I know 1:50/1:48 is "about" 28mm but since 28mm varies so much it was a bit of a gamble.
I'm not a fan of "modelling" but for the price the Revell longship is worth a look. The sails (not included in the shot) are hard white plastic, in a "billowing" shape.
GW's LOTR stuff is, ironically, pretty lifelike and one of the least "heroic" (i.e. ridiculously oversized) miniature lines - so I used it as my "frame of reference."
As you can see, the longship seems a little small - but not jarringly so. The miniatures' base makes it appear proportionately larger.
If you look at the size of the Viking roundshields, however, the scale seems pretty spot-on.
The "rounded bottom" of the model ship means it is only really good for acting as a "beached" longship - but that is all I really intended it for anyway - as a scenario marker for a raid, as I cannot think of any Viking boarding actions I would need to re-enact.
I dislike multi-part models.... ...but after all this is a "model kit" designed for those strange
I also notice there is a HMS Beagle which might stand in well for a pirate ship, and a S-100 S-Boot which might be useful in WW2 scenarios.
TL:DR Not bad for $25 - seems to fit 28mm fine - I'll let you know how much I fill up my "swear jar" completing it.