A dozen stunned West Tisbury property owners crowded the normally quiet town assessors meeting this week to question their assessments and tax bills, which have more than doubled this year.

The residents were looking for both tax relief and an explanation of a property valuation system they said they neither understand nor trust.

“Our tax bill more than doubled on a three-acre plot of land that’s been handed down for four or five generations,” said Andrew Moore following the Tuesday meeting, which he attended with four family members. “No one can prepare for something like this. We expect an incremental increase, but our taxes have doubled,” he said.

Most who attended the meeting are longtime property owners on the Tisbury Great Pond. They expressed open concern that they will be taxed off family land held for generations. And they raised concerns about the town assessing methods, questioning in particular whether a single large sale of property has unfairly skewed assessments in their neighborhood.

The assessors told the property owners they may file for tax abatements.

The deadline for such filings is Feb. 1. Property tax bills went out early this month.

The assessors also told the property owners that they will bring in representatives from Vision Appraisal Technology, the Northboro company that the town contracts with to prepare revaluations, in early February to explain their methodology.

Principal assessor Kristina West said yesterday that she spoke with Vision and a date will be set soon.

Following the meeting, Mr. Moore said, “Let me be clear, I have no anger toward the assessors. They are limited by the rules of the process. But at the heart of property taxes is this: what do you want the Island to be? Are you willing to lose all the history and the people of the Island?”

“We want to be able to hand the land to our children but I don’t know if we’ll be able to,” said his brother, Ally Moore.

On Tuesday afternoon the assessors allowed 15 minutes for questions before retiring to executive session on another matter.

Everett Jones and his brother, who own property on the Great Pond, attended the meeting after receiving a tax bill that more than doubled. Mr. Jones said he may hire an appraiser. “My property is unchanged from last year. It’s the land, not the house, causing the increase,” he said.

Nick Bayer of Clam Point Road questioned whether the valuations were done in accordance with Massachusetts law, which requires properties to be assessed at full and fair cash value, using comparable market sales as a guide. “I’m concerned about this. The assessors are regulated by the state. They are blinded by justice, so to speak. I think a couple of private handshake deals have happened,” he said.

The residents claim that a $19.5 million sale in 2006 of a Great Pond property that was assessed at $6.8 million is a principal reason behind the spike in their tax bills. Millard (Mickey) Drexler sold the Great Pond property to an unknown buyer represented by two limited liability companies. The residents said they believe the sale may not have been arm’s length and therefore should not be a factor in determining assessments.

Ms. West said that in fact three large sales on the Great Pond last year had an impact on valuations. In addition to the Drexler sale, she said the Manter property at Pondview that was assessed at $1.4 million sold for $3.2 million, and the Sweet property at Plumbush Point that was assessed at $1.9 million sold for $2.7 million. All three were arm’s length sales, Ms. West said.

She said in all, 57 properties on the Great Pond and at Seven Gates Farm saw a sharp increase in assessments this year. She said sales between family members, corporations and court-ordered sales were not included in the revaluation.