I thought we were the only ones that suffered that problem. That's pretty aggravating.
When I fiberglass boat gets hard frozen in the ice, there is a possibility of stressing the hull, or at worse actually crushing it. While I don't know if this is valid fear or not, but it's very stressful to be frozen in.
If I can prevent it with a D-Icer, then I certainly want to.
I've left fiberglass boats in very thick ice for years. Mostly sailboats. Once I let a 30 ft powerboat freeze in, and my only fear was the trim tabs & swim platform hanging of the transom.
Never had an issue with ice crushing the hull, however, the water level (under the ice) can fluctuate. The biggest worry there, was when the water dropped a foot, and the 18 inches of solid ice above it, was clinging to the surrounding docks & seawall. The boat was literally hanging (suspended) above the water by the thick ice, that hadn't dropped. I solved that with a chainsaw, cutting around the entire hull, about a foot out from the boat. She settled nicely back into the water as I finished the cut.
Thru hull fittings are another story. Even though they're below the water line in the area of what you'd think would be save liquid water, They'll still freeze if the temp in the bilge drops below freezing. Unless you plan to baby sit the bilge temp 24/7, these need to be winterized for safety. If one pops, you'll sink real quick.
Surprisingly, most sinkings happen in the spring. The owner forgot or simply missed one of the thru hull fittings. It quickly freezes in the cold bilge. No problem till the weather gets warmer. That's when it begins to thaw out, and it's that thawing action that causes the ice within the fitting to expand. Subsequently cracking the fitting.
Plastic, brass, it don't matter. I've even seen the thawing ice force the lightly secured rubber hose, off an otherwise sound brass fitting. It's real hard to figure out the problem when your boat is sitting on the bottom. Even if it just goes down a few feet, those Pearson 30's usually have an inboard gasoline atomic 4 sitting low in the bilge. The water will cause the engine oil to be displaced, completely coating every interior surface with a 3 coating of oil. Fuel in the gas tank may even be displaced through vent fittings. It could become a HazMat situation in the marina with spill containment and Coast Guard involvement.
Deicers can give a feeling of comfort, as the boat rocks back and forth, but they don't help the thru hull fitting problem. The good ones are also pretty pricey at around $400-500, and they typically only last 4-5 years before needing an expensive rebuild. They're also not cheap to operate. If you're real diligent, you can purchase timers and thermal switches at additional cost, and keep them off when not needed. However, depending on where you're located, you spend between $300 - 600 on electricity for just 3-4 months of operation.
Some boats are designed for cold weather living aboard, like those that regularly cruise Alaskan waters, or the North Sea of Sweden. I guarantee a Pearson 30 is not one of these.
Summer living aboard is hard enough. With all the added cost, and inconvenience, I couldn't imagine anyone willfully doing it during a harsh winter.