material will demand a bit of effort to ensure they all work

correctly inside your hull

Situated 90 degrees from one another this radio box layout

features a bolt-on servo tray making it easy to remove the servos,

receiver, etc. as a unit

A nylon clevis joins this hull’s throttle servo to the boat’s

carburettor and the bend in the rod allows some give in the event

the servo linkage over extends a bit

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