Amotorboat approaches you head-on and sounds one short blast. how do you signal that you agree to let it pass on your port (left) side?

The blast made by the vessel's driver is telling you that he intends to pass by your left side. If you agree with his intention, you will respond by sounding one short blast in return. If you are not in agreement with this move or you do not really understand the intention of the driver, you will give the danger signal which is five short rapid blasts.

Weight on heaven = mass * 2.178 = (42/9.8) * 2.718