Here are some key points about bevel gear shafts for boats based on the search results:

1. Types of Bevel Gears: There are several types of bevel gears including straight spiral hypoid gears and Zerol bevel gears, each with specific characteristics that make them suitable for different applications 1.
2. Functionality: The primary function of a bevel gear drive is to transmit power between intersecting shafts, often at a right angle. This is crucial in boats where the engine and propeller are not aligned 1.
3. Applications in Marine: Bevel gears are used in various marine systems such as propulsion, steering, winches, thrusters, stabilizers, and pumping systems. They ensure efficient power transfer, precise motion control, and reliable operation in harsh marine environments 3.
4. Advantages: Bevel gears offer versatility, compact design, smooth operation, and the ability to handle high loads. They are also reliable, durable, and efficient, which is essential for the demanding conditions of marine use 13.
5. Tolerances and Sensitivity: There are specific guidelines for the tolerances and sensitivity of bevel gear shafts, which are crucial for ensuring the proper functioning and minimizing issues such as interference or noise 2.
6. Straight Bevel Gears: In boats, straight bevel gears serve to transmit power, change direction, convert torque, ensure efficiency, provide reliability, and offer a compact design. They are versatile, compatible with other gear types, easy to maintain, and cost-effective