Icy Bites

By Tom Neale, 3/3/2011


There’s a lot more to be said about ice and boats than how you keep your beer cold. Although that’s a good start. But with the wonderful winter weather some of us have been enjoying, I thought I’d start with ice on the water.

We all know that you can’t run your boat (even if you wanted to) when the river or bay is frozen over hard. But many of us don’t know that it doesn’t take much freezing over to cause a problem. I remember a winter in the 1970s when they had to supply Tangier and Smith Islands in the Chesapeake with planes because the Chesapeake Bay had very thickly frozen over. That was a no brainer. Nobody was moving in boats. But I also remember several late falls when we were heading south on the ICW. The fresh water just south of the Great Bridge Locks in Virginia was covered with skim ice. It was probably less than a quarter inch thick. “No problem,” thought many skippers, anxious to gain warmer latitudes. They just cut through it with the greatest of ease. But they didn’t realize that their boats weren’t the only thing doing the cutting. This ice can be almost razor sharp. It’ll chew up the paint on a wooden hull, and then the hull itself, until the wood is essentially a gooey mush—sometimes leaking badly. With a fiberglass boat, it’ll quickly eat through the paint and then the gelcoat, leaving an ugly impaired layer of glass, the remaining thickness of which depends on how soon the boat got out of the ice. But Mr. Skipper, up on the fly bridge or ensconced back in the cockpit, isn’t seeing that until it’s too late. A steel boat has much better luck with thin ice, losing paint, but seldom any steel. But it still isn’t invulnerable.

Chez Nous waiting for the ice to break up and melt a bit before leaving the dock at Great Bridge.
Alvah Simon, a very tough guy, and his wife Diana decided to let their steel hulled sail boat become frozen into the ice up in the Arctic one winter, for the experience. This boat was tough and built for the occasion. And Alvah plans well and does things well. But the pressure of the ice over the duration bent the hull, despite the plans to prevent this. Ice expands as it freezes and this is something to reckon with.

We all know to reckon with this by draining all water pipes, water passages in engines and other vulnerable areas and/or filling them with anti freeze for a winter layup. (I got so tired of this I started going south for the winter around three decades ago.) But pipes and engine blocks aren’t the only soft spots.

For example, many rudders on sail and power boats are fiberglass. But seldom are they solid fiberglass. Usually there’s core inside and some sort of metal webbing for stiffening. Of course, the rudder shaft passes through the top and sometimes all the way out through the bottom. Often over the years water finds its way into the coring. When the boat is hauled the water or moisture may not drain out. A very hard prolonged freeze, coupled with a significant amount of water in the rudder, can cause expansion, pushing out the fiberglass exterior walls of the rudder, seriously weakening the rudder and setting up the conditions for even worse problems next winter. When you’re hauled check your rudder for any water, even small amounts, draining out. I’ve known some with this issue to drill a hole in the bottom of their rudders to insure that all water drains, and then plug it up with a suitable sealant in the spring.

Ice Breaker at Great Bridge.
This type of damage can also occur on other parts of a boat. Water trapped in voids of metal can expand, weakening or cracking the surrounding metal. This might be found in casting impurities in, for example, a shaft strut. It might also be found (less likely) in advanced (maybe not-so-advanced) crevice corrosion in stainless. Another devious trap can be found where a through hull was closed when the boat was hauled but water was on the inboard side of the valve and up in the hose. In theory, when water freezes, if there is room for it to expand, as upwards in a pipe or crack, it’ll expand in that direction with less likelihood of harm to surrounding structure. However, if the freeze is severe enough and the water column or layer is obstructed enough, damage may still occur.

There are various other obscure places where ice expansion could be an issue. For example, if your shaft seal is tight enough to keep water in the housing, and the boat is hauled and blocked up so that water didn’t run out of the shaft log and housing, this component could suffer damage. This is a stretch, because usually in the process water escapes from this component, but it can happen.

Another concern may be the transom of an outboard boat. When an outboard is bolted onto the transom of a boat it creates huge stress, not only by hanging there, but by pushing at an angle when the boat is throttled up to speed. Most transoms are built to withstand this, although I’ve seen transoms peeled back when they failed, particularly on old boats in the Bahamas. Typically a failure comes around and close to the motor mount or where the transom is glassed to the rest of the hull.

Transoms are often cored. Coring can range from balsa (hopefully not) to marine grade plywood to exotic synthetic material. With the constant pulling and stress application to a transom, it isn’t unusual to see cracks develop, particularly around the joint where the transom is attached to the hull. Often these cracks are cosmetic only, no more than gel coat deep. But, particularly with an older boat, or a poorly built boat, the cracks may be through the fiberglass skin, allowing water into the coring.

When you pull that boat out on the trailer at the last of the season check very carefully for any water seepage from the transom itself or cracks where the transom is joined to the hull. If there’s water inside the transom, it could expand during that hard long freeze and greatly weaken the transom. When you pull the cover off the boat in the spring, check the transom thoroughly for any damage of this nature. Look for bulges, tap for hollow sounding areas that might indicate separation of the skin from the coring, look for signs of water drainage, and look for new hairline cracks or old cracks that have widened or deepened.

While you’re messing around back there at the outboard, note whether it was left in the tilted or vertical position. Most outboard mechanics I’ve talked with recommend leaving an outboard vertical because, in this position, they’re supposed to, at least in theory, drain any water that might freeze. (Check with your manufacturer for their recommendation.) But, particularly if the outboard was stored by a yard, one sometimes sees an outboard stored at full tilt, even though the manual recommends against it. Sometimes an inexperienced worker will do this because he’s afraid the skeg will hit ground while towing or backing.

If you live and boat in Florida, sorry to have bored you. But count your blessings (as I know you do).


Tom’s Tips About Freezing

1. Some try to keep their boat heated during the winter, but this is very risky, both as to adequate heat and too much heat.
2. Too much heat comes when the heat source or its electrical supply ignites and burns the boat down. We’ve even seen well designed good quality electric space heaters melt down when turned off yet still plugged in.

Click Here for More Tips

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