A gang of 30 youths attacked Morecambe’s RNLI lifeboat station on Sunday night before threatening volunteers when they gave chase.
Colin Midwinter, volunteer deputy launching authority, said that the volunteers had just hosted a visit by another group of young people from Lancaster.
The gang smashed a large observational window, causing hundreds of pounds worth of damage, and then ran off when RNLI volunteers gave chase.
Mr Midwinter said volunteers managed to catch up with some of the youths near Poulton Park, who when challenged made threats of violence.
Lancashire Police said they were called out just after 9pm to reports of criminal damage. No-one has been arrested.
Mr Midwinter said: “It is sad to reflect that on a weekend when my granddaughter joined hundreds of other young people on the Scouts’ district camp and many others in the area were similarly engaged in positive activities; a small minority have nothing better to do than engage in mindless vandalism on a building funded by public donation for the purpose of saving lives.
“Fortunately, on this occasion, the damage was confined to a window.
“The vital communications equipment located behind it survived unscathed and so our operational capability has not been affected.”
Following the incident, Morecambe RNLI said they had been overwhelmed by support from members of the public.
A spokesman said: “Not for the first time, we have been overwhelmed by the support we have received from the public; one gentleman approached me outside the station and donated £30 towards the repair costs.
“Many more have promised similar help.
“Our Shore Works department have begun the repairs today and they will hopefully be completed later this week.
“To all those who have offered assistance, financial or otherwise, please accept our grateful thanks.
“It is very much appreciated.”