Saturday, 12 October 2013

Boat Stuff.

There are a very large number of books that have been written about all aspects of boats on the inland waterways. However, every few days I seem to learn something new.

When being constructed a boat will be ballasted to make the keel heavy. This weight will make the boat sit lower in the water and it will also aids the boats stability. However there are certain other functions that the blasting will be required to achieve. One is that the boat counter will be a minimum of two inches below the waterline. The ballast will also be used to give a slight bow up attitude. The ballast will also be placed to level the boat across the beam (width)

So it would be possible to identify that the lowest part of the boat is typically the skeg which is a fixed distance below the counter. In this case we could be using the counter as a benchmark. To accurately measure the distance between the skeg and the counter we would need to remove the boat from the water.

Or would we?

Your draft can change from time to time depending on the variable amount of boat loading. It is useful information to know what your typical draft is. The deepest part of the draft will be the back of the boat. There is a large heavy diesel engine, several large heavy batteries and a large tank that is filled with fuel. 

Using the weed hatch technique to measure your true draft: 

First remove the cover from the weed hatch.  Depending on the clarity of the water you may be able to see the skeg below the propeller. Using a tape measure you should be able to measure the distance between the bottom of the skeg and the water surface.  Now, take your boat pole and put a mark on the pole at the same depth as the distance between the skeg and the water surface.

Remember: Check the seal on the weed hatch cover a short while after being underway. If the seal is leaking, reseat the cover and check again later. If the seal is allowed to leak then water can enter into the engine room.

At each end of the boat are two tanks. One for water and one for diesel. Depending upon the amount of liquid in each tank. So the draft of the boat will change. If the diesel tank is low and the water tank is full. The back of the boat will be higher in the water. It is not unusual for the depth at each end of the boat to vary by an inch or two as the fluid levels change. 

Remember: When the boat is powered forward, the stern will sit lower in the water. The more power that is applied the deeper the stern will sit in the water.

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