Navy Blue Heavyweight Long Sleeve T-Shirt

The harbor does not stay warm for long. By September the mornings have an edge to them, and by October you are layering before you step outside. But there is a long stretch of the year — from the first cool days of fall through the last cold ones of spring — when what you want is not a hoodie, not a jacket, just a well-made long sleeve that handles the temperature without making a production of it. The Navy Blue Heavyweight Long Sleeve is that piece.

Navy is the right color for a long sleeve like this. It is the most versatile color in the Seaport lineup — the one that works under a hoodie on a cold morning, on its own on a mild afternoon, and everywhere in between. It is the color of the harbor at its most familiar: deep, calm, and always right. A navy long sleeve in heavy cotton is one of those pieces that does not go out of style because it was never really in style. It just works, season after season, year after year.

At 240 GSM, this is a genuinely heavyweight piece of cotton — substantial enough to wear on its own when the temperature is in that in-between range, structured enough to layer under a hoodie or jacket when it drops further. The embroidered Seaport logo and Authentic Gear sleeve patch are the details that make it specific: understated, precise, and considered.

Why You’ll Keep Reaching For It

100% pre-shrunk cotton means this shirt fits the same way on the hundredth wear as it did on the first. It does not shrink. It does not stretch out at the collar or lose its shape at the cuffs. At 240 GSM, the fabric has enough weight to feel like something real — not a thin layer that disappears after a season of regular wear, but a piece of clothing that holds its structure and gets better with time.

Navy also holds its color well. It does not fade into something pale or unrecognizable. It deepens slightly over time in a way that feels earned. The embroidery stays sharp. The sleeve patch stays put. This is the kind of piece you stop thinking about after a while — not because it is forgettable, but because it is always right.

Product Details

• 100% pre-shrunk cotton
• 240 GSM heavyweight construction
• Long sleeve silhouette
• Embroidered Seaport logo
• Signature Seaport Authentic Gear sleeve patch
• Crew neck

Designed in Boston. Rooted in Boston Harbor and built for life along the water.