Boat trailer jacks split into three types: swing jacks that stow flat for towing, fixed jacks that handle 2,500 to 7,000 lb, and 12-volt power jacks for push-button lifting.
The three types differ less in shape than in what they ask of your tongue, your back, and your wallet.
Swing Jacks: The Side-Mount Standard
A swing jack bolts or welds to the side of the tongue and pivots 90 degrees to lie flat during towing, keeping it clear of ramps and road debris.
- Mounting: bolt-on or weld-on at the side of the tongue.
The trade-off is lift height and stability. A swivel jack works on flat pavement, but a single wheel can sink into wet ramp gravel, and stowing horizontally means bending to crank it down.
Fixed And Drop-Leg Jacks For Heavier Loads
Fixed jacks stay vertical, carry heavier tongue weights, and suit trailers where a swing mechanism would be a weak point.
The leg slides down and pins in place, giving more lift travel without a crank handle doing all the work.
Welding and bolting both work, but the mount matters: some fixed jacks weld or bolt to an A-frame tongue. Boats and older utility trailers often use a straight tongue, which takes a weld-on or bolt-on jack because there’s no angled frame to clamp to.
Power Jacks And What They Cost You
If you launch solo or tire of cranking a loaded bow up a ramp, this is the category.
Trade-offs: they draw on your trailer or tow vehicle battery, cost more than manual jacks, and a dead battery leaves a jack you can’t move unless it has a manual override. Wiring must survive the same salt spray.
Matching A Jack To Your Tongue Weight
Size the jack against tongue weight, not gross trailer weight.
- Measure your tongue style. Square or rectangular tubes are required for some manual dual-wheel swing-back jacks.
- Confirm the capacity clears your tongue weight with room to spare.
- Check corrosion treatment if the trailer sees salt water.
- Decide on crank versus 12-volt based on how often you launch alone.
Lippert’s trailer jack replacement guide covers mount styles and swap options in more depth.
To compare specific models rather than categories, this roundup of tested boat trailer jacks breaks down capacity, mount type, and price side by side.
| Jack Type | Typical Capacity | Best For |
|---|---|---|
| Single-wheel swivel | 1,200 lb or less | Trailers rated 6,000 lb and down |
| Dual-wheel swivel | Around 1,500 lb | Soft ground, steadier footing |
| Drop-leg foot | 2,000–2,500 lb | Extra lift travel, mid-weight boats |
| Fixed | 2,500–7,000 lb | Heavy boats, A-frame tongues |
| Power (12V DC) | 2,500–5,000 lb | Solo launching, frequent use |
FAQs
Can I swap a swing jack for a fixed jack on the same tongue?
Often yes, if the mounting surface matches. Fixed jacks typically require welding or bolting to an A-frame; swing jacks bolt or weld to the side of the tongue. A straight-tongue trailer usually can’t take an A-frame-style fixed jack without an adapter, so measure your tongue geometry before ordering.
Is a 1,500 lb jack enough for my boat?
It depends on tongue weight, not boat length. Keep tongue weight at 10–15% of loaded trailer weight for large trailers and 6–10% for small ones.
Do I need a support plate with a jack wheel?
Check whether your jack model specifies one.
References & Sources
- Bulldog / B&H USA. “6400 Swivel Marine Jack Owners Manual” Source for the No. 6612 support plate warning on tongue weights over 250 lb.
- Lippert. “Ultimate Guide to Trailer Jack Replacement” Covers jack mount styles and replacement options.
- CURT Manufacturing. “Trailer Jacks” Reference for jack categories and capacity ranges.