An 18-month public hearing came to an end last week on a plan by Verizon to increase the height of its Vineyard Haven cell by 50 feet.

Confusion around the technical aspects of the project led to the unusually lengthy review process.

“This is a little different than what usually happens,” said commissioner Richard Toole who led the public hearing. “This has been months.”

Verizon uses the tower to route landline and emergency service calls to a tower in Falmouth. Although the tower has stood at 77 feet since the mid-1980s, Verizon representatives say the tower needs to be raised to 138 feet because of signal interference from trees and poor weather.

After seeing a tree survey from Vineyard arborist Tim Bolan, commissioners debated that assertion at the last hearing December and continued to press the applicant on Thursday, the fifth and final public hearing.

“This tower has been there for quite awhile,” commissioner Doug Sederholm said. “Why is there a problem coming up now? Or has the problem existed for many years?”

Geoghan Coogan, an Island attorney who represents Verizon, said the signal has degraded for a long time.

“There’s no profit in raising this tower to this height,” Mr. Coogan said. “We’re doing it so high because we have to. It really is as simple as that.”

He also said the proposed tower was designed for trees reaching 80 feet in feet. The current tallest tree in the tower’s path is approximately 75 feet tall, with growth expected at about six inches per year.

Commissioners continued to question Mr. Coogan about the details of the project.

Joan Malkin asked about the current level of signal degradation from the tower compared to the proposed amount of signal degradation if the tower is raised 50 feet. Mr. Sederholm pressed Verizon on the numbers, questioning why the signal beams need to be 30 feet apart when they have functioned at 10 feet apart for 30 years.

“I don’t know, but there has been quite a lot of signal loss already,” Mr. Coogan said.

Other commissioners focused on the aesthetics of a taller structure on Vineyard-Haven Edgartown Road.

“How much of a visual impact difference is there going to be between 110, 120, or 130 feet?” commissioner James Joyce said. “All this talk is getting very technical beyond anyone’s ability to understand, and really we just want to know about the tower height.”

MVC executive director Adam Turner said the commission took drone shots of the proposed tower but could come up with further visualizations if necessary. Eventually commissioners decided to close the public hearing, leaving the written record open until May 31.

Mr. Sederholm asked Verizon to provide the commission with signal degradation data from the proposed tower height.

In other business last Thursday, Mr. Turner said Alex Elvin has been hired as an assistant planner. Mr. Elvin has worked previously with the commission, helping them write a recent data report. He said Mr. Elvin would work remotely from Boston for a few days a week before transitioning into the full-time position on the Island.

The hiring comes after longtime DRI coordinator Paul Foley left the commission in April. Mr. Turner praised Mr. Elvin when he announced the hire on Thursday.

“He’s tremendously versatile, does a lot of environmental stuff, and has done a lot with elderly issues,” Mr. Turner said. “He’s also a great communicator, which I feel we need . . . going forward, what are we really standing for with these developments? He’ll help us with that.”

Mr. Turner also said the land use planning subcommittee will meet on June 3 to discuss the recent teardown of the Mill House, a historic Vineyard Haven home that was razed in April without first going through MVC review.

Mr. Turner said the commission would consider the project as if it was a request for demolition referral, and would retroactively analyze what elements of the house would have been lost.

“The process has to be followed,” Mr. Turner said.

“That’s the real message that I want to give. We have a process. It’s to give the commission a chance to review historic structures under our charter, and in this case we didn’t get that. And that’s my biggest issue with it.”