Technical advances made by the JCL group

To see the procedure used to make the hulls, click this Technocraft link, Here is some technical information on some of the innovations developed and implemented (or not) by the companies..

The engines in the marauder were placed in a sound-proofing enclosed bay which was accessible through a hatch or if major work was required, the floor boards were removable enabling the top of the engine bay to be removed entirely, this photograph shows the saloon floor boards removed, one of the 3 top panels removed, and to the lower right the access hatch opening in the aft stairwell.

The engines were suspended on struts that were fixed to a rubber 'silent block' support limiting vibration and noise from the engines transferring to the hull, all the wiring,cables & pipes etc. were passed through connections on the enclosure, leaving no passage for noise or smell from the enclosure into any part of the craft, here a picture of the arrangement without the enclosure showing the engines suspended (viewed from aft) in a new Marauder hull installation.

The struts supporting the engines viewed from Midships

Here we can see how the propellor shafts terminated in a pintle bearing suspended from the rudder, this enabled waterflow to travel un-impeded to the propellors (no 'P' bracket support behind the propellors) and the rudder to have maximum effect, while achieving a great weight saving and reducing vibration to the hull and inefficiency from water disturbance by the 'P' bracket.

In this photograph, I have enlarged a view of the propellor shafts so you can see how they went directly from the hull to the rudder support shaft, with no 'P' bracket as is usually employed.

This picture was taken during the launch of the first Marauder at Riverside, Norwich.

Here is a view of the exit from the hull thrust bearing, instead of the propshafts pushing against the engines, this arrangement applied the full power of the propshafts directly to the hull thrust bearing, and not against the engines/bulkheads reducing weight of materials neccesary for the re-inforcement of the bulkheads and engine supports in a normal setup. ( the picture comes from a hull undergoing a second refurbishment in 2000. hence the state of the fibreglass, the thrust bearing has been 'plugged' with a foam and plastic plug.)

Here you can see the inner side of the thrust bearing in the hull, in this space was a short drive shaft fitted with universal joints  connecting the prop shafts to the engine gearboxes.

Here is a piece of 'TECHNOBOARD' this piece comes from the settee boxes, but Technoboard was used throughout the yachts for bulkheads,doors & panels etc. This was made by spraying resin onto a 6'x4' plywood board over which a honeycomb cardboard had been stretched using a peg arrangement around the board, then another plywood board (which had one side sprayed with resin) was applied over the cardboard, sandwiching the honeycomb between the two boards. The sandwich was then compressed under vacuum until the resin cured and the boards were ready. The boards are extremely tough and resistant yet weigh a fraction of the comparable solid bulkhead that would be required to match. (this piece has suffered 25 years of use in extremely hot and wet conditions yet is still as strong as the day it was produced)

more details to follow...