Lewmar 50mm Synchro Halyard Block – Black, 1/4”–3/8” Line
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
Clean Halyard Runs, Minimal Friction
The Lewmar 50mm Synchro Halyard Block is purpose-built for halyard applications where a low-friction, fixed-head block keeps lines running straight and true from the masthead to the clutch or winch. Its high-density, free-spin plain bearing delivers smooth operation under load, while the patented shackle post lock makes mast attachment fast and secure without tools.
Built with stainless steel straps and glass-fibre reinforced cheeks, the Synchro series handles the demands of performance sailing while keeping overall weight to a minimum. Sheave, bearing, pin, and line size are matched for optimum efficiency across the 1/4”–3/8” line range.
Compatible Applications
- Main and jib halyard lead blocks at the mast base
- Spinnaker halyard turning blocks
- Fixed-head halyard routing on performance sailboats
- Line sizes: 1/4” to 3/8” (6–8mm)
- Block size: 50mm sheave diameter
Product Details
- Configuration: Halyard (fixed head)
- Sheave diameter: 50mm
- Line range: 1/4”–3/8” (6–8mm)
- Color: Black
- Bearing: High-density free-spin plain bearing
- Construction: Stainless steel straps, glass-fibre reinforced cheeks
- Attachment: Patented shackle post lock
- SKU: 239-29925021
Parts Desk Insights
Best Use Case: The halyard block is the right choice when you need a fixed-head block that stays aligned with the halyard run — typically at the mast base or on a turning point where a swivel head would add unnecessary complexity. The 50mm size is ideal for smaller performance sailboats and dinghies where keeping weight aloft is a priority. Step up to the 60mm Synchro Halyard Block for heavier loads or larger line sizes.
Other 50mm Synchro Blocks
- 50mm Synchro Block – Single, Black
- 50mm Synchro Block – Double, Black
- 50mm Synchro Block – Triple, Black
- 50mm Synchro Block – Single w/Becket, Black
- 50mm Synchro Block – Double w/Becket, Black
- 50mm Synchro Block – Single w/Becket & Cam, Black
- 50mm Synchro Block – Triple w/Becket & Cam, Black
- 50mm Synchro Block – Fiddle w/Becket, Black
- 50mm Synchro Block – Fiddle w/Cam, Black
Other Synchro Block Sizes
- 60mm Synchro Blocks – 5/16”–3/8” Line
- 72mm Synchro Blocks – 3/8”–1/2” Line
- 90mm Synchro Blocks – 1/2”–9/16” Line
Pair It With
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.