The left attempt is my workman with bib-and-brace overall.with the overall textured like sailor's waterproof and the shirt bump-mapped to look like a thick kntted sweater; plus my souwester hat.

The right attempt is an all-over overall including built-on feet and hood.

I have Poser 4.0.3 .

I welcome all suggestions.

Looks good... You might add a slicker, with a high collar to turn up agains the spray, too. A good pair of waterproof work gloves and a stocking cap would be nice add-ons to go with it.

Wouldn't they be wearing boots, halfway up their calves? 
DPH

I'm not sure if you are looking for a technial critique or a artistic one but since I'm a newbee for poser and 3d work, I can only make artistic sugestions. My first thought is one I often have when seeing pictures of people who do physical labor. He's too clean.  2nd the guy on the left's hat doesn't look like it's touching the head, except maybe on the crown. I'm not familiar with that style of hat (only seen it on the Gordan's fisherman) so maybe it's supposed to be that way.  Putting the chin strap behind the ears might help.  Maybe some hair might too. I don't know.  Also shouldn't there be a zipper of hooks for the straps?
The gut on the right looks like he's in a hazmat suit or a wet suit with boots to me, but again I am not familiar with this style. If that isn't how it's supposed to look, maybe a few folds in the clothing and getting rid of the panty lines might help if you can. Again I'm not that familiar with poser and I've never used 4 so those might not be possible. 
I must say they are better than any thing I can do with it. I could tell that the shirt was a bulky sweater without having to read your discription. The collar and cuffs help I think. And the folds around the elbows.
I hope this helps some otherwise just ignore it. :)

Likely they would wear different clothes according to the weather, Is there anywhere where I could get  plenty of images of work fishermen? Google search gets too much % of junk.

there are some amazing fisherman photographs here:

http://www.coreyfishes.com/

check some of those out for "real" fishermen!

If you're interested in accuracy...

At least on the East Coast of Canada (and my father fishes for a living, and I've spent time on the water) practically no one wears those hats any more.  Standard is baseball cap in nice weather.  In bad weather, all the jackets come with hoods.   And you wear the baseball cap.

The overall is pretty good.  And, the way they are shown is correct.  You wear them over the boots.

As for the survival suit, it needs a flap that wraps across the lower part of the face (when everything is buttoned up tight).  Colours bright orange or red.  Gloves are part of the suit.  Also needs reflective strips, epaulettes on the shoulders (used for grabbing the person), and assorted pockets.

Quote - Wouldn't they be wearing boots, halfway up their calves? 
DPH

On the survival suit, it's a one-piece.  No separate boots.

On the coverall, you always wear it over the boot (as shown).  The reason is, obviously, because if it is tucked into the boot water (and fish guts and other assorted nastiness) can get in to the boot as well.

Quote - Is there anywhere where I could get  plenty of images of work fishermen? Google search gets too much % of junk.

I don't know if these are useful, but I got them at both Ask and Google using "commerical fishing" as the search term:

Also, Rainbow Net & Rigging Ltd is a company that sells commercial fising gear, including clothing, and you may get some ideas from looking at their web site.

Thanks. Those images look useful, and the images of kit that came with them.

Sailors seem to have had many ideas about how to keep dry and warm in bad weather at sea. Before cotton was available to make oilskin, one sort of sea-waterproof was thick wool with the sheep grease left in to keep it waterproof.

One thing that was done was to let the hair grow long and let it hang down outside the back of the jacket, and to rub tar into the hair. That is why UK naval sailors still sometimes wear a square of cloth round their necks, as a carry-over from old times when it  was needed so the tarry plaits would not rub tar onto their uniforms.
What sort of things do sea-fishermen tend to wear when there is less cold and wet? I have heard plenty about English lobster fishermen being characterized by a blue jersey. On the Isles of Scilly they sometimes wore the name of his boat across his chest.

I may be able to help you here Anthony, i have an old recording of a one off documentry made by the bbc about 20 years ago, it follows a seanetter (spelling?) crew out of Amble (Northumberland) fishing for Cod, its about the politics of restricted fishing and the like but most is on the boat working so has loads of pics of what they wear and the boat, in and out, i'd be happy to send you a copy (we put it on DVD as it has lots of friends on it you see) if thats ok copyright wise, i'm not sure how passing on a recorded from TV DVD works, copyright wise......i doubt it will ever be shown again or made available for sale as it was only relevant at the time......opinions please.
The jumpers are know as Guernseys
http://www.guernseyknitwear.co.uk/
 and tradionally a family would have its own pattern, we have the same here (we pronounce it gansey) but its a more aran pattern, look here
http://www.iriss.co.uk/kits.htm
at the Oiled Aran jumper kit, but imagine it blue, dirty and stinking of fish and you have a high % of northumberland lobster and cod fishermen........if you ever need pictures of seanetters or cobles just yell i'm only a 5 minute walk from the harbor.......Steve, the Ex fisherman (i got sea sick :o)

What did they tend to wear on their heads?

I would imagine that the trouble with baseball caps is that they have no way to shed rain and spray outside the back of the jacket instead of inside.