Centek 3 in. Exhaust Thru-Hull with Flapper 1200299 | Black
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Centek 3 in. Exhaust Thru-Hull with Flapper 1200299
- Part Number: 1200299 (Centek Marine)
- Brand: Centek Marine
- Product Type: Marine Exhaust Thru-Hull with Flapper
- Color: Black
- Exhaust Hose Size: 3 in. / 76 mm ID
- Construction: Compression-molded fiberglass
- UPC: 808880120470
Centek 1200299 is a black compression-molded fiberglass marine exhaust thru-hull fitting for wet-exhaust systems using 3 in. / 76 mm inside-diameter exhaust hose. It installs through the transom or hull side at the exhaust discharge point, with the hose connecting to the inside shank and the flange and weighted rubber flapper remaining on the exterior. The external rubber flapper reduces backflow of water through the exhaust outlet when the boat is stopped, reversing, or exposed to following seas.
Dimensions
- Nominal Outside Diameter (A): 3.00 in. / 76 mm
- External Projection Length (B): 2.50 in. / 64 mm
- Overall Length (C): 5.50 in. / 140 mm
- Flange Diameter (D): 4.88 in. / 124 mm
- Thru-Hull / Shank Length (E): 3.00 in. / 76 mm
- Four pre-drilled mounting holes
Compatible Applications
Suitable for:
- Marine wet-exhaust systems requiring a 3 in. / 76 mm exhaust hose connection
- Transom or hull-side exhaust discharge installations
- New builds and exhaust-system replacements where a 4.88 in. / 124 mm exterior flange fits the mounting area
Confirm exhaust hose inside diameter, available hull or transom thickness, required flange diameter, and clearance for the external flapper before ordering.
Replacement Flapper
The external rubber flapper is serviceable separately. If the thru-hull body remains structurally sound, the flapper can be replaced without replacing the entire fitting using Centek repair kit 1200313, which includes a black rubber flapper, two mounting screws, and a small retaining plate.
Related Part Numbers
- Centek: 1200299 (this part — black)
- Distributor/Catalogue Reference: 383-1200299
- White equivalent: Centek 1200298
- Replacement 3 in. flapper repair kit: Centek 1200313
When to Replace the Thru-Hull
- Fiberglass body is cracked or structurally compromised
- Hose-connection shank is damaged or deformed
- Mounting flange or holes are deteriorated
- Exhaust leakage is visible around the fitting
- Fitting is being replaced as part of a full exhaust-system rebuild
If only the flapper shows wear, the flapper can be replaced separately using Centek 1200313 — a full thru-hull replacement is not required.
Installation Notes
- Confirm the hull opening and mounting area suit the 4.88 in. / 124 mm exterior flange
- Ensure the mating hull or transom surface is clean and flat before fitting
- Apply a marine-grade sealant around the flange for a watertight installation
- Use 3 in. / 76 mm ID marine exhaust hose on the interior connection
- Tighten all mounting hardware evenly — do not overtighten on the fiberglass flange
- Avoid excessive hose-clamp pressure on the fiberglass shank
- Confirm the flapper opens freely and swings clear of the hull after installation
- Inspect for exhaust and cooling-water leaks after startup
Parts Desk Insights
Best use case: Centek 1200299 is the go-to transom exhaust outlet for any wet-exhaust system running 3 in. exhaust hose where a fiberglass fitting is preferred over a metallic one. The compression-molded fiberglass body resists the corrosion that affects metallic exhaust fittings in marine service, and the weighted external flapper is effective at reducing water ingestion when the boat is stopped or backing down. It’s also an ideal choice for a direct replacement on any boat already fitted with a Centek thru-hull in this size.
Common issue: The most frequent ordering mistake is not verifying the flange diameter before purchasing. At 4.88 in. / 124 mm, the exterior flange is larger than the 3 in. hose opening, so the available mounting area on the transom or hull side needs to be confirmed. Customers also sometimes replace the entire thru-hull when only the rubber flapper has failed — the Centek 1200313 flapper repair kit is the more economical fix when the fiberglass body is still sound.
Shop all exhaust components in our Exhaust Systems collection or browse Engine Parts & Maintenance for related components.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.