Thick Ice / Moving a Narrowboat ?

[Naughty Cal]

Are you sure they are not magnesium?

Yes. They are aluminium.

 

Magnesium don't last us a season as we spend some of the year in salt water. Zinc don't protect in fresh water so we have switched to aluminium.

 

http://www.solentanodes.co.uk/collections/aluminium-volvo-anodes

 

http://www.solentanodes.co.uk/pages/zinc-aluminium-or-magnesium-anode

Edited October 23, 2015 by Naughty Cal

[Giant]

What is the benefit of aluminium anodes on an aluminium outdrive? I thought the whole principle of anodes relied on them being dissimilar from the metal they are protecting.

[midnight cowboy]

I believe (and would be interested to hear from the experts on this) that the repeated impacts of backing off and then running at an ice sheet do the gearbox bearings and engine mounts no good at all as the drive train is abruptly decelerated.

Depends how you reverse your prop - assuming you have a modern all in one lever control always pause in neutral - i.e. 12 0clock until the engine revs drop to idle before moving onto forward or reverse. On our old Northwich we have a separate throttle wheel and a reversing wheel - works the same. Only reverse without waiting in neutral in an emergency (probably too late to stop anyway!)

[Naughty Cal]

What is the benefit of aluminium anodes on an aluminium outdrive? I thought the whole principle of anodes relied on them being dissimilar from the metal they are protecting.

The anodes are a more noble alloy than the drive.

 

ETA: The benefit is that they protect the drive and last us longer then the magnesium anodes. As we spend 4-6 weeks in salt water each year the magnesium anodes needed changing every 6 months. Zincs wouldn't protect the drive in fresh water.

 

The aluminium anodes protect the drive in fresh, brackish and salt water and last us a couple of years before they need changing. And as an added bonus they are slightly cheaper then the magnesium and zinc anodes although this isn't a major concern so long as they are doing their job which they clearly are as we stripped the drive back to bare metal last year and there were no signs of corrosion.

Edited October 23, 2015 by Naughty Cal

[Giant]

The anodes are a more noble alloy than the drive.

 

Ah, that was the detail I was missing, OK.

 

The rest I well know - we have aluminium anodes on our steel hull for similar reasons.

[system 4-50]

If the ice is thick enough, would it be possible to fit ski s to a narrowboat? Propulsion would have to be by horse, of course. Would travelling around bends be the insuperable problem? Perhaps Professor Bizz could enlighten us?

[Peter X]

If the ice is thick enough, would it be possible to fit ski s to a narrowboat? Propulsion would have to be by horse, of course. Would travelling around bends be the insuperable problem? Perhaps Professor Bizz could enlighten us?

Boats on skis? It's been done in fiction at least. The Ice Schooner by Michael Moorcock, set on a future heavily frozen Earth, has the survivors going around in big ships on ice, propulsion being by sail not horses.

 

A steering mechanism to turn the skis should be quite easy, that's the least of the technical problems. You'd need a crane to get the boat up on top of its skis and the ice.

 

You'd need a huge thickness of ice to support a narrowboat, impossible I would think on UK canals, even up north in a bad winter. The unusual property of water that it expands a little as it cools from 4C down to freezing means that it takes a lot of very cold weather to produce thick ice, and its expansion when frozen so that it floats is quite handy, because if ice sank life on earth would cease.

[craftycarper]

Agreed.

 

We have been out in our GRP cruiser and our old GRP dinghy in the ice. Neither of which sustained any damage.

another yoghurt pot ice breaker, I had to meet a lorry some years back to move me from the mon/brec to sharpness, the lorry was in a lay bye a mile or so up the canal, but when I got there my boat was frozen solid, I had to get all the boats rocking in the marina to get her moving, and spent the next hour shitting myself as I cracked and crunched my way along the canal, I was amazed when I finally got their and picked her up on the hiab to find not a single scratch on the gel coat coat, I put it down to the fact that my yoghurt pot is much more pointed than a steel boat and simply slices it's way through, it did know damage to the boat but my heart was in the mouth the whole time

[Peter X]

In theory I suppose that if a crew member sat in the bow (well wrapped up against the cold) bashing the ice in front with a suitable tool, perhaps a boathook, that might fragment it enough to reduce wear on the blacking? Would this work in practice?

[IanD]

After Christmas up at Cosgrove with Kate & Snowy in 1985 (when I fell through the ice on Christmas day and did my Excalibur demonstration), we broke ice in Baron all the way back to and through London. By the time we got back the bilges were having to be pumped out every couple of hours because the ice had taken off some rivet heads on the bow (real ones, riverted iron hull). A few weeks later the boat sank overnight in eight feet of water with all their possesions on board because the boatyard fixing the hull forgot to keep the pumps going...

 

www.steamershistorical.co.uk/Web_FMC_Steamers/BARON.doc

[GreyLady]

After Christmas up at Cosgrove with Kate & Snowy in 1985 (when I fell through the ice on Christmas day and did my Excalibur demonstration), we broke ice in Baron all the way back to and through London. By the time we got back the bilges were having to be pumped out every couple of hours because the ice had taken off some rivet heads on the bow (real ones, riverted iron hull). A few weeks later the boat sank overnight in eight feet of water with all their possesions on board because the boatyard fixing the hull forgot to keep the pumps going...

 

www.steamershistorical.co.uk/Web_FMC_Steamers/BARON.doc

If ice can do that to 'real rivets' then plastic boats beware.

 

I do like rivets. :-)

Edited October 23, 2015 by GreyLady

[Naughty Cal]

I think thats answered the thread, if ice can do that to 'real rivets' then plastic boats beware.

 

I do like rivets. :-)

[GreyLady]

..

Edited October 24, 2015 by GreyLady

[Giant]

Despite being a steel boater I am going to back NC up on this one.

 

In fact iron & steel are far from ideal materials for icy conditions. When the Antarctic research ship Discovery was built in 1901, iron and steel shipbuilding were the norm, but the designers realised that the only way to make her survive the ice would be to build her from wood - metal would have cracked from the pressures & freezing temperatures. They had to drag a great number of wooden shipbuilders out of retirement to build her.

 

Modern composites such as glassfibre reinforced plastic have similar advantages - by flexing they are able to handle colossal loads. If you don't believe me then watch this video of a GRP glider wing under test:

 

 

ETA: The wing is carrying nearly 5 tons load when it breaks, compared to about 350kg in normal flight.

Edited October 23, 2015 by Giant

[GreyLady]

^ But it broke and its a plane not a boat and their was no ice.

[Giant]

^ But it broke and its a plane not a boat and their was no ice.

 

*sigh* yes, the point is to dispute the naive view implied earlier that plastic = weak, metal = strong.

[Phil Ambrose]

^ But it broke and its a plane not a boat and their was no ice.

It's called testing to destruction, a normal part of development. And judging by the popped rivets leading to sinking it would seem GRP faired better in the ice than an iron hull.

Phil

[BruceinSanity]

Depends how you reverse your prop - assuming you have a modern all in one lever control always pause in neutral - i.e. 12 0clock until the engine revs drop to idle before moving onto forward or reverse. On our old Northwich we have a separate throttle wheel and a reversing wheel - works the same. Only reverse without waiting in neutral in an emergency (probably too late to stop anyway!)

 

Yes, sure, good practice unless you enjoy changing the drive plate regularly.

 

My question was whether ice breaking places additional loads on the engine/gearbox/drive train and so far the answer seems to be no. We've boated in ice a few times to the detriment of the blacking round the bow. Backing off to get a run at the ice or to try and get round a curve does involve lumps of the stuff getting chomped by the prop (defo stay out of the tiller arc!) and that probably causes more stress than anything.

[gazza]

 

*sigh* yes, the point is to dispute the naive view implied earlier that plastic = weak, metal = strong.

Its an uphill struggle

 

I've mentioned it before, the RNLI have GRP boats that seem to do OK in some pretty rough sea states....

[Naughty Cal]

^ But it broke and its a plane not a boat and their was no ice.

You are clearly not from an engineering background

[GreyLady]

..

Edited October 24, 2015 by GreyLady

[Naughty Cal]

I am qualified in

 

Vehicle Mechanic with City n Guilds level 1 - 4

Vehicle Repair & Refinishing City n Guilds level 1- 4

 

Mind thats only 16 years in the motor trade so you may be right, are you qualified in Engineering NC ?

So why the lack of knowledge of material properties?

 

ETA: My OH, Liam, is a panel beater of 24 years. He has to have a knowledge of material properties and how they will behave to do his job properly. But he is a "real" panel beater not a strip and fitter

Edited October 23, 2015 by Naughty Cal

[Sea Dog]

We've boated in ice a few times to the detriment of the blacking round the bow.

Which is ok if that's something one has decided to accept. However, what about the moored boats one passes which have chosen not to roger their blacking only to have their blacking abraded away anyway by the movement of ice caused by passing ice breakers? My own few month old blacking in perfect condition was through to bare metal at the water (ice) line after just 2 days of this last winter. Towpath side undamaged, outboard side stripped so it was no coincidence.

[GreyLady]

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Edited October 24, 2015 by GreyLady

[GreyLady]

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Edited October 24, 2015 by GreyLady