Which of the following is a sign that bunks may need replacement?

Visible cracks or splinters on the bunks of a boat trailer are clear indicators that they may need replacement. Bunks serve as support for the boat during transport, and their integrity is vital for safely holding the boat in place. Over time, wear and tear along with exposure to the elements can cause the wood or material of the bunks to deteriorate, leading to cracks or splinters. This deterioration can compromise the stability and safety of the boat while it is being transported.

When bunks show visible damage, it is crucial to inspect them regularly, as continued use of compromised bunks can lead to more serious issues, such as the boat becoming unstable during transit or even shifting off the trailer.

The other options, such as excessive weight load and increased buoyancy, do not directly relate to the condition of bunks. Likewise, improved trailer stability often indicates that the bunks are still functioning well, which contrasts with the signs of wear that suggest replacement is necessary.