Frozen Lakes can Damage Boats and Docks
Not only is ice and water fluctuation harmful to docks, piers and boat launches, but can do serious damage to boats that are docked for the winter. Without a barrier of open water, negative effects could be cracks all the way to toppling over boats!
When water freezes into ice, it expands. The solid pressure of ice and water fluctuating can do harmful damage to pilings causing them to lift or tilt.

Prevent Boat and Dock Damage
Good Old Boat
With wooden hulls, water getting between the planks can freeze, spreading them apart and allowing more water to enter and re-freeze until a major leak (and possible sinking) occurs. (GoodOldBoat.com) The problems are usually less threatening with fiberglass boats. However, when thick ice forms around the hull of any boat, damage to the rudder and prop is possible. Also, when a boat is surrounded by ice, wind, and current will cause it to rock and pitch. The resultant grinding action of ice against the hull can cut away at the gel coat along the waterline of a fiberglass boat. With wood boats, ice can wear through the paint and gouge the hull. For all of these reasons, it’s important to prevent ice from forming around a boat that spends the winter in the water. (GoodOldBoat.com) To make sure the boat is floating in above-freezing water, a water de-icing system in the winter is the answer. These systems are just as practical for an individual boat at a private dock as they are for a large marina. For those who live where the waters freeze during the winter, the “bubbler” and underwater agitation-motors are a familiar sight, but how do they keep the water from freezing around our boats? (GoodOldBoat.com) Read More about Deicing at GoodOldBoat.com
Aeration
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Electric Aeration. Keeton Industries line of electrically powered deicing aeration systems are the premier brand in the deicing market. For the last four decades, we have strived to provide our customers with the best quality and value. These systems are by far the quietest systems you can find anywhere and will give you lasting results! Contact us for the right system for you!
Prevent Boat and Dock Damage Today! 800.493.4831
Source:
GoodOldBoat.com
http://www.goodoldboat.com/reader_services/articles/winteragitation.php

Prevent Boat and Dock Damage

I have 70 feet of dock in a lake the deep end is about 4.5 feet. What would i need to protect the dock from damage
Hi Joe,
For that dock we recommend our item PDI-3, which is a single compressor system that includes 3 lengths of de-icing tubing, each 50’ long. You could run one of the 50’ lengths down each side of the dock, and loop the other around the end of the dock as the de-icing tubing is flexible. The system comes with a 2 year warranty, and costs only about $1 to $2 per day to run, depending on your electrical rate. Cost of that system is $2285.00, let me know if you would like more information about that deicing system, send me email.
Thanks!
Kurt