Whilst not an SO40 I did fit my own SO34.2 with a Furuno radar, located on the mast between the two spreaders
I would carefully check the conduits that are installed by the factory. In our case the conduit that passed the main bulkhead had been crushed during installation, this required the radar cable to be fed down the mast compression post, which being stainless needed specialist drills (about 18mm) to gain access
The routing through the interior was quite straightforward but did require the removal of some of the interior panels.
Having the radar on the front of the mast does have advantages in terms of height, but comes with a number of downsides, including the Genoa rubbing against the radome, more complications whenever you remove the mast (although not difficult to cut the cable and install chocolate box connectors)
If the mast is stored during the winter there is more likelihood of damage in the yard to the scanner
With hindsight I think I would install an aft mounted pole, that would provide shorter cable runs, more accessibility etc etc
I installed the radar unit at the navigation station, but with the latest generation of weatherproof units believe that mounting externally would be a wiser option
When you fitted the radar scanner was the mast in position on the boat ? Do you know the conduit size in the mast ? Finally did you drill the front or side of the mast for cable entry at the scanner position ?
When the cable is inside the boat, at the mast shoe position I shall have no problem because the conduits are their to enable me to take the cable down to the chart table position. I am hoping to be able to "fish" the cable down the front conduit that is used for the steaming light but I am not sure of the conduit size.
Regret cannot now recollect conduit size, but vaguely think that it was not put into a conduit at all, . Mast was in the lowered posoition, and we removed the mast shoe so it was reasonably easy to fish out the cable. we installed small 1/2 inch plastic grommets (same as dinghy drains) through the mast to ensure a fair and smooth lead for the cable
I have a repeater that I intend to mount outside at the helm position, I would agree that sailing short handed the outside position is of more use. ( At the moment the Raymarine RL70CRC units are on offer at much reduced prices, possibly because of the new generation of plotters now available. ) I have though about a pole mount on the transom area but the cost and possible loss of signal from boom / sails/mast etc have guided me towards a mast mount. the conduit from the mast step on the SO40 is available from both sides of the main bulkhead so I would not expect the same problem you experienced.
:)I have managed to fit the radar scanner to the mast and fit the cable into the conduit which runs inside the front part of the mast, with the mast in position. It was a little difficult to fish the cable into the conduit but was completed successfully. Time in the bosuns chair about 4 hours.
Contact www.hsyacht.com, San Diego dealer for Jeanneau. They will only use one kind of mast mount as they have had trouble with all the most popular. It is very good looking, with a rail to protect the dome from headsail. I can't remember the name, but it is not much more expensive than most.
We decided to go with a mast mount in preference to a pole mounted or a gymbal mount on the backstay. We are assured by the installer that there should be no problems with the conduits. Our concern is that we have a shallow draft keel, and we wonder about adding that amount of weight at that height: will it contribute to the sharp rolling action of the boat?
Our next problem is how to mount a display at the wheel position. We have tried two different types of mount - one above the wheel and one that you can only access and see through the wheel. Both are unsatisfactory - any ideas - have any owners had this problem with positioning the display and what solutions have t hey come up with?