The Hexaratchet is the original ratcheting block (do sailnet site-search for: 'hexaratchet + 043').... the H7402 is the more modern
carbo-ratchet block but doesnt have a 'switch' to turn on/off the ratcheting feature. Both versions are similar in price. The
friction release value on each is: 10:1 on both .... meaning such blocks will hold 100 pounds of sheet force per 10 pounds of 'hand force' on the
line.
To make either of these styles work to maximum 'snub' you should at least have 180° of the sheave engaged with
line .... thats why the recommendation of having a hexaratchet or carbo-ratchet (H7402) at near the stern ... and the 'furtherest' block in the series 'away' from the
furler. Having the ratchet block 'behind you' and at the stern pretty much insures that at least half of the 'fluted' sheave is in contact with the control
line.
Where the hexartachet or carbo-ratchet REALLY comes in handy is when the
jib is already partly furled, its now blowing harder stink, and you dont want the extreme windloaded sail on the
furler to 'get away from you' and fully open by mistake; the ratcheting blocks with their 'fluted' sheave produce a LOT of friction on the
line ... 10:1 in comparison to the strain that you put onto the 'tail end' of the rope .... a non-ratchet block has NO controlable friction (1:1) from the pressure that which you 'tail' (resist) the control line. Ratchet blocks have to be 'matched' to the exact diameter of the line you are using.
These blocks are not substitutes for
cleats ... you will need either a cam
cleat or a
horn cleat to terminate the line.