Clever Blocks

[mich.b...@gmail.com]

Have you seen this guy and the blocks he has designed?

Very smart.

https://youtu.be/2efa3epOGgY

[Ginnie Jo Blue]

This is AMAZING. How do we not have this already? And adding it to the public domain? Impressive. 

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[Joe & Sue]

Yes, very cool. I've been searching for a double snatch block for my
screecher furling line. Two of these should do it.

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[Joe & Sue]

I started to order a couple only to find out that they're shipped from
Portugal. Does anyone know how the tariff situation would affect delivery?

[Jeff Oaklief]

I could totally make some of those... just need to pick up the lathe, some PA66 (MDS modified?... 80 bucks for a foot square 1/2" thick sheet ), some 5083-H111 (another 85 bucks or so)... get some access to a CNC (Seattle Makers?) and Bob's my uncle (Bob actually was my uncle...).

I might be tempted to reduce the double plate on the stack versions... but that does mean milling an additional part... and making the working load per sheave a little less overall.

Totally fun!

My guess is that if you were to make these on your own, you would have to make a bunch before they were cheaper than buying (say) a Garhauer block... and it makes me wonder if you really could not just drill out the pins on a off-the-shelf block and have a similar snatch block.  I wonder what folks will charge when they make these.

Jeff

On Wed, Feb 25, 2026 at 2:55 PM mich.b...@gmail.com <mich.b...@gmail.com> wrote:

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[Jeff Oaklief]

There are also these... https://www.knotandrope.com/collections/pulleys/products/mobile-single-pulley

I am planning on trying them out this summer.

Jeff

[Jonathan Kallay]

There's a YouTube conspiracy-theory vibe that makes it difficult to see what the meat of this is.

One interpretation is: "mass production causes commercial blocks to be worse than what you can make yourself if you're a hard-core DIYer, here's a recipe." Another is "I have discovered genuine innovations in block design, and because I'm a good person I'm putting them in the public domain." If it's the latter, one ought to expect at least one commercial block manufacturer to adopt those innovations and profit from a superior product until the others also adopt those innovations.

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[Paul English]

I 100% appreciate the public domain contribution.

I see a few key things that are innovative:

1. affordable large snatch blocks - all the large ones are shockingly expensive. Small ones are reasonably priced, and work well for tweakers/twings. 
2. stackable with bolts - AFAIK there aren't any *hardware stack* blocks sold intended to be used by the end user like this, even though some double & triple blocks are constructed like this. eg: https://www.fisheriessupply.com/lewmar-50-mm-synchro-triple-block-swivel/29925003bk - is clearly 3 physically separate blocks on a single long axle, built in a way that could be disassembled into a double or three separate single blocks.. if you had the necessary bits like axles of the correct size.  Karver's "whole thing" is that you can stitch together their blocks with rope - though they do sell a shim to make the not-flat cheek plates fit together snugly.
3. "sheave block" - or what I would call a foot block, or stanchion block - I'm not aware of anything else that is designed to bolt both down to the deck or switch out a shackle, or clamp for a stanchion. 
   

The video brought up one thing - galvanic corrosion. Perhaps he sails on fresh water? Most blocks with an SS axle and aluminum cheeks have a fairly thick plastic isolator. I don't think a bit of tef gel will cut it. My spinnaker blocks get *soaked*, as does anything at the bow, mast base or deck height. That is fixable in his design though.

The other stuff he didn't bring up:

1. Different blocks have different types of bearings for a reason. Sure - in an emergency swap out whatever you've got, but I've got $1500+ of destroyed Karver blocks on my cap shrouds that say "don't use super low friction ball bearing blocks in high constant load applications" (previous owner's mistake, not mine). His design as illustrated is a plain bearing but he's talking about it like it is interchangeable with a ball bearing block that blew up. Again - this is fixable in his design, but machining the bearing races into the sheave and axle, adding a retention ring etc are non-trivial.
2. Soft attachments for snatch blocks are clearly the way of the future - all the newer (and more expensive!) options here are soft: https://www.fisheriessupply.com/browse?terms=snatch%20block  and the fore-mentioned Karver blocks can be snatch blocks simply by using a soft shackle through the axle. Unfortunately making a hollow axle with radiused edges is either inherently expensive, or too "new hotness" to be cheap. :-/ More news on this when I replace and disassemble the destroyed Karver blocks and take a peek inside. ;-)
3. Reconfiguring these blocks involves a bunch of bits of hardware - screws, axles, shackles, clamps etc. So.. how many spare bits of hardware do you bring? At some point you might be better off just bring a few whole extra blocks.
4. If anything in his design violates an existing patent, this won't last

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[Andy Inglis]

What are the use cases for blocks with ball-bearings vs solid sheaves?

The stock sheaves on my puny, low-load Windrider main halyard sheaves have ball-bearings that commonly fail after 5-10 years. Owners then, or proactively, replace them with solid plastic sheaves, and they almost never fail. I’m curious under what situations the sheaves with ball bearings are preferable. 

Thanks!

On Feb 26, 2026, at 11:45 PM, Paul English <tall...@engmooski.net> wrote:



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[Jeff Oaklief]

I have always been told that solid Delrin or standard nylon sheaves have higher load capacity… to a point…

Jeff

Sent from my iPhone

On Feb 27, 2026, at 7:38 PM, Andy Inglis <andyin...@gmail.com> wrote:



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[Ginnie Jo Blue]

Just chiming in to say I’ve learned a lot from this thread. Thanks for everyone’s thoughtful contributions thus far. ❤️

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[Northwest Multihull Association Membership Officer]

Solid aka: "plain" bearings are some slippery stuff (usually Delrin nylon -  either the sheave or the axle, or a layer between) that is simply directly in contact with the sheave or the axle. They are appropriate for high constant loads because they have more contact surface! The "point load" of a single bearing on the race is quite a lot. Even if you split it among a couple of point loads from a couple of bearings by increasing the diameter. 

No matter how "low friction" the material in a solid bearing is, they always have more friction than ball, roller, needle etc bearings with less contact surface.

Roller bearings are in between ball bearings and solid/plain bearings - less contact surface than a solid/plain bearing, but more than a ball bearing. 

The stock mast sheaves on my Corsair 31 (and probably Jeff & Vince's) for the jib, screecher and spinnaker are all plain bearing - a solid nylon sheave on a stainless axle. Worth noting they all have a pretty wide diameter also - more contact surface = more friction, but will tolerate the higher loads better.  If one were to do a canting mast, a plain bearing for the cap shroud tension would be appropriate - though the FCT list has some folks canting their mast with Colligo lashing deadeyes - even more friction. 

But the main halyard top of mast has a ball bearing - but a HUGE diameter (120mm I think I recall) with the bearings near the outer radius - so lots of balls to distribute the load a bit more..and it was definitely failing after 20 years of use. So why? Obviously the main halyard has a very high, constant load, just like the jib, spinnaker and screecher? My guess is that the additional friction on the main halyard was just going to be too annoying that it was worth the (expensive!!) trade off. It did last 20 years after all! 

I *think* the stock mast base blocks were solid - why? They have to deal with the constant high load and have to be physically much smaller than the one at the top to fit at the mast base (I think - I could imagine a larger diameter fitting). And they're turning that load 90 degrees.  But the deck mounted turning blocks that route the halyards back to the clutches are bearings - roller bearings I think. These still have constant loads while the halyards are raised, but much much lower as they are just turning a corner that is much less than 90 degrees. 

My spin/screecher/jib blocks are all a bit squeaky, and I think that isn't a good sign, but it turns out they are unobtanium / fully custom at this point. Alex at Ballard sails suggested I consider the Harken V sheaves / blocks - roller bearings, but arranged in a V to deal with the mast rotation and side loads. Probably a good idea.. but $600 each! 

For the J/80's I race, for spinnaker sheets, everyone uses high load ball bearing ratchet-optional blocks - they are quite costly AND only last so long before blowing up. But to get the spin trim feel you need in light wind and be able to trim by hand in medium/high wind you need both the bearings and the (on/off optional) ratchet. The price and replacement price is part of the cost of performance. ;-)

Andy - regarding your solid-for-ball bearing swap - if the additional friction from a solid / plain bearing isn't a problem then it seems like a fine idea. A split-the-difference option would be roller bearings - if the ball bearings last 5-10 years, I wouldn't be surprised if roller bearings last long enough you wouldn't need to worry about replacement.

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Paul English

Membership Officer NWMA

membe...@northwestmultihull.org

[Paul English]

Wups - I skimmed over a detail in my already far too detailed post. 

Constant high load (halyards) puts all the pressure on one point - hence the need to distribute it over a bigger area with a solid / plain bearing OR as many ball (or roller) bearings as you can with a large diameter sheave with a large diameter bearing race.

Variable high load, like those J/80 spinnaker sheet blocks naturally distributes itself as you trim the sheet - every quarter inch of movement centers it on a different 3-4 bearings. Even though it is a high load, with active trimming the wear on the bearings and races is less than you'd think.

In a purchase system (main sheet, traveler) the load is distributed among legs - even though the load is high in total, each leg and each block handles much less - and the friction cost is quite high as it compounds, so ball or roller bearings are used to allow active trimming. 

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[Jeff Oaklief]

No worries Paul… you just explained in detail what I meant by “to a point”

😇

Sent from my iPhone

On Mar 1, 2026, at 10:14 AM, Paul English <tall...@engmooski.net> wrote:



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[Andy Inglis]

Ahhh, I love this group. 

BTW, Jeff, I greatly enjoyed your interview with Nigel and the Nutters!

On Mar 1, 2026, at 11:09 AM, Jeff Oaklief <jeffo...@gmail.com> wrote:

No worries Paul… you just explained in detail what I meant by “to a point”

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[Vincent DePillis]

Hey jeff-- do you know what the Nutters are using for human propulsion?

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[Jeff Oaklief]

They were somewhat coy… probably two people per prop… no flywheel.  That’s all I could get out of them.  We did talk propulsion but race boss only has so much time for each team… that part got cut

Jeff

Sent from my iPhone

On Mar 1, 2026, at 7:32 PM, Vincent DePillis <vincent....@gmail.com> wrote:



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