My Account
Shopping Cart

Forespar 903018 Marelon 1-1/8" Vented Loop Anti-Siphon Valve

Manufacturer

Forespar

<h3>About Forespar</h3><p>Founded in 1965 and headquartered in Rancho Santa Margarita, California, <strong>Forespar Products Corp.</strong> has built a decades-long reputation as one of the marine industry's most trusted manufacturers of sailing hardware and below-the-waterline plumbing systems. From competitive racers to bluewater cruisers, sailors around the world rely on Forespar's engineering precision and material innovation to keep their vessels safe, light, and seaworthy.</p><h3>Marelon®: The Material That Changed Marine Plumbing</h3><p>At the heart of Forespar's identity is <strong>Marelon®</strong>, a proprietary polymer composite formulation the company developed to address the chronic vulnerabilities of traditional bronze marine hardware. Marelon® components are inherently immune to corrosion and electrolysis — two of the most persistent threats to any vessel's underwater fittings. Whether above or below the waterline, Marelon® delivers structural integrity that matches or exceeds its metal counterparts, all at roughly half the weight of equivalent bronze parts. This weight savings matters significantly on performance sailboats where every pound of displacement counts.</p><p>Forespar's precision-molded Marelon® plumbing systems carry UL approval and meet A.B.Y.C. (American Boat and Yacht Council) standards, giving sailors and surveyors alike the confidence of knowing these components have passed rigorous independent testing. The result is a complete line of <a href="/7351-forespar-seacocks-200913">seacocks</a> and <a href="/7351-forespar-sea-strainers-200906">sea strainers</a> that are lighter, longer-lasting, and easier to service than traditional bronze or brass alternatives.</p><h3>On-Deck Innovation: Tiller Extensions &amp; More</h3><p>Forespar's innovation doesn't stop below the waterline. Their <a href="/7351-forespar-tiller-extensions-accessories-201068">tiller extensions and accessories</a> are engineered for responsive, fatigue-free helming, whether you're racing around the buoys or hand-steering offshore. With ergonomic designs and quality materials built to handle the stresses of saltwater sailing, Forespar tiller gear is a staple aboard racing dinghies and performance cruisers alike.</p><h3>Protecting Your Vessel Above and Below</h3><p>Forespar also addresses some of sailing's less glamorous but critically important concerns. Their <a href="/7351-forespar-ground-plateslightning-protection-products-200501">ground plates and lightning protection products</a> offer sailors a proven method for safely dissipating electrical charge during storms — a genuine life-safety consideration for any offshore passage-maker. Meanwhile, the marine environment's constant humidity makes mold and mildew an unavoidable challenge aboard any boat. Forespar's line of <a href="/7351-forespar-mold-mildew-products-200690">mold and mildew products</a> helps boaters protect upholstery, bilges, and living spaces from the biological growth that thrives in wet, enclosed environments.</p><h3>Why Sailors Choose Forespar</h3><ul style="list-style:disc"><li><strong>Proven material science:</strong> Marelon® is a proprietary composite trusted for corrosion and electrolysis resistance</li><li><strong>Weight advantage:</strong> Marelon® components weigh approximately half as much as comparable bronze parts</li><li><strong>Industry certifications:</strong> UL approved and A.B.Y.C. compliant plumbing systems</li><li><strong>Breadth of catalog:</strong> Over 100 products spanning deck hardware, plumbing, safety, and maintenance</li><li><strong>American heritage:</strong> Privately held and California-based since 1965</li></ul><p>Whether you're outfitting a new build, replacing aging through-hull fittings, or upgrading your helm station, Forespar offers a rigorously engineered solution backed by six decades of marine expertise.</p>

Part Number

903018
09/19/2036 1:28 PM
Sale Price

$35.78

In Stock (7)

delivery box

Usually delivered within 2 days

Authorize Seller Badge
No Hassle Returns

No Hassle Returns

Live-in-stock inventory

Live-in-stock inventory

Fitment guaranteed

Fitment guaranteed

Product Details

The Forespar 903018 Marelon Vented Loop is a vital safety component for any marine plumbing system, designed to prevent dangerous back-siphoning that could lead to flooding or sinking. This 1-1/8" vented loop is constructed from glass-reinforced Marelon composite material, offering superior corrosion resistance compared to traditional bronze fittings.

Key Features:

  • 1-1/8" thread size for secure connection to marine plumbing systems
  • Glass-reinforced Marelon composite construction resists corrosion and electrolysis
  • Vented design allows air to enter the line, preventing back-siphon effect
  • Lighter weight than bronze alternatives while maintaining strength
  • Suitable for use above the waterline in head, galley, and engine cooling systems
  • Will not deteriorate or corrode in saltwater environments

Vented loops work by creating an air break in the plumbing line when fluid flow stops, preventing water from being siphoned back into the boat. This is especially critical for marine sanitation systems and any through-hull connections below the waterline. The Marelon material offers exceptional durability and longevity in harsh marine environments without the risk of galvanic corrosion.

Products specifications

Dimensions

1 1/8"

Material

Marelon

Type

Vented Loops

Good experience, however, I was hoping that 'FREE SHIPPING' would be the standard for Autoplicity.

quick and easy, like it should be.........

Would really like these to be delivered by Friday!

Thanks

Great so far

Easy to find product and to check out.

great price and service

Very easy and best price

There.was a bit of miscommunication between sales and shipping departments, but my order was filled and shipped as stated. Very low price, in fact the lowest on the net, and I did alot of research. Other than the shipping issue, I'm very satisfied and will buy more parts from them soon. Thank you!!!

Share icon
Return Policy
Returns are easy at Boatplicity

Not happy with a purchase? No problem. We've made returning items as easy as possible. And most purchases can be returned for free for 30 days. Learn more about our Returns Policy