Reinforce composite for ice?

[HPeer]

We are looking at a composite construction catamaran. She is constructed of 1/4 ply covered by West Systems epoxy and glass. Only one or two layers at most. We live in Philadelphia and are concerned about ice. The Delaware is fresh in Philly and we can get significant ice here, not every year but it happens. I am concerned that if we left her in over the winter the ice would be a problem.

First I would appreciate reflections on that statement. Am I being overly cautious?

If not then is it possible to reinforce the hull sufficiently without adding excessive weight? I thought of kevlar but it seems that does nothing in compression. Are there other materials or methods that may work?

Many thanks,

Howard

[marshmat]

Hi Howard,

Generally speaking- and it is both difficult and dangerous to generalize when it comes to boats- catamarans tend to be fairly sensitive to added weight. An extra 5 mm of fibreglass thickness on a 10 m / 33' cat might add as much as half a tonne. It can be quite a significant load if the boat wasn't designed for the weight.

I have heard of lightly built vessels weathering the winter ice just fine, floating on their own bottoms. On the other hand, even heavy steel hulls can be crushed into pretzels if the ice mass decides to shift the wrong way. I don't think I'd be comfortable leaving a lightly built multi out in the ice for the winter; even with a heavy metal hull, I'd only consider it if it's kept in a sheltered area where the ice pack can't move.

Kevlar's appeal is in abrasion resistance- the stuff is insanely hard to cut or chafe through. It makes nice armour. Still, nothing can beat good solid metal when it comes to Man Vs. Ice....

[HPeer]

Marsh,

Thanks for the reply. I didn't mean to imply I would be in the pack, I would not do that even with a steel boat not specifically designed for the application.

My thought was more at a marina as a live aboard for the winter. Bubblers presumably would be available but then they may fail. Ice chunks may work their way into the slips from the river. Some jerk may plow ice as he pushes his way out. That kind of thing.

My Dad would sheath the bow of his work boat in sheet metal in the winter. We NEVER went home that he didn't check on his boat. Yet, one night the ice caught the boat to the dock at low tide and flooded it as the tide came in.

So I am leery of ice.

[mark775]

Well, I looked for pics of me walking around my FRP boat and couldn't (yet) find them, tho rest assured that boats are left in all the time to no ill effect. As was mentioned, it's when the ice is moved around that is a problem. I dump a bag of salt in the bilges, TKO, but never had anything other than a clump of salt come spring. Boats that leak might think differently. If you have power, an incandescent bulb will keep things "nice" and keep the bilge ice-free unless the ice is as thick as your draft or heated space is particularly drafty. I believe that these things are more important than static ice outside the hull. To me, the bubbler does nothing except make it easier to move the boat while it's cold.
Short response - there is no "crushing" force by ice, by itself. Would I do it where boats are moving four inches of ice? No.