Maintenance, Corrosion & Winter
De-Icer or Bubbler: Which Should Protect a Boat Lift Over Winter?
Quick answer
For a piling lift that stays in still water at least 4 ft deep, a bubbler line run around the pilings is the better default: it opens a narrow band where ice grips, keeps electricity out of the water, and draws about 414 VA against 684 to 1,092 VA for a 1/2 to 1 hp de-icer. Choose a propeller de-icer for current, tide, or a lift in shallow water beside deeper water. Neither stops wind-driven ice, and every state that regulates them wants the open water marked.
On this page
Use a bubbler for a piling-mounted lift in still water at least 4 ft deep, and a propeller de-icer when the water moves, rises and falls with a tide, or is too shallow at the lift for a bubbler line to work. Both move bottom water at about 39°F up to the 32°F surface, but they shape the opening differently, and for a lift the shape is the point. Ice damages a lift where it grips the pilings; a bubbler hose laid around them opens a narrow band exactly there, while even the smallest de-icer clears many times a lift's footprint.
The usual dealer answer is "it depends on your needs." It depends on three things you can check from the dock: depth at the pilings, whether the water moves in winter, and which state you are in.
- Default for a piling lift in still water 4 ft or deeper: bubbler line looped around the pilings
- Choose a de-icer for: current, tide, or shallow water at the lift
- Power: 1/2 hp compressor about 414 VA; Kasco de-icers 684 VA (1/2 hp) to 1,092 VA (1 hp) at 120 V
- Smallest Kasco de-icer, vertical, in the coldest band on its chart: 30 ft open circle
- New Hampshire signs: readable at 200 ft since August 4, 2026 (was 150 ft)
- Neither device stops wind-driven ice shove or protects a free-standing lift on footpads
Safety: open water around a dock is hidden under snow and deadly to anyone crossing the ice. Mark it every winter. A de-icer is a powered motor in the water: Kasco requires a GFCI-protected circuit and says no one should enter the water while it is connected. Have a licensed electrician supply the circuit, and read boat lift electrical on electric shock drowning before you hang anything powered off a dock.
First check: does this lift stay in at all?
Either device protects something fixed in place: a lift on driven pilings, an elevator lift on a seawall, the dock around them. A free-standing lift on footpads has almost no resistance to sideways ice load, and open water does not change that. Kasco's manual is plain: under certain conditions, "no de-icer can prevent damage from ice movement caused by wind or current." If your lift is free-standing, the answer is seasonal removal, not a device.
For lifts that stay, the job is narrow: keep ice from freezing onto the pilings, so a rising lake cannot jack them upward, and leave a gap against a sheet expanding as it warms. The mechanisms are in winterizing a boat lift, and embedment depth in piling requirements.
How each one moves water
A propeller de-icer (agitator, circulator) is a sealed, oil-filled motor and prop in a cage. Hung vertically it opens a roughly circular hole; angled, an oval that reaches well beyond the dock. Kasco's manual puts the unit 4 to 6 ft deep for vertical use, slightly shallower when angled, and at least 1 ft off the bottom.
A bubbler is an air compressor on the dock or in a boathouse feeding a weighted, perforated hose on the bottom. Bubbles rising along the hose carry bottom water up, so the open water follows the line you lay. Nothing in the water is electrical: Scott Aerator describes its 1/2 hp compressor system as aerating "with no electricity in the water." Pond Pro's de-icing airline kits pair a 1/4 hp compressor with 40 ft of line, a 1/2 hp compressor with 60 ft, and a high-flow 1/2 hp with 100 ft, with a 4 ft minimum depth.
| Factor | Propeller de-icer | Bubbler line |
|---|---|---|
| Shape of open water | Circle (vertical) or oval (angled) | A band that follows the hose |
| Electricity in the water | Yes, the motor and cord | No; compressor on shore |
| Minimum depth | Hangs in as little as 2 ft, but Kasco's chart assumes more than 4 ft and says shallow water reduces effect | 4 ft (Pond Pro) |
| Moving water | Can be aimed from upstream; Kasco sells a mount for moving ice and strong currents | Opening drifts with the current; no maker's figures |
| Thin-ice hazard | Larger, especially angled toward open lake | "Less likely to cause dangerously thin ice conditions" (NH LAKES) |
| Power at 120 V (amps x volts) | 684 VA (1/2 hp) to 1,092 VA (1 hp) | About 414 VA (1/2 hp compressor at 115 V) |
What a de-icer actually opens, by air temperature
Kasco publishes open water by average low air temperature and orientation for its three motor sizes. Angled figures are width by length; vertical figures are the diameter of the hole.
| Average low air temperature | 1/2 hp (2400D) | 3/4 hp (3400D/HD) | 1 hp (4400D/HD) |
|---|---|---|---|
| 34 to 20°F | 65 ft vertical; 30 x 100 ft angled | 85 ft; 35 x 120 ft | 90 ft; 40 x 150 ft |
| 19 to 0°F | 50 ft; 25 x 60 ft | 70 ft; 30 x 80 ft | 80 ft; 35 x 90 ft |
| -1 to -20°F | 35 ft; 25 x 55 ft | 50 ft; 30 x 75 ft | 65 ft; 35 x 85 ft |
| Below -20°F (labeled "Great Lakes" in the manual) | 30 ft; 20 x 40 ft | 45 ft; 25 x 50 ft | 55 ft; 30 x 60 ft |
Read the footnote first. Kasco assumes unobstructed water, a lake of 200 acres or more, 200 ft or more of water depth, and more than 4 ft of depth in the de-icing area, and adds that size "may vary greatly" with local conditions. A lift sits in a few feet of water among a dock, a boat and pilings that block surface flow, so expect less. That argues for the smallest unit on a controller, not a bigger motor.
Worked example: sizing for a four-piling lift
A vertical lift stands on four pilings set on a rectangle 11 ft wide and 22 ft long.
De-icer, hung vertically in the middle: the farthest pilings are at the corners, so the hole must span the diagonal: √(11² + 22²) = 24.6 ft. The smallest Kasco unit in the coldest band of its chart opens 30 ft. In a 34 to 20°F winter it opens 65 ft, which is about seven times the area of a 24.6 ft circle. Even allowing for shallow water, 1/2 hp is the ceiling for one lift.
Bubbler line around the pilings: the perimeter is 2 x (11 + 22) = 66 ft. That is beyond Pond Pro's 60 ft kit and inside its 100 ft high-flow kit, and the open water stays a band along the line.
What each costs to run
Volts times amps is a ceiling; real watts for a motor run somewhat lower. Kasco's 2400D draws 5.7 A at 120 V (684 VA), the 4400D 9.1 A (1,092 VA), and Scott's 1/2 hp compressor 3.6 A at 115 V (414 VA).
Run time decides the bill. NH LAKES says both types "only need a few hours each day" and recommends 2 to 4. Below, 3 hours a day against around the clock over a 120-day season, at July 2026 residential prices from the U.S. Energy Information Administration: 17.45 cents per kWh in Minnesota and 26.60 cents in New Hampshire.
| Device | 3 h a day (360 h) | Around the clock (2,880 h) |
|---|---|---|
| 1/2 hp bubbler compressor, 414 VA | 149 kWh: $26 MN, $40 NH | 1,192 kWh: $208 MN, $317 NH |
| 1/2 hp de-icer, 684 VA | 246 kWh: $43 MN, $65 NH | 1,970 kWh: $344 MN, $524 NH |
| 1 hp de-icer, 1,092 VA | 393 kWh: $69 MN, $105 NH | 3,145 kWh: $549 MN, $837 NH |
The controller matters more than the device. A 1 hp de-icer on a timer costs less to run than a bubbler left on all winter. Kasco's combined C-20 panel runs the unit only when the timer is on and the air is below the set temperature; its thermostat needs up to 30 minutes to read the air, so mount it out of direct sun.
The rules where lift owners use these most
Three states in lift country have written rules for these devices, and they differ in ways that change what you buy.
| State | Rule | What it requires |
|---|---|---|
| Minnesota | Minn. R. 6116.0020; Minn. Stat. 103G.611 | Aeration systems in protected waters need a DNR permit "unless the system is used exclusively for and is no larger than the minimum size adequate to keep dams, structures, or mooring areas free of ice." A permit costs $250 and brings $500,000 liability insurance, published notice, thin ice signs 4 to 6 ft high at most 100 ft apart, and weekly inspection. |
| Wisconsin | Wis. Stat. 167.26 | Applies to all navigable waters. Anyone "creating ice holes by aeration of water" may, instead of a board fence, barricade them with uprights and a rope 2.5 to 4.5 ft above the surface carrying reflectorized, fluorescent or lighted ribbon, or put up a highly visible reflectorized, fluorescent or lighted warning device, and remove it all after the ice melts. Fine up to $100 or up to 6 months. |
| New Hampshire | RSA 270:33 | Devices only "as necessary to protect legally existing permanent structures" on the owner's shoreline, and never so as to block access to the ice from anyone else's property. Signs must read DANGER, THIN ICE, be readable at not less than 200 ft, visible from all directions, with reflectors in the Department of Safety's color pattern. |
New Hampshire's 150 ft sign distance still circulates, including on the NH LAKES page, because it was the 2019 standard; the 2026 amendment raised it to 200 ft, so older signs may be too small. Minnesota's exemption is a sizing rule: a 1 hp de-icer angled out to open a 150 ft oval for one lift is hard to call "the minimum size adequate," while a bubbler band around the pilings or a 1/2 hp unit hung vertically on a controller fits the wording. In Wisconsin, a shoreline owner who knows of an opening loses the statute's liability exemption unless they warn the people they let cross to the ice.
Choosing for your site
| Situation | Choose | Why |
|---|---|---|
| Piling lift, still lake, 4 ft or more at the pilings | Bubbler loop around the pilings | Opens water where ice grips, narrow band, nothing powered in the water |
| Piling lift in under 4 ft, deeper water a short way out | De-icer in the deeper water, angled toward the lift | Kasco's method for shallow areas; a bubbler needs 4 ft |
| River or channel with winter current | De-icer on the upstream side, rigid mount | Current carries the opening downstream; Kasco advises de-icing from upstream |
| Tidal water | De-icer hung to split the tide range | Kasco: shallow at low tide, deep at high tide; see tidal installations |
| Elevator lift on a seawall, long straight wall | Bubbler line along the wall | A line follows a long straight run; see elevator boat lifts |
| Free-standing lift on footpads | Neither: remove it | Open water does not stop sideways ice load on the legs |
If you use a de-icer, hang it vertically, as NH LAKES advises, on a purpose-built bracket. With ropes, Kasco says to spread the two lines at least 8 ft apart, because starting torque twists close lines and can damage the cord.
Upkeep, and where neither works
Kasco's manual asks for a GFCI test at installation, after every reinstallation and monthly; repeated trips mean pull the unit, not reset it (see why a boat lift keeps tripping the GFCI). Check the shaft anode every two to three months and replace it at half size or when it turns white, the same galvanic logic as on the lift (corrosion protection). Replace seals and oil after three years; NH LAKES notes failed seals leak oil into the lake. A unit that switches itself off and on is cycling on its thermal overload: unplug it. A bubbler moves all of this onto dry land, and its bottom hose joins the spring maintenance checklist.
Neither device stops wind-driven ice, works where ice reaches the bottom or the bottom water is no warmer than the surface, or helps once the power fails. Kasco adds that de-icing "can also become less effective in extremely shallow conditions," so measure first with water depth requirements.
Frequently asked questions
Is a bubbler or a de-icer better for a boat lift?
For a piling lift in still water at least 4 ft deep, a bubbler line looped around the pilings is the better choice: it opens a narrow band where ice grips, puts no electricity in the water, and draws less power. A propeller de-icer is better in current, in tidal water, or where the lift sits in shallow water with deeper water nearby to aim from.
What size de-icer do I need for one boat lift?
Usually the smallest. A four-piling lift on an 11 by 22 ft rectangle needs a hole about 25 ft across. Kasco's chart gives its 1/2 hp unit a 30 ft hole even in the coldest band and 65 ft in a 34 to 20 degree winter, on ideal deep water. Real docks open less, so start at 1/2 hp on a timer and adjust the hang.
How big do thin ice signs need to be in New Hampshire?
Readable from at least 200 ft, visible from all directions, reading DANGER, THIN ICE, and fitted with reflectors in the Department of Safety's color pattern. The 200 ft distance took effect August 4, 2026; guidance written earlier still says 150 ft, which was the 2019 standard, so older signs may now be too small.
Sources and further reading
- Kasco Marine, De-icer Operation and Maintenance Manual 824404, 2021.1.3 (https://cdn.shopify.com/s/files/1/0632/8542/8412/files/824404_Kasco_De-Icer_Manual.pdf)
- Kasco Marine, De-icers trifold brochure and sizing guide, 2025 (https://kascomarine.com/wp-content/uploads/Kasco-Deicer-Trifold-2025.pdf)
- Scott Aerator, 1/2 hp Bubble Pro Max Compressor product page (https://scottaerator.com/products/hp-bubble-pro-max-compressor)
- Pond Pro, Can-Air de-icing airline bubbler system (https://www.pondpro.ca/can-air-de-icing-airline-bubbler-system/)
- NH LAKES, "Dock De-Icers," November 2023 (https://nhlakes.org/dock-de-icers/)
- New Hampshire RSA 270:33, as amended 2026, 127:1, effective August 4, 2026 (https://gc.nh.gov/rsa/html/XXII/270/270-33.htm)
- Minnesota Rules 6116.0020, Aeration permits (https://www.revisor.mn.gov/rules/6116.0020/) and Minnesota Statutes 103G.611, Water aeration safety (https://www.revisor.mn.gov/statutes/cite/103G.611)
- Minnesota DNR, Aeration Requirements Quick Guide, revised November 2, 2022 (https://files.dnr.state.mn.us/eco/lakeaeration/aeration-guide.pdf)
- Wisconsin Statutes 167.26, Leaving unguarded ice holes (https://docs.legis.wisconsin.gov/statutes/statutes/167/26)
- U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A, July 2026 (https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a)
- U.S. Geological Survey Water Science School, Water density (https://www.usgs.gov/special-topics/water-science-school/science/water-density)