Most trade between the City Martians is conducted by the land caravans but there are a few merchants that prefer to use skiffs to transport goods across the deserts. This or course has it's risks but more often than not they are bettered by the profits. The travel time is quicker than the land caravans but the chance of meeting Sky Martin raiding parties is increased tenfold.
The skiff convoys consist of two or three tug-neffs attached to several tenders that carry the cargo. As many as five tenders can be attached to the biggest tug-neffs but this is traded off for a slower speed. The tug-neff can be armed with several ballistas and usually the rear tender will have a ballista along with a crew that are ready to fight for their cargo.
The skiffs are made in a similar way to the Sky Martian skiffs and have a more bloated appearance than the elegant Sky Martian skiffs. There is some rumour that construction methods for the tugs have been traded for rare goods and information about the land caravans with certain Sky Martian clans but this, is as of yet, unfounded... If it is to be found that trade and information is being passed between the Skiff Merchants and the Sky Martians then there will be retribution from the City Martians for the betrayal.
The tenders are basically large hulls with a main deck and a small cargo hold below this deck. The tug-neff has a similar appearance to the Sky Martian skiffs albeit shorter and rounder with an upper deck at the rear which the trimsman will use and the captain of the convoy will have his place under this upper deck. The tugs and tenders usually aren't decorated but occasionally an affluent Skiff Merchant will adorn his tug with geometric patterns and these pattens can be used as an identification of the Skiff Merchant from a distance.
Using the trade winds that traverse the planet the Skiff Merchants ply their trade between as many cities as possible using well known routes through the lowland canyons; most trying their best to avoid the Sky Martians. During the night the tugs will preferably anchor against the cliffs of the canyons with a watch posted throughout the night. If the convoy finds itself in the open then they will reduce their height and anchor to the desert floor.
The crew themselves are made up of the braver City Martians and some of them can become somewhat of a legend to the more domestic City Martians. But, there is some resentment from many of the leading families as the Skiff Merchants become arrogant the longer they are in the sky. This arrogance is increasingly likened to the attitude of the Sky Martians and if it continues then the cities elders will have to make a decision as to what to do.