VHF Antenna for Catamaran

[Cteevan]

I need to replace the rusted vhf antenna on my 38' catamaran. From what I gather, sailboats generally use antennas rated 3 db because they roll / heel.

My question: do cats, with their more stable base, still use 3 db-rated anennas or do they bump up to 6 db...

Also, any specific VHF antennas recommended would be greatly appreciated. (I hope to install AIS as well, if that matters.)

Thanks in advance.

[makjeng]

I just finished installing a Glomex VHF whip on the targa bar of my 35' cat. It is a multi purpose setup:- primarily for AIS but also as backup for masthead VHF and AM/FM radio. It is a 6db 2.7M pole on SS base welded to a larger plate. A Glomex 3-way splitter (requires 12v) provides AIS, VHF (2-way) and AM/FM outlets. It is still early days but during installation I got an alarm as soon as I powered my instruments on. I cursed thinking that something was mis-wired but it had immediately acquired a valid threat. I was in the marina and just outside a search & rescue boat was approaching at 17kts.
I have not yet checked the VHF as I need to run a longer cable to it, but AM/FM also works well.
I purchased this kit on advice that a broader band VHF antenna will also be fine for AIS.

[colemj]

A rusted antenna? Usually these are SS or fiberglass.

6db will work on your cat, but I doubt you will see much practical difference over a 3db if mounting it on the masthead. The tradeoff will be the longer length of the 6db - if you are on the ICW in the US, check your total mast/antenna height.

Personally, I don't think there is much difference among the antenna manufacturers. Your largest gain will be in installing good coax, good fittings and properly soldering. After that, all similar antennas are essentially the same.

Mark