Story and photos provided by John Tiger, Jr.
The Right (and Wrong) Way to Install a Foot Throttle
Readers know I’m a staunch advocate for having the safety equipment necessary to properly drive a performance boat. That includes the right controls “at hand” (or “at foot” in this case) to enable the driver to keep both hands firmly on the steering wheel at all times.
These days, that means a high performance steering system (like Teleflex's SeaStar Pro hydraulic) with a remote trim control system with the buttons or switches located on the steering wheel, steering column or on a foot-controlled pad. It also includes a well-designed, properly installed and properly adjusted foot throttle.
THE EASY (WRONG) WAY The quickest way to install a foot throttle is to simply screw the throttle to the deck with wood screws. That's what most people do; it's what yours truly has been guilty of doing over the years, and unfortunately, it's even what many manufacturers and dealers do too. Using stainless wood screws doesn’t matter a whit; over time, the water that finds its way to the deck will get into the holes made by the wood screws and rot out the deck under and around the throttle mounting pad.
Thankfully for many, a significant number of hulls are built with composite decks, which eliminates the rot problem. But wood screws are not the way to mount anything in a boat. Through-bolts should be used whenever possible, especially when mounting components that will endure pressure, vibration or both–like foot throttles.
THE RIGHT WAY To do it right with through-bolts, you'll have to get to the underside of your deck. How do you do that? It isn't easy, and a little ingenuity goes a long way. One way is to cut a hole in the deck near the throttle and mount an inspection port with a cover. This probably isn't your best option. The port can look unattractive, and cutting the hole can also present new problems. You might cut into a stringer, or a stringer might block you from accessing the underside of the deck where you want to mount the foot throttle.
We fit the Bob's Machine Shop foot throttle slide plate to the mounting pad. Before we began the messy process of glassing the pad in place, we wanted to ensure that it all fit together.
There's an easier way, and it isn't difficult to execute. If there's vertical room under the driver's console for a half-inch or so of additional height under the throttle, you can fabricate a mounting pad for the throttle to sit on, and through-bolt the throttle to the pad. By using threaded stainless-steel T-nuts under the pad, you can keep the pad flush to the deck and only raise the throttle by the thickness of the pad you fabricate. You can generally find T-nuts in well-stocked hardware stores. My local supplier is a Tru-Serv hardware store; it carries both galvanized and stainless T-nuts. They are expensive, but worth it.
A T-nut is a small round threaded plate with teeth. The teeth are designed to be forcibly inserted into a substrate (like wood) and flush mounted, with the threads of the nut protruding up into the wood. Expect to pay about $1.50 apiece for a 4inch 20-thread stainless T-nut. You’ll only need four (thankfully) to mount your throttle.
We cut out squares and rectangles of fiberglass mat and woven roving to overlap and cover the mounting pad. We were sure to extend the mat's tabs out past the pad at least a couple inches, for extra strength.
The pad must be fiberglassed to the boat deck, and to do that, the carpet must be carefully cut and pulled back. This is the part that many balk at. Cutting carpet is a dicey operation, but if done properly, it can look like it's never been touched. Remember, the foot throttle's base plate will cover most of the pad itself, so there's room for a little trial-and-error to get the right fit. Also, if you elect to use an adjustable slide-plate under the throttle (so drivers of different heights and leg lengths can also drive the boat), you'll cover even more of the pad and hide carpet-cutting mistakes.
This is important: make sure the foot throttle full advance screw is adjusted so that it stops the pedal's travel at full throttle. If the pedal is allowed to travel even a hair further, the engine's carburetor or EF1 throttle body butterflies could be bent when the pedal is depressed.
Fashion a mounting plate from half-inch plywood; install the T-nuts; prepare the mounting surface for fiberglassing cut and size the fiberglass mat; glass in the mounting plate; test-fit the throttle; re-cover the plate with carpet; and finally adjust and mount the throttle. Doing it this way ensures you’ll have a solidly mounted throttle that won't pull loose even under the roughest conditions, and in the long-term, won't cause your boat's deck to rot prematurely.
Before you get started, here are a couple of tips to ease the installation process: Tip 1: To keep resin out of the T-nut threads, coat the four bolts with hot wax and screw them into the T-nuts. After the glass cures, you can simply unscrew the bolts. Tip 2: Before you complete the foot throttle installation, be sure to install the cable and adjust the throttle for proper engine idle speed, full throttle advance, and full pedal return to idle. It’s easier to do it now than trying to do it while lying on the deck under the console.
For all the added safety benefits, the dollar investment for this project is way down the scale. The entire job costs less than $25 for the fiberglass, hardware and wood. The time involved is about a day including curing and drying time. Finally, the difficulty factor is low. Just about anyone with a minimum of woodworking and fiberglassing experience can do it.