I don't think silicone will work so well at that sort of thickness as it is so rubbery. Equally , solid epoxy won't help either.
If you can bond in some drainpipe of suitable diameter and fill with antifreeze, that will probably offer a better option.
Might be worth posting on the Facebook group Boating South Devon. Some get advertised on there.
Contact Simon Turl Mooring Services - he may know of some available to rent.
Occasionally ads on noticeboard at Exe Sailing Club. Going there this evening so will post if there are any.
03 area...
Even if the AIS is not receiving, it will possibly be still be sending out other status info on NMEA. On the e7 there should be a system screen showing the NMEA input stream. Try looking at that to see what's happening.
Very good for getting old paint and filler off. They come with 1, 2 or 3 rows of teeth and 2 or 3 is better. I used polycarbide disks for a final finish to get last bits off. They (polycarbide ) do wear quickly so have a few to hand.
I prepped mine with mix of Tercoo, wire wheels and polycarbide pads (all powered!).
Filled any obvious voids with 2-pack filler and sanded back.
When I was ready, did a final clean to remove fresh surface rust and wiped down with thinners. No Fertan type product - couldn't see the point...
I have a fin keel version. Nice little boat, quite well behaved, stands up to more breeze than you might expect (maybe not so much for bilge keel?)
Quite a few were fitted out by owners, so finish can vary quite a lot. However, base construction seems pretty solid. Mk2/3 probably preferable due...
You'll need terminators at each end plus a power supply into backbone.
If you're not going to add much else, you could look at something like the Actisense all-in-one 4-way units and just connect drop cables from devices.
Not really much choice. Shakespeare / VTronix Hawk or some Glomex antennas come with windex. Their windex is also available separately (and can be fitted to VTronix antenna). More robust than Hawk type but perhaps not so responsive.
The Hawk wind indicator can also be bought separately to...