Radio Antennas

I posted a few weeks ago regarding a VHF background hum when transmitting. I have done some experimenting and have decided to replace my VHF antenna and cabling. The antenna I am considering will go on a 4 foot extension, so it should transmit above the GPS antenna and hopefully miss interfering with it. I am debating adding a second VHF radio to replace my remote mike that has a badly deteriorating exterior wire, as a new mike is almost as expensive as a new radio.
My question relates to antennas.
I am assuming that the 2 VHF radios cannot share one antenna (even if only one will transmit at a time). Shakespeare sells a splitter that allows one antenna to be used for both VHF and AM/FM radio. They also sell an antenna that comes with 2 separate cables that is used for the same purpose (VHF and AM/FM). Anyone out there used either of these or know anything about them?
I am also considering adding AIS in the future, and have been told it is best to use a separate antenna for that. Currently I have 4 antennas on the roof of my pilothouse (VHF, GPS, CB radio, and AM/FM radio). Each antenna is about 8 feet apart horizontally, and I don't want to add to the number of antennas. The three antennas (non GPS) are all Shakespeare (8 foot long) and one of them is labelled with a model number (which I searched and it turns out to be for CB). I am willing to lose the CB if that cannot be avoided.
What is the best (or at least workable) solution to my antenna needs (wants)? Funds are not unlimited (who has that ) so a lot to consider.
Thanks for your comments and suggestions,
Tom

curious about the purpose of the 2nd VHF. Only one steering station, correct?
IF the purpose is redundancy, I would make it a good handheld. Power, antenna, location independence; and less likelihood of a lightning event taking both out.
CB; I vote no.
AIS; I vote a separate, 39" metal AIS antenna, IF the intention is to Transmit AIS, which I also recommend.

AM/FM radios are becoming obsolete, in my opinion. I just removed my upper helm dash radio, needed space for new MFD. I could go with a remote unit controlled from MFD but really don’t ever use it. My plan is a small Bluetooth speaker thru my phone or iPad if I want music. One less antenna and frees up helm space for more important equipment.

I just replaced antennas on my NT 37. I combined AIS-B with VHF using a Morad antenna designed for both. I used a Raymarine AIS unit that includes a splitter.
https://www.morad.com/collections/antennas/products/vhf-antenna-159-hd-ais

I also replaced the antenna on my second VHF with a 4' Shakespeare and another 4' Shakespeare for FM. My boat came with a second VHF. If it didn't already have it, I would just use a handheld as backup.

The Morad is an excellent product made in Bellingham and such an arrangement would let you keep the CB.

I have enjoyed the performance of Morad and Pacific Aerials on my prior boats.

The price point, performance, and quality of Pacific Aerials blew me away. We installed a short (3’ or so), high-dB gain antenna down low on the stern of a center console Boston Whaler. This was a poor location for an antenna, but other mounting options would have meant quick destruction of the antenna. Testing revealed we could hit a CG tower over 30 miles away, and it was not a direct shot over water. Pacific Aerials also had some nice options pertinent to the wiring and mounting hardware.

I have been a Morad fan since they were on a work boat I ran in the early 90s. We supposedly had a lousy radio, reported by numerous crews. Installation of a new cable and Morad antenna caused the same radio to perform very well. I put Morad on our last boat, one each for the VHF and AIS.

An antenna upgrade for VHF and AIS is going to happen aboard IRENE in the next few months, and one of these two will get my business. I prefer the highest dB gain possible, and SEPARATE antennas for everything (no splitters).

I have no affiliation with either - just a happy customer - and not impressed with the common/overpriced brand.

Best Wishes

Thanks for the replies and suggestions.
I just discovered today, that my remote mike wire is not replaceable due to lack of parts, and that a new mike will not work with my old radio. Bummer!
The second VHF idea was as both a backup and to allow the monitoring of at least one other channel (full time). I admit, a bit of a luxury as I do have a handheld. So, for the time being, I will just remove the remote mike (it is only about 8 feet away from the "main mike" anyway). I do have only one steering station after all.

I have been looking closely at Morad antennas and appreciate the first hand knowledge. I am leaning toward a 6dB 4.5 foot antenna with a 5 foot extension.

As far as AM/FM goes, yes when at anchor, we usually listen to music from our IPod broadcast through the radio. We could go the bluetooth speaker route as well (using IPad instead). The only time I use the FM is when in our home port and I am down working on the boat! I think while I am at this, I will rebed all antenna mounts and clamshells on the roof.

Lots to consider, and if anyone has anything to add, please do
Thanks,
Tom