GRUNDENS NEPTUNE THERMO JACKET

The Neptune Thermo is a pull-over style (anorak) waterproof jacket from Grundens, designed largely for demanding conditions — fishing, commercial marine work, or any situation where you expect wind, spray, and cold. According to Grundens, it’s built with a polyurethane-coated fleece-lined fabric, intended to blend waterproofing with warmth and flexibility.

This medium-weight polyurethane-coated fleece lined fabric, hooded anorak pullover

is designed to be durable, windproof, warm, and functional.

Features

Here’s how it performs across key metrics, based on specs and customer feedback .

Attribute	What Grundens says about it	What Users & Independent Reviews Say	Verdict / Notes
Waterproofing	100% waterproof, with seams (welded or sealed)	Users generally confirm that it keeps them dry	Very good, but not flawless in extreme downpours or when aged. Proper seam sealing & maintenance matter.
Warmth / Thermal insulation	Fleece backing gives warmth and comfort in colder weather.	Some users report that it’s “very warm” to the point of causing sweat when active.	Excellent for cold, damp conditions—less ideal for high-exertion use unless ventilated or properly layered.
Flexibility / mobility	It’s intended to stretch and move with you; underarm gussets, athletic cut.	A JLC (Journal of Light Construction) review praises it as “lightweight” and “comfortable even when wearing nail bags.”	Strong — the mobility is a real asset, especially for work where you need reach, bending, etc.
Breathability / Venting	The design is more weighted toward waterproof + warmth than high-performance breathability.	The JLC reviewer notes that it “isn’t breathable” and that when the weather is cold and windy, it works well as a shell.	Moderate tradeoff: for heavy exertion, you may feel clammy unless you layer smartly or have breaks.
Fit & sizing	Athletic / active cut, with adjustable hem and cuffs.	Some users wished sleeves were a little longer, or the body a little longer.	Good for most, but check sizing charts and consider layering needs.
Hood, cuffs, hem, etc.	Adjustable hood, neoprene cuffs, adjustable hem.	Users generally like the hood’s size (fits over hats), though some think forehead coverage could be improved.	Solid. Minor nitpick on hood fit, but functional overall.
Durability / long-term use	Built for marine / fishing environments; designed for spray, salt, wear.	Some complaints of leaking seams in high-stress use. Grundens However, many commercial fishermen and forum users praise Grundens gear for ruggedness.	Very good, though life depends heavily on maintenance (cleaning, seam care, avoiding abrasion).
Value / cost-effectiveness	It’s positioned as a serious jacket for tough duty (not cheap rain shell)	Many users feel the price is fair for what you get — durability and performance for marine work.	Good value in its category, especially if you expect regular use in harsh conditions.

Comparisons & Real-World Use

• In the Journal of Light Construction, the reviewer compared the Neptune to his older go-to (the Grundens Petrus) and concluded that Neptune is the successor in many respects: lighter, more comfortable, with welded seams and neoprene cuffs to help block water intrusion.

• On forums (e.g. Rokslide), outdoorsmen report using Neptune (or variants) on harsh hunts in Alaska, with success: “We had pouring cold rain … I was always dry except for the sweat while hiking.” 

• The Neptune Thermo presumably shares much of its shell / waterproof architecture with other Neptune models (e.g. the standard Neptune jacket). Some specs (from physics / product pages) suggest a water resistance rating in the ~8,000 mm range for certain Neptune models.

Thus, in comparison to generic rain shells, the Neptune Thermo is more robust, warmer, and better suited to work use — but it doesn’t compete with highly breathable technical membranes (e.g. Gore-Tex Pro, eVent) in terms of moisture management.

Strengths & Weaknesses (Summary)

Strengths:

1. Reliable waterproofing — good for spray, wind, rain, especially in marine environments.

2. Thermal benefit — the fleece backing helps in colder weather; it’s more than a shell.

3. Mobility & flexibility — designed to move with the body, especially useful for working tasks.

4. Well-constructed features — adjustable hood, neoprene cuffs, adjustable hem, etc.

5. Durability potential — built for tough conditions; many users find it holds up.

6. Good value in its class — more protective and rugged than bargain rain shells, for a still reasonable price.

Weaknesses / Trade-offs:

• Breathability is limited — in high-output activity you may feel damp inside.

• Some users report seam or stitch leaks under very heavy rainfall.

• Fit & length: a few report sleeves or torso length as slightly short for tall users.

• Hood coverage over the forehead might be marginal.

• As with any coated / laminated jacket, maintenance (cleaning, seam care, avoiding abrasion) is crucial to longevity.

For those who need a rugged, warm, and waterproof jacket for harsh, damp environments — particularly on water, boats, fishing, or maritime work — the Grundens Neptune Thermo Jacket is a compelling option. It balances waterproofing and insulation, with a flexibility many heavier jackets lack.

If your primary use is intensive aerobic activity (e.g. trail running, hiking fast in rain), you might outpace its breathability. But for fishing, deck duty, or cold rainy conditions where staying dry matters more than maximizing venting, it shines.

Tips if you buy:

• Choose a size that allows for layering (e.g. a fleece or light insulating mid-layer) without making you overly tight.

• Maintain it: rinse off salt, avoid harsh detergents or softeners, re-seal seams if needed.

• Use under-layers that wick moisture, so sweat doesn’t get trapped next to your skin.

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