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Stainless Steel ESP swivel block

Stainless Steel ESP blocks are polished to a mirror finish to reflect your boat’s beauty whether it’s classic wood or a modern cruiser.

High-load axle bearings are suitable for multiple uses: mastbase blocks, deck organizers, turning blocks, control lines, vangs and mainsheets. Sideload ball bearings keep them spinning freely.

Available in hand-polished stainless steel or hardcoat-anodized aluminum with 5 mm or 75 mm diameter sheaves at attractive prices.

ESP Blocks Q&A


ESP block bearingsWhat does ESP mean?
ESP stands for Elegant Simple Products. ESP blocks have a simpler construction and bearing system than Black Magic® and stainless steel blocks, but they complement these lines with similar aesthetics. ESPs are strong, reliable, and cost-effective.

When would I use ESP blocks?
ESP blocks are designed to appear similar to Black Magic® and stainless steel blocks so they can be used in conjunction with these lines. With a high-strength axle bearing, they are best suited for running backstays, mastbase leads, halyards, and other applications with high static loads (loads that do not need constant adjustment). They also excel in any system exclusively trimmed by winch, where a slightly lower efficiency may not matter.

Can I use an ESP block for my mainsheet?
Harken recommends using extremely efficient ball bearing or roller bearing blocks for hand-trimmed mainsheets. However, ESPs may be suitable for some winch-trimmed mainsheet systems where slightly higher trimming loads aren’t detrimental.

Midrange Cruising ESP stand-up

Is there a way to stand up ESP blocks on a mastbase?
Yes, the 1634 Midrange/Cruising ESP stand-up with spring fits 57 and 75 mm blocks.

Are there any ESP blocks good for running backstays and vangs?
Yes, the 6099 ESP fiddle with a becket and Cam-Matic® cleat is perfect for the high-static loads (loads that do not need constant adjustment) in this application.

ESP deck organizer with becketWhy is there a becket on the end of ESP deck organizers?
It keeps the line on the last sheave. Rectangular styles do this also, but in a less noticeable way.

Can I stack ESP footblocks and deck organizers?
Yes, but be careful—as the manual states, the upper block can only handle 2/3 of the published Maximum Working Load. Longer bolts are equivalent to longer levers and they apply more force to the mounting surface. Overloading the upper block will damage the block or your deck.

Why doesn’t my footblock sheave run freely?
You may have over-tightened the fastener. Improper installation can permanently damage the block. Only tighten the fasteners wrist-tight as described in the manual; do not use a power driver.

Black Magic® blockCan I replace the sheave?
No, ESP blocks cannot be taken apart. If you require a serviceable block, Black Magic® blocks can be fully disassembled with an Allen wrench.

I lost the headpost and spacer when I removed the shackle pin—what should I do?
You can replace lost parts by contacting Harken Technical Service.

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