AIS Transponders - CSTDMA or SOTDMA?

[Slowboat35]

Anyone able to comment on which is more suitable for offshore leisure sailing?
Is SOTDMA overkill?

 

[Roberto]

FWIW, I have a CSTDMA and after having observed quite carefully its behaviour should I buy a new one I'd definitely take a SOTDMA. At times, I even switched my cstdma off, my messages had 4-5-6+ minutes of age, of course in areas of heavy traffic.

Re-reading it: for purely offshore sailing I would not mind, whereas in any place with over a few tens of classA stations I would definitely choose it.

 

[lustyd]

for offshore leisure sailing

It won't make a difference here that you'd notice, most of the difference is around behaviour when there's congestion. There are technical differences that make one "better" than the other but it's a numbers game that doesn't affect you when you need AIS to be working. Get the newer spec if you can, but if there's a significant premium on the price I wouldn't consider it worth the extra.
Where there's congestion, there's congestion, and that won't be helped by reserved time slots very much in the long run. Just like busy wifi and 4G you can either reduce the range or lose some data. Personally I liked the old way where commercial traffic had a better chance of being received by design

 

[AngusMcDoon]

Anyone able to comment on which is more suitable for offshore leisure sailing?
Is SOTDMA overkill?

For the Em-trak AIS transponders from fcmarine.co.uk it's about £60 more for an SOTDMA model above the equivalent CSTDMA.
Not a lot.