The trip, small pitch, tight game played by the burly Crumlin outfit and several scorned scoring chances saw the Seasiders meander their way home following a 29 points to 10 defeat.
Tenby started the encounter with a thundering break by number eight Sam Smith, playing his first game of the season, and it took some stout defending to prevent an early score.
Soon after, it was Crumlin on the attack and an offence at the breakdown provided their first scoring opportunity, but the ball sailed wide. Tenby were under pressure and some sloppy defending let Crumlin in for their first try with only 10 minutes played.
The United attempted to respond, but several attacking moves were nipped in the bud and it was down to Jimmy Davies to get things moving as he slotted over a penalty.
Minutes later, fullback Tom Dennis was taken out of the game by an unnecessary and over-aggressive tackle and was replaced by Scott Mclaughlin. Crumlin had a simple game plan, that of running everything back into their forwards for them too rumble on, then spin it out, one or two players wide, for the process to be repeated again and again; it paid dividends as they crossed for three additional tries in the first half to turn around 24-3 up.
With limited replacements, coach Kenny Davies stuck with the 15 players on the park and they found themselves on the back foot from the restart, with Crumlin seeking another score to completely wrap up the game.
Sound defence kept the home side at bay and Tenby won some quality ball and released their potent threequarters, which stretched the home side. With the final pass not going to hand and the odd opening not taken, however, the United suffered further agony when Crumlin added to their score, stretching the lead out to 29-3.
Mark Heywood went over for a try, converted by Mclaughlin, bringing the score to 29-10 and the game to a close.
Coach Kenny Davies was upbeat after the match, despite the heavy defeat, with the plus points being the performances of both Ben Cray and Geoff Martin against a pair of very big and experienced props, as well as the sound all-round display of Youth scrum-half Rhys Thomas in what was a very difficult match.
Various tactical refinements will be worked on at training in the week and no doubt tried out against Wednesday's opponents, the Welsh Accies. Emphasis, however, will be on tomorrow (Saturday) when Tenby travel to play Llandeilo in the second round of fixtures in Division 4 West, while the Seconds and Youth are home to Pembroke Dock Quins and Aberystwyth, respectively.
Team: T. Dennis (S. Mclaughlin), J. Davies, M. Heywood (J. Large), G. Brace (capt), K. Wright, N. Powling, R. Thomas, B. Cray, M. Lewis, G. Martin, G. Edwards, A. Jenkins, W. Williams, S. Smith, C. Brace.