Ice Breaking

It seems that the narrowboat fraternity (narrowboatist’s) are getting their knickers into a bit of a twist. What with the ensuing thaw they are all making plans to move on, fill up water and diesel tanks, empty holding tanks, stock up on provisions etc. However the horror of what lies ahead of them fills them with dread. They will have to potentially ice break past GRP boats.

My lord, the way they speak you would think that GRP boats are made of egg shell. Narrowboatists seem to be under the impression that anything not made of steel will buckle, fold in two and sink at the mere thought of ice and should the worse happen and a piece of ice touches a GRP hull it will instantaneously sink to the bottom of the canal/river.

They appear to be imagining mythical sheets of ice that can slice a boat in two being pushed from the bows of their steel tubes, sawing boats in half right, left and centre. The reality of course is much more down to earth and little if any damage will be caused to GRP and wooden hulled boats by ice from passing boats.

The pattern in which a boat breaks the ice is dependent on the hull type. Displacement hulls push water so it stands to reason that they attempt to push through ice. This causes the ice to crack in front of the boat then as the boat pushes further through the ice it breaks the leading edges into smaller pieces that sit on the surface. Nothing that will damage a structurally sound hull of any construction.

Planing hulls climb out of the water. They behave in a similar manner in ice. Last year during our ice breaking adventure we noticed that Naughty-Cals bow rides over the ice immediately in front of the boat before crashing through the ice to break it. This process creates small pieces of ice again far too small to cause damaged hulls to moored boats.

It is also worth bearing in mind that GRP hulls have a relatively thick hull construction. Modern planning craft work on a rough basis of 1mm for every 1ft of length, thus a 25ft boat such as Naughty-Cal will have a general hull thickness of almost an inch with thicker sections where high forces are expected, for example around the transom where the thickness will be almost twice that of the hull. River boats tend to have a thinner hull construction but again the force needed to push a blunt piece of ice through a piece of GRP maybe half an inch thick is well beyond the capabilities of your average narrowboat.

So come on guys, let’s get real here.