Had a 4-1 on my Westsail 32,
Morgan 35 and
current Pearson 35 using plain axle fiddle blocks. The 4-1 on those big
mainsail boats worked okay with end boom sheeting though does take a bit of muscle hard on the
wind when it's blowing. Would think a 4-1 on your size
boat would provide more than adequate mechanical advantage. Might want to check out your blocks to see if the sheaves are moving freely. One hanging up would add a lot of force necessary to pull in the sheet.
The more
parts in the tackle, the more line you have to pull. Going to a 6-1 will mean 1/3rd more line, if my calculations are correct, for a given adjustment. If you do decide to go with more
parts to the system think about a double tail/2 speed set up. On a 6-1, you pull on both ends of the sheet for a 3-1 advantage for speed then go to using just one sheet when you need the
power or fine tuning. They are pricey from
Harken and the like but Garhauer makes a set up that is affordable though not
cheap. You can find it in their online catalogue listed as a vang.
Garhauer Marine Hardware -12024817
I'm officially in to my 7th decade and getting lazy so went with 6-1 two speed set up. Gives me all the
power I need for the much larger sail than yours. Really like the ability to go with 3-1 when need to haul in lots of line quickly like before a jibe and then go to the 6-1 for power.
Traveller track is the
cheap part of a traveller setup. If you've got the Harken car or were willing to spend the bucks for it, then why not just change out the existing track for the Harken set up. Harken makes a track with sliding fasteners that can be moved to fit any old holes drilled for the previous fastener. One of those and you wouldn't even have to do any drilling. On your size
boat, a pin stop positioner for the car would be way cheaper than the line setups. Have 2-1 line positioner for the car on the P35 and it has more than enough power to position the car, even in strong winds.
With the growing use of permanent vangs, travelers are kind of useless. The vangs do most of the
work keeping a flat sail and the main sheet just controls position of the boom. Might think about spending
money on a permanent vang rather than on a new traveller. You could use standup fiddle blocks with cam
cleats on either side of the
cockpit or even a
single in the middle to position the boom. The Harken Catalogue used to have illustrations of different block set ups. There may be some ideas in their if you have their catalogue or can find one of the older one.