Interaction

Question 1

In reference to squat what is the H/T ratio?

Answer 1

H (depth) / T(Static Draft)

Question 2

Define squat.

Answer 2

The loss of underkeel clearance as a ship moves forward from being at rest.

Question 3

What are the two types of squat?

Answer 3

Mean bodily sinkage and trim ratio fore and aft

Question 4

Describe Bernoulli’s principal.

Answer 4

Pressure drops perpendicular to the flow when linear velocity is increased.

Question 5

Squat is more likely to occur at the bow in full bodied ships with a block coefficent greater than?

Answer 5

Greater than 0.7

Question 6

Where squat is more likely to occur on fine lined ships with a block coefficent less than 0.7?

Answer 6

At the stern.

Question 7

If the block coefficent is very near to 0.7 where is squat likely to occur?

Answer 7

Evenly at the bow, midbody, and stern.

Question 8

Define static underkeel clearance.

Answer 8

The water depth minus the midship draft when a vessel is stationary.

Question 9

How does LCB affect squat.

Answer 9

The LCB will dictate at which end the vessel will sink more due to the effects of squat.

Question 10

What is the single most effective means to reduce squat.

Answer 10

Reduce speed.

Question 11

Define squat buffer.

Answer 11

The amount of UKC required by a regulatory agency. Refered to as Y2.

Question 12

What are the signs that a vessel has entered shallow water conditions.

Answer 12

1. Maximum Ship Squat Increases 2. Mean Bodily Sinkage Increases 3. Ship will generally develop excess trim by the head or stern 4. Wave making increases 5. Ship becomes more sluggish to maneuver 6. Draught indicators on the bridge will indicate changes in the end drafts 7. Prop RPM will decrease, upto 20% of service RPM. 8. Drop in speed 9. Ship may begin to vibrate suddenly due to resonant frequencies of the entrained water. 10. Rolling, pitching, and heaving will be reduced 11. Mud appearing in the water around the vessel 12. Tactical diamter will increase 13. Stopping times increase 14. Rudder effectiveness decreases. 15. Width of wake increases.

Question 13

What depth is concidered shallow water (MacElrevey)

Answer 13

1.5 times vessels draft

Question 14

Does rate of turn increase with decrease in UKC

Answer 14

No. Rate of turn is constant, for practical pourposes, but turning circle diameter increases.

Question 15

How much can a turn diameter increase between deep and shallow water.

Answer 15

Up to 2 times

Question 16

Does steering on a directionally unstable ship improve in shallow water?

Answer 16

Yes. So long as it does not have a high block coefficent and ends up squatting at the bow.

Question 17

Does a ship carry further in deep water or shallow water? (MacElrevey)

Answer 17

Shallow Water