The 100-metre rope was imported from the US, and has several steel clips attached which allow the team to mark out the softball diamond accurately.
Mr Clarke said club members put their heart and soul into running the club and were gutted at the theft.
Saturday's game was cancelled due to weather but Mr Clarke said he was unsure whether next Friday's games, in which 11 youth teams are scheduled to play, would go ahead.
The club, which has 70 members and 113 young people in youth teams, are meeting on Wednesday to discuss what to do.
"We haven't got the money to replace it. We're a sports club, we travel over the hill to play and a lot of our fundraising goes towards that," Mr Clarke said.
The club's base belongs to Masterton District Council, but Mr Clarke said the club had invested a lot of time and money into it.
"We've spent thousands of dollars building this park to be what it is, to have this happen is a kick in the guts. This is a sports club, we're not here for profit, we're here to give people a chance to play softball."
Mr Clarke said whoever stole the gear was a "lowlife that should be hung, quartered and drawn", but he would happily accept return of the gear.
Masterton police handled several other burglaries and vandalism incidents during the weekend.
Senior Sergeant Warwick Burr said a Hessey St home was damaged after burglars broke in while residents were away, leaving damage to walls, a broken window and furniture strewn around. Nothing was stolen.
Another burglary was reported on Friday morning, thought to have happened some time in the past three weeks, as again the occupants were away.
Mr Burr said a 42-inch television, an X-Box, a laptop and shearing gear were taken from the Beetham St home.
Makoura College was hit by taggers who marked 17 places at the school.
Principal Tom Hullena said it was the worst tagging the school had seen in two years.
Anyone with information can call Masterton police on 06 370 0378 or anonymously Crimestoppers on 0800 555 111.