Many trailer boards do not last over 5 years before mold and rot weaken areas...examine closely! None of mine lasted 6 years.
These 4 boards are $55 for the short outside and $119 for the long inside boards...plus 20 galvanized or SS 1.5 by 3/8 lag screws.
Just do the outside replacements one year then the inside the other if cost is a factor. I have done this 2x now and can e mail exact
steps and what you need...took me about 90 minutes today for the inside boards...had to launch boat first of course.
Keep in mind trailer boards usually break at the launch to ruin your day or ruin your trip home.