Replacing or installing the steering is not just mechanical work, but a critical step in ensuring safety on the water. Often, owners of small boats are faced with a situation where an old cable is used. Teleflex Or the analogue fails and the marking has long since worn off, and at that point the question is, how long would a new element have to be to provide a full angle of rotation without dragging or sagging?
The wrong length of the steering thrust can lead to the fact that you simply can not install the motor on the trawler, or, worse, the mechanism will jam at full speed. In this article, we will discuss the calculation methods, nuances for different types of motors and features. cable-system management.
There are several length standards that depend on the engine power and the type of gearbox, and understanding these parameters will allow you to avoid unnecessary trips to the store and ensure that your boat or PVC will be perfectly controlled.
Dependence of length on type of steering mechanism
The first thing to determine before buying is the type of steering gear you have, and the main division is between low-power (typically up to 50 hp) and more powerful engines. Rack and Pinion (cog-rail), where the cable has a specific shape of the tip and strict requirements for length.
In systems Rack Steering The length of the cable directly affects the number of turns of the steering wheel from stop to stop. Standard is a value of 2.7 or 3.4 revolutions. If you install the cable shorter than necessary, the rail will simply rest on the limiter before the motor turns to its maximum angle, which will reduce maneuverability.
For high-powered motors, gearboxes are pushed, and the length of the cable determines not only the angle of rotation, but also the force that is applied to the tuber, and the cable that is too long will have a backlash, and the cable that is too short will create a constant voltage in the mechanism.
⚠️ Warning: Never use cables from systems Rack They're not compatible with gear steering machines, and vice versa, and the tips and the stroke of the rod are not structurally compatible, which will cause the gearbox to break.
Method of calculation of length for replacement
If the markings on the old cable are not preserved, which happens in 90% of cases due to corrosion and salt water, you will have to take manual measurements, and the most reliable way is to measure the length of the old cable from the center of the tip to the center of the other tip, without straightening it completely so as not to damage the internal structure.
In the case when the old cable is not at all (for example, when refitting a boat), you need to use the calculation formula. gear-rail Measure the distance from the center of the steering machine to the center of the transom, add the distance to the center of the engine and multiply by the factor of stock.
The way to calculate gearboxes is different, and it's important to take the bend radius into account, and standard practice is to measure the path of the cable from the steering column to the motor along the gasket trajectory, adding 15-20 cm to form the loops and connect.
When measuring the path of the cable, use a soft tape measure or rope, laying them exactly where the cable will lie, and a straight line between the points will give the wrong result.
Standard dimensions and conformity table
Manufacturers, such as Teleflex, Si-Tex or MercruiserThe most common sizes are 9 feet (2.74 m) to 22 feet (6.7 m) for single-circuit systems.
It is important to understand that the actual length of the cable may differ slightly from the labeling due to manufacturing tolerances, so always round the value up to the nearest standard size when calculating.
Below is a table of conformity marking and real length, which will help you navigate when choosing a spare part in the catalogs:
| Marking (Foots) | Length (Meters) | Typical application | Diameter of cable |
|---|---|---|---|
| 10 ft | 3.05m | Small PVC boats, engines up to 40 hp | 3/16" (4.8 mm) |
| 12 ft | 3.66 m | Aluminum boats, engines 40-60 hp | 3/16" (4.8 mm) |
| 15 ft | 4.57 m | Boats with console, engines 60-90 hp | 1/4" (6.4 mm) |
| 18 ft | 5.49 m | Large boats, engines 90-115 hp | 1/4" (6.4 mm) |
| 20 ft | 6.10 m | Heavy boats, engines 115+ hp | 5/16" (7.9 mm) |
Always choose the next standard size cable if your measurements fall between two values, preferably a small margin of length than a shortage.
Features of installation on PVC and aluminum boats
The steering of inflatable boats is very specific, and often uses hinged transes that can shift under load, and the length of the cable should take into account the possible deformation of the transom when it comes to planing.
For aluminum boats, corrosion is critical. The cable passageways across the side must be carefully sealed. If the cable is rubbed against the metal, you will get a worn braid and a jammed steering wheel in the season.
In the editing on PVC boats There is often a problem of not having enough space to bend the cable, and the minimum bend radius for most cables is 8 inches (20 cm), and breaking this rule will lead to the dissection of the inner core.
⚠️ Note: When laying the cable over the side of the boat, use special sleeves or corrugated. Direct contact of the braid with the aluminum edge of the hole is guaranteed to lead to rubbing.
Common mistakes in selection and installation
One of the most common mistakes is tip-type ignition. Ball-tipped cables (for rack systems) and threaded sleeve cables (for red-ticketed ones) look similar, but are not interchangeable. Trying to put the wrong type will make it impossible to fix thrust.
The second mistake is tension. Many beginners try to pull the rope "like a string." This is strictly forbidden. The system should have a minimum backlash that allows the mechanism to select the slack when turning. The overtight cable creates tremendous friction and quickly wears out the gears.
The third mistake is lubrication. When you install the new cable, it's recommended to lubricate it slightly with lithium lubrication, but don't overdo it. The excess lubrication will attract sand and dirt, which will turn into an abrasive paste inside the braid.
What happens if the cable is too long?
If the cable is much longer than necessary, it will not be possible to fit normally into the compartment of the steering machine. The hinges will interfere with the running of the rail, which will lead to rudder jerks or complete jamming of the mechanism in extreme positions.
Diagnosis of wear and the need for replacement
There are indirect indications that the length of the cable has become a problem or that it needs to be replaced. If the steering wheel has become tight to only one side, it may be that the cable inside the braid has begun to delaminate ("crack"), which has increased its effective diameter and friction.
The rust coming out of the braid is a sure sign that the seal is broken, water is in, the grease is washed, and the rope will soon jam, in which case the replacement is mandatory, and you need to change the entire kit.
Check the status of the cable traction should be done annually, before you start navigation. Take off the tips and check the smoothness of the inner vein. If you feel "steps" or jamming when you move your hand, the resource is exhausted.
☑️ Diagnostics of the steering cable
FAQ: Frequently asked questions
Can I build up a short steering cable?
Absolutely not. The steering cable is a single precision mechanism, and welding or twisting will disrupt the balance and strength, causing the cable to break at the wrong time, only a complete replacement.
How often should the steering cable be changed?
Lifespan depends on the operating conditions: salt water is 3-5 years old, fresh water is up to 7-10 years old, but if you feel an increase in force on the tiller or jerks, you need to change immediately.
What is the difference between SS and Non-SS?
Marking SS (Stainless Steel) means that the inner vein is made of stainless steel, which is critical for seawater. Conventional cables (Non-SS) have a galvanized vein and rust quickly in salty environments.
Can I use a car cable for a boat?
No, motor vehicle cables (e.g. for gas or clutch) are not designed to carry variable loads of this amplitude and do not have the necessary protection from water.