The Dinghy Derrick has been extensively tested on our rigs using both Zodiac and Avon GRP RIBs with double floors.  We water ballast the compartment between the floors, and add a 4 to 6 HP 4-stroke motor. 

A typical analysis of this load is:

Zodiac Cadet RIB 290 Neo      65 kgs     -or-   Avon Rover RIB 280               61 kgs

Yamaha 4/6 HP wet weight      28 kgs     -or-   Mariner 4HP                           27 kgs

Water ballasting at                    50% of total void of 78 litre                             39 kgs

Total test load                  130 kgs/  286 Lbs

ARK Marine Ltd. certify the maximum service load to be 130 kgs (286 Lbs) excluding the weight of the Derrick itself of 44 Kgs.(97 Lbs)

The installation kit carries strain gauge readings from the test rig to assist the fitter.