Hull Material for Ice Protection

In the Great Lakes, wooden boats for commercial use have been "steeled over" for a long time. http://www.harveyhadland.com/pics000.htm

 

If wood is the chosen hull material I think S-glass outside and kevlar inside makes best use of material qualities. The bow should have a heavier lamination schedule and a lot of rake to ride up on sea level ice rather than push through it. Following whales and avoiding ice: we should all be so lucky

 

Impact in case of collision. The crushing of the support planks is why I originally wanted something rigid and first thought of titanium.

Aluminum maybe?

 

Sloan,

As the husband of a novelist, I am ever on call to discuss technical details for fictional stories.

First, you would never sheath a wood boat with metal, other than with copper on the bottom to act as an antifoulant. That was done in the 19th century to prevent bottom growth on wood ships, and it lasted into the 20th century and was applied to yachts when they were still being built of wood.

With the advent of composites, metal bottoms were unnecessary, and anti-fouling paint went through tremendous growth. As you may know, most bottom paints contain high quantities of copper. But even this is changing now with scientific advances to even get the copper out of antifouling paint in favor of chemicals or additives that are friendlier to the environment.

However, for the purposes of your novel, copper sheathing, perhaps thicker than normal might be a possibility, if it is essential to the story. But this is what Donald Street (well-know sailor) has to say about copper sheathing on wooden boats (1973, The Ocean Sailing Yacht): "...copper fouls in about a month in tropical waters, [and] a tremendous amount of time must be spen in scrubbing. Even if the copper sheathing is painted, it fouls much more quickly than wod coated with the same bottom paint. Another disadvantage is that copper sheathing is very expensive. And unless the copper is of a very high grade, it begins to corrode thorugh at the waterline in about two years." I know you said the boat would be in cold waters, but the other points to appreciate are that it does not necessarily work all that well compared to the latest in anti-fouling paints (now nearly 40 years later), and if we know anything about raw materials these days, they are even more expensive that ever, and harder to come by.

So, what to do? I would not recomend Kevlar as a sheathing, at least not by itself. Kevlar is very difficult to lay up (it is lighter than resin and it tends to "float" when laying it up). Also, it may be good for puncture resistance, but it is lousy for abrasion resistance. If Kevlar laminate gets abraided, like ice floes against a hull, the abrasions expose the Kevlar fibers and they go fuzzy, and you cannot repair them easily--the fuzz does not wet out again. I would not put Kevlar on the boat all by itself.

If the yacht has to be made out of wood, then sheathing it in a few layers of fiberglass would be a solution. And if you want Kevlar in there, then the Kevlar should be vacuum bagged onto the wood hull first, and then some layers of fiberglass laminated and vacuum bagged over that. S-2 glass fabrics are stronger and stiffer than the more typical E-glass fabrics and have much better abrasion and puncture resistance than E-glass fabrics. In this way, you get the best of all worlds--the fiberglass provides fairly good abrasion resistance that is relatively easily repaired, and the Kevlar protects against puncture through the hull.

You could also consider just an extra layer of wood--if the hull is built with one normal thickness of wood (how thick?--pick a number), then an extra layer from say a foot above the waterline going down to the keel would not be unreasonable. If desired, coat this with some layers of fiberglass.

As a final thought, most cruisers of Arctic and Antarctic waters will build a metal boatin either steel or aluminum for sailing in icy waters. Steel would be the first choice, in my opinion--it is stronger and stiffer generally, also cheaper than aluminum. Aluminum is lighter, and it is an attractive material in many ways. Either of these would work.

Good luck, I hope this helps.

Eric

 

But why? Theres no sea ice around Iceland

 

Eric,
Thank you very much. Magnus had also suggested a kevlar/S-glass approach. I think that's the way to go. The S-glass on the outside will provide the collision resistance and the underlaid kevlar will provide puncture resistance. Plus, the relatively lighter weight (as opposed to steel or iron) will keep it relatively fast and maneuverable.

Please correct me if I have any of this wrong.

Funny side note--I have a friend who's a blue-water sailor. Whenever I attempt to discuss this with him, he's tries to talk me out of the trip. I've told him it's for a novel and I'm not actually going to do it myself, but I'm not sure he believes me.

Anyway, thanks again, Eric and Magnus and everyone who replied. I researched every suggestion and--while I may have rejected some afterwards--I did learn a lot. I now know what S-glass is, about the "Bowdoin" and the "Titanium Lady" and a little about shipping on the great lakes.

 

Depending on the style of the novel, I'd wonder about trying to build a 'bumper' for the boat: A lightweight forehull, that sits a bit forward of the real hull (and tapers back to it), mounted on springs that allow it to move back (and probably up) under impact. You'd want it cheap enough to be disposable if it gets damaged (thin sheet steel would be my guess), and you'd probably take it off for most cruising. The idea is to absorb impacts (at least enough for the main hull to take the rest), and abrasion doesn't matter, as it's not the actual hull - just replace it if it gets too abraded.

Of course, I've never heard of or seen such a thing, and I'm not sure how hard it would be to make... (And freezing temps could cause ice in the springs, which could cause problems.)

 

You guys are giving me a headache. Ice grade ship is not about cladding it is about the structure supporting it. You to brace inside of ship, and panels. Your welds or whatever bonding techniques have to hold. Also some materials like cheap steel or fiberglas May shatter if hit from cold.

 

Rather unconvinced about kevlar inside guys. What's it going to do given an already solid wooden hull? Unless we are talking about the wood purely as a core material I'm not sure it will do that much. A kevlar skin on the outside on the other hand will have spectacular resistance to bangs bashes and so on - I've seen a kevlar exterior/foam sandwich dinghy parked under a steel barge in F6 winds and come out without significant damage - and it can have (and would be conventional to) have a thin layer of glass over the top to give a sacrificial layer for fuzz proofing. If the wood is to be a core, I would go kevlar inside and out.

 

That is just what we are saying. My suggestion was Kevlar against the hull on the outside surface of the wood, and covered over with the fiberglass. There would be no composite on the inside surface of the hull.

Eric

 

I agree with you. There are two issues, the underlying structural strength of the hull and abrasion resistance. Wrapping weak hull in S glass or kevlar only addresses one issue.
But since this thread is all concerning a work of fiction it's not really important.

 

Thanks guys.

I'll speak to the shipwright and see that the hull is well braced internally.

 

Well Macguiver would brace inside of Hull with broomsticks, make snowplow looking thing from the fishing hold covers. He would usekeke giant laggard bolts to secure panels to wood. No need to make whole boat ice proof, at end boat sinks while hero is rescued like African Queen.

 

Carry a sledge hammer and if it does get damaged just bang it back into shape rather than disposing of it. Or better yet leave it on the farm.

 

I believe the answer lies in the man portrayed to a degree.
How have you developed the character?
Does he have a fascination with 19th century pilot charts and did research into whaling ships of yore?
Or
Does he have more of a ultra modern technical bend?

What is the real nemesis & threat foiled by the hull?
Perhaps not the ice..

Ships vary a great deal and reflect the man- define him and the material choices becomes obvious.