MARITIME COMMUNITY

Shipping bulk cargo wintertime in north Atlantic means that your cargo most likely will be exposed to severe weather conditions while crossing the open sea. What can you do in order to have maximum protection for your cargo? Sometimes a charter requirement to the ship is demanding the use of hatch cover tape. The reason for this is that the joint between the various sections in the outside hatch cover is where most of the leaks occur. This is considered being the weak point of the hatch. Most hatch covers on ships are folding type. It simply means that there are multiple sections in a hatch cover and when it opens it simply folds like a paper so the storing space required while open is minimum. The storing space for the open cover is usually in between the various hatch openings. While a hatch cover is open you can easy see the condition and also the type of joint it has between the each section. Usually they are overlapping and the bottom section comes with a fairly heavy-duty rubber gasket that receives the overlapping part of the other section. Additional to the weight of each hatch cover section there is also a mechanical securing. All sides and top has a mechanism called hatch cover cleats, that helps pulling it all together and securing it properly. Hatch cover tape has been around for many years and will most likely continue to be in demand for this particular use for many years to come. It is a very cheap insurance for your cargo and relative easy to install. Most ship crews are familiar with the application. Choosing the right type of tape for a particular application can sometimes be a problem. It is very important that the right hatch cover tape is chosen for your application.  The side of the hatch should have a different tape from the one used on top. Sufficient use of heat when installing the tape makes for very good adhesion. For some tips on installation go to THIS article. Some additional tips can also be available by contacting the editor. Most of the major supply centers have this type of product available usually on relative short notice.

When your ship is calling ports in the cold north it is good to feel safe that your lifeboat engine will start if need be. There are a variety of preventive measures that you can take and it all adds up to a more secure lifeboat.

Let us start with the starting battery. When a battery is fully charged and exposed to 0 deg F it has only 40 % cranking power. It is at 100% cranking power when the temperature is 80 deg F. To prevent this loss of cranking power we can install a heated box for the battery. Using a heated box we must have a thermostat to prevent over heating. We can also install battery thermal heating pad. This is a thermal pad that wraps around the battery. It is available for most sizes of batteries.

For the engine we can heat the oil pan in a similar way. There is a silicone heating pad made for this purpose and it comes with adhesive backing and can be glued to the oil pan.  The availability for these heating pads is in 220v and 120v. For the oil pan size depend on the volume of your engine oil. Max watt output that I have found so far is 400W.

These two small modifications to your lifeboat will greatly improve your chances of having a trouble free voyage in the cold north.
If you need any more information, feel free to leave a comment with your contact details.

The old systems details was left out in the last post and I was aksked to give more details on how it worked and why it failed.

Here are some of the working of it;

This system would use air as a medium, so the diaphragm separated the oil from the rest of the system. If it was full of diesel fuel, it would give a false reading because the ‘head pressure’ (the height of the gauge above the bottom of the tank) would introduce an offset equivalent to whatever volume of oil in the tank at the height of the pressure gauge. Effectively, whatever height the pressure gauge was, it would read zero whenever the oil was at the same level as the gauge, or negative when it was below the height of the gauge.

The failure probably occurred when the diaphragm or fittings in the sensor leaked and filled it with oil.

Back in the old days.. gauging was done with an external gauge glass for visual viewing of the tank level. There was also some sensor type gauging systems the cam along using a sensor with a tube connection to an external indicator gauge.

How do you covert an old system like this to a more modern system using digital displays etc.

Here are one senario using a day tank for 3.35 tons of  diesel fuel with a density of .8284 as a sample;

You need a pressure transducer that can be physically adapted to the bottom of the tank, and it would be electrically hooked up to a digital indicator programmed to read the pressure but is scaled (programmed) to convert the pressure into volume. The scaling would be calculated from the depth and dimensions of the tank, using the density of oil.

In this case, you need a pressure transducer that reads 1.72 PSI, or 47.63 in. H2O, or 3.5 in. Hg, minimum. (Don’t get one that reads more than twice that, however. You lose resolution.) This is quite low. Be sure that the ‘wetted’ components of the transducer are compatible with Diesel fuel. (Usually not a problem as most of the time they use Stainless Steel.)

The pressure of oil when the tank is full is 47.63 in. H2O as you supplied a density of .8284 for Diesel. If your tank is 57.5 in. deep then that is how you select the transducer. The digital indicator is scaled accordingly to convert into litres, gallons, etc. for every inch of depth.
Mounting brackets for the transducers are usually available from most dealers