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Ronstan Orbit Series 55 Ratchet These new Ronstan Orbit blocks are aimed at the dinghy market, but can be used in small keelboats in low load applications. Ideal for Spinnaker sheets and mainsheet systems where the ratchet helps in holding a load. We look at the Orbit range, the 55 series block and its uses and features How the Orbit 55 series works Then we look at the block under load and sea trials Conclusion including what to look out for Ronstan description and specs Ronstan Orbit Range ; The Ronstan Orbit range covers blocks from 40mm, 55mm and 70mm diameter sheaves. The 40 and 70 come with auto ratchet only, while the 55 we are looking at here has the 3 choices; auto, ratchet and free wheel. We are looking at the single 55 series block, however the 55 series come with single, double, triple, cheek fiddle with choice of beckets and adjustable cleats. Features Specs; Technical specs for the 55 Ratchet: max Rope diameter: 3/8"; max. safe working load: 550 lbs.; breaking load: 1,650 lbs.; weight: 2.8 oz; Retail is $61.95.Recommended for Dinghy mainsheet
systems & Spinnaker sheets on dinghies
These new Orbit low friction and light blocks from Ronstan have 2 settings. First is Manual mode, which allows switching the Ratchet on and off, and then Auto Ratchet mode which engages the Ratchet when a load comes on. In auto mode the ratchet comes on when the sheet is loaded but disengages when you release the sheet. Used by International 14 duo Lindsay Irwin and Mike Perry, and also tested by Laser world Champ Michael Blackburn during its development. The Orbit blocks are light cool looking and run very free in Ratchet off mode. The block is light partly due to the composite construction and the loop style attachment.
How the Orbit series 55 works ;
The reason for an Auto Ratchet is so that when you are trimming, you can handle a increase in the load. Loads go up and down and when a load comes on the ratchet engages allowing you to handle the load without a winch. There are manual switched ratchets i.e. ratchet on and off. The problem here is when you are trimming, say a spinnaker it is not so easy to simply turn the ratchet on or off. On larger boats you may use a Winch, the Orbit blocks discussed here are not recommended for use with a Winch.
Attaching the orbit block
The image shows the loop opened up ready to be attached to a pad eye. The loop is simply closed by pushing the loop back into the head of the block and closing the retainer clip.  You need something pointed to open the retaining clip.
The close up image shows how you change the ratchet settings.
The black slider engages Auto Ratchet by locking the red switch, when its slides over.
 The red switch in manual mode allows you to turn the
ratchet on & off. The slider and switch are accessible on both sides of
the block.
The orbit series 55 blocks were tested on a J/24 spinnaker with a 3/8 inch diameter line for comfort. The setting we wanted to test most was the auto ratchets as it the feature we were looking for and so we tested on a bench with a load sensor and then afloat. I would imagine Ronstan would say this block is too small for this size of boat. See Ronstan recommendations below. Bench Test
It is hard to get 500lbs by hand, and a winch was needed to get this load. Under this load and through 180 degrees it was hard to get the ratchet to release, and it felt jerky. To get the ratchet to release a big flick of the sheet was needed.
Sailing Test The sailing test included using the block on the forward part of a J24 spinnaker system.
This would also work for any small sports boats like Melges 24, J22 etc. The spinnaker sheet here is bending through 90 degrees. In this case under real life loads i.e. less than 500lbs probably less than 100lbs, the ratchet disengaged easily. Even in light air the ratchet came on, but released in a gybe as soon as the trimmer stopped pulling and released the sheet.
One thing we learnt was that to get the block to release well you need to flick or push the line toward the block. The ratchet releases when the load comes off it so release your pull fast.
Its interesting to read users comments and to see what they know. One laser sailor tried the block and only found out after reading the laser forum that he could engage auto mode, after he complained that it was hard to change the switch from ratchet to free while sailing. The forums sorted him out.
So the block can handle the loads, but through 180 degress the ratchet did not release well. However through 90 deg the ratchet disengaged easily. My recommendation is to use the ratchet through the 90 deg turn. To clarify a 90 degree turn is any where between 70 deg to 110deg. This allows enough line grip for the ratchet to work but not so much tat the ratchet will not disengage. These test only represent a few hours of sailing and bench work at this point. We will add later how the block holds up after continuous use. The block passed our test as much as we did, and proved to be a good choice on a small dinghy or high performance dinghy for spinnaker or mainsheet systems where releasing and load carrying are important. Great for asymmetrical spinnakers, when you need the sheet to run out fast and then need a ratchet when the spinnaker fills and the load comes on. The Ronstan is not the only block like this. Harken & Holt also have auto ratchets, and aslo have good reviews Do not use for halyards or other high load applications. One of the dangers with auto ratchets is when the block gets to or beyond its safe working load it locks up and the ratchet will not disengage. Check the SWL of any block to make sure you are using in it within the manufacturers stated range. Use the Orbit 55 series on a larger boat or a function with higher loads, will end up damaging the block and or not working properly. The retainer clip may wear out if you remove the block each time you go sailing, so have spares or leave them on.
Automatic and Manual ratchet in one block Up to 20:1 holding power Easily fitted and securely retained Dyneema® Link head Smooth easing of sheets High performance cleating Sheave: Hard anodized Aluminum Ball Bearings: High compression strength carbon black Aceetal Frame/Cheeks: Toughened, glass fibre reinforced Nylon Rope Link: UV stabilised, multi-strand impregnated SK75 Dyneema® Applications Dinghy mainsheet systems Spinnaker sheets on dinghies Control line applications on larger yachts
* Selected Series 55 models.
Simple and secure attachment
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The Orbit is very light. Ronstan Orbit design uses an optimum number
of ball bearings in loaded areas and eliminates them in inactive areas.
Weight is reduced through fiber reinforced composites in the block head,
cleat arms and beckets. 
The
block is attached via a loop, also called Dynema Link or Loup, which saves weight
and allows
alignment. 
The
Bench test included loading the 55 series block through a 180 degree
turn, to 500lbs, which is close to the SWL. During the process we went
well over the 500lbs with no ill effect. The block stood up to the loads
easily. 
