How Does a Boat Trailer Jack Work

So you have a new boat and the perfect trailer for it, and now need a way to mount the trailer on the hitch ball. You look around, do your research, and discover something unexpected – your recommended jack has a bracket instead of a hitch ball. In fact most marine-grade tongue jacks do. Your camper jack certainly didn’t have this! What is this strange contraption on your boat jack and why do you need a bracket?
Boat trailer jacks in many ways resemble camper trailer jacks, except they substitute brackets for hitch balls as the attachment point to the frame. In effect they allow you to raise your trailer for hitching / unhitching when using the trailer coupler is impractical. But camper jacks also connect to the trailer frame via the hitch ball coupler – so why the difference?
The answer is in the unique feature of most boats. If you’ve spent any time outfitting one, you probably noticed how heavy the engines are. A mid-size boat engine (say, 150 hp) can easily exceed 500 lbs in weight. That means roughly 15-20% of the boat’s weight is shifted all the way to the back! So since boat trailers tend to have more of their weight towards the rear where the prop engines are, the bracket mount jack provides the flexibility of positioning the mount point. Generally speaking, rear-heavier loads require the mount bracket attachment to be shifted towards the rear.
Another defining feature of boat trailers is the caster wheel at the bottom of the jack. For boat trailer tongue weights around 5,000 lbs or lighter, the wheels allow movement of the trailer to and from the hitch vehicle. As you may remember, tongue weights are supposed to be 10%-15% of the total weight of boat and trailer, which means that unless you’re hauling around a fully loaded yacht, you are probably under that threshold.
The only other thing you need to know about boat trailer jack caster wheels is the great plastic versus rubber debate. For most applications, polyurethane plastic caster wheels are a better option for your boat jack – they don’t require inflation, which makes them longer lasting, and on smooth surfaces do an excellent job of moving your trailer. Poly wheels are firm enough to handle thousands of pounds of weight, while still keeping your garage floor in pristine condition. As for pneumatic rubber casters, they are the better choice for movement over rough terrain. Rubber wheels grip uneven surfaces and provide shock absorption better than poly ones.
So if you have a motorboat, you probably should have a tongue jack with a wheel to move it around. For some tips on choosing the right one, check out our buyer guides for boat jacks and trailer jacks in general.