Hull material for arctic cruising

[TollyWally]

In a former life I worked in a shipyard building steel vessels, mostly for the navy. We'd insulate them with dense fiberglass bats with a canvas like covering. We spotwelded copper "nails" on 6-8" centers and pushed the bats
over the spikes. There was a clip you pushed on over the protruding spike. Then we covered the seams with either this high tech nylon cloth tape or a fiberglass tape with lagging compound. Kind of a pain in the ass to do nice work but it was possible. Most of the time we would erect panels over the top of the insulation. All on Uncle Sam's dime so I don't know how the costs were. A bit of a hassle to remove if you needed to weld on the outside hull skin but a million times easier than if you foamed it.

Did you refer to "Glassfiber" saying "Fiberglass"? Something like "Rockwool"?

These glass wool, or mineral wool materials have all some problematic properties.
First, they are more or less hygroscopic, some can hold hughe amounts of water. Not what we need.
Second, they hold fumes pretty good and long. That is a problem with almost all foams too. Except the rubber based ones, like Neoprene and Armaflex.

The reason why the navies like that stuff: it is fire resistant! A good characteristic in battles.
The canvas like cloth btw. IS fiberglas fabric, if we are talking the same stuff.
We used that combination (and all the commercial fleet too), to replace asbestos / plaster on steam engines, tubing, boilers etc.

Regards
Richard

[Ad Hoc]

Richard

yes, i believe he is referring to mineral wool..or Rockwool, with its trade name. May be even FireMaster.....but all the same things really.

[rugludallur]

I expect to launch my boat next spring, most of the steel work is done, just a bit more stainless. I'll probably move directly to making the interior before blasting and insulating, then unbolt the interior, blast, paint and I'm planning on using foam unless I find a better alternative (hence the question).
Rockwool is one of the worst insulators for marine application, it soaks up water like a sponge and looses all insulation properties in the process.

R.

Jarl
http://dallur.com

Originally Posted by rugludallur

I expect to launch my boat next spring, most of the steel work is done, just a bit more stainless.

You know stainless steel rusts! Get it electropolished if possible (and affordable). It will last several times longer!

Regards
Richard

[rugludallur]

Yeah, all the stainless is acid pickled and polished to a mirror finish either by hand or by electropolishing, above water it's all 316/A4(31603/1.4404) but below waterline (sterntube, etc) it's 318 (2205/1.4462).

As a design principle all mounting plates/flanges are stainless and there are no through hull/deck bolts, this way I keep the insulation nice and dry There are also no plastic through hulls, where plastic sensors/transducers are mounted they are inside a steel cap so even if they are crushed the hull will not leak, they are also mounted recessed to decrease the chances of damage.

A new design which we used is to make the actual sterntube removable, it's mounted inside a sleeve and screwed in from the inside and only welded in a single circle on the outside, this way it can be replaced and this also minimizes distortion from welding and the loss of corrosion resistance inherent in welding duplex steels.
I get shutters when I look at a nice steel boat that's been blasted and painted and someone has made 100 bolt holes in it for a genoa track and winches, no doubts where rust will form and when the leaks spring the water will all be soaked up by the insulation.

Everything up here in Iceland is required to be up to spec for Arctic conditions, extra strength in the stern, extra framing and Grade A steel are mandatory for the boat to get a registration along with X-rayd welds.

Most of the work can be seen in the boatbuilding GALLERY if one is patient enough to scroll through the photos.
Regards
Jarl
http://dallur.com

[Korvasieni]

Here in finland lived a great persona, Pertti Duncker.
He had never saild, went to a boat-fair in 78 and got exited.
He then did the main lines on his yard, did the dravings, built the 12 m. boat in les than 2 yers, started sailing an practise, and left out for several years.

Ok to the point.
He then did several trips, and one was to the antarctica, and i think he was pleasd hi made the boat of steel.

Here is an english writing, with pictures, about the trip.
http://personal.inet.fi/yritys/merivuokko/ice.htm

The guy died last november, and left a big mark in finnish sailing.

[Autodafe]

Thanks for the input Korvasieni, I'm just about to read the link you posted.

The more I research the more I think that the capability of any boat is determined by the seamanship of the captain more than design or material - within limits, obviously.

[ImaginaryNumber]

Autodafe,
Are you still working on your arctic cruising catamaran? If so, I'd be interested in hearing where you're at.

[Autodafe]

Thanks for the interest.
The build has been pretty stagnant for a couple of years while I get finances in order, but as of today I now have a workshop sorted and cash burning a hole in my bank account. I'll start a thread here once I have some progress to look at.
As the design stands at the moment the only dedicated "Arctic" feature is a well insulated cabin.

[ImaginaryNumber]

Do you have a general design that you're brave enough to share? I've been particularly interested in what the pod looks like, with all the accommodations in it rather than split between the hulls. Also curious what you decided about the height of the sheer of the hulls. I remember you inquired about that in another thread.

[Autodafe]

I have to admit that I'm pretty embarrassed by my drafting skills , but I'm happy to share the design. I'll post some basic layouts when I get time with my scanner.

Despite being under 30 I still do my design work on paper.

[Wynand N]

Originally Posted by Autodafe

Despite being under 30 I still do my design work on paper.

Thats good and also means that you understand the basics of boat designs and the calculations needed for hydrostatics.

To many "software designers" out there that do not even know what a buttock or diagonal line and its purpose is.
Any fool can produce a set of calcs and lines with FreeShip, Prolines etc and other similar design programs but putting pencil to paper sort the men from the boys....

[Autodafe]

I've started a thread for my current design:

Pod cat square rigger cold weather cruiser project