RS Aero Forum

Please Register or Login to post to the forum.

Home >> Class Rules - Queries & Suggestions >> Mainsheet 57 mm ratchet block, Are auto ratchet blocks allowed

Mainsheet 57 mm ratchet block, Are auto ratchet blocks allowed

That is correct:

1 X 40 mm auto-ratchet on the aft boom loops &

1 X 57 / 60 mm Manual Ratchet on the deck / toestrap mount.

27/12/2025 18:42:00
Jonathan Rickels
Posts: 120

Jonathan,
So I'm clear, your suggestion is to mount 1 ratchet block on the aft boom loops only, and keep the switchable ratchet block that is mounted on the deck.
Thanks again for your input.
Scott

27/12/2025 16:08:00
Napa Scott
Posts: 10

I mounted the 1st Harken 40 mm Auto-Ratchet on the forward loops.

I found i didn't have the feel of the ratchet through the mainsheet as much as I do when I mounted the 2nd Allen block on the aft loops. Which I much prefer.

I do not see a need for two 40 mm ratchets on the boom.

I still have a manual 57 mm ratchet on the central swivel / spring. So far I have only sailed the Allen ratchet in light wind. I can see me using the manual ratchet when i'm getting overpowered and tired.

27/12/2025 15:05:00
Jonathan Rickels
Posts: 120

Jonathan,
Did you mount the ratchet block on the front spot or the aft spot on the boom? Do you think there would ever be a need for two ratchet blocks on the boom?
Thanks,
Scott

22/12/2025 18:59:00
Napa Scott
Posts: 10

The choice between manual or auto ratchet is indepenedent of the rule; they are both ratchet blocks.

I have used an auro-ratchet on both my 1st Aero 2014-2022 & my 2nd 2022 on.

The Harken 57 mm manual ratchet I found difficult to switch between ratchet and free runing, so when the 1st auto's came out I fitted a Harken and found it a great improvement.

When i moved to my 2nd boat Harken had refined their auto-ratchet producing 3 different models distinguished by their grip on the mainsheet: 1X, 1.5X, 2X. They also have higher threshold versions. I cannot hold a loaded mainsheet for long without suffering pain in myn hands; over 3 club races back to back i found my performance tailing off noticeably by the 3'rd race. The auto-ratchet helps alleviate.

The loading at which the ratchet engages & releases is not published by Harken. The 2X grip, the same block Mark uses has an adjustment for the threshold. This is the 1st block I fitted on the new boat. It was verry good with the threshold wound down, light, but it did wear the mainsheet vert smooth, so worsening my grip, aftervtwo years use.

Allen by contrast do publish the threshold for their auto-ratchets; it's 10 Kg callibrated with a 180mdegree wrap of the rope. Be aware you are very unlikely to achieve a 180 deg' wrap on the main 57 mm block. Even 90 deg wrap will only be achieved beating upwind with the boom into the transom. This means a greater pull is required to engage the ratchet.

Both Harken and Allen seem to have realised this and have now released 40 mm auto-ratchets; which could possibly be fitted to the boom.

However neither can accommodate the Aero boom loops. I tried the Harken using soft attach 2 mm vectran through it's centre. But the side plates crushed against the sheave reducing it's ability to free run when easing the boom rounding the windward mark; whther onto a reach or a run.

The Allen 40 mm can be fixed using their Aero loop adapter. I filed down the top spigot and then used it upside down on top of the block; passing the loops through the fixing holes above the sheave. And reverting to a standard manual ratchet block for the main 57 mm block. And so far it has worked very well: ratcheting when needed and easing off when needed. and so far the new mainsheet shows no signs of wear.

It's only been fitted for a couple of months, so early days yet. But it's looking promising.

15/12/2025 10:30:00
Jonathan Rickels
Posts: 120

I have used Harken 2168 57mm Power3 Carbo Ratchamtic Block - 2X Grip for several years and it works great. Certainly no need for a cleat in strong winds and I usually sail a 9 rig.

10/12/2025 17:19:00
Mark1654
Posts: 24

I think,that the question is, if the use of an automatic ratched block like the Harken Ratchamatic is class legal.
Thes automatic block have the ratched function if there if a certain tension on the sheet. If in low winds there is no tension on the sheet, they behave automatically like a block without ratching fuction.

Maybei the Harken Description is more clear than my words:

"The Carbo Ratchamatic® is a load-sensing ratchet block that rolls freely in both directions under low loads and automatically engages the ratchet as loads increase. Shifting between ratchet and light-air modes is seamless. The spring on the HTE (high-threshold engage) version of the 57 mm Carbo Ratchamatic blocks was made stiffer to delay the point where the ratchet engages, allowing the block to run free more of the time. The ratchet function engages at higher loads to allow the old kite sheet to run free for crisper gybes."

My interpretation would be, that they are class legal as long as they are "similar size", but I am also not 100% sure.

10/12/2025 17:10:00
mheber
Posts: 76

Hi Chris

See CR C.6.1.3(n) "Any of the mainsheet blocks may be replaced by a ratchet block of similar size to the block as Originally Supplied".

I am not sure what your question is.

Keep well
David (Int Measurer)

10/12/2025 16:39:00
David Rickard
Posts: 75

The published rules suggest any ratchet block of similar size may be used. Does this apply to a block like the Harken Ratchamatic? Does anyone have experience good or bad with them they would care to share. Thanks

((((Any of the mainsheet blocks may be replaced by a ratchet block of similar size to the block as Originally Supplied)))

04/06/2024 03:12:00
Chris
Posts: 7

RS Aero Forum

Mainsheet 57 mm ratchet block, Are auto ratchet blocks allowed

Contact