Seaman helps in more ways than a Medic. It may be because I dont purchase Premium account but I still get lots of sailor deaths with a Medic on board. It seems I have better attack, reload and accuracy as well as ship defense with Seaman. If you buy premium then the Medic may reduce sailor death from critical strikes by AP shells.

a medic is only useful on CVs.  Says that in the NF game guide.

There is plenty of threads on seaman.   They will increase the ability of all
other sailors on board.    You will often see an increase in SD with a seaman on board.  This is particularly useful on low lvl BBs.

Others have seen an increase in ship speed and reloading speed.

A seaman with good stats in Fighter, Bomber will help with their ability.

The NF guide says that the ability number shown on a seamen is not an ability but a percentage.   Exactly how that percentage is applied is somewhat of a mystery.  It is not a direct percentage boost.

Testing has shown that seaman tend to be specialists depending on their stats.  A seamen with good plane stats and poor gunnery stats will not be that much of a help with gunnery.

Since gunners tend to hit caps, a seaman will no longer be helpful in gunnery at some point, but it might help boost SD to 900 plus help with repair and restore if that is needed.

Seaman will work on all ships, but a medic ONLY on CVs for the purpose of lowering crew deaths.

medics were useful until l they patched out the High pilot deaths

now stacking seamen on cvs supposedly helps  your stats

unless they have done a Ninja patch which you never know

Couple of tips: Don't use Seaman or Medic on a BB. Your supports should be 5 Engies 3 Reps 2 AA if you're an AA nation such as KM MN or IJN or 6 engies 4 reps if you're a non AA nation such as SN RN or RM.

Also never listen to or bother reading anything JohnnyQuick posts.

If you do a search you can find a bunch of informitive posts on how a seaman effects the other sailors.

The easiest way to understand it is at 100% ability, the numbers on the right hand side of the sailor are added to each sailor. If you use 2 seaman, you get dimishing effects but still effective.

I use both on my CV, Medic and Seaman, Medic helped me reducing de pilots death, even with the pilots death patch people mention so often.

I was losing 5 to 10 sailors (rookies + experts + some times a vet) in battles, by the time i started using the Medic i bearly lose any rookie.

The seaman boosted my pilots skills, even with average based pilots the seaman can make a big change on them.

Both work wonders for me, its all about trying and not asking people that "know about it".