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by Big Pete
Sun Aug 02, 2009 12:31 am
Forum: The Workshop
Topic: Packing material for water cooled prop shafts
Replies: 19
Views: 7382

Re: Packing material for water cooled prop shafts

Probably any natural fibre coated in Tallow will do, I don't think it does any harm to give the packing a liberal coating of grease when you fit it either. Obvious key points for anyone not used to this old type of seal is that the shaft should be polished as smooth as possible so it does not shred ...
by Big Pete
Sat Aug 01, 2009 11:51 pm
Forum: The Workshop
Topic: Crankshaft Deflection
Replies: 22
Views: 16058

Re: Crankshaft Deflection

One thing I didn't mention earlier is that if the engine has a camshaft drive chain, the tension in that will try to lift the crankshaft and bend it. This bend will always be in the same direction in relation to the engine , but will vary its direction relative to the crankshaft as it turns.(same as...
by Big Pete
Sat Aug 01, 2009 9:30 am
Forum: The Workshop
Topic: Conrod question
Replies: 15
Views: 6401

Re: Conrod question

Hi Guys, I can see how the surface roughness of the fractures surfaces ensure perfect alignement when the rod is re-assembled. For the fracture to fit together perfectly when the rod is re-assembled it must be a "short", brittle fracture, this implies that the cast material is not at all d...
by Big Pete
Fri Jul 31, 2009 3:38 am
Forum: Training Room
Topic: 3rds EKG-Double Bottom Tank Question
Replies: 4
Views: 6692

Re: 3rds EKG-Double Bottom Tank Question

One important function of the double bottom tank is structural strength. The first ship to be fitted with double bottom tanks was Brunel's S.S. Great Britain and she went aground on the Irish Coast on her maiden voyage and survived intact for a year before she was salvaged, and she is still with us ...
by Big Pete
Fri Jul 31, 2009 3:16 am
Forum: Training Room
Topic: Another second class motor question
Replies: 2
Views: 2425

Re: Another second class motor question

Hi Walker, I haven't sailed on a 15, 000 ton cargo ship. The place to find this information is on a Classification Society Website, where you will find the rules that determine these things. If the plating is made of high tensile steel it will be thinner than if made of ordinary steel. If you were l...
by Big Pete
Fri Jul 31, 2009 2:32 am
Forum: Training Room
Topic: difference between a blower and a compressor
Replies: 2
Views: 11987

Re: difference between a blower and a compressor

I think you have got it pretty well covered. To me a blower would always be a rotary device, designed for large flow rates with a low differential pressure. Turbocharger, supercharger, Rootes blower, even an electric fan for aerating a sewage plant. A compressor on the other hand, may be reciprocati...
by Big Pete
Fri Jul 31, 2009 2:07 am
Forum: Training Room
Topic: 3rd class motor question
Replies: 2
Views: 2472

Re: 3rd class motor question

Hi, You were actually asking about the clearance volume of the cylinder, Martin told you how to calculate the swept volume. The clearance volume is the space above the piston when it is at top dead centre. The total volume or capacity of the cylinder is the swept volume plus the clearance volume. Th...
by Big Pete
Fri Jul 31, 2009 1:56 am
Forum: Training Room
Topic: Help! Just can't get pass the 2nd Class motor Orals
Replies: 14
Views: 11638

Re: Help! Just can't get pass the 2nd Class motor Orals

I think all the previous posts have covered everything except Fuel. UK Regulations used to be that you should have sufficient fuel on board for the estimated consumption to the next Port plus a safety margin of 3 days or 3% whichever was less. You can always be cought out by the unexpected. I was to...
by Big Pete
Fri Jul 31, 2009 1:36 am
Forum: Training Room
Topic: 2nd class motor question
Replies: 2
Views: 2190

Re: 2nd class motor question

Hi, This is a very good question. I suspect the reason that you have had no replies is that no one knows what a blast air line is. Apart from the blast air lines (Tuyeres) in a steel blast furnace, the only blast air lines I know of are completely obsolete. In the early days of the dastardly Dr Dies...
by Big Pete
Thu Jul 30, 2009 5:35 am
Forum: The Workshop
Topic: pv fiassco
Replies: 11
Views: 3795

Re: pv fiassco

Hi again, Further to my earlier post I have had problems in the past with totally spurious cards caused by blockages or leakages of the indicator cock, or leakages on the screw thread on the cock connection to the indicator machine. If everything has been overhauled, all the fuel rack standouts on t...
by Big Pete
Thu Jul 30, 2009 2:18 am
Forum: The Workshop
Topic: Crankshaft Deflection
Replies: 22
Views: 16058

Re: Crankshaft Deflection

Hi Diesel Dame, Taking leads is a way of measuring bearing clearances. Open up the bearing, and place lengths of lead wire (hence the name) across the bearing journal, refit the top half of the bearing and tighten down according to makers instructions. The lead wire will then be flattenned down to t...
by Big Pete
Wed Jul 29, 2009 2:12 am
Forum: The Workshop
Topic: pv fiassco
Replies: 11
Views: 3795

Re: pv fiassco

Hi,

This may be a stupid question, but have you tried changing or overhauling the indicator cock itself?
Big Pete.
by Big Pete
Wed Jul 29, 2009 2:00 am
Forum: The Workshop
Topic: Crankshaft Deflection
Replies: 22
Views: 16058

Re: Crankshaft Deflection

Hi Sorry I have not answered before, As fitted the crankshaft is perfectly aligned with the bearings, usually deflections are small except where they are influenced by the mass of the flywheel, hanging off the end of the crankshaft which will cause the the end of the crankshaft to droop. Try to visu...
by Big Pete
Sat May 09, 2009 8:39 am
Forum: The Workshop
Topic: Corrosion pieces
Replies: 6
Views: 4619

Re: Corrosion pieces

Hi Guys, Thanks for your replies, they confirmed the way I was thinking. In the drawings the corrossion pieces are just short lengths of pipe, in the middle of the pipework between the sea inlet and the cooler and between the cooler and the overboard discharge. On the drawings we have a total of 6 p...
by Big Pete
Mon Apr 27, 2009 10:31 am
Forum: The Workshop
Topic: Corrosion pieces
Replies: 6
Views: 4619

Corrosion pieces

Can anyone help me? According to the drawings of the sea water system on my ship, Corrossion pieces were fitted in the pipe systems. Most of the system is made of 90% Copper, 10% Nickel Alloy, with chemical dosing pipes in stainless steel. There are some pipes in Galvanised steel, which I suspect mu...

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