If you tip in a non ship currency a currency not easily available then you can put the crew member in a position of having to convert to US $ causing a potential fee charge.
You also cause confusion as to how this goes to the crew member directly or to the pool first and what is the current conversion rate.
It is possible the Pursers office might look after this conversion but the main point is someone now has to convert and place into the pool or if above the norm to the crew member.
My feeling is stick to the guideline and currency used by the ship.
What we have done at times is after leaving the tips we also include some local currency that the ship will dock at for them to use when in port.
Celebrity Infinity-1, Dawn Princess-1, Sea Princess-2, Golden Princess-2, HA Maasdam-1, SS Cavina-1
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