Every dock section you walk on transfers its weight to a handful of support points: the posts. Those posts carry the load down to the lakebed, and the crossarms spread the load between them so no single post is doing all the work. When this system is sound, your dock stays level and doesn't bounce or sway underfoot. When it isn't, you feel it in every step — and over time, a wobbly dock puts stress on the connections and deck sections a
bove it.
bove it.
The good news: you don't have to replace the whole dock to fix the problem. Most stability issues are solved at the support level.
Start with the Right Posts
Posts are the backbone of the dock, so size matters. Alumi-Span's standard is 2" OD aluminum dock posts, which they recommend for all new applications. They're lighter and last longer than the older 1.9" OD posts found on many existing docks. If you're building new, go with 2". If you're retrofitting an older dock, measure carefully before ordering, because the two sizes don't mix.
Aluminum posts are the best choice for a few reasons: they won't rot like wood, they resist corrosion better than steel, and they are lighter for pulling in and out season after season. Many Alumi-Span docks are still in service after more than 50 years, and that longevity starts with the posts.
Don't Forget the Crossarms
Posts hold the dock up, but crossarms and platform trusses hold the posts together. They tie adjacent posts into a rigid frame, which is what keeps the whole structure from racking or twisting when a wave hits or when someone steps on the edge of the deck. If your dock has always felt a little "loose," missing or undersized crossarms are often the culprit.
Need to Know how to Build a Boat Dock?
Alumi-Span has been building docks since 1956, and we sell everything down to the nuts and bolts, so you can upgrade your existing dock piece by piece instead of starting over.
If you need instructions on how to build a boat dock, or if you’re just not sure what your dock needs, give us a call at 855-523-2444 or click here to submit a contact form — we’re more than happy to help you match the right parts to your dock.
